1
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Tikkasalo OP, Leppä K, Launiainen S, Peltoniemi M, Mäkipää R, Rinne-Garmston KT, Sahlstedt E, Young GHF, Bokareva A, Lohila A, Korkiakoski M, Schiestl-Aalto P, Lehtonen A. Modeling the response of Norway spruce tree-ring carbon and oxygen isotopes to selection harvest on a drained peatland forest. TREE PHYSIOLOGY 2024; 44:tpad119. [PMID: 37756632 PMCID: PMC10993295 DOI: 10.1093/treephys/tpad119] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/27/2023] [Revised: 08/22/2023] [Accepted: 09/19/2023] [Indexed: 09/29/2023]
Abstract
Continuous cover forestry (CCF) has gained interest as an alternative to even-aged management particularly on drained peatland forests. However, relatively little is known about the physiological response of suppressed trees when larger trees are removed as a part of CCF practices. Consequently, studies concentrating on process-level modeling of the response of trees to selection harvesting are also rare. Here, we compared, modeled and measured harvest response of previously suppressed Norway spruce (Picea abies) trees to a selection harvest. We quantified the harvest response by collecting Norway spruce tree-ring samples in a drained peatland forest site and measuring the change in stable carbon and oxygen isotopic ratios of wood formed during 2010-20, including five post-harvest years. The measured isotopic ratios were compared with ecosystem-level process model predictions for ${\kern0em }^{13}$C discrimination and ${\kern0em }^{18}$O leaf water enrichment. We found that the model predicted similar but lower harvest response than the measurements. Furthermore, accounting for mesophyll conductance was important for capturing the variation in ${\kern0em }^{13}$C discrimination. In addition, we performed sensitivity analysis on the model, which suggests that the modeled ${\kern0em }^{13}$C discrimination is sensitive to parameters related to CO2 transport through stomata to the mesophyll.
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Affiliation(s)
- Olli-Pekka Tikkasalo
- Natural Resources Institute Finland (LUKE), Latokartanonkaari 9, FI-00790 Helsinki, Finland
| | - Kersti Leppä
- Natural Resources Institute Finland (LUKE), Latokartanonkaari 9, FI-00790 Helsinki, Finland
| | - Samuli Launiainen
- Natural Resources Institute Finland (LUKE), Latokartanonkaari 9, FI-00790 Helsinki, Finland
| | - Mikko Peltoniemi
- Natural Resources Institute Finland (LUKE), Latokartanonkaari 9, FI-00790 Helsinki, Finland
| | - Raisa Mäkipää
- Natural Resources Institute Finland (LUKE), Latokartanonkaari 9, FI-00790 Helsinki, Finland
| | - Katja T Rinne-Garmston
- Natural Resources Institute Finland (LUKE), Latokartanonkaari 9, FI-00790 Helsinki, Finland
| | - Elina Sahlstedt
- Natural Resources Institute Finland (LUKE), Latokartanonkaari 9, FI-00790 Helsinki, Finland
| | - Giles H F Young
- Natural Resources Institute Finland (LUKE), Latokartanonkaari 9, FI-00790 Helsinki, Finland
| | - Aleksandra Bokareva
- Natural Resources Institute Finland (LUKE), Latokartanonkaari 9, FI-00790 Helsinki, Finland
| | - Annalea Lohila
- Finnish Meteorological Institute, P.O. Box 503, FI-00101 Helsinki, Finland
- Institute for Atmospheric and Earth System Research (INAR)/Physics, Faculty of Sciences, University of Helsinki, P.O. Box 68, FI-00014 Helsinki, Finland
| | - Mika Korkiakoski
- Finnish Meteorological Institute, P.O. Box 503, FI-00101 Helsinki, Finland
| | - Pauliina Schiestl-Aalto
- Institute for Atmospheric and Earth System Research (INAR)/Physics, Faculty of Sciences, University of Helsinki, P.O. Box 68, FI-00014 Helsinki, Finland
| | - Aleksi Lehtonen
- Natural Resources Institute Finland (LUKE), Latokartanonkaari 9, FI-00790 Helsinki, Finland
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2
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Yuan R, Li F, Ye R. Global diagnosis of land-atmosphere coupling based on water isotopes. Sci Rep 2023; 13:21319. [PMID: 38044338 PMCID: PMC10694138 DOI: 10.1038/s41598-023-48694-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2023] [Accepted: 11/29/2023] [Indexed: 12/05/2023] Open
Abstract
Land-atmosphere coupling (LAC) plays a significant role in weather and climate and is related to droughts and heatwaves. We propose a simple and efficient LAC diagnosis method based on the analysis of water isotopes in atmospheric water vapour and precipitation. Using the method, we identify the primary LAC hotspot regions of the globe and reveal the seasonality of LAC strength. We find that LAC strength exhibits a relationship with latitude. Low latitudes present stronger LAC strength and contribute more significantly to the overall LAC area compared to boreal middle and high latitudes. It's important to note that LAC primarily manifests in the troposphere and is detected in the lower stratosphere of low latitudes, with limited influence observed in the stratosphere. However, the impact of LAC is noticeable in the upper stratosphere in boreal middle and high latitudes. Moreover, the seasonality of LAC strength is pronounced. On a global scale, the season with the strongest LAC is boreal autumn in the Northern Hemisphere but boreal summer in the Southern Hemisphere. Notably, this pattern does not exhibit a seesaw effect between the two hemispheres. Our isotope-based LAC diagnosis method captures the major LAC hotspots found in previous work and validates the seasonality of LAC within these hotspots. This substantiates the reliability and effectiveness of our isotope-based approach.
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Affiliation(s)
- Ruiqiang Yuan
- School of Environment and Resource Sciences, Shanxi University, Taiyuan, China.
| | - Fei Li
- School of Environment and Resource Sciences, Shanxi University, Taiyuan, China
| | - Ruyu Ye
- School of Environment and Resource Sciences, Shanxi University, Taiyuan, China
- Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing, China
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3
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Chen J, Chen J, Zhang XJ, Peng P, Risi C. A century and a half precipitation oxygen isoscape for China generated using data fusion and bias correction. Sci Data 2023; 10:185. [PMID: 37024510 PMCID: PMC10079680 DOI: 10.1038/s41597-023-02095-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2022] [Accepted: 03/22/2023] [Indexed: 04/08/2023] Open
Abstract
The precipitation oxygen isotopic composition is a useful environmental tracer for climatic and hydrological studies. However, accurate and high-resolution precipitation oxygen isoscapes are currently lacking in China. In this study, a precipitation oxygen isoscape in China for a period of 148 years is built by integrating observed and iGCMs-simulated isotope compositions using an optimal hybrid approach of three data fusion and two bias correction methods. The temporal and spatial resolutions of the isoscape are monthly and 50-60 km, respectively. Results show that the Convolutional Neural Networks (CNN) fusion method performs the best (correlation coefficient larger than 0.95 and root mean square error smaller than 1‰), and the other two data fusion methods perform slightly better than the bias correction methods. Thus, the isoscape is generated by using the CNN fusion method for the common 1969-2007 period and by using the bias correction methods for remaining years. The generated isoscape, which shows similar spatio-temporal distributions to observations, is reliable and useful for providing strong support for tracking atmospheric and hydrological processes.
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Affiliation(s)
- Jiacheng Chen
- State Key Laboratory of Water Resources & Hydropower Engineering Science, Wuhan University, Wuhan, 430072, China
- Hubei Key Laboratory of Water System Science for Sponge City Construction, Wuhan University, Wuhan, 430072, China
| | - Jie Chen
- State Key Laboratory of Water Resources & Hydropower Engineering Science, Wuhan University, Wuhan, 430072, China.
- Hubei Key Laboratory of Water System Science for Sponge City Construction, Wuhan University, Wuhan, 430072, China.
| | - Xunchang J Zhang
- USDA-ARS Oklahoma and Central Plains Agricultural Research Center, 7207W. Cheyenne St., El Reno, OK, 73036, USA
| | - Peiyi Peng
- Chongqing Southwest Research Institute for Water Transport Engineering, Chongqing Jiaotong University, Chongqing, 400016, China
| | - Camille Risi
- Laboratoire de Meteorologie Dynamique, IPSL, CNRS, Ecole Normale Superieure, Sorbonne Universite, PSL Research University, Paris, France
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4
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Liang MC, Laskar AH, Barkan E, Newman S, Thiemens MH, Rangarajan R. New constraints of terrestrial and oceanic global gross primary productions from the triple oxygen isotopic composition of atmospheric CO 2 and O 2. Sci Rep 2023; 13:2162. [PMID: 36750626 PMCID: PMC9905602 DOI: 10.1038/s41598-023-29389-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2022] [Accepted: 02/03/2023] [Indexed: 02/09/2023] Open
Abstract
Representations of the changing global carbon cycle under climatic and environmental perturbations require highly detailed accounting of all atmosphere and biosphere exchange. These fluxes remain unsatisfactory, as a consequence of only having data with limited spatiotemporal coverage and precision, which restrict accurate assessments. Through the nature of intimate coupling of global carbon and oxygen cycles via O2 and CO2 and their unique triple oxygen isotope compositions in the biosphere and atmosphere, greater insight is available. We report analysis of their isotopic compositions with the widest geographical and temporal coverage (123 new measurements for CO2) and constrain, on an annual basis, the global CO2 recycling time (1.5 ± 0.2 year) and gross primary productivities of terrestrial (~ 170-200 PgC/year) and oceanic (~ 90-120 PgC/year) biospheres. Observed inter-annual variations in CO2 triple oxygen isotopic compositions were observed at a magnitude close to the largest contrast set by the terrestrial and oceanic biospheres. The seasonal cycles between the east and west Pacific Ocean were found to be drastically different. This intra-annual variability implies that the entire atmospheric CO2 turnover time is not much longer than the tropospheric mixing time (less than ~ 5 months), verifying the derived recycling time. The new measurements, analyses, and incorporation of other global data sets allow development of an independent approach, providing a strong constraint to biogeochemical models.
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Affiliation(s)
- Mao-Chang Liang
- Institute of Earth Sciences, Academia Sinica, Taipei, Taiwan.
| | - Amzad H. Laskar
- grid.465082.d0000 0000 8527 8247Physical Research Laboratory, Ahmedabad, Gujarat India
| | - Eugeni Barkan
- grid.9619.70000 0004 1937 0538Institute of Earth Sciences, Hebrew University of Jerusalem, Jerusalem, Israel
| | - Sally Newman
- grid.20861.3d0000000107068890Division of Geological and Planetary Science, California Institute of Technology, Pasadena, CA USA ,grid.511040.10000 0001 2034 9638Present Address: Bay Area Air Quality Management District, San Francisco, USA
| | - Mark H. Thiemens
- grid.266100.30000 0001 2107 4242Department of Chemistry and Biochemistry, University of California at San Diego, La Jolla, CA USA
| | - Ravi Rangarajan
- grid.28665.3f0000 0001 2287 1366Institute of Earth Sciences, Academia Sinica, Taipei, Taiwan ,Present Address: Department of Public Health, College of Health Sciences, University of Doha for Science and Technology, Doha, Qatar
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5
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Hassanzadeh A, Valdivielso S, Vázquez-Suñé E, Criollo R, Corbella M. An open source Python library for environmental isotopic modelling. Sci Rep 2023; 13:1895. [PMID: 36732615 PMCID: PMC9895077 DOI: 10.1038/s41598-023-29073-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2022] [Accepted: 01/30/2023] [Indexed: 02/04/2023] Open
Abstract
Isotopic composition modelling is a key aspect in many environmental studies. This work presents Isocompy, an open source Python library that estimates isotopic compositions through machine learning algorithms with user-defined variables. Isocompy includes dataset preprocessing, outlier detection, statistical analysis, feature selection, model validation and calibration and postprocessing. This tool has the flexibility to operate with discontinuous inputs in time and space. The automatic decision-making procedures are knitted in different stages of the algorithm, although it is possible to manually complete each step. The extensive output reports, figures and maps generated by Isocompy facilitate the comprehension of stable water isotope studies. The functionality of Isocompy is demonstrated with an application example involving the meteorological features and isotopic composition of precipitation in N Chile, which are compared with the results produced in previous studies. In essence, Isocompy offers an open source foundation for isotopic studies that ensures reproducible research in environmental fields.
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Affiliation(s)
- Ashkan Hassanzadeh
- grid.420247.70000 0004 1762 9198Institute of Environmental Assessment and Water Research (IDAEA/CSIC), C/ Jordi Girona 18-26, 08034 Barcelona, Spain ,grid.7080.f0000 0001 2296 0625Departament de Geologia, Universitat Autònoma de Barcelona (UAB), Edificis C, Bellaterra, 08193 Barcelona, Spain
| | - Sonia Valdivielso
- grid.420247.70000 0004 1762 9198Institute of Environmental Assessment and Water Research (IDAEA/CSIC), C/ Jordi Girona 18-26, 08034 Barcelona, Spain
| | - Enric Vázquez-Suñé
- grid.420247.70000 0004 1762 9198Institute of Environmental Assessment and Water Research (IDAEA/CSIC), C/ Jordi Girona 18-26, 08034 Barcelona, Spain
| | - Rotman Criollo
- grid.466857.e0000 0000 8518 7126Mediterranean Institute for Advanced Studies (IMEDEA, UIB-CSIC), 07190 Esporles, Spain
| | - Mercè Corbella
- grid.7080.f0000 0001 2296 0625Departament de Geologia, Universitat Autònoma de Barcelona (UAB), Edificis C, Bellaterra, 08193 Barcelona, Spain
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6
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Leppä K, Tang Y, Ogée J, Launiainen S, Kahmen A, Kolari P, Sahlstedt E, Saurer M, Schiestl‐Aalto P, Rinne‐Garmston KT. Explicitly accounting for needle sugar pool size crucial for predicting intra-seasonal dynamics of needle carbohydrates δ 18 O and δ 13 C. THE NEW PHYTOLOGIST 2022; 236:2044-2060. [PMID: 35575976 PMCID: PMC9795997 DOI: 10.1111/nph.18227] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/02/2021] [Accepted: 05/07/2022] [Indexed: 05/14/2023]
Abstract
We explore needle sugar isotopic compositions (δ18 O and δ13 C) in boreal Scots pine (Pinus sylvestris) over two growing seasons. A leaf-level dynamic model driven by environmental conditions and based on current understanding of isotope fractionation processes was built to predict δ18 O and δ13 C of two hierarchical needle carbohydrate pools, accounting for the needle sugar pool size and the presence of an invariant pinitol pool. Model results agreed well with observed needle water δ18 O, δ18 O and δ13 C of needle water-soluble carbohydrates (sugars + pinitol), and needle sugar δ13 C (R2 = 0.95, 0.84, 0.60, 0.73, respectively). Relative humidity (RH) and intercellular to ambient CO2 concentration ratio (Ci /Ca ) were the dominant drivers of δ18 O and δ13 C variability, respectively. However, the variability of needle sugar δ18 O and δ13 C was reduced on diel and intra-seasonal timescales, compared to predictions based on instantaneous RH and Ci /Ca , due to the large needle sugar pool, which caused the signal formation period to vary seasonally from 2 d to more than 5 d. Furthermore, accounting for a temperature-sensitive biochemical 18 O-fractionation factor and mesophyll resistance in 13 C-discrimination were critical. Interpreting leaf-level isotopic signals requires understanding on time integration caused by mixing in the needle sugar pool.
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Affiliation(s)
- Kersti Leppä
- Natural Resources Institute Finland00790HelsinkiFinland
| | - Yu Tang
- Natural Resources Institute Finland00790HelsinkiFinland
- Faculty of Agriculture and Forestry, Institute for Atmospheric and Earth System Research (INAR)/Forest SciencesUniversity of Helsinki00014HelsinkiFinland
| | | | | | - Ansgar Kahmen
- Department of Environmental Sciences – BotanyUniversity of Basel4056BaselSwitzerland
| | - Pasi Kolari
- Faculty of Science, Institute for Atmospheric and Earth System Research (INAR)/PhysicsUniversity of Helsinki00014HelsinkiFinland
| | | | - Matthias Saurer
- Forest Dynamics, Swiss Federal Institute for ForestSnow and Landscape Research (WSL)8903BirmensdorfSwitzerland
| | - Pauliina Schiestl‐Aalto
- Faculty of Science, Institute for Atmospheric and Earth System Research (INAR)/PhysicsUniversity of Helsinki00014HelsinkiFinland
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7
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Lin W, Barbour MM, Song X. Do changes in tree-ring δ 18 O indicate changes in stomatal conductance? THE NEW PHYTOLOGIST 2022; 236:803-808. [PMID: 36200332 DOI: 10.1111/nph.18431] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/17/2022] [Accepted: 07/31/2022] [Indexed: 06/16/2023]
Affiliation(s)
- Wen Lin
- School of Life Sciences and Oceanography, Shenzhen University, Shenzhen, 518000, China
- Shenzhen Key Laboratory of Marine Bio-resource and Eco-environmental Sciences, Shenzhen University, Shenzhen, 518000, China
| | - Margaret M Barbour
- Te Aka Mātuatua - School of Science, University of Waikato, Hamilton, 3240, New Zealand
| | - Xin Song
- School of Life Sciences and Oceanography, Shenzhen University, Shenzhen, 518000, China
- Shenzhen Key Laboratory of Marine Bio-resource and Eco-environmental Sciences, Shenzhen University, Shenzhen, 518000, China
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8
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Abstract
The widely accepted “Milankovitch theory” explains insolation-induced waxing and waning of the ice sheets and their effect on the global climate on orbital timescales. In the past half century, however, the theory has often come under scrutiny, especially regarding its “100-ka problem.” Another drawback, but the one that has received less attention, is the “monsoon problem,” which pertains to the exclusion of monsoon dynamics in classic Milankovitch theory even though the monsoon prevails over the vast low-latitude (∼30° N to ∼30° S) region that covers half of the Earth’s surface and receives the bulk of solar radiation. In this review, we discuss the major issues with the current form of Milankovitch theory and the progress made at the research forefront. We suggest shifting the emphasis from the ultimate outcomes of the ice volume to the causal relationship between changes in northern high-latitude insolation and ice age termination events (or ice sheet melting rate) to help reconcile the classic “100-ka problem.” We discuss the discrepancies associated with the characterization of monsoon dynamics, particularly the so-called “sea-land precession-phase paradox” and the “Chinese 100-ka problem.” We suggest that many of these discrepancies are superficial and can be resolved by applying a holistic “monsoon system science” approach. Finally, we propose blending the conventional Kutzbach orbital monsoon hypothesis, which calls for summer insolation forcing of monsoons, with Milankovitch theory to formulate a combined “Milankovitch-Kutzbach hypothesis” that can potentially explain the dual nature of orbital hydrodynamics of the ice sheet and monsoon systems, as well as their interplays and respective relationships with the northern high-latitude insolation and inter-tropical insolation differential. Orbital-scale climate variations of Earth are dictated by ice sheet and monsoon Views of “monsoon system science” reinforce the Kutzbach monsoon hypothesis A unified Milankovitch-Kutzbach hypothesis better explains the orbital dual nature
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Protracted Indian monsoon droughts of the past millennium and their societal impacts. Proc Natl Acad Sci U S A 2022; 119:e2207487119. [PMID: 36122235 PMCID: PMC9522357 DOI: 10.1073/pnas.2207487119] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Protracted droughts lasting years to decades constitute severe threats to human welfare across the Indian subcontinent. Such events are, however, rare during the instrumental period (ca. since 1871 CE). In contrast, the historic documentary evidence indicates the repeated occurrences of protracted droughts in the region during the preinstrumental period implying that either the instrumental observations underestimate the full spectrum of monsoon variability or the historic accounts overestimate the severity and duration of the past droughts. Here we present a temporally precise speleothem-based oxygen isotope reconstruction of the Indian summer monsoon precipitation variability from Mawmluh cave located in northeast India. Our data reveal that protracted droughts, embedded within multidecadal intervals of reduced monsoon rainfall, frequently occurred over the past millennium. These extreme events are in striking temporal synchrony with the historically documented droughts, famines, mass mortality events, and geopolitical changes in the Indian subcontinent. Our findings necessitate reconsideration of the region's current water resources, sustainability, and mitigation policies that discount the possibility of protracted droughts in the future.
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10
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Rainwater Isotopic Composition in the Ecuadorian Andes and Amazon Reflects Cross-Equatorial Flow Seasonality. WATER 2022. [DOI: 10.3390/w14132121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The variability of the rainfall stable isotopic values (δ2Hp, δ18Op) in the Ecuadorian Amazon to the Andes presents a marked local “altitude” effect. At the same time, this complex orography creates diverse precipitation regimes (unimodal, bimodal, and three-modal) that make it difficult to establish a relationship with the local amount. Nevertheless, stations along these regions show a similar intra-annual isotopic variability, with lower values during MAM and ON. In contrast, higher values are found during DJF and JAS in a w-shaped pattern, suggesting a common regional controller. A monthly δ2Hp and δ18Op collection campaign was established in Central Ecuador (n = 30) to complement stations biased towards the northern and southern parts. Based on back trajectory analysis, the results demonstrated that moisture arrives from two primary sources: the Tropical North Atlantic (DJFM) and the Amazon Basin (JAS). Nevertheless, their convergence (AMJ and ON) is the crucial factor modulating the lowest isotopic values. Precisely, this convergence is stronger at the V-Index region (5° S–5° N, 65°–75° W), where the wind seasonality and reversal at low levels are enhanced, allowing the inter-hemispheric moisture flux transport (cross-equatorial flow). We propose that the amount of rainfall located at the V-Index region is a more robust approach for explaining the δ2Hp and δ18Op variability rather than the local amount.
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11
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Southern hemisphere forced millennial scale Indian summer monsoon variability during the late Pleistocene. Sci Rep 2022; 12:10136. [PMID: 35710914 PMCID: PMC9203564 DOI: 10.1038/s41598-022-14010-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2021] [Accepted: 05/31/2022] [Indexed: 11/22/2022] Open
Abstract
Peninsular India hosts the initial rain-down of the Indian Summer Monsoon (ISM) after which winds travel further east inwards into Asia. Stalagmite oxygen isotope composition from this region, such as those from Belum Cave, preserve the vital signals of the past ISM variability. These archives experience a single wet season with a single dominant moisture source annually. Here we present high-resolution δ18O, δ13C and trace element (Mg/Ca, Sr/Ca, Ba/Ca, Mn/Ca) time series from a Belum Cave stalagmite spanning glacial MIS-6 (from ~ 183 to ~ 175 kyr) and interglacial substages MIS-5c-5a (~ 104 kyr to ~ 82 kyr). With most paleomonsoon reconstructions reporting coherent evolution of northern hemisphere summer insolation and ISM variability on orbital timescale, we focus on understanding the mechanisms behind millennial scale variability. Finding that the two are decoupled over millennial timescales, we address the role of the Southern Hemisphere processes in modulating monsoon strength as a part of the Hadley circulation. We identify several strong and weak episodes of ISM intensity during 104–82 kyr. Some of the weak episodes correspond to warming in the southern hemisphere associated with weak cross-equatorial winds. We show that during the MIS-5 substages, ISM strength gradually declined with millennial scale variability linked to Southern Hemisphere temperature changes which in turn modulate the strength of the Mascarene High.
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12
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Rapid increases in shrubland and forest intrinsic water-use efficiency during an ongoing megadrought. Proc Natl Acad Sci U S A 2021; 118:2118052118. [PMID: 34930849 DOI: 10.1073/pnas.2118052118] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/11/2021] [Indexed: 11/18/2022] Open
Abstract
Globally, intrinsic water-use efficiency (iWUE) has risen dramatically over the past century in concert with increases in atmospheric CO2 concentration. This increase could be further accelerated by long-term drought events, such as the ongoing multidecadal "megadrought" in the American Southwest. However, direct measurements of iWUE in this region are rare and largely constrained to trees, which may bias estimates of iWUE trends toward more mesic, high elevation areas and neglect the responses of other key plant functional types such as shrubs that are dominant across much of the region. Here, we found evidence that iWUE is increasing in the Southwest at one of the fastest rates documented due to the recent drying trend. These increases were particularly large across three common shrub species, which had a greater iWUE sensitivity to aridity than Pinus ponderosa, a common tree species in the western United States. The sensitivity of both shrub and tree iWUE to variability in atmospheric aridity exceeded their sensitivity to increasing atmospheric [CO2]. The shift to more water-efficient vegetation would be, all else being equal, a net positive for plant health. However, ongoing trends toward lower plant density, diminished growth, and increasing vegetation mortality across the Southwest indicate that this increase in iWUE is unlikely to offset the negative impacts of aridification.
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13
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Tada M, Yoshimura K, Toride K. Improving weather forecasting by assimilation of water vapor isotopes. Sci Rep 2021; 11:18067. [PMID: 34521864 PMCID: PMC8440787 DOI: 10.1038/s41598-021-97476-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2020] [Accepted: 08/26/2021] [Indexed: 11/24/2022] Open
Abstract
Stable water isotopes, which depend on meteorology and terrain, are important indicators of global water circulation. During the past 10 years, major advances have been made in general circulation models that include water isotopes, and the understanding of water isotopes has greatly progressed as a result of innovative, improved observation techniques. However, no previous studies have combined modeled and observed isotopes using data assimilation, nor have they investigated the impacts of real observations of isotopes. This is the first study to assimilate real satellite observations of isotopes using a general circulation model, then investigate the impacts on global dynamics and local phenomena. The results showed that assimilating isotope data improved not only the water isotope field but also meteorological variables such as air temperature and wind speed. Furthermore, the forecast skills of these variables were improved by a few percent, compared with a model that did not assimilate isotope observations.
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Affiliation(s)
- Masataka Tada
- Japan Weather Association, 55F Sunshine City 60, Higashiikebukuro 3-1-1, Toshima-ku, Tokyo, 170-6055, Japan
| | - Kei Yoshimura
- Institute of Industrial Science, The University of Tokyo, 5-1-5, Kashiwanoha, Kashiwa-shi, Chiba, 277-8574, Japan.
| | - Kinya Toride
- Institute of Industrial Science, The University of Tokyo, 5-1-5, Kashiwanoha, Kashiwa-shi, Chiba, 277-8574, Japan.,Department of Atmospheric Sciences, University of Washington, Seattle, WA, 98195, USA
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14
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Precipitation isotope time series predictions from machine learning applied in Europe. Proc Natl Acad Sci U S A 2021; 118:2024107118. [PMID: 34162705 DOI: 10.1073/pnas.2024107118] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Hydrogen and oxygen isotope values of precipitation are critically important quantities for applications in Earth, environmental, and biological sciences. However, direct measurements are not available at every location and time, and existing precipitation isotope models are often not sufficiently accurate for examining features such as long-term trends or interannual variability. This can limit applications that seek to use these values to identify the source history of water or to understand the hydrological or meteorological processes that determine these values. We developed a framework using machine learning to calculate isotope time series at monthly resolution using available climate and location data in order to improve precipitation isotope model predictions. Predictions from this model are currently available for any location in Europe for the past 70 y (1950-2019), which is the period for which all climate data used as predictor variables are available. This approach facilitates simple, user-friendly predictions of precipitation isotope time series that can be generated on demand and are accurate enough to be used for exploration of interannual and long-term variability in both hydrogen and oxygen isotopic systems. These predictions provide important isotope input variables for ecological and hydrological applications, as well as powerful targets for paleoclimate proxy calibration, and they can serve as resources for probing historic patterns in the isotopic composition of precipitation with a high level of meteorological accuracy. Predictions from our modeling framework, Piso.AI, are available at https://isotope.bot.unibas.ch/PisoAI/.
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15
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Li Q, Liu Y, Nakatsuka T, Liu R, Cai Q, Song H, Wang S, Sun C, Fang C. Delayed warming in Northeast China: Insights from an annual temperature reconstruction based on tree-ring δ 18O. THE SCIENCE OF THE TOTAL ENVIRONMENT 2020; 749:141432. [PMID: 32805438 DOI: 10.1016/j.scitotenv.2020.141432] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/28/2020] [Revised: 07/09/2020] [Accepted: 07/31/2020] [Indexed: 06/11/2023]
Abstract
Global warming has had an unprecedented impact on environmental changes and thus human life in mid-high latitude regions. As one of the areas most affected by global warming, Northeast China has suffered from a series of ecological crises, including warming-induced water deficits, permafrost thaw, and extended growing seasons. The change in annual average temperature (annual T) variations in Northeast China since the Industrial Revolution are still not fully understood, mainly because of the lack of long-term instrumental data and high-resolution annual T reconstructions. Here, we present the first annual T reconstruction (r = -0.683, p < .001, n = 60) for 1818-2012 in Northeast China, which may also be the first temperature reconstruction based on tree-ring δ18O in China. The reconstruction is significantly related to temperature variations over mid-high latitude Eurasia and agree (p < .01) with several long-term hydroclimatic reconstructions in the surrounding area. When the internal variability in the reconstruction was high, the decadal to multidecadal cycles were significant. Further analysis found that the reconstruction was mainly affected by the East Asian Summer Monsoon (EASM) and North Atlantic Oscillation (NAO). The reconstruction was significantly negatively correlated with several time series of annual T in the Northern Hemisphere, which showed that there is a substantial difference in annual T between Northeast China and other regions of the Northern Hemisphere. The difference mainly existed before the 1950s. From the 1850s to the 1950s, the annual T in Northeast China decreased slightly. However, extreme warming began in the 1950s in Northeast China, and this warming has been unprecedented during the past two centuries. If the warming trend since the 1950s continues, then it will lead to devastating disasters to forest and permafrost ecosystems in Northeast China.
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Affiliation(s)
- Qiang Li
- State Key Laboratory of Loess and Quaternary Geology, Institute of Earth Environment, Chinese Academy of Sciences, Xi'an 710061, China; CAS Center for Excellence in Quaternary Science and Global Change, Xi'an 710061, China; Interdisciplinary Research Center of Earth Science Frontier (IRCESF) and Joint Center for Global Change Studies (JCGCS), Beijing Normal University, Beijing 100875, China.
| | - Yu Liu
- State Key Laboratory of Loess and Quaternary Geology, Institute of Earth Environment, Chinese Academy of Sciences, Xi'an 710061, China; CAS Center for Excellence in Quaternary Science and Global Change, Xi'an 710061, China; Interdisciplinary Research Center of Earth Science Frontier (IRCESF) and Joint Center for Global Change Studies (JCGCS), Beijing Normal University, Beijing 100875, China; School of Human Settlements and Civil Engineering, Xi'an Jiaotong University, Xi'an 710049, China.
| | - Takeshi Nakatsuka
- Graduate School of Environmental Studies, Nagoya University, Nagoya 464-8601, Japan
| | - Ruoshi Liu
- School of Human Settlements and Civil Engineering, Xi'an Jiaotong University, Xi'an 710049, China
| | - Qiufang Cai
- State Key Laboratory of Loess and Quaternary Geology, Institute of Earth Environment, Chinese Academy of Sciences, Xi'an 710061, China; CAS Center for Excellence in Quaternary Science and Global Change, Xi'an 710061, China; Interdisciplinary Research Center of Earth Science Frontier (IRCESF) and Joint Center for Global Change Studies (JCGCS), Beijing Normal University, Beijing 100875, China
| | - Huiming Song
- State Key Laboratory of Loess and Quaternary Geology, Institute of Earth Environment, Chinese Academy of Sciences, Xi'an 710061, China; CAS Center for Excellence in Quaternary Science and Global Change, Xi'an 710061, China; Interdisciplinary Research Center of Earth Science Frontier (IRCESF) and Joint Center for Global Change Studies (JCGCS), Beijing Normal University, Beijing 100875, China
| | - Shengjie Wang
- College of Geography and Environmental Science, Northwest Normal University, Lanzhou 730070, China
| | - Changfeng Sun
- State Key Laboratory of Loess and Quaternary Geology, Institute of Earth Environment, Chinese Academy of Sciences, Xi'an 710061, China; CAS Center for Excellence in Quaternary Science and Global Change, Xi'an 710061, China; Interdisciplinary Research Center of Earth Science Frontier (IRCESF) and Joint Center for Global Change Studies (JCGCS), Beijing Normal University, Beijing 100875, China
| | - Congxi Fang
- State Key Laboratory of Loess and Quaternary Geology, Institute of Earth Environment, Chinese Academy of Sciences, Xi'an 710061, China; CAS Center for Excellence in Quaternary Science and Global Change, Xi'an 710061, China; Interdisciplinary Research Center of Earth Science Frontier (IRCESF) and Joint Center for Global Change Studies (JCGCS), Beijing Normal University, Beijing 100875, China
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16
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Li H, Sinha A, Anquetil André A, Spötl C, Vonhof HB, Meunier A, Kathayat G, Duan P, Voarintsoa NRG, Ning Y, Biswas J, Hu P, Li X, Sha L, Zhao J, Edwards RL, Cheng H. A multimillennial climatic context for the megafaunal extinctions in Madagascar and Mascarene Islands. SCIENCE ADVANCES 2020; 6:6/42/eabb2459. [PMID: 33067226 PMCID: PMC7567594 DOI: 10.1126/sciadv.abb2459] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/10/2020] [Accepted: 08/12/2020] [Indexed: 06/02/2023]
Abstract
Madagascar and the Mascarene Islands of Mauritius and Rodrigues underwent catastrophic ecological and landscape transformations, which virtually eliminated their entire endemic vertebrate megafauna during the past millennium. These ecosystem changes have been alternately attributed to either human activities, climate change, or both, but parsing their relative importance, particularly in the case of Madagascar, has proven difficult. Here, we present a multimillennial (approximately the past 8000 years) reconstruction of the southwest Indian Ocean hydroclimate variability using speleothems from the island of Rodrigues, located ∼1600 km east of Madagascar. The record shows a recurring pattern of hydroclimate variability characterized by submillennial-scale drying trends, which were punctuated by decadal-to-multidecadal megadroughts, including during the late Holocene. Our data imply that the megafauna of the Mascarenes and Madagascar were resilient, enduring repeated past episodes of severe climate stress, but collapsed when a major increase in human activity occurred in the context of a prominent drying trend.
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Affiliation(s)
- Hanying Li
- Institute of Global Environmental Change, Xi'an Jiaotong University, Xi'an, China
| | - Ashish Sinha
- Department of Earth Science, California State University, Dominguez Hills, Carson, CA, USA.
| | - Aurèle Anquetil André
- François Leguat Giant Tortoise and Cave Reserve, Anse Quitor, Rodrigues Island, Mauritius
| | - Christoph Spötl
- Institute of Geology, University of Innsbruck, 6020 Innsbruck, Austria
| | - Hubert B Vonhof
- Max Planck Institute of Chemistry, Hahn-Meitnerweg 1, Mainz, Germany
| | - Arnaud Meunier
- François Leguat Giant Tortoise and Cave Reserve, Anse Quitor, Rodrigues Island, Mauritius
| | - Gayatri Kathayat
- Institute of Global Environmental Change, Xi'an Jiaotong University, Xi'an, China
| | - Pengzhen Duan
- Institute of Global Environmental Change, Xi'an Jiaotong University, Xi'an, China
| | - Ny Riavo G Voarintsoa
- Department of Earth and Environmental Sciences, Katholieke Universiteit Leuven, Leuven, Belgium
| | - Youfeng Ning
- Institute of Global Environmental Change, Xi'an Jiaotong University, Xi'an, China
| | - Jayant Biswas
- National Cave Research and Protection Organization, Raipur, India
| | - Peng Hu
- Center for Monsoon System Research, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Xianglei Li
- Department of Earth Sciences, University of Minnesota, Minneapolis, MN, USA
| | - Lijuan Sha
- Institute of Global Environmental Change, Xi'an Jiaotong University, Xi'an, China
| | - Jingyao Zhao
- Institute of Global Environmental Change, Xi'an Jiaotong University, Xi'an, China
| | - R Lawrence Edwards
- Department of Earth Sciences, University of Minnesota, Minneapolis, MN, USA
| | - Hai Cheng
- Institute of Global Environmental Change, Xi'an Jiaotong University, Xi'an, China.
- Department of Earth Sciences, University of Minnesota, Minneapolis, MN, USA
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17
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Jones MC, Berkelhammer M, Keller KJ, Yoshimura K, Wooller MJ. High sensitivity of Bering Sea winter sea ice to winter insolation and carbon dioxide over the last 5500 years. SCIENCE ADVANCES 2020; 6:6/36/eaaz9588. [PMID: 32917607 PMCID: PMC7467686 DOI: 10.1126/sciadv.aaz9588] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/25/2019] [Accepted: 07/17/2020] [Indexed: 06/11/2023]
Abstract
Anomalously low winter sea ice extent and early retreat in CE 2018 and 2019 challenge previous notions that winter sea ice in the Bering Sea has been stable over the instrumental record, although long-term records remain limited. Here, we use a record of peat cellulose oxygen isotopes from St. Matthew Island along with isotope-enabled general circulation model (IsoGSM) simulations to generate a 5500-year record of Bering Sea winter sea ice extent. Results show that over the last 5500 years, sea ice in the Bering Sea decreased in response to increasing winter insolation and atmospheric CO2, suggesting that the North Pacific is highly sensitive to small changes in radiative forcing. We find that CE 2018 sea ice conditions were the lowest of the last 5500 years, and results suggest that sea ice loss may lag changes in CO2 concentrations by several decades.
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Affiliation(s)
- Miriam C Jones
- Florence Bascom Geoscience Center, U.S. Geological Survey, Reston, VA 20192, USA.
| | - Max Berkelhammer
- Department of Earth and Environmental Sciences Chicago, University of Illinois at Chicago, Chicago, IL 60607, USA
| | - Katherine J Keller
- Florence Bascom Geoscience Center, U.S. Geological Survey, Reston, VA 20192, USA
- Department of Earth and Planetary Sciences, Harvard University, Cambridge, MA 02138, USA
| | - Kei Yoshimura
- Institute of Industrial Science, University of Tokyo, Tokyo, Japan
| | - Matthew J Wooller
- Alaska Stable Isotope Facility, College of Fisheries and Ocean Sciences and Institute of Northern Engineering, University of Alaska Fairbanks, Fairbanks, AK 99775, USA
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18
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Enriched East Asian oxygen isotope of precipitation indicates reduced summer seasonality in regional climate and westerlies. Proc Natl Acad Sci U S A 2020; 117:14745-14750. [PMID: 32532921 DOI: 10.1073/pnas.1922602117] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Speleothem oxygen isotope records over East Asia reveal apparently large and rapid paleoclimate changes over the last several hundred thousand years. However, what the isotopic variation actually represent in terms of the regional climate and circulation is debated. We present an answer that emerges from an analysis of the interannual variation in amount-weighted annual δ18O of precipitation over East Asia as simulated by an isotope-enabled model constrained by large-scale atmospheric reanalysis fields. 18O-enriched years have reduced summer seasonality both in terms of precipitation isotopes and in the large-scale circulation. Changes occur between June and October, where the δ18O of precipitation (δ18Op) transitions from the isotopically heavier winter to the lighter summer regime. For 18O-enriched years, this transition is less pronounced. Variations in precipitation amount alone are insufficient to explain the amount-weighted annual δ18Op between 18O-enriched and 18O-depleted years. Reduced summer seasonality is also expressed in the low-level monsoonal southerlies and upper-level westerlies; for the latter, the northward migration across the Tibetan Plateau in the summer is less pronounced. Our result thus implicates the westerlies across the plateau as the proximate cause of East Asian paleomonsoon changes, manifested as a modulation of its summer peak.
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19
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Chen D, Zhou F, Dong Z, Zeng A, Ou T, Fang K. A tree-ring δ18O based reconstruction of East Asia summer monsoon over the past two centuries. PLoS One 2020; 15:e0234421. [PMID: 32516330 PMCID: PMC7282632 DOI: 10.1371/journal.pone.0234421] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2019] [Accepted: 05/26/2020] [Indexed: 11/25/2022] Open
Abstract
The East Asian summer monsoon (EASM) exhibits considerable decadal variations since the late 20th century. Efforts to examine long-term behaviors and dynamics of the EASM are impeded largely due to the shortness of instrumental meteorological records. So far, reconstructions of the EASM with annual resolution from its core regions remain limited. We conduct the first 200-year robust EASM reconstruction based on tree-ring cellulose δ18O records derived from Pinus massoniana trees growing in the middle Yangtze River basin, one of the core EASM areas. The δ18O chronology accounts for 46.2% of the actual variation in an index of the EASM from 1948 to 2014. The reconstructed EASM indicates that the monsoon intensity was below average before the 1950s, peaked in the 1950s-1970s, and then began to decline. The reconstructed EASM is negatively correlated with the El Niño-Southern Oscillation (ENSO), but this teleconnection is dynamic through time, i.e. enhanced (reduced) ENSO variability coheres with strong (weak) EASM-ENSO connections. In addition, despite high ENSO variability since the 1980s, the EASM-ENSO relationship weakened possibly due to anthropogenic impact, particularly aerosol emissions.
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Affiliation(s)
- Dai Chen
- National Forestry and Grassland Administration, National Park Administration, Beijing, China
| | - Feifei Zhou
- Key Laboratory of Humid Subtropical Eco-geographical Process, Ministry of Education, College of Geographical Sciences, Fujian Normal University, Fuzhou, China
| | - Zhipeng Dong
- Key Laboratory of Humid Subtropical Eco-geographical Process, Ministry of Education, College of Geographical Sciences, Fujian Normal University, Fuzhou, China
| | - A’ying Zeng
- Key Laboratory of Humid Subtropical Eco-geographical Process, Ministry of Education, College of Geographical Sciences, Fujian Normal University, Fuzhou, China
| | - Tinghai Ou
- Department of Earth Sciences, Regional Climate Group, University of Gothenburg, Gothenburg, Sweden
| | - Keyan Fang
- Key Laboratory of Humid Subtropical Eco-geographical Process, Ministry of Education, College of Geographical Sciences, Fujian Normal University, Fuzhou, China
- Department of Earth Sciences, Regional Climate Group, University of Gothenburg, Gothenburg, Sweden
- * E-mail:
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20
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Relating Moisture Transport to Stable Water Vapor Isotopic Variations of Ambient Wintertime along the Western Coast of Korea. ATMOSPHERE 2019. [DOI: 10.3390/atmos10120806] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Atmospheric water vapor transfers energy, causes meteorological phenomena and can be modified by climate change in the western coast region of Korea. In Korea, previous studies have utilized precipitation isotopic compositions in the water cycle for correlations with climate variables, but there are few studies using water vapor isotopes. In this study, water vapor was directly collected by a cryogenic method, analyzed for its isotopic compositions, and used to trace the origin and history of water vapor in the western coastal region of Korea during the winter of 2015/2016. Our analysis of paired mixing ratios with water vapor isotopes can explain the mechanism of water vapor isotopic fractionation and the extent of the mixing of two different air masses. We confirm the correlation between water vapor isotopes and meteorological parameters such as temperature, relative humidity, and specific humidity. The main water vapor in winter was derived from the continental polar region of northern Asia and showed an enrichment of 10 per mil (δ18O) through the evaporation of the Yellow Sea. Our results demonstrate the utility of using ground-based isotope observations as a complementary resource for constraining isotope-enabled Global Circulation Model in future investigations of atmospheric water cycles. These measurements are expected to support climate studies (speleothem) in the west coast region of Korea.
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21
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Basu S, Sanyal P, Pillai AAS, Ambili A. Response of grassland ecosystem to monsoonal precipitation variability during the Mid-Late Holocene: Inferences based on molecular isotopic records from Banni grassland, western India. PLoS One 2019; 14:e0212743. [PMID: 30995235 PMCID: PMC6469751 DOI: 10.1371/journal.pone.0212743] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2018] [Accepted: 02/08/2019] [Indexed: 11/19/2022] Open
Abstract
Banni, located in the arid western India, is one of the largest tropical grasslands of the Asian continent. The net primary production in this grassland ecosystem is currently mediated by precipitation during the Indian summer monsoon (ISM). However, timing of the grassland expansion and its link to the intensity of monsoonal precipitation remains enigmatic due to the paucity of datasets. The major objective of this study is to understand the changes in monsoonal precipitation and vegetation for the last 4600 cal yr BP using hydrogen and carbon isotopic composition of n-alkanes (δDn-alkane and δ13Cn-alkane) measured from two core sediments (Chachi and Luna) in Banni region. The δ13CC29 and δ13CC31 values for Chachi core sediments vary from −30.9 ‰ to −27.2 ‰ and −34.4 ‰ to −25 ‰ respectively. The δ13Cn-alkane values from the core sediments are converted into %C4 plants based on a binary mixing model using the end-member δ13Cn-alkane values derived from the dominant modern vegetation in the Banni region. The prominent feature of the paleovegetation curve is the marked increase in the δ13Cn-alkane values after 2500 cal yr BP, which suggests proliferation of C4 grasses in this region. Similar changes after 2500 cal yr BP have also been observed in the δDn-alkane values. The δDC29 values are used to calculate δD value of paleoprecipitation that varied from 10 ‰ to −60.2 ‰. A significant increase in the δD values of paleoprecipitation (ca. 25 ‰) indicates a weakened ISM precipitation after ca. 2500 cal yr BP. The regional aridification and frequent fire events may have helped the expansion of C4 plant dominated grassland ecosystem in Banni region. Correlation between paleoclimatic records suggests that the southward migration of intertropical convergence zone and more frequent warm phases of El-Nino Southern Oscillation have triggered the weakening of monsoonal precipitation in the tropical region.
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Affiliation(s)
- Sayak Basu
- Indian Institute of Science Education and Research Kolkata, Mohanpur, West Bengal, India
- * E-mail:
| | - Prasanta Sanyal
- Indian Institute of Science Education and Research Kolkata, Mohanpur, West Bengal, India
| | - Anusree A. S. Pillai
- National Centre for Biological Sciences (NCBS), GKVK Campus, Bangalore, Karnataka, India
- Manipal Institute of Higher Education, Madhav Nahar, Manipal, Karnataka, India
| | - Anoop Ambili
- Indian Institute of Science Education and Research Kolkata, Mohanpur, West Bengal, India
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22
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Szejner P, Wright WE, Belmecheri S, Meko D, Leavitt SW, Ehleringer JR, Monson RK. Disentangling seasonal and interannual legacies from inferred patterns of forest water and carbon cycling using tree-ring stable isotopes. GLOBAL CHANGE BIOLOGY 2018; 24:5332-5347. [PMID: 29999573 DOI: 10.1111/gcb.14395] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/23/2017] [Revised: 05/31/2018] [Accepted: 06/20/2018] [Indexed: 06/08/2023]
Abstract
Tree-ring carbon and oxygen isotope ratios have been used to understand past dynamics in forest carbon and water cycling. Recently, this has been possible for different parts of single growing seasons by isolating anatomical sections within individual annual rings. Uncertainties in this approach are associated with correlated climate legacies that can occur at a higher frequency, such as across successive seasons, or a lower frequency, such as across years. The objective of this study was to gain insight into how legacies affect cross-correlation in the δ13 C and δ18 O isotope ratios in the earlywood (EW) and latewood (LW) fractions of Pinus ponderosa trees at thirteen sites across a latitudinal gradient influenced by the North American Monsoon (NAM) climate system. We observed that δ13 C from EW and LW has significant positive cross-correlations at most sites, whereas EW and LW δ18 O values were cross-correlated at about half the sites. Using combined statistical and mechanistic models, we show that cross-correlations in both δ13 C and δ18 O can be largely explained by a low-frequency (multiple-year) mode that may be associated with long-term climate change. We isolated, and statistically removed, the low-frequency correlation, which resulted in greater geographical differentiation of the EW and LW isotope signals. The remaining higher-frequency (seasonal) cross-correlations between EW and LW isotope ratios were explored using a mechanistic isotope fractionation-climate model. This showed that lower atmospheric vapor pressure deficits associated with monsoon rain increase the EW-LW differentiation for both δ13 C and δ18 O at southern sites, compared to northern sites. Our results support the hypothesis that dominantly unimodal precipitation regimes, such as near the northern boundary of the NAM, are more likely to foster cross-correlations in the isotope signals of EW and LW, potentially due to greater sharing of common carbohydrate and soil water resource pools, compared to southerly sites with bimodal precipitation regimes.
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Affiliation(s)
- Paul Szejner
- Laboratory of Tree-Ring Research, University of Arizona, Tucson, Arizona
| | - William E Wright
- Laboratory of Tree-Ring Research, University of Arizona, Tucson, Arizona
| | - Soumaya Belmecheri
- Laboratory of Tree-Ring Research, University of Arizona, Tucson, Arizona
| | - David Meko
- Laboratory of Tree-Ring Research, University of Arizona, Tucson, Arizona
| | - Steven W Leavitt
- Laboratory of Tree-Ring Research, University of Arizona, Tucson, Arizona
| | - James R Ehleringer
- Stable Isotope Ratio Facility for Environmental Research, Department of Biology, University of Utah, Salt Lake City, Utah
| | - Russell K Monson
- Laboratory of Tree-Ring Research, University of Arizona, Tucson, Arizona
- Department of Ecology and Evolutionary Biology, University of Arizona, Tucson, Arizona
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23
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Contributions of Atmospheric Transport and Rain–Vapor Exchange to Near-Surface Water Vapor in the Zhanjiang Mangrove Reserve, Southern China: An Isotopic Perspective. ATMOSPHERE 2018. [DOI: 10.3390/atmos9090365] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Coastal mangroves are increasingly recognized as valuable natural resources and important sites of water and carbon exchange. In this study, we examine atmospheric water cycling in the boundary layer above a coastal mangrove forest in southern China. We collected site observations of isotopic ratios in water vapor and precipitation along with core meteorological variables during July 2017. Our evaluation of these data highlights the influences of large-scale atmospheric transport and rain–vapor exchange in the boundary layer water budget. Rain–vapor exchange takes different forms for different types of rainfall events. The evolution of isotopic ratios in water vapor suggests that substantial rain recycling occurs during the passage of large-scale organized convective systems, but that this process is much weaker during rainfall associated with less organized events of local origin. We further examine the influences of large-scale transport during the observation period using a Lagrangian trajectory-based moisture source analysis. More than half (63%) of the boundary layer moisture during the study period traced back to the South China Sea, consistent with prevailing southerly to southwesterly flow. Other important moisture sources included mainland Southeast Asia and the Indian Ocean, local land areas (e.g., Hainan Island and the Leizhou Peninsula), and the Pacific Ocean. Together, these five regions contributed more than 90% of the water vapor. The most pronounced changes in isotopic content due to large-scale transport during the study period were related to the passage of Tropical Storm Talas. The outer rain bands of this tropical cyclone passed over the measurement site on 15–17 July, causing a sharp reduction in the heavy isotopic content of boundary layer water vapor and a substantial increase in deuterium excess. These changes are consistent with extensive isotopic distillation and rain–vapor exchange in downdrafts associated with the intense convective systems produced by this storm.
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24
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Dee SG, Nusbaumer J, Bailey A, Russell JM, Lee JE, Konecky B, Buenning NH, Noone DC. Tracking the Strength of the Walker Circulation with Stable Isotopes in Water Vapor. JOURNAL OF GEOPHYSICAL RESEARCH. ATMOSPHERES : JGR 2018; 123:7254-7270. [PMID: 30467529 PMCID: PMC6242291 DOI: 10.1029/2017jd027915] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/18/2017] [Accepted: 05/25/2018] [Indexed: 05/05/2023]
Abstract
General circulation models (GCMs) predict that the global hydrological cycle will change in response to anthropogenic warming. However, these predictions remain uncertain, in particular for precipitation [IPCC, 2013]. Held and Soden [2006] suggest that as lower-tropospheric water vapor concentration increases in a warming climate, the atmospheric circulation and convective mass fluxes will weaken. Unfortunately, this process is difficult to constrain, as convective mass fluxes are poorly observed and incompletely simulated in GCMs. Here, we demonstrate that stable hydrogen isotope ratios in tropical atmospheric water vapor can trace changes in temperature, atmospheric circulation and convective mass flux in a warming world. We evaluate changes in temperature, the distribution of water vapor, vertical velocity (ω) and advection, and water isotopes in vapor (δD V ) in water isotopeenabled GCM experiments for modern vs. high CO 2 atmospheres to identify spatial patterns of circulation change over the tropical Pacific. We find that slowing circulation in the tropical Pacific moistens the lower troposphere and weakens convective mass flux, both of which impact the δD of water vapor in the mid-troposphere. Our findings constitute a critical demonstration of how water isotope ratios in the tropical Pacific respond to changes in radiative forcing and atmospheric warming. Moreover, as changes in δD V can be observed by satellites, our results develop new metrics for the detection of global warming impacts to the hydrological cycle and, specifically, the strength of the Walker Circulation.
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Affiliation(s)
- Sylvia G Dee
- Brown University, Department of Earth, Environmental, and Planetary Sciences, Providence, RI 02912
- Brown University, Institute at Brown for Environment and Society, Providence, RI 02912
| | | | | | - James M Russell
- Brown University, Department of Earth, Environmental, and Planetary Sciences, Providence, RI 02912
- Brown University, Institute at Brown for Environment and Society, Providence, RI 02912
| | - Jung-Eun Lee
- Brown University, Department of Earth, Environmental, and Planetary Sciences, Providence, RI 02912
- Brown University, Institute at Brown for Environment and Society, Providence, RI 02912
| | | | - Nikolaus H Buenning
- Department of Earth Sciences, University of Southern California, Los Angeles, CA, 90089
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25
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Stable isotopes in water vapor and rainwater over Indian sector of Southern Ocean and estimation of fraction of recycled moisture. Sci Rep 2018; 8:7552. [PMID: 29765055 PMCID: PMC5954022 DOI: 10.1038/s41598-018-25522-5] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2017] [Accepted: 03/22/2018] [Indexed: 12/01/2022] Open
Abstract
Stable Hydrogen and Oxygen isotopic composition of water vapor, rainwater and surface seawater show a distinct trend across the latitude over the Southern Indian Ocean. Our observations on isotopic composition of surface seawater, water vapor and rainwater across a transect covering the tropical Indian Ocean to the regions of the Southern Ocean showed a strong latitudinal dependency; characterized by the zonal process of evaporation and precipitation. The sampling points were spread across diverse zones of SST, wind speed and rainfall regimes. The observed physical parameters such as sea surface temperature, wind speed and relative humidity over the oceanic regions were used in a box model calculation across the latitudes to predict the isotopic composition of water vapor under equilibrium and kinetic conditions, and compared with results from isotope enabled global spectral model. Further, we obtained the average fraction of recycled moisture across the oceanic transect latitudes as 13.4 ± 7.7%. The values of recycled fraction were maximum at the vicinity of the Inter Tropical Convergence Zone (ITCZ), while the minimum values were recorded over the region of subsidence and evaporation, at the Northern and Southern latitudes of the ITCZ. These estimates are consistent with the earlier reported recyling values.
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26
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Stable Water Isotopologues in the Stratosphere Retrieved from Odin/SMR Measurements. REMOTE SENSING 2018. [DOI: 10.3390/rs10020166] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
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27
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Benetti M, Steen-Larsen HC, Reverdin G, Sveinbjörnsdóttir ÁE, Aloisi G, Berkelhammer MB, Bourlès B, Bourras D, de Coetlogon G, Cosgrove A, Faber AK, Grelet J, Hansen SB, Johnson R, Legoff H, Martin N, Peters AJ, Popp TJ, Reynaud T, Winther M. Stable isotopes in the atmospheric marine boundary layer water vapour over the Atlantic Ocean, 2012-2015. Sci Data 2017; 4:160128. [PMID: 28094798 PMCID: PMC5240618 DOI: 10.1038/sdata.2016.128] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2016] [Accepted: 12/05/2016] [Indexed: 11/09/2022] Open
Abstract
The water vapour isotopic composition (1H216O, H218O and 1H2H16O) of the Atlantic marine boundary layer has been measured from 5 research vessels between 2012 and 2015. Using laser spectroscopy analysers, measurements have been carried out continuously on samples collected 10-20 meter above sea level. All the datasets have been carefully calibrated against the international VSMOW-SLAP scale following the same protocol to build a homogeneous dataset covering the Atlantic Ocean between 4°S to 63°N. In addition, standard meteorological variables have been measured continuously, including sea surface temperatures using calibrated Thermo-Salinograph for most cruises. All calibrated observations are provided with 15-minute resolution. We also provide 6-hourly data to allow easier comparisons with simulations from the isotope-enabled Global Circulation Models. In addition, backwards trajectories from the HYSPLIT model are supplied every 6-hours for the position of our measurements.
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Affiliation(s)
- Marion Benetti
- Institute of Earth Sciences, University of Iceland, Reykjavik, Iceland
- LOCEAN, Sorbonne Universités, UPMC/CNRS/IRD/MNHN, Paris, France
| | | | - Gilles Reverdin
- LOCEAN, Sorbonne Universités, UPMC/CNRS/IRD/MNHN, Paris, France
| | | | - Giovanni Aloisi
- LOCEAN, Sorbonne Universités, UPMC/CNRS/IRD/MNHN, Paris, France
| | - Max B. Berkelhammer
- Department of Earth and Environmental Sciences, University of Illinois, Chicago, Illinois, USA
| | - Bernard Bourlès
- LEGOS, UMR 5566 (University of Toulouse, CNES, CNRS, IRD, UPS), Institut de Recherche pour le Développement (IRD), CS 10070, 29280 Plouzané, France
| | - Denis Bourras
- LATMOS—IPSL, Universite Pierre et Marie Curie, Paris, France
- Aix-Marseille Université, CNRS/INSU, IRD, Mediterranean Institute of Oceanography (MIO), UM 110, 13288 Marseille, France
| | | | - Ann Cosgrove
- Department of Earth and Environmental Sciences, University of Illinois, Chicago, Illinois, USA
| | - Anne-Katrine Faber
- Centre for Ice and Climate, Niels Bohr Institute, University of Copenhagen, Denmark
| | - Jacques Grelet
- US191-Imago, Institut de Recherche pour le Développement (IRD), BP 70, 29280 Plouzané, France
| | - Steffen Bo Hansen
- Centre for Ice and Climate, Niels Bohr Institute, University of Copenhagen, Denmark
| | - Rod Johnson
- Bermuda Institute of Ocean Sciences, St George’s GE 01, Bermuda
| | - Hervé Legoff
- LOCEAN, Sorbonne Universités, UPMC/CNRS/IRD/MNHN, Paris, France
| | - Nicolas Martin
- LOCEAN, Sorbonne Universités, UPMC/CNRS/IRD/MNHN, Paris, France
| | | | - Trevor James Popp
- Centre for Ice and Climate, Niels Bohr Institute, University of Copenhagen, Denmark
| | - Thierry Reynaud
- IFREMER, UMR 6523 LOPS (CNRS/IFREMER/IRD/UBO), CS 10070, 29280 Plouzané, France
| | - Malte Winther
- Centre for Ice and Climate, Niels Bohr Institute, University of Copenhagen, Denmark
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Tierney JE, Pausata FSR, deMenocal PB. Rainfall regimes of the Green Sahara. SCIENCE ADVANCES 2017; 3:e1601503. [PMID: 28116352 PMCID: PMC5242556 DOI: 10.1126/sciadv.1601503] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/01/2016] [Accepted: 11/29/2016] [Indexed: 05/05/2023]
Abstract
During the "Green Sahara" period (11,000 to 5000 years before the present), the Sahara desert received high amounts of rainfall, supporting diverse vegetation, permanent lakes, and human populations. Our knowledge of rainfall rates and the spatiotemporal extent of wet conditions has suffered from a lack of continuous sedimentary records. We present a quantitative reconstruction of western Saharan precipitation derived from leaf wax isotopes in marine sediments. Our data indicate that the Green Sahara extended to 31°N and likely ended abruptly. We find evidence for a prolonged "pause" in Green Sahara conditions 8000 years ago, coincident with a temporary abandonment of occupational sites by Neolithic humans. The rainfall rates inferred from our data are best explained by strong vegetation and dust feedbacks; without these mechanisms, climate models systematically fail to reproduce the Green Sahara. This study suggests that accurate simulations of future climate change in the Sahara and Sahel will require improvements in our ability to simulate vegetation and dust feedbacks.
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Affiliation(s)
- Jessica E. Tierney
- Department of Geosciences, University of Arizona, 1040 East Fourth Street, Tucson, AZ 85721, USA
- Corresponding author.
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Tanoue M, Ichiyanagi K, Yoshimura K. Verification of the isotopic composition of precipitation simulated by a regional isotope circulation model over Japan. ISOTOPES IN ENVIRONMENTAL AND HEALTH STUDIES 2016; 52:329-342. [PMID: 26988409 DOI: 10.1080/10256016.2016.1148695] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/30/2015] [Accepted: 12/19/2015] [Indexed: 06/05/2023]
Abstract
The isotopic composition (δ(18)O and δ(2)H) of precipitation simulated by a regional isotope circulation model with a horizontal resolution of 10, 30 and 50 km was compared with observations at 56 sites over Japan in 2013. All simulations produced reasonable spatio-temporal variations in δ(18)O in precipitation over Japan, except in January. In January, simulated δ(18)O values in precipitation were higher than observed values on the Pacific side of Japan, especially during an explosively developing extratropical cyclone event. This caused a parameterisation of precipitation formulation about the large fraction of precipitated water to liquid detrained water in the lower troposphere. As a result, most water vapour that transported from the Sea of Japan precipitated on the Sea of Japan side. The isotopic composition of precipitation was a useful verification tool for the parameterisation of precipitation formulation as well as large-scale moisture transport processes in the regional isotope circulation model.
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Affiliation(s)
- Masahiro Tanoue
- a School of Engineering , The University of Tokyo , Tokyo , Japan
| | - Kimpei Ichiyanagi
- b Graduate School of Science and Technology , Kumamoto University , Kumamoto , Japan
| | - Kei Yoshimura
- c Atmosphere and Sea Research Institute and Institute of Industrial Science, The University of Tokyo , Tokyo , Japan
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Griffiths ML, Kimbrough AK, Gagan MK, Drysdale RN, Cole JE, Johnson KR, Zhao JX, Cook BI, Hellstrom JC, Hantoro WS. Western Pacific hydroclimate linked to global climate variability over the past two millennia. Nat Commun 2016; 7:11719. [PMID: 27271972 PMCID: PMC4899856 DOI: 10.1038/ncomms11719] [Citation(s) in RCA: 59] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2016] [Accepted: 04/25/2016] [Indexed: 11/09/2022] Open
Abstract
Interdecadal modes of tropical Pacific ocean-atmosphere circulation have a strong influence on global temperature, yet the extent to which these phenomena influence global climate on multicentury timescales is still poorly known. Here we present a 2,000-year, multiproxy reconstruction of western Pacific hydroclimate from two speleothem records for southeastern Indonesia. The composite record shows pronounced shifts in monsoon rainfall that are antiphased with precipitation records for East Asia and the central-eastern equatorial Pacific. These meridional and zonal patterns are best explained by a poleward expansion of the Australasian Intertropical Convergence Zone and weakening of the Pacific Walker circulation (PWC) between ∼1000 and 1500 CE Conversely, an equatorward contraction of the Intertropical Convergence Zone and strengthened PWC occurred between ∼1500 and 1900 CE. Our findings, together with climate model simulations, highlight the likelihood that century-scale variations in tropical Pacific climate modes can significantly modulate radiatively forced shifts in global temperature. Interdecadal modes of tropical Pacific ocean-atmosphere circulation have a strong influence on global temperature. Here, the authors present a 2000-year hydroclimate record from the Indo-Pacific, which suggests that century-scale variations in these modes are also linked with global temperature variability.
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Affiliation(s)
- Michael L Griffiths
- Department of Environmental Science, William Paterson University, Wayne, New Jersey 07470, USA
| | - Alena K Kimbrough
- Research School of Earth Sciences, Australian National University, Canberra, Australian Capital Territory 0200, Australia
| | - Michael K Gagan
- Research School of Earth Sciences, Australian National University, Canberra, Australian Capital Territory 0200, Australia
| | - Russell N Drysdale
- School of Geography, University of Melbourne, Parkville, Victoria 3010, Australia.,EDYTEM, UMR CNRS 5204, Université de Savoie, 73376 Le Bourget du Lac, France
| | - Julia E Cole
- Department of Geosciences, University of Arizona, Tucson, Arizona 85721, USA.,Department of Atmospheric Sciences, University of Arizona, Tucson, Arizona 85721, USA
| | - Kathleen R Johnson
- Department of Earth System Science, University of California, Irvine, California 92697-3100, USA
| | - Jian-Xin Zhao
- School of Earth Sciences, University of Queensland, Brisbane, Queensland 4072, Australia
| | - Benjamin I Cook
- NASA Goddard Institute for Space Studies, New York, New York 10025, USA
| | - John C Hellstrom
- School of Earth Sciences, The University of Melbourne, Parkville, Victoria 3010, Australia
| | - Wahyoe S Hantoro
- Research Center for Geotechnology, Indonesian Institute of Sciences, Bandung 40135, Indonesia
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31
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Salamalikis V, Argiriou AA, Dotsika E. Isotopic modeling of the sub-cloud evaporation effect in precipitation. THE SCIENCE OF THE TOTAL ENVIRONMENT 2016; 544:1059-1072. [PMID: 26779956 DOI: 10.1016/j.scitotenv.2015.11.072] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/17/2015] [Revised: 11/09/2015] [Accepted: 11/14/2015] [Indexed: 06/05/2023]
Abstract
In dry and warm environments sub-cloud evaporation influences the falling raindrops modifying their final stable isotopic content. During their descent from the cloud base towards the ground surface, through the unsaturated atmosphere, hydrometeors are subjected to evaporation whereas the kinetic fractionation results to less depleted or enriched isotopic signatures compared to the initial isotopic composition of the raindrops at cloud base. Nowadays the development of Generalized Climate Models (GCMs) that include isotopic content calculation modules are of great interest for the isotopic tracing of the global hydrological cycle. Therefore the accurate description of the underlying processes affecting stable isotopic content can improve the performance of iso-GCMs. The aim of this study is to model the sub-cloud evaporation effect using a) mixing and b) numerical isotope evaporation models. The isotope-mixing evaporation model simulates the isotopic enrichment (difference between the ground and the cloud base isotopic composition of raindrops) in terms of raindrop size, ambient temperature and relative humidity (RH) at ground level. The isotopic enrichment (Δδ) varies linearly with the evaporated raindrops mass fraction of the raindrop resulting to higher values at drier atmospheres and for smaller raindrops. The relationship between Δδ and RH is described by a 'heat capacity' model providing high correlation coefficients for both isotopes (R(2)>80%) indicating that RH is an ideal indicator of the sub-cloud evaporation effect. Vertical distribution of stable isotopes in falling raindrops is also investigated using a numerical isotope-evaporation model. Temperature and humidity dependence of the vertical isotopic variation is clearly described by the numerical isotopic model showing an increase in the isotopic values with increasing temperature and decreasing RH. At an almost saturated atmosphere (RH=95%) sub-cloud evaporation is negligible and the isotopic composition hardly changes even at high temperatures while at drier and warm conditions the enrichment of (18)Ο reaches up to 20‰, depending on the raindrop size and the initial meteorological conditions.
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Affiliation(s)
- V Salamalikis
- Laboratory of Atmospheric Physics, Department of Physics, University of Patras, GR 26500 Patras, Greece.
| | - A A Argiriou
- Laboratory of Atmospheric Physics, Department of Physics, University of Patras, GR 26500 Patras, Greece
| | - E Dotsika
- Stable Isotope Unit, Institute of Nanoscience and Nanotechnology, National Center of Scientific Research 'Demokritos', Ag. Paraskevi Attikis, 15310 Athens, Greece
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32
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BELGAMAN HA, ICHIYANAGI K, TANOUE M, SUWARMAN R. Observational Research on Stable Isotopes in Precipitation over Indonesian Maritime Continent. ACTA ACUST UNITED AC 2016. [DOI: 10.4145/jahs.46.7] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
- Halda A. BELGAMAN
- Graduate School of Science and Technology, Kumamoto University
- Agency for Assessment and Application of Technology (BPPT), Indonesia
| | - Kimpei ICHIYANAGI
- Graduate School of Science and Technology, Kumamoto University
- Japan Agency for Marine-Earth Science and Technology (JAMSTEC)
| | - Masahiro TANOUE
- Institute of Engineering Innovation, School of Engineering, The University of Tokyo
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33
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Trends and oscillations in the Indian summer monsoon rainfall over the last two millennia. Nat Commun 2015; 6:6309. [PMID: 25686877 DOI: 10.1038/ncomms7309] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2014] [Accepted: 01/14/2015] [Indexed: 11/08/2022] Open
Abstract
Observations show that summer rainfall over large parts of South Asia has declined over the past five to six decades. It remains unclear, however, whether this trend is due to natural variability or increased anthropogenic aerosol loading over South Asia. Here we use stable oxygen isotopes in speleothems from northern India to reconstruct variations in Indian monsoon rainfall over the last two millennia. We find that within the long-term context of our record, the current drying trend is not outside the envelope of monsoon's oscillatory variability, albeit at the lower edge of this variance. Furthermore, the magnitude of multi-decadal oscillatory variability in monsoon rainfall inferred from our proxy record is comparable to model estimates of anthropogenic-forced trends of mean monsoon rainfall in the 21st century under various emission scenarios. Our results suggest that anthropogenic-forced changes in monsoon rainfall will remain difficult to detect against a backdrop of large natural variability.
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34
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Paired oxygen isotope records reveal modern North American atmospheric dynamics during the Holocene. Nat Commun 2014; 5:3701. [PMID: 24739337 DOI: 10.1038/ncomms4701] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2013] [Accepted: 03/21/2014] [Indexed: 11/08/2022] Open
Abstract
The Pacific North American (PNA) teleconnection has a strong influence on North American climate. Instrumental records and century-scale reconstructions indicate an accelerating tendency towards the positive PNA state since the mid-1850s, but much less is known about long-term PNA variability. Here we reconstruct PNA-like climate variability during the mid- and late Holocene using paired oxygen isotope records from two regions in North America with robust, anticorrelated isotopic response to the modern PNA. We identify mean states of more negative and positive PNA-like climate during the mid- and late Holocene, respectively. Superimposed on the secular change between states is a robust, quasi-200-year oscillation, which we associate with the de Vries solar cycle. These findings suggest the persistence of PNA-like climate variability throughout the mid- and late Holocene, provide evidence for modulation of PNA over multiple timescales and may help researchers de-convolve PNA pattern variation from other factors reflected in palaeorecords.
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35
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Diagnosing Atmospheric Influences on the Interannual 18O/16O Variations in Western U.S. Precipitation. WATER 2013. [DOI: 10.3390/w5031116] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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Jasechko S, Sharp ZD, Gibson JJ, Birks SJ, Yi Y, Fawcett PJ. Terrestrial water fluxes dominated by transpiration. Nature 2013; 496:347-50. [PMID: 23552893 DOI: 10.1038/nature11983] [Citation(s) in RCA: 226] [Impact Index Per Article: 20.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2012] [Accepted: 02/04/2013] [Indexed: 11/09/2022]
Abstract
Renewable fresh water over continents has input from precipitation and losses to the atmosphere through evaporation and transpiration. Global-scale estimates of transpiration from climate models are poorly constrained owing to large uncertainties in stomatal conductance and the lack of catchment-scale measurements required for model calibration, resulting in a range of predictions spanning 20 to 65 per cent of total terrestrial evapotranspiration (14,000 to 41,000 km(3) per year) (refs 1, 2, 3, 4, 5). Here we use the distinct isotope effects of transpiration and evaporation to show that transpiration is by far the largest water flux from Earth's continents, representing 80 to 90 per cent of terrestrial evapotranspiration. On the basis of our analysis of a global data set of large lakes and rivers, we conclude that transpiration recycles 62,000 ± 8,000 km(3) of water per year to the atmosphere, using half of all solar energy absorbed by land surfaces in the process. We also calculate CO2 uptake by terrestrial vegetation by connecting transpiration losses to carbon assimilation using water-use efficiency ratios of plants, and show the global gross primary productivity to be 129 ± 32 gigatonnes of carbon per year, which agrees, within the uncertainty, with previous estimates. The dominance of transpiration water fluxes in continental evapotranspiration suggests that, from the point of view of water resource forecasting, climate model development should prioritize improvements in simulations of biological fluxes rather than physical (evaporation) fluxes.
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Affiliation(s)
- Scott Jasechko
- Department of Earth and Planetary Sciences, University of New Mexico, Albuquerque, New Mexico 87131, USA.
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Royles J, Ogée J, Wingate L, Hodgson DA, Convey P, Griffiths H. Temporal separation between CO2 assimilation and growth? Experimental and theoretical evidence from the desiccation-tolerant moss Syntrichia ruralis. THE NEW PHYTOLOGIST 2013; 197:1152-1160. [PMID: 23311300 DOI: 10.1111/nph.12114] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/22/2012] [Accepted: 11/25/2012] [Indexed: 06/01/2023]
Abstract
The extent of an external water layer around moss tissue influences CO(2) assimilation. Experiments on the desiccation-tolerant moss Syntrichia ruralis assessed the real-time dependence of the carbon and oxygen isotopic compositions of CO(2) and H(2)O in terms of moss water status and integrated isotope signals in cellulose. As external (capillary) water, and then mesophyll water, evaporated from moss tissue, assimilation rate, relative water content and the stable isotope composition of tissue water (δ(18)O(TW)), and the CO(2) and H(2)O fluxes, were analysed. After drying, carbon (δ(13)C(C)) and oxygen (δ(18)O(C)) cellulose compositions were determined. During desiccation, assimilation and (13)CO(2) discrimination increased to a maximum and then declined; δ(18)O(TW) increased progressively by 8‰, indicative of evaporative isotopic enrichment. Experimental and meteorological data were combined to predict tissue hydration dynamics over one growing season. Nonsteady-state model predictions of δ(18)O(TW) were consistent with instantaneous measurements. δ(13)C(C) values suggest that net assimilation occurs at 25% of maximum relative water content, while δ(18)O(C) data suggests that cellulose is synthesized during much higher relative water content conditions. This implies that carbon assimilation and cellulose synthesis (growth) may be temporally separated, with carbon reserves possibly contributing to desiccation tolerance and resumption of metabolism upon rehydration.
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Affiliation(s)
- Jessica Royles
- Department of Plant Sciences, University of Cambridge, Downing Street, Cambridge, CB2 3EA, UK
- British Antarctic Survey, High Cross, Madingley Road, Cambridge, CB3 0ET, UK
| | - Jérôme Ogée
- INRA, UR1263 EPHYSE, 71 Avenue Edouard Bourleaux, 33140, Villenave d'Ornon, France
| | - Lisa Wingate
- Department of Plant Sciences, University of Cambridge, Downing Street, Cambridge, CB2 3EA, UK
- INRA, UR1263 EPHYSE, 71 Avenue Edouard Bourleaux, 33140, Villenave d'Ornon, France
| | - Dominic A Hodgson
- British Antarctic Survey, High Cross, Madingley Road, Cambridge, CB3 0ET, UK
| | - Peter Convey
- British Antarctic Survey, High Cross, Madingley Road, Cambridge, CB3 0ET, UK
| | - Howard Griffiths
- Department of Plant Sciences, University of Cambridge, Downing Street, Cambridge, CB2 3EA, UK
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Kennett DJ, Breitenbach SFM, Aquino VV, Asmerom Y, Awe J, Baldini JUL, Bartlein P, Culleton BJ, Ebert C, Jazwa C, Macri MJ, Marwan N, Polyak V, Prufer KM, Ridley HE, Sodemann H, Winterhalder B, Haug GH. Development and disintegration of Maya political systems in response to climate change. Science 2012; 338:788-91. [PMID: 23139330 DOI: 10.1126/science.1226299] [Citation(s) in RCA: 91] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
The role of climate change in the development and demise of Classic Maya civilization (300 to 1000 C.E.) remains controversial because of the absence of well-dated climate and archaeological sequences. We present a precisely dated subannual climate record for the past 2000 years from Yok Balum Cave, Belize. From comparison of this record with historical events compiled from well-dated stone monuments, we propose that anomalously high rainfall favored unprecedented population expansion and the proliferation of political centers between 440 and 660 C.E. This was followed by a drying trend between 660 and 1000 C.E. that triggered the balkanization of polities, increased warfare, and the asynchronous disintegration of polities, followed by population collapse in the context of an extended drought between 1020 and 1100 C.E.
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Affiliation(s)
- Douglas J Kennett
- Department of Anthropology, Pennsylvania State University, University Park, PA 16802, USA.
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Buenning NH, Stott L, Yoshimura K, Berkelhammer M. The cause of the seasonal variation in the oxygen isotopic composition of precipitation along the western U.S. coast. ACTA ACUST UNITED AC 2012. [DOI: 10.1029/2012jd018050] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Ishizaki Y, Yoshimura K, Kanae S, Kimoto M, Kurita N, Oki T. Interannual variability of H218O in precipitation over the Asian monsoon region. ACTA ACUST UNITED AC 2012. [DOI: 10.1029/2011jd015890] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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41
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Lee JE, Risi C, Fung I, Worden J, Scheepmaker RA, Lintner B, Frankenberg C. Asian monsoon hydrometeorology from TES and SCIAMACHY water vapor isotope measurements and LMDZ simulations: Implications for speleothem climate record interpretation. ACTA ACUST UNITED AC 2012. [DOI: 10.1029/2011jd017133] [Citation(s) in RCA: 74] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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42
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Zhu M, Stott L, Buckley B, Yoshimura K, Ra K. Indo-Pacific Warm Pool convection and ENSO since 1867 derived from Cambodian pine tree cellulose oxygen isotopes. ACTA ACUST UNITED AC 2012. [DOI: 10.1029/2011jd017198] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Risi C, Noone D, Worden J, Frankenberg C, Stiller G, Kiefer M, Funke B, Walker K, Bernath P, Schneider M, Wunch D, Sherlock V, Deutscher N, Griffith D, Wennberg PO, Strong K, Smale D, Mahieu E, Barthlott S, Hase F, García O, Notholt J, Warneke T, Toon G, Sayres D, Bony S, Lee J, Brown D, Uemura R, Sturm C. Process-evaluation of tropospheric humidity simulated by general circulation models using water vapor isotopologues: 1. Comparison between models and observations. ACTA ACUST UNITED AC 2012. [DOI: 10.1029/2011jd016621] [Citation(s) in RCA: 86] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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44
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Risi C, Noone D, Worden J, Frankenberg C, Stiller G, Kiefer M, Funke B, Walker K, Bernath P, Schneider M, Bony S, Lee J, Brown D, Sturm C. Process-evaluation of tropospheric humidity simulated by general circulation models using water vapor isotopic observations: 2. Using isotopic diagnostics to understand the mid and upper tropospheric moist bias in the tropics and subtropics. ACTA ACUST UNITED AC 2012. [DOI: 10.1029/2011jd016623] [Citation(s) in RCA: 69] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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45
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Yoshimura K, Frankenberg C, Lee J, Kanamitsu M, Worden J, Röckmann T. Comparison of an isotopic atmospheric general circulation model with new quasi-global satellite measurements of water vapor isotopologues. ACTA ACUST UNITED AC 2011. [DOI: 10.1029/2011jd016035] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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46
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Buenning NH, Noone DC, Riley WJ, Still CJ, White JWC. Influences of the hydrological cycle on observed interannual variations in atmospheric CO18O. ACTA ACUST UNITED AC 2011. [DOI: 10.1029/2010jg001576] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Interannual variability in the oxygen isotopes of atmospheric CO2 driven by El Niño. Nature 2011; 477:579-82. [PMID: 21956330 DOI: 10.1038/nature10421] [Citation(s) in RCA: 178] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2010] [Accepted: 08/04/2011] [Indexed: 11/08/2022]
Abstract
The stable isotope ratios of atmospheric CO(2) ((18)O/(16)O and (13)C/(12)C) have been monitored since 1977 to improve our understanding of the global carbon cycle, because biosphere-atmosphere exchange fluxes affect the different atomic masses in a measurable way. Interpreting the (18)O/(16)O variability has proved difficult, however, because oxygen isotopes in CO(2) are influenced by both the carbon cycle and the water cycle. Previous attention focused on the decreasing (18)O/(16)O ratio in the 1990s, observed by the global Cooperative Air Sampling Network of the US National Oceanic and Atmospheric Administration Earth System Research Laboratory. This decrease was attributed variously to a number of processes including an increase in Northern Hemisphere soil respiration; a global increase in C(4) crops at the expense of C(3) forests; and environmental conditions, such as atmospheric turbulence and solar radiation, that affect CO(2) exchange between leaves and the atmosphere. Here we present 30 years' worth of data on (18)O/(16)O in CO(2) from the Scripps Institution of Oceanography global flask network and show that the interannual variability is strongly related to the El Niño/Southern Oscillation. We suggest that the redistribution of moisture and rainfall in the tropics during an El Niño increases the (18)O/(16)O ratio of precipitation and plant water, and that this signal is then passed on to atmospheric CO(2) by biosphere-atmosphere gas exchange. We show how the decay time of the El Niño anomaly in this data set can be useful in constraining global gross primary production. Our analysis shows a rapid recovery from El Niño events, implying a shorter cycling time of CO(2) with respect to the terrestrial biosphere and oceans than previously estimated. Our analysis suggests that current estimates of global gross primary production, of 120 petagrams of carbon per year, may be too low, and that a best guess of 150-175 petagrams of carbon per year better reflects the observed rapid cycling of CO(2). Although still tentative, such a revision would present a new benchmark by which to evaluate global biospheric carbon cycling models.
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Sjolte J, Hoffmann G, Johnsen SJ, Vinther BM, Masson-Delmotte V, Sturm C. Modeling the water isotopes in Greenland precipitation 1959–2001 with the meso-scale model REMO-iso. ACTA ACUST UNITED AC 2011. [DOI: 10.1029/2010jd015287] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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Field RD, Jones DBA, Brown DP. Effects of postcondensation exchange on the isotopic composition of water in the atmosphere. ACTA ACUST UNITED AC 2010. [DOI: 10.1029/2010jd014334] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Robert D. Field
- Department of Physics; University of Toronto; Toronto Canada
| | | | - Derek P. Brown
- Department of Atmospheric and Oceanic Sciences and Cooperative Institute for Research in Environmental Sciences; University of Colorado; Boulder Colorado USA
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Liu Z, Bowen GJ, Welker JM. Atmospheric circulation is reflected in precipitation isotope gradients over the conterminous United States. ACTA ACUST UNITED AC 2010. [DOI: 10.1029/2010jd014175] [Citation(s) in RCA: 66] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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