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Fadnavis S, Asutosh A, Chavan P, Thaware R, Tilmes S. Amplified drying in South Asian summer monsoon precipitation due to anthropogenic sulfate aerosols. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2024; 343:123175. [PMID: 38142031 DOI: 10.1016/j.envpol.2023.123175] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/25/2023] [Revised: 10/09/2023] [Accepted: 12/13/2023] [Indexed: 12/25/2023]
Abstract
A declining trend in Indian summer monsoon precipitation (ISMP) in the latter half of the 20th century is a scientifically challenging and societally relevant research issue. Heavy aerosol loading over India is one of the key factors in modulating the ISMP. Using the state-of-the-state-of-the-art chemistry-climate model, ECHAM6-HAMMOZ, the impacts of South Asian anthropogenic sulfate aerosols on the Indian summer monsoon precipitation were investigated against: (1) 2010 La Niña (excess monsoon), (2) 2015 El Niño (deficit monsoon) in comparison to (3) normal monsoon 2016. Sensitivity simulations were designed with 48% enhancement in South Asian SO2 emissions based on a trend estimated from Ozone Monitoring Instrument (OMI) satellite observations during 2006-2017. The model simulations showed that sulfate aerosols reduce ISMP by 27.5%-43.3 %, while simulations without sulfate loading enhanced ISMP by 23% in 2010 La Niña and reduction by 35% in 2015 El Niño. This paper reports that sulfate aerosols loading over India reduce precipitation by aerosol-induced direct and indirect effects by inducing atmospheric cooling, weakening in the convection, and reduction in moisture transport to Indian landmass. This paper emphasizes the necessity of alternate use of energy to reduce sulfate aerosol emissions to solve water issues in South Asia.
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Affiliation(s)
- Suvarna Fadnavis
- CCCR, Indian Institute of Tropical Meteorology, Pune, Ministry of Earth Sciences, India.
| | - A Asutosh
- National Center for Atmospheric Research, Boulder, CO, USA
| | - Prashant Chavan
- CCCR, Indian Institute of Tropical Meteorology, Pune, Ministry of Earth Sciences, India
| | - Rakshit Thaware
- CCCR, Indian Institute of Tropical Meteorology, Pune, Ministry of Earth Sciences, India
| | - Simone Tilmes
- National Center for Atmospheric Research, Boulder, CO, USA
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2
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Patel A, Mallik C, Chandra N, Patra PK, Steinbacher M. Revisiting regional and seasonal variations in decadal carbon monoxide variability: Global reversal of growth rate. THE SCIENCE OF THE TOTAL ENVIRONMENT 2024; 909:168476. [PMID: 37984655 DOI: 10.1016/j.scitotenv.2023.168476] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/30/2023] [Revised: 10/09/2023] [Accepted: 11/08/2023] [Indexed: 11/22/2023]
Abstract
Carbon monoxide (CO) is one of the important trace gases in the atmosphere capturing the evolution of chemical properties of the troposphere. Here we analyze the growth rates of CO during the period of 1991-2020 using in situ measurements from the World Meteorological Organization's (WMO) Global Atmospheric Watch (GAW) program. The analysis of trends has been done on different spatial and temporal scales. Our analysis supports the decline in the overall CO mixing ratios over the globe but inter-decadal and regional trend analysis has shown heterogeneous changes in the given period of study. On average, there has been a decrease of -16.22 ± 1.92 ppb and -4.5 ± 0.64 ppb observed at the sites in the northern hemisphere (NH) and southern hemisphere (SH), respectively. This decline occurred at rates of -0.80 ± 0.12 ppb yr-1 in the NH and - 0.12 ± 0.03 ppb yr-1 in the SH. Bifurcating the annual trends for seasonal analysis reveals the impact of emissions, chemistry and atmospheric transport on CO variation over different regional clusters of stations. Seasonal trend analysis provides further evidence regarding heterogeneous patterns in the South-East Asia region. Our study highlights a slowdown in CO decline during the 2011-2020 decade when compared to the rate of decrease observed in 2001-2010. This is inferred from the variability and much slower decline of CO emissions across different regions, contributing to a weakening in CO trends.
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Affiliation(s)
- Ankit Patel
- Department of Atmospheric Science, Central University of Rajasthan, Ajmer 305801, India
| | - Chinmay Mallik
- Department of Atmospheric Science, Central University of Rajasthan, Ajmer 305801, India.
| | - Naveen Chandra
- Research Institute for Global Change, JAMSTEC, Yokohama 2360001, Japan
| | - Prabir K Patra
- Research Institute for Global Change, JAMSTEC, Yokohama 2360001, Japan; Research Institute for Humanity and Nature, Kyoto, Japan
| | - Martin Steinbacher
- Empa, Swiss Federal Laboratories for Materials Science and Technology, CH-8600 Duebendorf, Switzerland
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Nair HRCR, Budhavant K, Manoj MR, Andersson A, Satheesh SK, Ramanathan V, Gustafsson Ö. Aerosol demasking enhances climate warming over South Asia. NPJ CLIMATE AND ATMOSPHERIC SCIENCE 2023; 6:39. [PMID: 37252186 PMCID: PMC10199435 DOI: 10.1038/s41612-023-00367-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/26/2022] [Accepted: 05/03/2023] [Indexed: 05/31/2023]
Abstract
Anthropogenic aerosols mask the climate warming caused by greenhouse gases (GHGs). In the absence of observational constraints, large uncertainties plague the estimates of this masking effect. Here we used the abrupt reduction in anthropogenic emissions observed during the COVID-19 societal slow-down to characterize the aerosol masking effect over South Asia. During this period, the aerosol loading decreased substantially and our observations reveal that the magnitude of this aerosol demasking corresponds to nearly three-fourths of the CO2-induced radiative forcing over South Asia. Concurrent measurements over the northern Indian Ocean unveiled a ~7% increase in the earth's surface-reaching solar radiation (surface brightening). Aerosol-induced atmospheric solar heating decreased by ~0.4 K d-1. Our results reveal that under clear sky conditions, anthropogenic emissions over South Asia lead to nearly 1.4 W m-2 heating at the top of the atmosphere during the period March-May. A complete phase-out of today's fossil fuel combustion to zero-emission renewables would result in rapid aerosol demasking, while the GHGs linger on.
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Affiliation(s)
- H. R. C. R. Nair
- Department of Environmental Science and the Bolin Centre for Climate Research, Stockholm University, Stockholm, Sweden
| | - Krishnakant Budhavant
- Maldives Climate Observatory at Hanimaadhoo, H. Dh. Hanimaadhoo, Maldives
- Divecha Centre for Climate Change, Indian Institute of Science, Bangalore, India
| | - M. R. Manoj
- Department of Environmental Science and the Bolin Centre for Climate Research, Stockholm University, Stockholm, Sweden
- Divecha Centre for Climate Change, Indian Institute of Science, Bangalore, India
| | - August Andersson
- Department of Environmental Science and the Bolin Centre for Climate Research, Stockholm University, Stockholm, Sweden
| | - S. K. Satheesh
- Divecha Centre for Climate Change, Indian Institute of Science, Bangalore, India
- Centre for Atmospheric and Oceanic Sciences, Indian Institute of Science, Bangalore, India
- DST-Centre of Excellence in Climate Change, Indian Institute of Science, Bangalore, India
| | - V. Ramanathan
- Scripps Institution of Oceanography, University of California San Diego, La Jolla, CA USA
| | - Örjan Gustafsson
- Department of Environmental Science and the Bolin Centre for Climate Research, Stockholm University, Stockholm, Sweden
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Fadnavis S, Sagalgile A, Sonbawne S, Vogel B, Peter T, Wienhold FG, Dirksen R, Oelsner P, Naja M, Müller R. Comparison of ozonesonde measurements in the upper troposphere and lower Stratosphere in Northern India with reanalysis and chemistry-climate-model data. Sci Rep 2023; 13:7133. [PMID: 37130920 PMCID: PMC10154380 DOI: 10.1038/s41598-023-34330-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2023] [Accepted: 04/27/2023] [Indexed: 05/04/2023] Open
Abstract
The variability and trend of ozone (O3) in the Upper troposphere and Lower Stratosphere (UTLS) over the Asian region needs to be accurately quantified. Ozone in the UTLS radiatively heats this region and cools the upper parts of the stratosphere. This results in an impact on relative humidity, static stability in the UTLS region and tropical tropopause temperature. A major challenge for understanding ozone chemistry in the UTLS is sparse observations and thus the representation of precursor gases in model emission inventories. Here, we evaluate ozonesonde measurements during August 2016 at Nainital, in the Himalayas, against ozone from multiple reanalyses and the ECHAM6-HAMMOZ model. We find that compared to measurements both reanalyses and ECHAM6-HAMMOZ control simulation overestimate ozone mixing ratios in the troposphere (20 ppb) and in the UTLS (55 ppb). We performed sensitivity simulations using the ECHAM6-HAMMOZ model for a 50% reduction in the emission of (1) NOx and (2) VOCs. The model simulations with NOX reduction agree better with the ozonesonde observations in the lower troposphere and in the UTLS. Thus, neither reanalyses nor ECHAM6-HAMMOZ results can reproduce observed O3 over the South Asian region. For a better representation of O3 in the ECHAM6-HAMMOZ model, NOX emission should be reduced by 50% in the emission inventory. A larger number of observations of ozone and precursor gases over the South Asian region would improve the assessment of ozone chemistry in models.
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Affiliation(s)
- Suvarna Fadnavis
- Indian Institute of Tropical Meteorology, Center for Climate Change Research, Pune, India.
| | - Archana Sagalgile
- Indian Institute of Tropical Meteorology, Center for Climate Change Research, Pune, India
| | - Sunil Sonbawne
- Indian Institute of Tropical Meteorology, Center for Climate Change Research, Pune, India
| | - Bärbel Vogel
- Forschungszentrum Jülich GmbH, IEK-7, Jülich, Germany
| | - Thomas Peter
- Institute for Atmospheric and Climate Science (IAC), Swiss Federal Institute of Technology (ETH), Zürich, Switzerland
| | - Frank G Wienhold
- Institute for Atmospheric and Climate Science (IAC), Swiss Federal Institute of Technology (ETH), Zürich, Switzerland
| | - Ruud Dirksen
- Deutscher Wetterdienst (DWD) GRUAN Lead Centre, Meteorologisches Observatorium Lindenberg, Tauche, Germany
| | - Peter Oelsner
- Deutscher Wetterdienst (DWD) GRUAN Lead Centre, Meteorologisches Observatorium Lindenberg, Tauche, Germany
| | - Manish Naja
- Aryabhatta Research Institute of Observational Sciences (ARIES), Nainital, India
| | - Rolf Müller
- Forschungszentrum Jülich GmbH, IEK-7, Jülich, Germany
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Wu D, Shi T, Niu X, Chen Z, Cui J, Chen Y, Zhang X, Liu J, Ji M, Wang X, Pu W. Seasonal to sub-seasonal variations of the Asian Tropopause Aerosols Layer affected by the deep convection, surface pollutants and precipitation. J Environ Sci (China) 2022; 114:53-65. [PMID: 35459514 DOI: 10.1016/j.jes.2021.07.022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2021] [Revised: 07/09/2021] [Indexed: 06/14/2023]
Abstract
The Asian Tropopause Aerosols Layer (ATAL) refers to an accumulation of aerosols in the upper troposphere and lower stratosphere during boreal summer over Asia, which has a fundamental impact on the monsoon system and climate change. In this study, we primarily analyze the seasonal to sub-seasonal variations of the ATAL and the factors potentially influencing those variations based on MERRA2 reanalysis. The ability of the reanalysis to reproduce the ATAL is well validated by CALIPSO observations from May to October 2016. The results reveal that the ATAL has a synchronous spatiotemporal pattern with the development and movement of the Asian Summer Monsoon. Significant enhancement of ATAL intensity is found during the prevailing monsoon period of July-August, with two maxima centered over South Asia and the Arabian Peninsula. Owing to the fluctuations of deep convection, the ATAL shows an episodic variation on a timescale of 7-12 days. Attribution analysis indicates that deep convection dominates the variability of the ATAL with a contribution of 62.7%, followed by a contribution of 36.6% from surface pollutants. The impact of precipitation is limited. The ATAL further shows a clear diurnal variation: the peak of ATAL intensity occurs from 17:30 to 23:30 local time (LT), when the deep convection becomes strongest; the minimum ATAL intensity occurs around 8:30 LT owing to the weakened deep convection and photochemical reactions in clouds. The aerosol components of the ATAL show different spatiotemporal patterns and imply that black carbon and organic carbon come mainly from India, whereas sulfate comes mainly from China during the prevailing monsoon period.
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Affiliation(s)
- Dongyou Wu
- College of Atmospheric Sciences, Lanzhou University, Lanzhou 730000, China
| | - Tenglong Shi
- College of Atmospheric Sciences, Lanzhou University, Lanzhou 730000, China
| | - Xiaoying Niu
- College of Atmospheric Sciences, Lanzhou University, Lanzhou 730000, China
| | - Ziqi Chen
- College of Atmospheric Sciences, Lanzhou University, Lanzhou 730000, China
| | - Jiecan Cui
- College of Atmospheric Sciences, Lanzhou University, Lanzhou 730000, China
| | - Yang Chen
- College of Atmospheric Sciences, Lanzhou University, Lanzhou 730000, China
| | - Xueying Zhang
- Jilin Weather Modification Office, Changchun 130000, China
| | - Jun Liu
- College of Atmospheric Sciences, Lanzhou University, Lanzhou 730000, China
| | - Mingxia Ji
- College of Atmospheric Sciences, Lanzhou University, Lanzhou 730000, China
| | - Xin Wang
- College of Atmospheric Sciences, Lanzhou University, Lanzhou 730000, China; School of Earth System Science, Tianjin University, Tianjin 300072, China
| | - Wei Pu
- College of Atmospheric Sciences, Lanzhou University, Lanzhou 730000, China.
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Fadnavis S, Müller R, Chakraborty T, Sabin TP, Laakso A, Rap A, Griessbach S, Vernier JP, Tilmes S. The role of tropical volcanic eruptions in exacerbating Indian droughts. Sci Rep 2021; 11:2714. [PMID: 33526810 PMCID: PMC7851170 DOI: 10.1038/s41598-021-81566-0] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2020] [Accepted: 01/06/2021] [Indexed: 01/30/2023] Open
Abstract
The Indian summer monsoon rainfall (ISMR) is vital for the livelihood of millions of people in the Indian region; droughts caused by monsoon failures often resulted in famines. Large volcanic eruptions have been linked with reductions in ISMR, but the responsible mechanisms remain unclear. Here, using 145-year (1871-2016) records of volcanic eruptions and ISMR, we show that ISMR deficits prevail for two years after moderate and large (VEI > 3) tropical volcanic eruptions; this is not the case for extra-tropical eruptions. Moreover, tropical volcanic eruptions strengthen El Niño and weaken La Niña conditions, further enhancing Indian droughts. Using climate-model simulations of the 2011 Nabro volcanic eruption, we show that eruption induced an El Niño like warming in the central Pacific for two consecutive years due to Kelvin wave dissipation triggered by the eruption. This El Niño like warming in the central Pacific led to a precipitation reduction in the Indian region. In addition, solar dimming caused by the volcanic plume in 2011 reduced Indian rainfall.
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Affiliation(s)
| | - Rolf Müller
- Forschungszentrum Jülich GmbH, IEK7, Jülich, Germany
| | | | - T P Sabin
- Indian Institute of Tropical Meteorology, MoES, Pune, India
| | - Anton Laakso
- Finnish Meteorological Institute, Kuopio, Finland
| | - Alexandru Rap
- School of Earth and Environment, University of Leeds, Leeds, UK
| | - Sabine Griessbach
- Forschungszentrum Jülich GmbH, Jülich Supercomputing Center, Jülich, Germany
| | - Jean-Paul Vernier
- National Institute of Aerospace, Hampton, VA, USA
- NASA Langley Research Center, Hampton, VA, USA
| | - Simone Tilmes
- National Center for Atmospheric Research, Boulder, USA
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7
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Changing patterns in aerosol vertical distribution over South and East Asia. Sci Rep 2021; 11:308. [PMID: 33431935 PMCID: PMC7801640 DOI: 10.1038/s41598-020-79361-4] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2020] [Accepted: 11/23/2020] [Indexed: 11/09/2022] Open
Abstract
Changing patterns in aerosol concentrations over the Asian region is well documented with a concurrent increase over India and a marked reduction over China. However, aerosol vertical distribution in the changing climate is not fully understood. By combining long-term satellite observations from MODIS and CALIOP, here we show rapid changes in the aerosol vertical distribution over the South and East Asia covering India and China. A statistically significant decreasing (increasing) trend in the boundary layer (free troposphere) aerosol concentrations is noticed over India. ERA-Interim reanalysis model suggests that this increase in free tropospheric aerosol concentrations are due to the lifting of boundary layer pollutants through an increase in convection (and vertical velocity) in a changing climate. In contrast, a consistent decreasing trend is observed over China irrespective of the altitude. Interestingly, a decreasing trend in Aerosol Optical Depth is observed over the northwest India and we relate this to an observed increase in precipitation leading to increase in the vegetation. It is also found that long-term oscillations like QBO, ENSO and solar cycle significantly affect the aerosol concentrations. Thus, it is prudent to conclude that background meteorology and dynamics play an important role in changing patterns of aerosol vertical distribution.
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