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Measurements of Cloud Radiative Effect across the Southern Ocean (43° S–79° S, 63° E–158° W). ATMOSPHERE 2020. [DOI: 10.3390/atmos11090949] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The surface radiation environment over the Southern Ocean within the region bound by 42.8° S to 78.7° S and 62.6° E to 157.7° W is summarised for three austral summers. This is done using ship-based measurements with the combination of downwelling radiation sensors and a cloud imager. We focus on characterising the cloud radiative effect (CRE) under a variety of conditions, comparing observations in the open ocean with those in the sea ice zone. For comparison with our observed data, we obtained surface data from the European Centre for Medium-Range Weather Forecasts fifth reanalysis (ERA5). We found that the daily average cloud fraction was slightly lower in ERA5 compared with the observations (0.71 and 0.75, respectively). ERA5 also showed positive biases in the shortwave radiation effect and a negative bias in the longwave radiation effect. The observed mean surface CRE of −164 ± 100 Wm−2 was more negative than the mean surface CRE for ERA5 of −101 W m−2.
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Kirpes R, Bonanno D, May NW, Fraund M, Barget AJ, Moffet RC, Ault AP, Pratt KA. Wintertime Arctic Sea Spray Aerosol Composition Controlled by Sea Ice Lead Microbiology. ACS CENTRAL SCIENCE 2019; 5:1760-1767. [PMID: 31807677 PMCID: PMC6891865 DOI: 10.1021/acscentsci.9b00541] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/01/2019] [Indexed: 06/10/2023]
Abstract
The Arctic is experiencing the greatest warming on Earth, as most evident by rapid sea ice loss. Delayed sea ice freeze-up in the Alaskan Arctic is decreasing wintertime sea ice extent and changing marine biological activity. However, the impacts of newly open water on wintertime sea spray aerosol (SSA) production and atmospheric composition are unknown. Herein, we identify SSA, produced locally from open sea ice fractures (leads), as the dominant aerosol source in the coastal Alaskan Arctic during winter, highlighting the year-round nature of Arctic SSA emissions. Nearly all of the individual SSA featured thick organic coatings, consisting of marine saccharides, amino acids, fatty acids, and divalent cations, consistent with exopolymeric secretions produced as cryoprotectants by sea ice algae and bacteria. In contrast, local summertime SSA lacked these organic carbon coatings, or featured thin coatings, with only open water nearby. The individual SSA composition was not consistent with frost flowers or surface snow above sea ice, suggesting that neither hypothesized frost flower aerosolization nor blowing snow sublimation resulted in the observed SSA. These results further demonstrate the need for inclusion of lead-based SSA production in modeling of Arctic atmospheric composition. The identified connections between changing sea ice, microbiology, and SSA point to the significance of sea ice lead biogeochemistry in altering Arctic atmospheric composition, clouds, and climate feedbacks during winter.
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Affiliation(s)
- Rachel
M. Kirpes
- Department
of Chemistry, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Daniel Bonanno
- Department
of Chemistry, University of the Pacific, Stockton, California 95211, United States
| | - Nathaniel W. May
- Department
of Chemistry, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Matthew Fraund
- Department
of Chemistry, University of the Pacific, Stockton, California 95211, United States
| | - Anna J. Barget
- Department
of Chemistry, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Ryan C. Moffet
- Department
of Chemistry, University of the Pacific, Stockton, California 95211, United States
| | - Andrew P. Ault
- Department
of Chemistry, University of Michigan, Ann Arbor, Michigan 48109, United States
- Department
of Environmental Health Sciences, University
of Michigan, Ann Arbor, Michigan 48109, United States
| | - Kerri A. Pratt
- Department
of Chemistry, University of Michigan, Ann Arbor, Michigan 48109, United States
- Department
of Earth & Environmental Sciences, University
of Michigan, Ann Arbor, Michigan 48109, United States
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Stephenson SR, Wang W, Zender CS, Wang H, Davis SJ, Rasch PJ. Climatic Responses to Future Trans-Arctic Shipping. GEOPHYSICAL RESEARCH LETTERS 2018; 45:9898-9908. [PMID: 30487657 PMCID: PMC6243199 DOI: 10.1029/2018gl078969] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/29/2018] [Revised: 08/26/2018] [Accepted: 09/08/2018] [Indexed: 06/09/2023]
Abstract
As global temperatures increase, sea ice loss will increasingly enable commercial shipping traffic to cross the Arctic Ocean, where the ships' gas and particulate emissions may have strong regional effects. Here we investigate impacts of shipping emissions on Arctic climate using a fully coupled Earth system model (CESM 1.2.2) and a suite of newly developed projections of 21st-century trans-Arctic shipping emissions. We find that trans-Arctic shipping will reduce Arctic warming by nearly 1 °C by 2099, due to sulfate-driven liquid water cloud formation. Cloud fraction and liquid water path exhibit significant positive trends, cooling the lower atmosphere and surface. Positive feedbacks from sea ice growth-induced albedo increases and decreased downwelling longwave radiation due to reduced water vapor content amplify the cooling relative to the shipping-free Arctic. Our findings thus point to the complexity in Arctic climate responses to increased shipping traffic, justifying further study and policy considerations as trade routes open.
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Affiliation(s)
| | - Wenshan Wang
- Department of Earth System ScienceUniversity of CaliforniaIrvineCAUSA
| | - Charles S. Zender
- Department of Earth System ScienceUniversity of CaliforniaIrvineCAUSA
| | - Hailong Wang
- Pacific Northwest National LaboratoryRichlandWAUSA
| | - Steven J. Davis
- Department of Earth System ScienceUniversity of CaliforniaIrvineCAUSA
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