Influence of sea-ice anomalies on Antarctic precipitation using source attribution in the Community Earth System Model
We conduct sensitivity experiments using a general circulation model that has an explicit water source tagging capability forced by prescribed composites of pre-industrial sea-ice concentrations (SICs) and corresponding sea surface temperatures (SSTs) to understand the impact of sea-ice anomalies on...
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ftcopernicus:oai:publications.copernicus.org:tc75599 2023-05-15T13:55:28+02:00 Influence of sea-ice anomalies on Antarctic precipitation using source attribution in the Community Earth System Model Wang, Hailong Fyke, Jeremy G. Lenaerts, Jan T. M. Nusbaumer, Jesse M. Singh, Hansi Noone, David Rasch, Philip J. Zhang, Rudong 2020-02-04 application/pdf https://doi.org/10.5194/tc-14-429-2020 https://tc.copernicus.org/articles/14/429/2020/ eng eng doi:10.5194/tc-14-429-2020 https://tc.copernicus.org/articles/14/429/2020/ eISSN: 1994-0424 Text 2020 ftcopernicus https://doi.org/10.5194/tc-14-429-2020 2020-07-20T16:22:26Z We conduct sensitivity experiments using a general circulation model that has an explicit water source tagging capability forced by prescribed composites of pre-industrial sea-ice concentrations (SICs) and corresponding sea surface temperatures (SSTs) to understand the impact of sea-ice anomalies on regional evaporation, moisture transport and source–receptor relationships for Antarctic precipitation in the absence of anthropogenic forcing. Surface sensible heat fluxes, evaporation and column-integrated water vapor are larger over Southern Ocean (SO) areas with lower SICs. Changes in Antarctic precipitation and its source attribution with SICs have a strong spatial variability. Among the tagged source regions, the Southern Ocean (south of 50 ∘ S) contributes the most (40 %) to the Antarctic total precipitation, followed by more northerly ocean basins, most notably the South Pacific Ocean (27%), southern Indian Ocean (16 %) and South Atlantic Ocean (11 %). Comparing two experiments prescribed with high and low pre-industrial SICs, respectively, the annual mean Antarctic precipitation is about 150 Gt yr −1 (or 6 %) more in the lower SIC case than in the higher SIC case. This difference is larger than the model-simulated interannual variability in Antarctic precipitation (99 Gt yr −1 ). The contrast in contribution from the Southern Ocean, 102 Gt yr −1 , is even more significant compared to the interannual variability of 35 Gt yr −1 in Antarctic precipitation that originates from the Southern Ocean. The horizontal transport pathways from individual vapor source regions to Antarctica are largely determined by large-scale atmospheric circulation patterns. Vapor from lower-latitude source regions takes elevated pathways to Antarctica. In contrast, vapor from the Southern Ocean moves southward within the lower troposphere to the Antarctic continent along moist isentropes that are largely shaped by local ambient conditions and coastal topography. This study also highlights the importance of atmospheric dynamics in affecting the thermodynamic impact of sea-ice anomalies associated with natural variability on Antarctic precipitation. Our analyses of the seasonal contrast in changes of basin-scale evaporation, moisture flux and precipitation suggest that the impact of SIC anomalies on regional Antarctic precipitation depends on dynamic changes that arise from SIC–SST perturbations along with internal variability. The latter appears to have a more significant effect on the moisture transport in austral winter than in summer. Text Antarc* Antarctic Antarctica Sea ice South Atlantic Ocean Southern Ocean Copernicus Publications: E-Journals Antarctic Austral Indian Pacific Southern Ocean The Antarctic The Cryosphere 14 2 429 444 |
institution |
Open Polar |
collection |
Copernicus Publications: E-Journals |
op_collection_id |
ftcopernicus |
language |
English |
description |
We conduct sensitivity experiments using a general circulation model that has an explicit water source tagging capability forced by prescribed composites of pre-industrial sea-ice concentrations (SICs) and corresponding sea surface temperatures (SSTs) to understand the impact of sea-ice anomalies on regional evaporation, moisture transport and source–receptor relationships for Antarctic precipitation in the absence of anthropogenic forcing. Surface sensible heat fluxes, evaporation and column-integrated water vapor are larger over Southern Ocean (SO) areas with lower SICs. Changes in Antarctic precipitation and its source attribution with SICs have a strong spatial variability. Among the tagged source regions, the Southern Ocean (south of 50 ∘ S) contributes the most (40 %) to the Antarctic total precipitation, followed by more northerly ocean basins, most notably the South Pacific Ocean (27%), southern Indian Ocean (16 %) and South Atlantic Ocean (11 %). Comparing two experiments prescribed with high and low pre-industrial SICs, respectively, the annual mean Antarctic precipitation is about 150 Gt yr −1 (or 6 %) more in the lower SIC case than in the higher SIC case. This difference is larger than the model-simulated interannual variability in Antarctic precipitation (99 Gt yr −1 ). The contrast in contribution from the Southern Ocean, 102 Gt yr −1 , is even more significant compared to the interannual variability of 35 Gt yr −1 in Antarctic precipitation that originates from the Southern Ocean. The horizontal transport pathways from individual vapor source regions to Antarctica are largely determined by large-scale atmospheric circulation patterns. Vapor from lower-latitude source regions takes elevated pathways to Antarctica. In contrast, vapor from the Southern Ocean moves southward within the lower troposphere to the Antarctic continent along moist isentropes that are largely shaped by local ambient conditions and coastal topography. This study also highlights the importance of atmospheric dynamics in affecting the thermodynamic impact of sea-ice anomalies associated with natural variability on Antarctic precipitation. Our analyses of the seasonal contrast in changes of basin-scale evaporation, moisture flux and precipitation suggest that the impact of SIC anomalies on regional Antarctic precipitation depends on dynamic changes that arise from SIC–SST perturbations along with internal variability. The latter appears to have a more significant effect on the moisture transport in austral winter than in summer. |
format |
Text |
author |
Wang, Hailong Fyke, Jeremy G. Lenaerts, Jan T. M. Nusbaumer, Jesse M. Singh, Hansi Noone, David Rasch, Philip J. Zhang, Rudong |
spellingShingle |
Wang, Hailong Fyke, Jeremy G. Lenaerts, Jan T. M. Nusbaumer, Jesse M. Singh, Hansi Noone, David Rasch, Philip J. Zhang, Rudong Influence of sea-ice anomalies on Antarctic precipitation using source attribution in the Community Earth System Model |
author_facet |
Wang, Hailong Fyke, Jeremy G. Lenaerts, Jan T. M. Nusbaumer, Jesse M. Singh, Hansi Noone, David Rasch, Philip J. Zhang, Rudong |
author_sort |
Wang, Hailong |
title |
Influence of sea-ice anomalies on Antarctic precipitation using source attribution in the Community Earth System Model |
title_short |
Influence of sea-ice anomalies on Antarctic precipitation using source attribution in the Community Earth System Model |
title_full |
Influence of sea-ice anomalies on Antarctic precipitation using source attribution in the Community Earth System Model |
title_fullStr |
Influence of sea-ice anomalies on Antarctic precipitation using source attribution in the Community Earth System Model |
title_full_unstemmed |
Influence of sea-ice anomalies on Antarctic precipitation using source attribution in the Community Earth System Model |
title_sort |
influence of sea-ice anomalies on antarctic precipitation using source attribution in the community earth system model |
publishDate |
2020 |
url |
https://doi.org/10.5194/tc-14-429-2020 https://tc.copernicus.org/articles/14/429/2020/ |
geographic |
Antarctic Austral Indian Pacific Southern Ocean The Antarctic |
geographic_facet |
Antarctic Austral Indian Pacific Southern Ocean The Antarctic |
genre |
Antarc* Antarctic Antarctica Sea ice South Atlantic Ocean Southern Ocean |
genre_facet |
Antarc* Antarctic Antarctica Sea ice South Atlantic Ocean Southern Ocean |
op_source |
eISSN: 1994-0424 |
op_relation |
doi:10.5194/tc-14-429-2020 https://tc.copernicus.org/articles/14/429/2020/ |
op_doi |
https://doi.org/10.5194/tc-14-429-2020 |
container_title |
The Cryosphere |
container_volume |
14 |
container_issue |
2 |
container_start_page |
429 |
op_container_end_page |
444 |
_version_ |
1766262100409188352 |