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Title: Local Atmospheric Response to an Open-Ocean Polynya in a High-Resolution Climate Model

For this scientific paper, we study the atmospheric response to an open-ocean polynya in the Southern Ocean by analyzing the results from an atmospheric and oceanic synoptic-scale resolving Community Earth System Model (CESM) simulation. While coarser-resolution versions of CESM generally do not produce open-ocean polynyas in the Southern Ocean, they do emerge and disappear on interannual timescales in the synoptic-scale simulation. This provides an ideal opportunity to study the polynya’s impact on the overlying and surrounding atmosphere. This has been pursued here by investigating the seasonal cycle of differences of surface and air-column variables between polynya and non-polynya years. Our results indicate significant local impacts on turbulent heat fluxes, precipitation, cloud characteristics, and radiative fluxes. In particular, we find that clouds over polynyas are optically thicker and higher than clouds over sea ice during non-polynya years. Although the lower albedo of polynyas significantly increases the net shortwave absorption, the enhanced cloud brightness tempers this increase by almost 50%. Also, in this model, enhanced longwave radiation emitted from the warmer surface of polynyas is balanced by stronger downwelling fluxes from the thicker cloud deck. Impacts are found to be sensitive to the synoptic wind direction. Strongest regional impacts are found whenmore » northeasterly winds cross the polynya and interact with katabatic winds. Finally, surface air pressure anomalies over the polynya are only found to be significant when cold, dry air masses strike over the polynya, i.e. in case of southerly winds.« less
Authors:
; ; ; ; ; ; ;
Publication Date:
Report Number(s):
LA-UR-16-20689; PNNL-SA-122019
Journal ID: ISSN 0894-8755
Grant/Contract Number:
AC52-06NA25396; AC05-76RL01830
Type:
Published Article
Journal Name:
Journal of Climate
Additional Journal Information:
Journal Volume: 30; Journal Issue: 5; Journal ID: ISSN 0894-8755
Publisher:
American Meteorological Society
Research Org:
Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
Sponsoring Org:
USDOE Office of Science (SC). Regional and Global Climate Modeling Program; USDOE
Contributing Orgs:
Pacific Northwest National Lab. (PNNL), Richland, WA (United States); United States Air Force Academy, Colorado Springs, CO (United States); Texas A & M Univ., College Station, TX (United States)
Country of Publication:
United States
Language:
English
Subject:
54 ENVIRONMENTAL SCIENCES; 58 GEOSCIENCES; Planetary Sciences; sea ice; southern ocean; cloud cover; general circulation models
OSTI Identifier:
1343648
Alternate Identifier(s):
OSTI ID: 1338761; OSTI ID: 1346290

Weijer, Wilbert, Veneziani, Milena, Stössel, Achim, Hecht, Matthew W., Jeffery, Nicole, Jonko, Alexandra, Hodos, Travis, and Wang, Hailong. Local Atmospheric Response to an Open-Ocean Polynya in a High-Resolution Climate Model. United States: N. p., Web. doi:10.1175/JCLI-D-16-0120.1.
Weijer, Wilbert, Veneziani, Milena, Stössel, Achim, Hecht, Matthew W., Jeffery, Nicole, Jonko, Alexandra, Hodos, Travis, & Wang, Hailong. Local Atmospheric Response to an Open-Ocean Polynya in a High-Resolution Climate Model. United States. doi:10.1175/JCLI-D-16-0120.1.
Weijer, Wilbert, Veneziani, Milena, Stössel, Achim, Hecht, Matthew W., Jeffery, Nicole, Jonko, Alexandra, Hodos, Travis, and Wang, Hailong. 2017. "Local Atmospheric Response to an Open-Ocean Polynya in a High-Resolution Climate Model". United States. doi:10.1175/JCLI-D-16-0120.1.
@article{osti_1343648,
title = {Local Atmospheric Response to an Open-Ocean Polynya in a High-Resolution Climate Model},
author = {Weijer, Wilbert and Veneziani, Milena and Stössel, Achim and Hecht, Matthew W. and Jeffery, Nicole and Jonko, Alexandra and Hodos, Travis and Wang, Hailong},
abstractNote = {For this scientific paper, we study the atmospheric response to an open-ocean polynya in the Southern Ocean by analyzing the results from an atmospheric and oceanic synoptic-scale resolving Community Earth System Model (CESM) simulation. While coarser-resolution versions of CESM generally do not produce open-ocean polynyas in the Southern Ocean, they do emerge and disappear on interannual timescales in the synoptic-scale simulation. This provides an ideal opportunity to study the polynya’s impact on the overlying and surrounding atmosphere. This has been pursued here by investigating the seasonal cycle of differences of surface and air-column variables between polynya and non-polynya years. Our results indicate significant local impacts on turbulent heat fluxes, precipitation, cloud characteristics, and radiative fluxes. In particular, we find that clouds over polynyas are optically thicker and higher than clouds over sea ice during non-polynya years. Although the lower albedo of polynyas significantly increases the net shortwave absorption, the enhanced cloud brightness tempers this increase by almost 50%. Also, in this model, enhanced longwave radiation emitted from the warmer surface of polynyas is balanced by stronger downwelling fluxes from the thicker cloud deck. Impacts are found to be sensitive to the synoptic wind direction. Strongest regional impacts are found when northeasterly winds cross the polynya and interact with katabatic winds. Finally, surface air pressure anomalies over the polynya are only found to be significant when cold, dry air masses strike over the polynya, i.e. in case of southerly winds.},
doi = {10.1175/JCLI-D-16-0120.1},
journal = {Journal of Climate},
number = 5,
volume = 30,
place = {United States},
year = {2017},
month = {3}
}