Local Atmospheric Response to an Open-Ocean Polynya in a High-Resolution Climate Model
- Los Alamos National Laboratory, Los Alamos, New Mexico
- Texas A&M University, College Station, Texas
- U.S. Air Force Academy, Colorado Springs, Colorado
- Pacific Northwest National Laboratory, Richland, Washington
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.
- Research Organization:
- Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
- Sponsoring Organization:
- USDOE; USDOE Office of Science (SC). Regional and Global Climate Modeling Program
- Contributing Organization:
- 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)
- Grant/Contract Number:
- AC52-06NA25396; AC05-76RL01830
- OSTI ID:
- 1343648
- Alternate ID(s):
- OSTI ID: 1338761; OSTI ID: 1346290
- Report Number(s):
- LA-UR-16-20689; PNNL-SA-122019
- Journal Information:
- Journal of Climate, Journal Name: Journal of Climate Vol. 30 Journal Issue: 5; ISSN 0894-8755
- Publisher:
- American Meteorological SocietyCopyright Statement
- Country of Publication:
- United States
- Language:
- English
Web of Science
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