Investigating the local atmospheric response to a realistic shift in the Oyashio Sea surface Temperature Front
Alexander, Michael A.
MetadataShow full item record
KeywordAtmosphere-ocean interaction; Atmospheric circulation; Boundary layer; Cyclogenesis/cyclolysis; Diabatic heating; Extratropical cyclones
The local atmospheric response to a realistic shift of the Oyashio Extension SST front in the western North Pacific is analyzed using a high-resolution (HR; 0.25°) version of the global Community Atmosphere Model, version 5 (CAM5). A northward shift in the SST front causes an atmospheric response consisting of a weak surface wind anomaly but a strong vertical circulation extending throughout the troposphere. In the lower troposphere, most of the SST anomaly–induced diabatic heating is balanced by poleward transient eddy heat and moisture fluxes. Collectively, this response differs from the circulation suggested by linear dynamics, where extratropical SST forcing produces shallow anomalous heating balanced by strong equatorward cold air advection driven by an anomalous, stationary surface low to the east. This latter response, however, is obtained by repeating the same experiment except using a relatively low-resolution (LR; 1°) version of CAM5. Comparison to observations suggests that the HR response is closer to nature than the LR response. Strikingly, HR and LR experiments have almost identical vertical profiles of . However, diagnosis of the diabatic quasigeostrophic vertical pressure velocity (ω) budget reveals that HR has a substantially stronger response, which together with upper-level mean differential thermal advection balances stronger vertical motion. The results herein suggest that changes in transient eddy heat and moisture fluxes are critical to the overall local atmospheric response to Oyashio Front anomalies, which may consequently yield a stronger downstream response. These changes may require the high resolution to be fully reproduced, warranting further experiments of this type with other high-resolution atmosphere-only and fully coupled GCMs.
Author Posting. © American Meteorological Society, 2015. This article is posted here by permission of American Meteorological Society for personal use, not for redistribution. The definitive version was published in Journal of Climate 28 (2015): 1126–1147, doi:10.1175/JCLI-D-14-00285.1.
Showing items related by title, author, creator and subject.
Allen, R. A.; Fletcher, R.; Holmboe, J.; Namias, Jerome; Willett, Hurd C. (Massachusetts Institute of Technology and Woods Hole Oceanographic Institution, 1940-04)The following report is presented as a statement of progress made at the Massachusetts Institute of Technology (M.I.T.) in the investigation into the possibility of extending the range of reliable weather forecasts. This ...
The Tokar Gap jet : regional circulation, diurnal variability, and moisture transport based on numerical simulations Davis, Shannon R.; Pratt, Lawrence J.; Jiang, Houshuo (American Meteorological Society, 2015-08-01)The structure, variability, and regional connectivity of the Tokar Gap jet (TGJ) are described using WRF Model analyses and supporting atmospheric datasets from the East African–Red Sea–Arabian Peninsula (EARSAP) region ...
Impact of surface forcing on Southern Hemisphere atmospheric blocking in the Australia–New Zealand sector Ummenhofer, Caroline C.; McIntosh, Peter C.; Pook, Michael J.; Risbey, James S. (American Meteorological Society, 2013-11-01)Characteristics of atmospheric blocking in the Southern Hemisphere (SH) are explored in atmospheric general circulation model (AGCM) simulations with the Community Atmosphere Model, version 3, with a particular focus on ...