Linkage between winter air temperature over the subtropical Western Pacific and the ice extent anomaly in the Sea of Okhotsk
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This study deals with the correlation between ice extent in the Sea of Okhotsk and the interannual variability of winter (December–February) air temperature over the subtropical Western Pacific from 1979 to 2008. The analysis indicates that the increase in sea ice extent coincides not only with cooling over the Sea of Okhotsk and the adjacent area, but also with significant warming over the subtropical Western Pacific that extends from the surface to the middle troposphere. This meridional dipole pattern of tropospheric temperature anomalies (cooling in the high latitudes and warming in the low latitudes) primarily results from dynamical processes driven by the large-scale atmospheric circulation change. A heat budget diagnosis reveals that when ice extent in the Sea of Okhotsk increases by one standard deviation, the tropospheric air temperature over the subtropical Western Pacific rises by about 0.25°C. It also suggests that the adiabatic heating and stationary eddy heat flux convergence may be the most important factors, which account for 30 and 15% of the warming, respectively. In addition, these two factors also coordinate to result in significant cooling over the Sea of Okhotsk and the adjacent regions.
KeywordsWestern Pacific Sea ice extent The Sea of Okhotsk Thermal feedback Heat budget Meridional temperature advection Eddy heat flux
We thank three reviewers for their insightful suggestions and comments. This study is supported by the NSFC under contract of 41006113 and 40821063, by the National Basic Research Program of China (2007CB411803), and by MELRS0920 of Xiamen University (for Yang and Hu). Wang is supported by the RUSALCA modeling project of NOAA Office of Arctic Research.
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