5.16
Possible Feedbacks of Winter Sea Ice in the Greenland and the Barents Seas on the Local Atmosphere
Bingyi Wu, Institute of Marine Sciences, School of Fisheries and Ocean Sciences, University of Alaska Fairbanks, Fairbanks, AK; and J. Wang
Using the Arctic monthly sea ice concentration dataset (1953-1995) and the National Center for Environmental Prediction/National Center for Atmospheric Research (NCEP/NCAR) Re-analysis dataset (1958-1995), we investigate possible feedback of sea ice variations in the Greenland and the Barents Seas on the local atmosphere in terms of composite, correlation and regression analysis methods. The results show that on the one hand, atmospheric circulation determines winter (Feb.-Apr.) sea ice anomalies in the Greenland and Barents Seas; on the other hand, sea ice anomaly displays important feedback influences on the local atmospheric boundary layer. Atmosphere affects sea ice in term of dynamic process (wind stress), while the feedback of sea ice on atmospheric boundary layer is a thermodynamic process. Sea ice variations in the Greenland and the Barents Seas strongly affect the local air temperature. The influence extends upwards from sea surface to 700 hPa. The vertical se gradients between 850 and 700 hPa are greater over sea ice than that over open seawater, implying that a more stable boundary layer formed below the 700 hPa over sea ice. It is the net radiation cooling to determine variations of the vertical se gradient because air temperature advections do not show any effective influences on the vertical se gradient. When a heavy (light) sea ice occurs in the Greenland and the Barents Seas, atmospheric stability over the Nordic Sea strengthens (weakens) obviously.
Session 5, High-Latitude Feedbacks and Climate Sensitivity (Continued)
Wednesday, 14 May 2003, 1:45 PM-3:30 PM
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