NUMERICAL SIMULATIONS ON INFLUENCE OF SEA-ICE THICKNESS AND EXTENT VARIATION IN ARCTIC ON ATMOSPHERIC CIRCULATION

By using IAP 2L-GCM,the influence of variation of sea ice thickness and extent in Arctic on atmospheric circulation,especially on East A sian climate variations is investigated.The results indicate that an nearly reasonable distribution of sea-ice thickness in A rcticin the model leads directly to stronger winter and summer monsoon over East Asia,and improves the model's simulation results for Siberia High and Icelandic Low in winter.On the other hand,sea-ice thickness variation can excite the teleconnection wave trains across Asian Continent,and in the low latitude region,the wave propagates from the Western Pacific across the equat or to the Eastern Pacific.In addition,variation of seaice thickness also influences convective act ivities over A sian low latitude region.The effect of winter seaice extent in the Kara and the Barents Seas on atmospheric circulation in the following spring and summer is also significant.The simulation result shows that when winter seaice extent in the target region is larger (sm aller) than normal,(1) in spring (from April to June),positive (negative) SLP anomalies occupy the northern central Pacific,which lead directly to weakened (deepened) A leutian Low and light (heavy) seaice in Bering Sea;(2) in summer,thermal depression in A sian Continent is deepened (weakened),and Subtropical High in the western Pacific shifts northward (southward) from its normal position and to be strengthened (weakened).