Tuesday, 24 January 2012
Evaluation of Snow Cover Effect on Stratosphere-Troposphere Circulation Using Observation and Global Circulation Model
Hall E (New Orleans Convention Center )
Since Baldwin and Dunkerton (1999) clarified propagation of low-frequency modes of atmospheric motion from stratosphere into troposphere resulted in change in tropospheric weather patterns, many follow-on studies have disclosed the effect of autumn Eurasian snow cover as a precursor to establish the atmospheric circulation interaction between stratosphere-troposphere during winter. Especially, the autumn Eurasian snow cover anomalous distribution induce stratosphere-troposphere atmospheric variability during following winter and affects surface synoptic weather condition is established as a definite mechanism based on snow cover-albedo theory. First, this theory is verified using Snow Cover and synoptic observational data set. How autumn Eurasian snow cover affects the wave activity flux(WAF) and geopotential height which is related to planetary scale atmospheric wave activity is analyzed. Using the cross covariance analysis, seasonal relationship between snow cover and two variables are verified. Second, Global Circulation Model is used to simulate the interaction between snow cover and stratosphere-troposphere atmospheric motion. It is found that GCM simulates lower snow cover seasonal variability and more confined structure than observation in previous study. To solve this problem, several sensitivity experiments are performed.