A Study on Relationship between Freezingthawing Processes of the Qinghai‐Xizang Plateau and the Atmospheric Circulation Over East Asia

Abstract

AbstractThe seasonal freezing‐thawing process on the Qinghai‐Xizang Plateau is analyzed using the data of maximum depth of frozen soil from 64 stations, precipitation observations from 160 stations in China, and the NCAR/NCEP analysis. We have found that the seasonal freezing‐thawing process on the Qinghai‐Xizang Plateau not only affects the circulations above the plateau but also has impact on the circulation over East Asia. During the years when the frozen soil is shallower (deeper) compared to normal time, the South Asian high in July is stronger (weaker) and is located far to the west (east), the Indian cyclone is stronger (weaker), the subtropics high of the west Pacific is weaker (stronger) and is located far to the east (west), and the easterly jet stream over the southern plateau is stronger (weaker). We also found the correlation between freezing‐thawing processes and the summer monsoon activities. Three zones of significant correlation exist between the maximum depth of frozen soil and the summer (July) precipitation in China which has the same distribution as the summer mean rainfall patterns. Thus, the sensible and latent heating associated with the freezing‐thawing processes is an important factor that influences the climate over East Asia.