Variation Characteristics Of Summer Land Skin Temperature In Eurasian Continent And Its Relationship With East Asian Summer Monsoon

Using the NCEP/NCAR monthly reanalysis data(including temperature, wind and height fields) and the74factors of general circulation from China National Climate Center, we analyze the variation features of summer skin land temperature in Eurasian Continent and its relationship with the atmosphere circulation and Asian summer monsoon. The results show that:(1) Summer land skin temperature in Eurasia is the highest in July, and the Mean-square deviation is the largest in June. Mean-square deviation at the high latitudes is larger than at low latitudes.The summer skin land temperature in whole area of Eurasia has been a warming trend since late1970s.(2) The main feature of summer land skin temperature in Eurasian continent is consistent throughout the region. Apart from the area around, there is a warming trends in other areas,Tibet plateau shows cooling trend,while between40～65°N summer skin land temperature increases significantly. Summer skin land temperature shows "-+-" or "+-+-" anomalous patterns at higher latitudes and appears characteristics of interannual and interdecadal oscillations. Warming or cooling trend mainly reflects on the interdecadal variations of the summer skin temperature.(3)According to the climatic and spatio-temporal variability characteristics of summer land skin temperature in Eurasia, there5key areas of variation of summer skin land temperature has been identified. Their have different variance characteristics of summer skin land temperature(4) Westerly index and EU index are closely linked to main characteristics of summer skin land temperature in Eurasia, westerly index has a close association with the warming temperature zone(between40-65°N), while the EU index with the distribution of high latitude areas temperature anomalies. Westerly wind index can explain10.9%contribution variance of the summer skin land temperature in Eurasia,EU can explain8.3%.(5) The circulation factors which effect on different key areas are different. Key area1and North Africa Deputy High is relevant significantly. Key area2and North Africa under high intensity, European polar vortex in the Atlantic Ocean area, the northern hemisphere polar vortex area, the Atlantic circulation are relevant significantly. Key area3and subtropical high ridge-line in the northern hemisphere, North Africa high intensity, North Africa Atlantic subtropical high ridge-line in North America, polar vortex in the region-area, the northern hemisphere polar vortex strength are relevant significantly. Key area4and the northern hemisphere polar vortex center location are most relevant significantly. Key area5and polar vortex in the region-area,the northern hemisphere polar vortex strength under high intensity in the northern hemisphere, East Pacific Deputy High strength are relevant significantly.(6) The significant positive correlation area with East-Asian summer monsoon is along the East side of Tibetan plateau (ET), the significant negative correlation area in North of the Mongolia plateau (NM). Summer land skin temperature of both the two regions has different relationship with the East Asian summer monsoon on decadal-scale. Both the correlations are significant before1985, but the correlations are no longer significant after1985.