Characteristics of spatiotemporal distribution of extreme temperature events over China mainland in different climate states against the backdrop of most probable temperature

Abstract

Daily max temperature records of National Meteorological Information Center from 1961 to 2009 over China mainland are divided into three climate states of 19611990,19712000,19812009 (just called StateⅠ, StateⅡ, State Ⅲ respectively). Most probable temperature(MPT) and extreme temperature events are defined according to the skewed function. The spatiotemporal distribution characteristics of frequency and strength of extreme temperature events over China mainland in different climate sates against the backdrop of MPT are analyzed. Spatially, frequency and strength of extremly high temperature in summer decrease significantly in the Yangtze-Huaihe river valley and the Yellow river and Huaihe River valley in StateⅠ and increase significantly in the arid-semiarid region and the econormically developed Yangtze River delta in State Ⅲ. The frequency of extremely low temperature in winter reduces remarkably in the north part and the Yangtze River delta in StateⅡ and in the Qinghai-Tibet Plateau, the southeast part of northeast China, the Yangtze River delta in State Ⅲ. The strength of extremely low temperature in winter reduces on the whole and provincial characteristics are not obvious. The frequency and the strength of extreme temperature events are consistont spatially. Temporally, the frequency and the strength of extremely high temperature in summer increase obviously both in StateⅡ and State Ⅲ. The frequency and the strength of extremely low temperature in winter reduce obviously in StateⅡ and the reducing trend slows down in State Ⅲ. Extremely high temperature in summer occurs frequently and extremely low temperature in winter remains stable. Extremity of high temperature in summer is stronger while in winter is stable relatively. The frequency and the strength of extreme temperature events are consistent temporally. During the common time period of States Ⅰ,Ⅱ and Ⅲ, the frequency of extremely high temperature events in the last state was always less than the former while the low temperature events are more, which is in accordance with the fact that the background temperature steps up with the states; the strength of extremely high temperature events in the latter state is less than that of the former while the strength of extremely low temperature events is stronger. For the abrupt change of climate at the end of the 1970 s and the beginning of the 1980 s, the frequency of extreme high temperature events decreases before the change and increases obviously after the change while the ones of extremely low temperature do not change significantly correspondingly; the strength of extremely high temperature events decreassd slightly before the change and increases obviously after the change while the strength of extremely low temperature does not change significantly for the change but the whole strength after the change is slightly lower than the one before the change.