The Climatic Change Trend and Seasonal Characteristics of Daily Temperature Extremes in China for the Latest 40 Years

Extreme events have heavy negative effects on the society causing great economic loss so they have attracted much attention. Using maximal/minimum daily tempera ture data from 194 stations for the period of 1961—2000 of China and adopting indices of extreme climate, seasonal characteristics and the changes of daily tem perature extremes are analyzed. The indices of temperature extremes are introduc ed concluding absolute and relative definition. Then the annual indices of hot a nd cold extreme events are discussed. In order to compare the differences of the indices among different seasons, the season indices are also researched. The re sults indicate the hot extreme indices and cold extreme indices defined by absol ute threshold show the trend of summer and winter, but the result of absolute an nual indices of temperature extremes is not satisfying because the differences between southern and northern are not considered. Another indices based on the pe rcentage definitions indicate that cold and hot extremes indices are anisomerous. Hot days and cold days are not consistent and the indices in same area between hot days and cold days are not symmetrical. But indices for hot nights and cold nights show good consistency and symmetry. The indices change little for daytim e but change rapidly at night. The indices of seasonal temperature extremes show that the changes of indices in spring and autumn are most indistinctive, while the indices in winter is the most notable. The cold indices of spring, autumn an d winter are decreasing while trends of summer indices are increasing most of th e time.