Trends for pan evaporation during 1959-2000 in China

Abstract

Evaporation, influenced by water and energy conditions, reflected the combined effects of climate, vegetation and soil in different basins. Trend analyses of pan evaporation were conducted on 298 stations and significant trends were also explored by the Kendall τ and Linear fitted model method during 1959-2000 in China. The causes for the changes of pan evaporation were discussed in different basins of China. The results presented that decreasing trends were detected in most of stations of China, which ranged from -0.02 to -30.48mm a-2. The spatial distribution of trends presented that most of negative trends stations were detected in mid-latitude regions of China, followed by basin in south region, Northeast region and southwest region. The causes for the changes of pan evaporation, influenced by the water and energy conditions, changed in different basins of China and generally sunshine hours and maximum air temperature were the most important meteorological variables to influence the changes of pan evaporation, followed by relative humidity, wind speed, average air temperature and minimum air temperature in the whole country.