Abstract
Evaporation is a critical process in the material and energy cycle of land-atmosphere system. The Yellow River basin (YRB) experienced severe water shortage in the past several decades. The spatial and temporal characteristics of pan evaporation (PE) and their changes are of vital importance to the understanding of the hydrological process and water resources in the YRB.
In this paper, the temporal and spatial changes of PE in the YRB from 1971 to 2000 were examined in detail. The major findings are as the follows:(1) there was an increasing trend in the YRB for PE starting from the late of 1980's although the general trend of global PE change was decrease;(2) the PE decreased in most areas of the YRB in spring and summer, but most parts increased in autumn and winter. At the mean time there exist areas, like the Fenhe River basin, where PE increased in all the seasons; and (3) sunshine hours decrease and wind speed decrease were the major causes for PE decrease from 1971 to 2000 and sunshine increase led to PE increase from the late of 1980's.
