Abstract:Soil moisture is a key variable in the terrestrial water cycle,and plays a key role in the exchanges of water and energy in the land-atmosphere interface.In this study,the ECV(Essential Climate Variable)soil moisture product derived from multiple satellites during 1988-2010 in the middle and lower researches of the Yangtze River basin is validated with agrometeorological observations,then further compared with the soil moisture from NCEP and ERA-Interim reanalysis datasets.The ECV satellite soil moisture appears to be highest in winter and lowest in summer,which agrees well with the agrometeorological observations.However,the datasets of both the NCEP and ERA-Interim reanalysis appear to be lowest in winter and highest in summer,which are clearly opposite to the ECV data and agrometeorological observations.As for the interannual variations,the ECV data are reasonably consistent with the agrometeorological observations and both groups of reanalysis data,especially in spring and autumn.This is particularly true in the area north of the Yangtze River and the surrounding areas of Dongting Lake and Poyang Lake,where their correlation coefficients reach 0.7~0.9.During the period of 1988-2010,the ECV satellite soil moisture appears to increase in winter,yet shows a declining trend in summer.