长江中下游地区1988—2010年遥感土壤湿度的时空变化

利用农业气象站观测资料对长江中下游地区1988-2010年遥感土壤湿度进行了验证，并与NCEP和ERA-Interim土壤湿度做了对比分析。研究表明，ECV遥感土壤湿度冬季平均土壤湿度最高，春季和秋季次之，夏季平均土壤湿度最低；这种季节性干湿变化与农业气象站观测资料一致。但是，NCEP和ERA-Interim土壤湿度再分析资料，则夏季平均土壤湿度高，春季和秋季次之，而冬季平均土壤湿度最低；这种季节性变化与ECV遥感土壤湿度和农业气象站观测资料呈反位相。就年际变化而言，ECV遥感土壤湿度与农业气象站观测资料和两套再分析资料均有较高的一致性，并在春季和秋季最高，尤其是在长江以北地区和长江以南洞庭湖、鄱阳湖两大湖区，相关系数达到0.7~0.9；而夏季一致性最低，相关系数仅为0.4左右。在研究时段，ECV土壤湿度在冬季明显增加，在夏季则有明显下降趋势。

Spatio-temporal variations of remote sensing soil moisture during the period of 1988-2010 in the middle and lower researches of the Yangtze River Basin

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.