Spatial And Temporal Distribution Of Satellite Remote Sensing Soil Moisture And Its Feedback To Atmospheric Precipitation

Soil moisture adjusts and controls water vapor and energy exchange between the lower atmosphere and land by changing the surface albedo, soil heat capacity, sensible heat and latent heat, which has significant impacts on climate change and weather process. Soil moisture also helps to improve the forecast ability. This study adopts ECV satellite remote sensing soil moisture data, which was produced by the European space agency, and verifying it with observation data derived from Agricultural & meteorological observatory in the middle and lower reaches of the Yangtze river region. It is also compared with NCEP/ERA-Interim reanalysis soil moisture datasets. The results showed that ECV data was consistent with station data, but had an opposite phase with the NCEP/ERA-interim reanalysis soil moisture data; so that the ECV has higher credibility than reanalysis soil moisture data on the seasonal variability in the middle and lower reaches of the Yangtze River region. In terms of inter-annual variability, the ECV and the station data showed a high consistency with the two sets of reanalysis data. During the study period, soil moisture was seen to have the tendency of humidifying in winter and drying in summer.In addition, this study includes a comparison between ECV data with the VIC soil moisture data which is simulated by the large-scale land hydrological VIC model on nationwide was done. The results show that both ECV and VIC data’s seasonal and inter-annual variation maintained very good consistency in the Hetao region, while the two sets of data showed a reverse phase in seasonal variation between may and September over the Huaihe river basin, presenting a weak positive correlation in their inter-annual variability. There is a reverse phase between the two sets of data within the seasonal variation over MinJiang river basin, while there are big differences on the inter-annual variability.On this basis, this study used the Ensemble Kalman Filter to assimilate ECV remote sensing soil moisture into the WRF model. Different numerical experiments were designed to investigate soil moisture anomalies in the middle and lower reaches of the Yangtze river basin in summer, and how it might affect atmospheric processes within the same period. The results showed negative anomalies in soil moisture during summer in the middle and lower reaches of the Yangtze River basin, which had little effect on the amount of precipitation in the area. Yet, it was seen to affect the overall spatial distribution of rainfall.