Blending Satellite Observed, Model Simulated, and in Situ Measured Soil Moisture over Tibetan Plateau

Abstract

Abstract:The inter-comparison of different soil moisture (SM) products over the Tibetan Plateau (TP) reveals the inconsistency among different SM products, when compared to in situ measurement. It highlights the need to constrain the model simulated SM with the in situ measured data climatology. In this study, the in situ soil moisture networks, combined with the classification of climate zones over the TP, were used to produce the in situ measured SM climatology at the plateau scale. The generated TP scale in situ SM climatology was then used to scale the model-simulated SM data, which was subsequently used to scale the SM satellite observations. The climatology-scaled satellite and model-simulated SM were then blended objectively, by applying the triple collocation and least squares method. The final blended SM can replicate the SM dynamics across different climatic zones, from sub-humid regions to semi-arid and arid regions over the TP. This demonstrates the need to constrain the model-simulated SM estimates with the in situ measurements before their further applications in scaling climatology of SM satellite products.

Validation of Spaceborne and Modelled Surface Soil Moisture Products with Cosmic-Ray Neutron Probes

“…These can be used as additional quality scores of soil moisture time series. Several applications of TC to soil moisture time series have been published [43,[117][118][119][120][121][122][123][124][125][126][127]. Gruber et al [128] list the assumptions made to perform the TC analysis: (i) Linearity between the true soil moisture signal and the observations; (ii) signal and error stationarity; (iii) independency between the errors and the soil moisture signal (error orthogonality); and (iv) independency between the errors of three soil moisture time series (zero error cross-correlation).…”

First Assessment of Sentinel-1A Data for Surface Soil Moisture Estimations Using a Coupled Water Cloud Model and Advanced Integral Equation Model over the Tibetan Plateau

“…It is sensitive to climate change due to its unique geographical features and ecological environments [3]. Current studies have made great efforts to obtain the surface biogeophysical parameters in this region [38,39]. However, validation endeavours regarding satellite-based soil moisture products from the Tibetan Plateau reveal an unsatisfactory performance [2,[40][41][42].…”

Analysis of the Qinghai-Xizang Plateau Monsoon Evolution and Its Linkages with Soil Moisture

“…Therefore, the ESA CCI soil moisture dataset is not suitable for the current study. The limited availability of satellite-based soil moisture estimates over the plateau within ESA CCI merged product mainly due to the inherent difficulties in retrieving soil moisture from permafrost and seasonally frozen ground [30]. Apparently, the ESA CCI soil moisture product is not suitable for the climate change studies at sub-continental and long-time scale due to the sparse retrieval of soil moisture over frozen land surfaces.…”

“…Previous evaluations of several reanalysis data for China showed that the ERA-40 reanalysis might generally capture the inter-annual variations of soil moisture from the surface to deeper layers [27,28]. Reasonable performances for ECMWF soil moisture analyses in the humid monsoon period were found using in situ measurements over the plateau [29,30]. Liu et al [31] indicated that the ERA-Interim soil moisture has better performance over the plateau compared to the National Centers for Environmental Prediction (NCEP) Climate Forecast System Reanalysis (CFSR).…”