Integrating Optical and Microwave Satellite Observations for High Resolution Soil Moisture Estimate and Applications in CONUS Drought Analyses
by Donglian Sun, Yu Li, Xiwu Zhan, Chaowei Yang, Ruixin Yang
Remote Sensing, Vol.13, No.1, 2024;
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In this study, optical and microwave satellite observations are integrated to estimate soil moisture at the same
spatial resolution as the optical sensors (5km here) and applied for drought analysis in the continental United States. A
new refined model is proposed to include auxiliary data like soil texture, topography, surface types, accumulated pre_x005fcipitation, in addition to Normalized Difference Vegetation Index (NDVI) and Land Surface Temperature (LST) used in
the traditional universal triangle method. It is found the new proposed soil moisture model using accumulated precipitation demonstrated close agreements with the U.S. Drought Monitor (USDM) spatial patterns. Currently, the USDM is
providing a weekly map. Recently, “flash†drought concept appears. To obtain drought map on daily basis, LST is
derived from microwave observations and downscaled to the same resolution as the thermal infrared LST product and
used to fill the gaps due to clouds in optical LST data. With the integrated daily LST available under nearly all weather
conditions, daily soil moisture can be estimated at relatively higher spatial resolution than those traditionally derived
from passive microwave sensors, thus drought maps based on soil moisture anomalies can be obtained on daily basis
and made the flash drought analysis and monitoring become possible.