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United States Department of Agriculture

Agricultural Research Service

Research Project: USING REMOTE SENSING & MODELING FOR EVALUATING HYDROLOGIC FLUXES, STATES, & CONSTITUENT TRANSPORT PROCESSES WITHIN AGRICULTURAL LANDSCAPES Title: Soil temperature error propagation in passive microwave retrieval of soil moisture

Authors
item Holmes, Thomas
item Jackson, Thomas

Submitted to: Specialist Meeting on Microwave Remote Sensing
Publication Type: Proceedings
Publication Acceptance Date: March 5, 2010
Publication Date: August 1, 2010
Citation: Holmes, T.R., Jackson, T.J. 2010. Soil temperature error propagation in passive microwave retrieval of soil moisture. Specialist Meeting on Microwave Remote Sensing. p. 67-70.

Technical Abstract: In the near future two dedicated soil moisture satellites will be launched (SMOS and SMAP), both carrying an L-band radiometer. It is well known that microwave soil moisture retrieval algorithms must account for the physical temperature of the emitting surface. Solutions to this include: difference or ratio indices; forecast model products; thermal infrared satellite observations; and high frequency passive microwave estimates. The availability of multifrequency observations in the same data stream as part of past low-frequency passive microwave missions has made the use of high frequency temperature estimates, specifically 37 GHz (Ka-band), an attractive option. SMOS and SMAP will not include a 37 GHz (Ka-band) microwave radiometer. Therefore, alternative algorithms and data sources will be utilized. One proposed approach is the use of temperature output from numerical weather prediction (NWP) models. This temperature estimate will need to closely match the spatial resolution and the overpass time of SMOS and SMAP (between 6 and 7 am/pm local time). To date, very little analysis has been performed to assess the accuracy of the NWP forecasts in terms of land surface temperature. In addition, the relationship between the model products and the requirements of radiative transfer and soil moisture retrieval algorithm temperature requirements needs to be assessed. A radiative transfer model as implemented in the most commonly used soil moisture retrieval algorithms will be used to assess sensitivity to errors in the estimated surface temperature. Results will be illustrated with data from currently available C-band satellite data and L-band tower observations. These results should contribute to improved algorithm design and implementation for the new L-band satellite missions.

Last Modified: 9/22/2014
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