Hydrologic length scale of L-band radiometric soil moisture retrievals
Abstract
Remotely sensed microwave soil moisture retrievals are typically assigned a nominal sensing depth scale into the soil column based on radiometric properties of soils and the observation system. We instead calculate a hydrologic length scale, based on conservation of water mass in a surface layer, defined by the data streams of satellite soil moisture and precipitation retrievals. The length scale is derived using a variance budget relationship based on three variables: the autocorrelation and variance of surface soil moisture and the variance of the net flux into the column (precipitation minus estimated outflow), which can be estimated directly from the soil moisture and precipitation time series. The length scale is found to vary in space as well as seasonally, is generally larger than the 50 mm nominal radiometric length scale for the soil moisture retrievals, and is correlated with local hydroclimate conditions. Limitations and interpretations of "box models" for both hydrologic and radiometric physics are discussed.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2018
- Bibcode:
- 2018AGUFM.H42G..02G
- Keywords:
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- 1833 Hydroclimatology;
- HYDROLOGYDE: 1843 Land/atmosphere interactions;
- HYDROLOGYDE: 1855 Remote sensing;
- HYDROLOGYDE: 1866 Soil moisture;
- HYDROLOGY