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Title: TEMPORAL STABILITY OF WATERSHED SCALE SOIL MOISTURE FROM IN-SITU POINT MEASUREMENTS IN SMEX02

Author
item Cosh, Michael
item Jackson, Thomas
item BINDLISH, RAJAT - SSAI
item Prueger, John

Submitted to: BARC Poster Day
Publication Type: Abstract Only
Publication Acceptance Date: 3/7/2003
Publication Date: 5/1/2003
Citation: Cosh, M.H., Jackson, T.J., Bindlish, R., Prueger, J.H. 2003. Temporal Stability of Watershen Scale Soil Moisture from In-Situ Measurements in SMEX02, 2003, Abs.8. BARC Poster Day.

Interpretive Summary:

Technical Abstract: Watershed scale soil moisture estimates are necessary to validate current remote sensing products, such as those from the Advanced Microwave Scanning Radiometer (AMSR). Unfortunately, remote sensing technology does not currently resolve the land surface at a scale that is easily observed with ground measurements. One approach to validation is to use existing soil moisture measurement networks and scales these point observations up to the resolution of remote sensing footprints. As part of the Soil Moisture Experiment 2002 (SMEX02), one such soil moisture gaging system was implemented in the Walnut Creek Watershed, Iowa, which when calibrated, provided robust estimates of the soil moisture average for a watershed throughout the summer of 2002. Twelve in-situ soil moisture probes were installed across the watershed. These probes recorded soil moisture at a depth of 5 cm from June 29th, 2002 to August 19th, 2002. The sampling sites were analyzed for temporal and spatial stability by several methods including mean relative difference, Spearman rank, and correlation coefficient analysis. Representative point measurements were scaled up to the watershed scale (~25 km) and shown to be accurate indicators with low variance and bias of the watershed scale soil moisture distribution. This work establishes the validity of this approach to provide watershed scale soil moisture estimates in this study region for the purposes of satellite validation. Also, the potential errors in this type of analysis are explored. This analysis is a first step in the implementation of large-scale soil moisture validation using existing networks such as the Soil Climate Analysis Network (SCAN) and several Agricultural Research Service watersheds as a basis for calibrating soil moisture satellite products.