Abstract: SMAP Soil Moisture Drying More Rapid Than Observed in Situ Following Rainfall Events. (ASA, CSSA and SSSA International Annual Meetings (2016))

204-4 SMAP Soil Moisture Drying More Rapid Than Observed in Situ Following Rainfall Events.

See more from this Division: SSSA Division: Soil Physics and Hydrology
See more from this Session: Remote Sensing of Land Surface and Vadose Zone Hydrologic Processes Oral

Tuesday, November 8, 2016: 8:50 AM

Phoenix Convention Center North, Room 131 A

Peter Shellito, UCB 399, University of Colorado at Boulder, Boulder, CO, Eric Small, University of Colorado Boulder, Boulder, CO, Andreas Colliander, Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, Rajat Bindlish, USDA-ARS, Beltsville, MD, Michael H. Cosh, 10300 Baltimore Ave, USDA-ARS, Beltsville, MD, Aaron Berg, University of Guelph, Guelph, ON, Canada, David D. Bosch, USDA-ARS, Tifton, GA, Todd G. Caldwell, University Station, Box X, University of Texas-Austin, Austin, TX, Dave Goodrich, USDA-ARS, Tucson, AZ, Heather McNairn, Agriculture and Agri-Food Canada, Ottawa, ON, Canada, John H. Prueger, National Laboratory for Agriculture and the Environment, Ames, IA, Patrick Starks, Grazinglands Research Laboratory, USDA-ARS, El Reno, OK, Rogier van der Velde, ITC Faculty, University of Twente, Enschede, Netherlands and Jeffrey Walker, Civil Engineering, Monash University, Clayton, Australia

Audio File Recorded Presentation

Abstract:

We examine soil drying rates by comparing observations from the NASA Soil Moisture Active Passive (SMAP) mission to surface soil moisture from in situ probes during drydown periods at SMAP validation sites. SMAP and in situ observe soil drying behavior differently after rainfall. We modeled this process by fitting an exponential curve to 63 drydown events: the median SMAP drying timescale is 44% shorter and the magnitude of drying is 35% greater than in situ measurements. We also calculated drying rates between consecutive observations from 193 events. For 6 days after rainfall, soil moisture from SMAP dries at twice the rate of in situ measurements. Restricting in situ observations to times of SMAP observations does not change the drying timescale, magnitude, or rate. Therefore, observed differences are likely due to SMAP’s sensing depth being shallow (<5 cm) following a rainfall event and increasing as the soil dries.

See more from this Division: SSSA Division: Soil Physics and Hydrology
See more from this Session: Remote Sensing of Land Surface and Vadose Zone Hydrologic Processes Oral

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