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
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