Multi-Resolution L-Band Microwave Observations for Growing Vegetation during SMAPVEX16-IA

Microwave observations, such as those at L-band, are highly sensitive to soil moisture in the upper few centimeters (near-surface). The NASA Soil Moisture Active/Passive (SMAP) mission includes passive sensor at L-band that provides global observations of SM at 36 km, with a repeat coverage of every 2-3 days. These observations can significantly improve root zone soil moisture when data assimilated into land surface models (LSMs). The SMAP Validation Experiment-2016 (SMAPVEX16) was conducted during the summer from May through August 2016 in predominantly agricultural regions in Iowa (SMAPVEX16-IA) and Manitoba. During the experiment, aircraft and ground-based observations of L-band active and passive signatures of corn and soybean were obtained at the SMAP incidence angle of 40•. The aircraft measurements were obtained from the NASA/JPL Passive Active L- and S-band Sensor (PALS) during the time of SMAP overpasses from May 23 through June 3 and from August 3 through August 16, 2016. The ground-based University of Florida (UFLMR) and University of Michigan L-band Radiometer (UMLMR) systems observed microwave signatures of soybean and corn, respectively, at the Sweeney Farms, about 70 km north of Ames, IA. The ground-based sensors conducted every 15-minutes observations from May 23 through September 2, 2016. In addition, soil, vegetation, and micro-meteorological conditions were also monitored throughout the growing season. In this study, we discuss the satellite observations from SMAP and ESA Soil Moisture and Ocean Salinity (SMOS) along with those from PALS, and UFLMR/UMLMR at differing resolutions to understand implications of spatial heterogeneity on soil moisture retrievals in agricultural regions. resolutions. The preliminary results show SMAP observations at 36 km correspond well with the ground-based observations for corn, the predominant land cover in the region.