SMAP Active Passive Soil Moisture Dynamics During the Climate Extremes Across the Southern and Western US During Spring and Early Summer 2015

The western United States is experiencing a severe multiyear drought. Drought is often associated with extreme warm temperatures, heatwaves and wildfires. One major challenge for drought outlook is to correctly map the extent and intensity of drought. Accurate representation of surface conditions is prerequisite to characterizing its evolution in weather models. Because capturing processes related to soil moisture-atmosphere interaction (e.g., convective triggering) require data with spatial scale of a few kilometers, the availability of accurate SMAP soil moisture data with high temporal and spatial resolution will significantly advance our understanding of these processes. Furthermore, the ability of SMAP to retrieve soil moisture over low to moderate vegetation water content enables investigation of the vegetation impact on the soil moisture-atmosphere feedback. Utilization of such unprecedented data in studying the role of soil moisture-atmosphere interaction in severe drought development and recovery not only helps understand physical processes behind drought-related extreme phenomena, but also improves drought forecast skill (e.g., via improving the weather forecast models to better capture both severity and lead time of drought forecast). NASA's Soil Moisture Active Passive (SMAP) mission was launched on January 31st, 2015. The objective of the mission is global mapping of surface soil moisture and landscape freeze/thaw state. SMAP utilizes an L-band radar and radiometer sharing a rotating 6-meter mesh reflector antenna. Merging of the high-resolution active (radar) and coarse-resolution but high-sensitivity passive (radiometer) L-band observations enable an unprecedented combination of accuracy, resolution, coverage and revisit-time for soil moisture retrievals. Experimentally a much higher resolution global surface soil moisture data set is also produced at 3 km. However, on July 7th, 2015, the SMAP radar encountered an anomaly and is currently inoperable. Efforts are being made to revive the SMAP radar. Due to the present status of the SMAP observatory, nearly ~2.5 months (from spring to early summer of 2015) of the SMAP Active Passive product at 3 km will be available for the proposed study.