A Texas Flood from Land to Ocean Observed by SMAP

Floods are natural hazards that can have damaging impacts not only on affected land areas but also on the adjacent coastal waters. NASA's Soil Moisture Active Passive (SMAP) mission provides measurements of both surface soil moisture and sea surface salinity (SSS), offering the opportunity to study the effects of flooding events on both terrestrial and marine environments. Here, we present analysis of a severe flood that occurred in May 2015 in Texas using SMAP observations and ancillary satellite and in situ data that describe the precipitation intensity, the evolving saturation state of the land surface, the flood discharge peak, and the resulting freshwater plume in the Gulf of Mexico. We describe the spatiotemporal evolution of the different variables, their relationships, and the associated physical processes. Specifically, we identify a freshwater plume in the north-central Gulf, being distinct from the typical Mississippi River plume, that is attributable to the Texas flood.