The Soil Moisture Active Passive (SMAP) "Soil Moisture 36 km (L3, Passive, Day)" layers display a daily global composite of surface soil moisture in cm³/cm³ posted to a 36 km EASE-Grid 2.0 derived from the Single Channel Algorithm V-Pol (SCA-V), the baseline soil moisture algorithm, for the 6:00 a.m. descending (DayAM) half-orbit passes of the SMAP radiometer. The SMAP radiometer measures natural thermal emission emanating from the soil surface. The variation in the intensity of this radiation depends on the dielectric properties and temperature of the target medium, which for the near surface soil layer is a function of the amount of moisture present.

The SMAP spacecraft carries two instruments, a radar (active) and a radiometer (passive), that together make global measurements of land surface soil moisture and freeze/thaw state. It is useful for monitoring and predicting natural hazards such as floods and droughts, understanding the linkages between Earth’s water, energy and carbon cycles, and reducing uncertainties in predicting weather and climate.

References: SMAP L3 Radiometer Global Daily 36 km EASE-Grid Soil Moisture

Data field: soil_moisture