SnowEx20 COSMOS Rover Soil Moisture, Version 1 and SnowEx20 COSMOS Stationary Soil Moisture, Version 1 data sets, are now available at the NASA National Snow and Ice Data Center Distributed Active Archive Center (NSIDC DAAC). SnowEx20 COSMOS Rover Soil Moisture, Version 1 contains the raw and processed data files from a COSMOS Rover soil moisture probe. The COSMOS Rover uses fast neutron counting to estimate soil moisture over a region up to 300m from the vehicle. Data were collected in one-minute intervals over four days (04 November to 07 November 2019) of driving around Grand Mesa, Colorado. Raw data parameters include atmospheric pressure, temperature, and relative humidity. These raw observations were converted to volumetric soil moisture in the processed data files.