High Temporal Resolution Time-Series of Calibrated Radar Backscatter and Interferometric Phase and Coherence of Snowpack at Davos-Laret During Winter 2019-2020 Using the WBSCAT Microwave Scatterometer

Estimation of snow water equivalent (SWE) from microwave measurements requires models that are responsive to the complex variability of radar backscatter from the snowpack during the winter season. WBSCAT is a tower-based microwave scatterometer that that can acquire coherent, polarimetric measurements of radar backscatter over the frequency range from 1-40 GHz. These data can help us identify key observation parameters, correlated with SWE, snow structure, and temperature, to support development of new missions and the retrieval of SWE estimates within the capabilities of current and planned radar missions including TerraSAR-X, Sentinel-1, and NISAR.

WBSCAT was deployed on a tower 8-meters above the ground during the 2019-2020 winter season at the Davos-Laret Remote Sensing Field Laboratory (SnowLab) in cooperation with the WSL Institute of for Snow and Avalanche Research [1]. The site is located at 1414 meters altitude over a relatively flat grass ground cover. Nearly continuous measurements of fully-polarimetric coherent radar backscatter began in October 2019 and continued until May 2020. WBSCAT has been developed for the European Space Agency (ESA) by Gamma Remote Sensing to support microwave studies of a wide range of ground covers including snow and ice [2].

We present time-series of the normalized radar cross-section of the snowpack, as well as interferometric phase and coherence. Combined with in-situ measurements of the snowpack state, including temperature, moisture, structure, and SWE, this constitutes a unique data set for studying the relationship of the state of the snowpack with calibrated radar measurements.

[1] A. Wiesmann et. al., "ESA SnowLab Project: 4 Years of Wide Band Scatterometer Measurements of Seasonal Snow," in Proc. IEEE Int. Geosci. Remote Sens. Symp., Yokohama, Japan, July 2019.

[2] C, Werner et al. "The ESA Wideband Microwave Scatterometer (WBSCAT): Design and Implementation," in Proc. IEEE Int. Geosci. Remote Sens. Symp., Yokohama, Japan, July 2019.