Validation of the combined active and passive microwave snow retrieval algorithm by using NASA SnowEx 2017 and ESA NoSREx 2009-12

To monitor a global distribution of snow water equivalent (SWE), much more efforts have been recently made geared toward a satellite mission to observe SWE. This paper focuses on evaluating a performance of the already developed algorithm based on the active and passive microwave volume scattering approach to retrieve SWE from space. The validation is achieved by comparing two independent observations: 1) microwave volume scattering measurements such as a brightness temperature, and a backscattering coefficient of snow, and 2) in-situsnow observations including snow grain size, temperature, density, and depth which are essential contributions to microwave signatures.

Specifically, NASA SnowEx 2017 and ESA NoSREx 2009-12 dataset are used to provide the airborne and ground-based volume scattering observations and in-situ snow measurements conducted during the two field campaigns. Coincident and collocated satellite observations are also analyzed to provide with the brightness temperature on the same scenes of the field campaigns. Improved comparison statistics by using the retrieved SWE compared to the observed SWE will be reported. In addition, the sensitivity studies by using in-situand modeled snow observation are demonstrated to evaluate the influence of the snow microstructures on the microwave volume scattering signals for a future algorithm development based on microwave active and passive combined method.