A New GrainSize Lookup Table for the Airborne Snow Observatory

TitleA New GrainSize Lookup Table for the Airborne Snow Observatory
Publication TypeConference Proceedings
Year of Conference2018
AuthorsOlson, Matthew, and Skiles McKenzie
Conference Name86th Annual Western Snow Conference
Conference LocationAlbuquerque, New Mexico

The Airborne Snow Observatory (ASO) is a coupled lidar and imaging spectrometer system developed by NASA-JPL to more accurately quantify important snowpack properties. Along with snow depth and water equivalency, ASO has the ability to drastically improve measurements of snow albedo, a major factor regulating the absorption of solar radiation and consequently snowmelt. Snow grain size is one of the primary parameters controlling the broadband albedo of a snowpack. Imaging spectrometry has provided the ability to examine snow grain size over basin-wide scales. Nolin and Dozier (2000) developed a method using imaging spectrometer data to estimate the optical grain size of a snow surface by relating the reflectance centered around an ice absorption feature at 1030 nm to optical grain size. Due to the operational demands of product delivery (24-hour turnaround time), the Nolin-Dozier approach to grain size retrievals has not yet been implemented in the CASI processing pipeline. Additionally, the CASI imaging spectrometer only covers a portion of the grain size absorption feature, requiring an updated relationship between the ice absorption feature and the grain size. Here, we created a look up table for the CASI spectral range and resolution using two methods, and compare grain size retrievals to current operational methodology. (KEYWORDS: snow hydrology, snow melt, snow energy balance, optical grain size, remote sensing)