Characterizing ICESat‐2 Snow Depths Over the Boreal Forests and Tundra of Alaska in Support of the SnowEx 2023 Campaign

Abstract Recent studies show that the Ice, Clouds, and Land Elevation Satellite‐2 (ICESat‐2) can achieve decimeter‐level accuracy over forested and mountainous sites in the western United States, as well as over the glaciers of Alaska. However, there has yet to be an assessment on ICESat‐2 snow depths over the boreal forests and tundra of Alaska, both of which are significant reservoirs of snow during the winter season. We present two case studies of retrieving snow depth using ICESat‐2 over Alaska. We focus on two field sites used by the NASA SnowEx 2022/2023 campaigns: Farmer's Loop/Creamer's Field near Fairbanks, AK (forest) and Upper Kuparuk/Toolik on the Arctic North Slope (tundra). When validated against airborne LiDAR flown by the University of Alaska, Fairbanks (UAF), we find median biases of −6.3 to +2.1 cm among three ICESat‐2 data products in the tundra region. Biases over the boreal forest are higher at 7.5–13 cm. Utilizing the open source tool SlideRule, we observe little change in results when filtering by the ICESat‐2 signal photon confidence scheme or by the vegetation filter. However, uncertainties in snow depth decrease with coarser Sliderule‐derived snow depths. The number of signal photons (i.e., signal strength) has an influence on retrievals, with a large number of photons per ICESat‐2 return providing more accurate snow depths. The initial results are promising, and we expect to expand this effort to other ICESat‐2 overpasses over the SnowEx field sites.