Snow water equivalent estimates from airborne radar in the St. Elias Mountains

Quantifying the input mass from snow accumulation on rapidly changing glaciers is critical to establishing baseline states and predicting responses to climate change. Some of the largest glaciers in the world are located in the St. Elias Mountains in Southeast Alaska and Southwest Yukon; however, the input mass to these glaciers is poorly constrained. Here we used airborne radar sounding combined with in situ measurements of snow properties, and satellite imagery from Landsat 8/9 and Sentinel 1, to estimate the winter mass balance on the Bering, Hubbard, Kaskawulsh, Logan, Seward, Walsh, and Yahtse glaciers. Along-track snow water equivalent measurements for the winter accumulation period range from 0 to 3 m in 2018, 0.2 to 3.4 m in 2021, and 1.1 to 3.3 m in 2023. On-glacier measurements from the Seward and Kaskawulsh glaciers provided a mean seasonal snow density of 438 ± 22 kg m-3 which leads to a real dielectric permittivity of 1.86 ± 0.12, similar to values from other Alaskan glaciers. We observed that the maritime glaciers Yahtse, Bering, Hubbard, and Seward receive significantly more accumulation than the more inland glaciers.