30 May 2022
30 May 2022

Snow stratigraphy observations from Operation IceBridge surveys in Alaska using S/C band airborne ultra-wideband FMCW radar

Jilu Li, Fernando Rodriguez-Morales, Carl Leuschen, John Paden, Daniel Gomez-Garcia, and Emily Arnold Jilu Li et al.
  • The Center for Remote Sensing of Ice Sheets, University of Kansas, Lawrence, KS 66045, USA

Abstract. During the concluding phase of the NASA Operation IceBridge (OIB), we successfully completed two airborne measurement campaigns (in 2018 and 2021, respectively) using a compact S/C band radar installed on a Single Otter aircraft and collected data over Alaskan mountains, ice fields, and glaciers. We observed snow strata in ice facies, wet-snow/percolation facies and dry snow facies from radar data. This paper reports seasonal snow depths derived from our observations. We found large variations in seasonal radar-inferred depths assuming a constant relative permittivity for snow equal to 1.89. The majority of the seasonal depths observed in 2018 were between 3.2 m and 4.2 m, and around 3 m in 2021. We also identified the transition areas from wet-snow facies to ice facies for multiple glaciers based on the snow strata and radar backscattering characteristics. Our analysis focuses on the measured strata of multiple years at the caldera of Mount Wrangell to estimate the local snow accumulation rate. We developed a method for using our radar readings of multi-year strata to constrain the uncertain parameters of interpretation models with the assumption that most of the snow layers detected by the radar at the caldera are annual accumulation layers. At a 2004 ice core and 2005 temperature sensor tower site, the locally estimated average snow accumulation rate is ~2.89 m w. e. a-1 between the years 2002 and 2021. Our estimate of the snow accumulation rate between 2005 and 2006 is 2.82 m w. e. a-1, which matches closely to the 2.75 m w. e. a-1 inferred from independent ground-truth measurements made the same year. We also found a linear increasing trend of 0.011 m w. e. a-1 per year between the years 2002 and 2021. With this trend, we extrapolated the snow accumulation back to 1992 and obtained an average accumulation rate of 2.74 w. e. a-1 between the years 1992 and 2004, which agrees well with the value of 2.66 w. e. a-1 for the same period determined from the ice core data retrieved at the caldera in 2004. The results reported here verified the efficacy of our method, its assumption, and the interpretation models.

Jilu Li et al.

Status: final response (author comments only)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on egusphere-2022-368', William D. Harcourt, 06 Aug 2022
    • AC1: 'Reply on RC1', Jilu Li, 21 Oct 2022
  • RC2: 'Comment on egusphere-2022-368', HP Marshall, 19 Sep 2022
    • AC2: 'Reply on RC2', Jilu Li, 21 Oct 2022

Jilu Li et al.

Data sets

CReSIS Snow Radar Data Products John Paden, Jilu Li, Carl Leuschen

Jilu Li et al.


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Short summary
Ice mass loss from Alaskan glaciers is an important contributor to global sea level rise. Snow depth and accumulation on these glaciers are key components to understand and model the process of glacier mass loss. In this paper, we reported the observed seasonal snow depth distribution, developed a method to estimate snow accumulation rate at Mt. Wrangell caldera, and identified transition areas from wet-snow zones to ablation zones by analyzing our radar observations in Alaska in 2018 and 2021.