EGUsphere EGUsphere EGUsphere EGUsphere Copernicus Publications Göttingen, Germany 10.5194/egusphere-2026-5140 Brief communication: First NISAR Interferometric snow water equivalent change retrieval evaluated against airborne lidar Hoppinen Zachary https://orcid.org/0000-0003-0916-7774 1 Marshall Hans-Peter 2 Palomaki Ross https://orcid.org/0000-0002-3304-9914 3 Kane Coleman 2 Ciafone Siobhan https://orcid.org/0009-0009-7418-4045 4 O'Neel Shad https://orcid.org/0000-0002-9185-0144 4 Van Der Weide Thomas https://orcid.org/0000-0001-6691-2473 2 Geophysical Institute, University of Alaska Fairbanks, 2156 Koyukuk Drive, Fairbanks, AK, USA Department of Geosciences, Boise State University, 1910 University Drive, Boise, ID 83725, USA Institute of Arctic and Alpine Research, University of Colorado, 4001 Discovery Dr, Boulder, CO 80303, USA Cold Regions Research and Engineering Laboratory, US Army Engineer Research and Development Center, 72 Lyme Road, Hanover, NH 03755, USA 23 09 2026 2026 1 11 Copyright: © 2026 Zachary Hoppinen et al. 2026 This work is licensed under the Creative Commons Attribution 4.0 International License. To view a copy of this licence, visit https://creativecommons.org/licenses/by/4.0/ This article is available from https://egusphere.copernicus.org/preprints/2026/egusphere-2026-5140/ The full text article is available as a PDF file from https://egusphere.copernicus.org/preprints/2026/egusphere-2026-5140/egusphere-2026-5140.pdf

NISAR's global L-band repeat-pass interferometry should be sensitive to snow water equivalent change (&Delta;SWE). We compare &Delta;SWE from an operational NISAR interferogram to near-coincident airborne lidar snow-depth change over a February 2026 pair in southwest Idaho. Across the scene, &Delta;SWE correlates well with the lidar depth change (<em>r</em> = 0.82, rising to <em>r</em> = 0.93 above a coherence of 0.2). The agreement is dominated by variability at scales above ~1 km (<em>r</em> &asymp; 0.94), while the correlation at sub-kilometer scales is weaker (<em>r</em> &asymp; 0.42), improving over open terrain and at incidence angles below 50&deg;. These results provide the first direct evidence that NISAR phase can measure dry-snow accumulation.

 National Aeronautics and Space Administration 80NSSC25K7452 80NSSC25M7047