EGU24-4137, updated on 08 Mar 2024
EGU General Assembly 2024
© Author(s) 2024. This work is distributed under
the Creative Commons Attribution 4.0 License.

Comparing multisensor optical-radar approaches for snow water equivalent retrievals

Jack Tarricone1,2, Ross Palomaki3, Karl Rittger3, Hans-Peter Marshall4, Anne Nolin5, and Carrie Vuyovich1
Jack Tarricone et al.
  • 1NASA Goddard Space Flight Center, Hydrological Sciences Laboratory, Washington, USA
  • 2NASA Goddard Space Flight Center, NASA Postdoctoral Program, Washington, USA
  • 3University of Colorado Boulder, Institute of Arctic and Alpine Research, Boulder, USA
  • 4Boise State University, Department of Geosciences, Boise, USA
  • 5University of Nevada Reno, Department of Geography, Reno, USA

No current remote sensing technique can accurately measure snow water equivalent (SWE) from space for mountain hydrologic applications. Optical sensors are robust for measuring the fractional snow-covered area (fSCA) at various spatial and temporal resolutions. Yet, these optical methods are limited by cloud cover and do not provide information on SWE. Synthetic aperture radar (SAR) can penetrate clouds, has a fine spatial resolution, and various algorithms allow us to quantify both SWE magnitude and changes. However, SAR cannot discriminate between snow-free and snow-covered areas when the snow is dry. To address this SWE monitoring challenge, we evaluate a multisensor approach that leverages the strengths of both optical and radar sensors. Our study aims to better understand the variability between common snow cover data products and how that uncertainty propagates into InSAR-based SWE retrieval techniques. We analyzed four UAVSAR InSAR pairs from one flight line over the Sierra Nevada, CA, during the SnowEx 2020 campaign and compared six satellite-based snow cover products. First, we computed InSAR-based SWE change estimates using in situ snowpack data. We then compared the summed SWE change values with a moving window analysis to quantify product variability. Lastly, we tested the volumetric SWE results for statistical differences. Results show that moderate-resolution (375–500 m) NDSI-based products provide broadly similar volumetric SWE change results to those using more complex spectral unmixing and machine learning retrieval methods. This suggests that the readily available moderate-resolution snow cover products from MODIS are adequate for an optical-radar SWE monitoring approach. Future work should focus on understanding how sub-canopy snow in forested regions affects snow cover product accuracy and variability. Furthermore, near-real-time, high-resolution cloud- and gap-filled optically-derived snow cover data will be important for supporting water resources decision-making.

How to cite: Tarricone, J., Palomaki, R., Rittger, K., Marshall, H.-P., Nolin, A., and Vuyovich, C.: Comparing multisensor optical-radar approaches for snow water equivalent retrievals, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4137,, 2024.