1. Evaluating L-band InSAR snow water equivalent retrievals with repeat ground-penetrating radar and terrestrial lidar surveys in northern Colorado.
- Author
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Bonnell, Randall, McGrath, Daniel, Tarricone, Jack, Marshall, Hans-Peter, Bump, Ella, Duncan, Caroline, Kampf, Stephanie, Lou, Yunling, Olsen-Mikitowicz, Alex, Sears, Megan, Williams, Keith, Zeller, Lucas, and Zheng, Yang
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SYNTHETIC aperture radar , *GROUND penetrating radar , *REMOTE sensing , *WATER supply , *TIME series analysis - Abstract
Snow provides critical water resources for billions of people, making the remote sensing of snow water equivalent (SWE) a highly prioritized endeavor, particularly given ongoing climate change impacts. Synthetic aperture radar (SAR) is a promising method for remote sensing of SWE because radar penetrates snow, and SAR interferometry (InSAR) can be used to estimate changes in SWE (Δ SWE) between SAR acquisitions. We calculated Δ SWE retrievals from 10 NASA L-band (1–2 GHz, ∼25 cm wavelength) uninhabited aerial vehicle SAR (UAVSAR) acquisitions covering a ∼640 km 2 swath in northern Colorado during the winters of 2020 and 2021. UAVSAR acquisitions coincided with ∼117 mm of accumulation in 2020 and ∼282 mm of accumulation in 2021. Δ SWE retrievals were evaluated against measurements of SWE from repeat ground-penetrating radar (GPR) and terrestrial lidar scans (TLSs) collected during the NASA SnowEx time series campaigns at two field sites (total area =∼0.2 km 2) as well as SWE measurements from seven automated stations distributed throughout the UAVSAR swath. For single InSAR pairs, UAVSAR Δ SWE retrievals yielded an overall r of 0.72–0.79 and an RMSE of 19–22 mm when compared with TLS and GPR Δ SWE retrievals. UAVSAR Δ SWE showed some scatter with Δ SWE measured at automated stations for both study years, but cumulative UAVSAR SWE yielded a r of 0.92 and an RMSE of 42 mm when compared to total SWE measured by the stations. Further, UAVSAR Δ SWE RMSEs differed by <10 mm for coherences (i.e., the complex interferometric coherence) of 0.10 to 0.90, suggesting that coherence has only a small influence on the Δ SWE retrieval accuracy. Given the evaluations presented here and in other recent studies, the upcoming NASA-ISRO SAR (NISAR) satellite mission, with a 12 d revisit period, offers an exciting opportunity to apply this methodology globally. [ABSTRACT FROM AUTHOR]
- Published
- 2024
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