Dar Roberts David R. Thompson Philip Brodrick Brent Wilder Niklas Bohn Christopher J. Crawford Nimrod Carmon Carrie Vuyovich Jeff Dozier Edward Bair 2025 <p><span>Key to the success of spaceborne missions is understanding snowmelt in our warming climate, as this has implications for nearly 2 billion people. An obstacle is that surface reflectance products over snow show an erroneous hook with decreases in the visible wavelengths, causing per-band and broadband reflectance errors of up to 33 % and 11 %, respectively. This hook is sometimes mistaken for soot or dust but can result from three artifacts: (1) background reflectance that is too dark, (2) an assumption of level terrain, or (3) differences in optical constants of ice. Sensor calibration and directional effects may also contribute. Solutions are being implemented.</span></p> application/pdf 10.5194/tc-19-2315-2025 en European Geosciences Union Brief communication: Not as dirty as they look, flawed airborne and satellite snow spectra article