Implications of Detection Methods on Characterizing Atmospheric River Contribution to Seasonal Snowfall Across Sierra Nevada, USA

Abstract

This study investigates the extent to which the diagnosed contribution of atmospheric rivers (ARs) to the seasonal cumulative snowfall (CS) is related to the AR detection approach utilized. Using both satellite integrated water vapor (IWV)-based and reanalysis integrated vapor transport (IVT)-based methodologies, the corresponding AR-derived CS distributions were characterized over the Sierra Nevada (USA) from 1998 to 2015. AR detection methods indicated that ARs yield greater orographic enhancement of the seasonal CS than non-AR storms above ~2,100–2,300 m for the IWV-based approach and over all elevations for the IVT-based detection approach across the western (i.e., windward) Sierra Nevada. Due to differences in the methodologies, the IWV-based approach diagnosed 2.1 times fewer ARs than the IVT-based approach. As a result, the ARs diagnosed using the IWV-based detection method yielded an average 33% of the total range-wide CS annually as opposed to 56% from the IVT-based detection method.