资源环境科技发展态势分析平台

A detailed picture of how snowfall varies across high-elevation mountain ranges in both space and time remains a knowledge gap in understanding the montane hydrologic cycle. Previous studies generally used point-scale snow measurements in an attempt to represent the spatial variability of snowfall across a range; however, these traditional approaches provide incomplete insight into the cumulative snowfall (CS) distribution from the basin-scale to the mountain range-scale. In this study, a high-resolution, spatially distributed snow reanalysis was utilized to characterize 31 winters (water years 1985-2015) of snowfall distributions, snowfall accumulation rates, and snowstorms across the Sierra Nevada (USA). The CS data set (quantified in units of snow water equivalent) was verified against over 2600 station years of in situ observations. The seasonal CS was found to have mean and root-mean-squared differences of 24 and 12 cm, respectively, and a correlation of 0.96 with snow pillow observations. Using this novel CS information, results indicated that the CS accumulates rapidly across all 20 basins examined with, on average, at least 50% of the integrated CS accumulating in less than or equal to 6 days or three snowstorms over each basin. The largest (or leading) snowstorms each season yield similar to 27% of the CS, on average, and most frequently last 4 days. Across the range, over 40% of the leading snowstorms occur in February. This study showed that the hydroclimatology of the Sierra Nevada is driven by hydrological extremes as manifested in the high interannual variability of its seasonally integrated CS, 4.4-41.3 km(3), during the 31 years.