Continuous Snow and Rain Data at 500 to 4400 m Altitude near Annapurna, Nepal, 1999–2001

Abstract

Knowledge of spatial and altitudinal variations in precipitation in high mountains is integral to quantifying alpine climates and to calibrating interactions between climate and surface processes. To date, however, few meteorological networks exist in alpine settings. A network of 14 meteorological stations was installed across the Annapurna Range in central Nepal in 1999 and expanded in subsequent years to 19 stations. In order to measure snow depths and water equivalents in high-altitude sites, a combination of look-down distance rangers and gamma-ray loggers was installed at 5 sites. The data from this network delineate a strong south-to-north gradient in monsoonal precipitation. Precipitation peaks at 5032 mm yr−1 at about 3000 m altitude on the southern side, which is also approximately the lowest altitude of winter snow in the area. Annual precipitation decreases to ∼1100 mm yr−1 in the rain shadow to the north of the Himalayan crest. Although snow depth and snow water equivalent content are strongly dependent on station altitude, snow depth shows little spatial variation at a given altitude, partly due to the surprisingly low local wind speeds. Based on extrapolation of mean monthly summer lapse rate of air temperature, only snow precipitates above 5883 m.