Measuring Winter Precipitation in a Mountain Catchment

Measuring winter precipitation (principally snowfall) in a mountain catchment is difficult. The magnitude of gauge under catch is affected by variable density during deposition, wind speed and direction, and site conditions such as vegetation and topography. Though numerous studies have been conducted to quantify gauge under catch as a function of wind in order to develop correction factors, all used gauge catch at a reference site to represent 'true' deposition. None used direct measurement of snow on the ground, and few involved measurement locations within a catchment to sample a range of site conditions and wind exposures. In this study we evaluate data from 10 precipitation measurement sites within a mountain catchment. Each site includes an Alter-shielded and an unshielded 8-inch Belfort-type precipitation gauge, sonic snow depth, wind speed and direction, temperature, humidity, and solar radiation sensors. In addition, one site includes a snow pillow, and a series of seven near by bi-weekly snow course measurements provide density estimates for the precipitation measurement sites. Unshielded and shielded gauge catch are compared to wind corrected catch using the dual-gauge and the WMO wind correction approaches. Snow depth is combined with snow density derived from the snow pillow and the near-by snow courses to estimate true snow deposition near the measurement sites. This research will improve our understanding of the relationships between precipitation, deposition, and gauge catch in mountainous regions.