Insights into mountain precipitation and snowpack from a basin‐scale wireless‐sensor network

Abstract

A spatially distributed wireless‐sensor network, installed across the 2154 km2 portion of the 5311 km2 American River basin above 1500 m elevation, provided spatial measurements of temperature, relative humidity, and snow depth in the Sierra Nevada, California. The network consisted of 10 sensor clusters, each with 10 measurement nodes, distributed to capture the variability in topography and vegetation cover. The sensor network captured significant spatial heterogeneity in rain versus snow precipitation for water‐year 2014, variability that was not apparent in the more limited operational data. Using daily dew‐point temperature to track temporal elevational changes in the rain‐snow transition, the amount of snow accumulation at each node was used to estimate the fraction of rain versus snow. This resulted in an underestimate of total precipitation below the 0°C dew‐point elevation, which averaged 1730 m across 10 precipitation events, indicating that measuring snow does not capture total precipitation. We suggest blending lower elevation rain gauge data with higher‐elevation sensor‐node data for each event to estimate total precipitation. Blended estimates were on average 15–30% higher than using either set of measurements alone. Using data from the current operational snow‐pillow sites gives even lower estimates of basin‐wide precipitation. Given the increasing importance of liquid precipitation in a warming climate, a strategy that blends distributed measurements of both liquid and solid precipitation will provide more accurate basin‐wide precipitation estimates, plus spatial and temporal patters of snow accumulation and melt in a basin.

Canopy Effects on Snow Accumulation: Observations from Lidar, Canonical-View Photos, and Continuous Ground Measurements from Sensor Networks

“…The difference of the canopy effect on snow accumulation at the lower elevations is also affected by the rain-on-snow events. Analyzing rain-on-snow events would need more meteorological data, especially temperature and relative humidity, for estimating the rain-snow partition along the elevation gradient [43]. A rain event can accelerate snowmelt by altering the energy balance of the snowpack [44,45].…”

Author response to referee comment #2 on essd-2018-70

“…Distributed snow depth and soil temperature and moisture combined with two meteorological stations provide a means of testing and evaluating hydrologic processes in a productive montane forest. The Wolverton basin research site serves as a southern comparison point with installations in the Kings River (SSCZO;2008-present;Bales et al, 2018), Merced River (MRB;2006-present;Roche, 2017), Stanislaus River (2013present, Pickard, 2015, American River (2014-present;Zhang et al, 2016, 2017a, b), and Feather River (2016Avanzi et al, 2018) basins. Studies compiled to date indicate that hydrological variables, including snow depth, the timing and rate of snow melt, and soil moisture, are susceptible to changing climate patterns like warmer temperature or increased vegetation water demands in this part of the Sierra Nevada.…”

Spatially distributed water-balance and meteorological data from the Wolverton catchment, Sequoia National Park, California

“…Distributed snow depth and soil temperature and moisture combined with two meteorological stations provide a means of testing and evaluating hydrologic processes in a productive montane forest. The Wolverton basin research site serves as a southern comparison point with installations in the Kings River (SSCZO;2008-present;, Merced River (MRB;2006-present;Roche, 2017), Stanislaus River (2013present, Pickard, 2015), American River (2014-present; Zhang et al, 2016, 2017a, b), and Feather River (2016Avanzi et al, 2018) basins. Studies compiled to date indicate that hydrological variables, including snow depth, the timing and rate of snow melt, and soil moisture, are susceptible to changing climate patterns like warmer temperature or increased vegetation water demands in this part of the Sierra Nevada.…”