Multi-Platform Data Fusion for more Accurate Spatial Estimation of the Sierra Nevada Snow

Over 100 wireless sensors for monitoring realtime snow conditions were deployed in ten clusters distributed across the headwaters of the American River Basin of the Sierra Nevada.  The sensors are strategically placed to measure snow depth, temperature, relative humidity, solar radiation, and soil moisture across elevation gradient, heterogeneous slope, aspect and canopy-covered montane regions. Meanwhile, time series of snow water equivalent (SWE) maps were reconstructed using National Land Data Assimilation Systems (NLDAS) data and fractional Snow Coverage Area (fSCA) from MODIS for 2001-2014 snowmelt seasons using energy-balance model (Guan et. al., 2013) and the maps would be reconstructed every year after the snow melt-out date. Both data sources are spatially blended using k-nearest neighbors algorithm for extrapolating the current snow conditions from the sensor-networks data.