Integration of SNODAS Data Products and the PRMS Model - An Evaluation Of Streamflow Simulation and Forecasting Capabilities

The U.S. Geological Survey (USGS) hydrologic model PRMS is being used to simulate and predict daily snowmelt runoff for a number of basins in the western United States. PRMS is a distributed-parameter model that uses the concept of polygon or gridded hydrologic response units (HRUs) to account for the spatial and temporal distribution of snow accumulations and melt. It was developed for application to a wide range of basins where available meteorological data are typically limited to daily precipitation and maximum and minimum air temperature. An energy balance and water balance are computed daily for each HRU. The sum of the water balances of each HRU, weighted on a HRU-area basis, produces the daily basin response. The Snow Data Assimilation System (SNODAS) is a modeling and data assimilation system developed by the National Weather Service's National Operational Hydrologic Remote Sensing Center (NOHRSC) to provide estimates of snow cover, snow water equivalent, snowmelt, and associated snowpack variables at a 1-km spatial resolution to support hydrologic modeling and analysis. SNODAS includes procedures to ingest and downscale output from Numerical Weather Prediction (NWP) models; a physically based, spatially-distributed energy-and-mass-balance snow model; and procedures to assimilate satellite-derived, airborne and ground-based observations of snow covered area (SCA) and snow water equivalent. These gridded products can be used for comparing and/or updating spatially distributed state variables in PRMS. Comparison of PRMS and SNODAS SCA on selected basins show comparable results. (Abstract only)