HR: 0830h
AN: C41B-0965 INVITED     [PDF]
TI: Scale Dependence Between Hydrologic and Atmospheric Models
AU: * Morehead, M D
EM: morehead@uidaho.edu
AF: Ecohydraulics Research Group, University of Idaho, 800 Park Blvd. Plaza IV, Suite 200, Boise, ID 83712 United States
AU: Marks, D
EM: danny@nwrc.ars.usda.gov
AF: USDA-ARS Northwest Watershed Research Center, 800 Park Blvd Suite 105, Boise, ID 83712 United States
AU: Winstral, A
EM: awinstra@nwrc.ars.usda.gov
AF: USDA-ARS Northwest Watershed Research Center, 800 Park Blvd Suite 105, Boise, ID 83712 United States
AB: A disparity tends to exist between the scales simulated by atmospheric models intended as input for hydrologic modeling and those at which hydrologic modelers simulate processes especially snow accumulation and depletion in mountainous terrain. Two different models are used to generate input atmospheric data at various scales to drive a snow hydrology model and test the sensitivity of the snow processes at various forcing scales. One of the input atmospheric models is the nested grid atmospheric model, RAMS, developed at Colorado State University. The second input model uses IPW (Image Processing Workbench) to distribute measured climatic variables over complex landscapes. The snow energy balance model is the grid based ISNOBAL. The simulations are performed in the Reynolds Creek Experimental Watershed (RCEW) in the Owyhee Mountains of South-Western Idaho. RCEW is well instrumented with distributed rain gauges, meteorological sites, snow pillows, and discharge weirs. A Rain-on-Snow flooding event is used for the simulations which occurred during the end of December 1996 and the beginning of January 1997. The analysis is showing that atmospheric grids on the order of tens of kilometers miss much of the detailed atmospheric dynamics controlling snowfall in the complex terrain of the Owyhee Mountains and lead to incorrect hydrologic results if simplistic downscaling techniques are used. The detailed variability in the precipitation gauges is on the order of a kilometer or less and the snow pack variability is on even smaller scales. It is hypothesized that atmospheric forcing need to be modeled down to scales on the order of 1 kilometer and then redistributed by wind effects to accurately depict the complex conditions in mountainous terrain.
DE: 1800 HYDROLOGY
DE: 1833 Hydroclimatology
DE: 1854 Precipitation (3354)
DE: 1860 Runoff and streamflow
DE: 1863 Snow and ice (1827)
SC: Cryosphere [C]
MN: 2003 Fall Meeting