HR: 0800h
AN: H11C-0679    [Abstracts]
TI: Evaluation of Ensemble Meteorological Forcing in a Distributed Hydrological Model: Decomposing the Nonlinear Basin Response
AU: * Tai, K
EM: tai@nmt.edu
AF: Department of Earth and Environmental Science, New Mexico Institute of Mining and Technology, Socorro, NM 87801, United States
AU: Vivoni, E
EM: vivoni@nmt.edu
AF: Department of Earth and Environmental Science, New Mexico Institute of Mining and Technology, Socorro, NM 87801, United States
AU: Gochis, D
EM: gochis@ucar.edu
AF: National Center for Atmospheric Research, PO Box 3000, Boulder, CO 80307-3000, United States
AB: In this study, we perform a sensitivity study of a distributed hydrological model using ensemble meteorological forcing, which can contribute to the development of a fully- coupled hydrometeorological prediction system. To do so, we couple the Advanced Research Weather Research Forecasting (WRF) model to the TIN-based Real-time Integrated Basin Simulator (tRIBS) hydrological model in an off-line mode. Our particular case study focuses on a warm-season mesoscale convective storm event occurring in the Four Corners region of the Southwest US during the late monsoon season of September 2003. We are primarily interested in assessing the non-linearity in the simulated hydrological response for a set of different rainfall products during a large, semiarid flood event in Upper Rio Puerco, New Mexico. We test three different rainfall products: (1) a simple multiplicative method to rescale observed NEXRAD fields; (2) a simple rescaling of the simulated WRF precipitation fields; (3) and an ensemble of WRF simulations generated using different initial soil moisture condition. For each case, we determine the degree of nonlinearity observed in the simulated streamflow as a measure of the hydrologic sensitivity to precipitation forcing. For the WRF ensemble runs, we assign a range of soil moisture perturbations uniformly across the model domain. The results from the various experiments are statistically analyzed in order to isolate the hydrologic impacts of changes in precipitation character (intensity, distribution and frequency) and initial soil moisture. Our results quantify the amount of nonlinearity that is due to the imposed changes in precipitation or soil moisture character. For many of our results, the hydrologic system amplifies small spatial and temporal errors in rainfall input introduced either through the ensemble method or via the sensitivity analysis. This study provide insights to the generation of ensemble WRF rainfall forcing and its subsequent impact on warm season flood forecasting in the North American Monsoon region.
DE: 1800 HYDROLOGY
DE: 1840 Hydrometeorology
DE: 1843 Land/atmosphere interactions (1218, 1631, 3322)
DE: 1847 Modeling
DE: 1866 Soil moisture
SC: Hydrology [H]
MN: 2007 Fall Meeting