HR: 0800h
AN: H11B-1265    [Abstracts]
TI: Scale-dependency of Sub-grid Parameterization
AU: * Sharif, H
EM: hatim.sharif@utsa.edu
AF: University of Texas at San Antonio, 6900 N Loop 1604 W, San Antonio, TX 78249
AU: Miller, N
EM: nlmiller@lbl.gov
AF: Berkeley National Lab, 1 Cyclotro Road, Berkeley, CA 94720
AB: The representation of spatially heterogeneous land surface states and fluxes is essential for modeling processes that are nonlinearly related to the land surface states, such as the partitioning of sensible and latent heat fluxes. The contrast between the fine spatial scales at which this heterogeneity is manifest and the coarser scales at which most land surface models are run remains a challenging problem in land surface hydrology. We performed a 51-year simulation of water and energy fluxes over the entire Arkansas-Red River Basin using a fully distributed land surface model, TOPLATS. The simulations were performed at fine temporal (hourly) and spatial (1 km2) resolution in an effort to bridge the gap between traditional fine scale hydrologic modeling catchment scales, and coarser regional scale (e.g. 64km) land surface modeling The effects of sub-grid variability of inputs and parameters below the land surface model grid resolution will be represented. In this study, the land surface model, TOPLATS, was run with forcings and model parameters at varying levels of aggregation and the effects of sub-grid heterogeneity were investigated for aggregated grid resolutions of 1kmx1km up to 64kmx64km.. The differences among the fluxes produced by forcings and parameters at various resolutions provide a quantitative measure of the non-linearity in the land surface responses. The impact of factors such as wet/dry conditions and validity of the model hydrologic assumptions is evaluated. Alternative strategies that include running the spatially -averaged grids with a distribution of variables (e.g. soil-topographic index and soil properties) are evaluated. Discussion on how the sub-grid gets partitioned will be provided. Procedures to adjust states and fluxes computed at coarse resolutions will also be discussed.
DE: 1805 Computational hydrology
DE: 1839 Hydrologic scaling
DE: 1847 Modeling
SC: Hydrology [H]
MN: Fall Meeting 2005