HR: 1340h
AN: H13C-0425    [Abstracts]
TI: Validation and Error Characterization of GPCP-1DD Precipitation Product over the Contiguous United States
AU: McPhee, J
EM: mcphee@seas.ucla.edu
AF: UCLA, 5732D Boelter Hall; Department of Civil and Environmental Engineering, Los Angeles, CA 90095
AU: * Margulis, S
EM: margulis@seas.ucla.edu
AF: UCLA, 5732D Boelter Hall; Department of Civil and Environmental Engineering, Los Angeles, CA 90095
AB: A validation and error characterization study of the GPCP-1DD precipitation product over the contiguous United States is presented. Daily precipitation estimates over a 1-degree grid are compared against aggregated precipitation values obtained from the forcing field of the North American Land Data Assimilation System (LDAS). LDAS daily values are consistent with the CPC gauge-based daily precipitation product, and hence can be regarded as realistic ground-truth values with full coverage of the United States. Continuous and categorical measures of skill are presented, so that both the ability of GPCP-1DD to identify a precipitation event and its accuracy in determining cumulative precipitation amounts are evaluated. Daily values are aggregated into seasonal averages, and spatial averages are computed for five arbitrarily defined climate zones that cover most of the study area. Results show that in general there is good agreement between GPCP-1DD and LDAS values, except for particular areas where GPCP-1DD is unable to identify high-intensity events. For those events correctly identified by GPCP-1DD, computation of continuous statistics show that average bias is negligible in most areas of the U.S. except for humid regions north of parallel 40øN. However, the RMSE statistics shows that differences in estimated precipitation for individual 1-degree cells can be significant, exceeding in most cases the magnitude of the average precipitation. Beyond the validation, the error characterization presented here can significantly enhance the utility of the GPCP 1DD product for use in ensemble hydrologic modeling and forecasting.
DE: 3322 Land/atmosphere interactions
DE: 3354 Precipitation (1854)
DE: 3360 Remote sensing
DE: 1854 Precipitation (3354)
SC: Hydrology [H]
MN: 2004 AGU Fall Meeting