Tibetan Plateau precipitation as depicted by gauge observations, reanalyses and satellite retrievals

摘要

The European Centre for Medium-range Weather Forecasts (ECMWF) reanalysis ERA-40, ERA-Interim, University of Washington (UW) data, APHRODITE's Water Resources (APHRODITE), and Tropical Rainfall Measuring Mission (TRMM) Multisatellite Precipitation Analysis (TMPA) precipitation estimates are compared with each other and with the corrected gauge observations over the Tibetan Plateau (TP) at both basin and plateau scales. The ERA-40 generally can capture the broad spatial and temporal distributions in the gauge-based precipitation estimates over the TP. However, the ERA-40 shows little agreement with the gauge-based precipitation in annual variations for the years before 1979. The anticipated improvements in the ERA-Interim precipitation relative to ERA-40 have not been realized in this study. It greatly overestimates the Corrected-China Meteorological Administration (CMA) (by 74-290%) and other datasets, although the ERA-Interim has a better correspondence than ERA-40 with the Corrected-CMA data at both annual and monthly scales among the selected basins. All the products can detect the large-scale precipitation regime, including the monsoon-dominated precipitation in summer and the westerly-wind-induced precipitation in winter. The Corrected-CMA and APHRODITE estimates generally show decreasing trends in summer and increasing trends in spring and winter precipitation during 1961-2007 at both basin and plateau scales. However, the Corrected-CMA shows larger values in trends and more cases with significance than the APHRODITE, suggesting the effects of the undercatch corrections on the precipitation trends. The use of precipitation derived from current reanalysis projects is less preferable for hydrology analysis than the TP observational data at basin scales. However, using gauge-based precipitation datasets as hydrologic model forcings should be careful in the river basins where gauge station network is spare, such as in the Yarlung zangbo river basin. Satellite products still hold a great potential for providing high-resolution precipitation information in remote regions such as the western TP, although more evaluations are needed on the feasibility of satellite precipitation products on the TP where the topography is complex and rainfall rate is highly variable.