Extended Abstract (756K)7.3
Performance of High-Resolution Satellite Precipitation Products over China
Yan Shen, CMA National Meteorological Information Center, Beijing, China; and A. Xiong and P. Xie
An analysis of hourly precipitation is constructed on a 0.25olat/lon grid over China for a 3-year period from 2004 – 2006 by interpolating gauge observations at over 2,000 stations. First, analyzed fields of ratio between hourly observations and daily precipitation climatology of Xie et al. (2006) are created by interpolating the corresponding station values. Gridded values of hourly precipitation are then computed by multiplying the hourly ratio with the climatology. This two-step approach is adopted to improve the quantitative accuracy of the analysis and to take into account of the orographic effects in precipitation included in the definition of the daily climatology. Quality of the hourly analysis is reasonably good especially over the eastern portion of the country where gauge network is quite dense.
The gauge-based precipitation analysis is applied to examine the performance of five selected high-resolution satellite precipitation estimates including the CMORPH of Joyce et al. (2004), the TRMM 3B42RT of Huffman et al. (2004), TRMM 3B42 of Huffman et al. (2006), the NRL blended product of Turk et al. (2004), and the PERSIANN of Hsu et al. (1997). Satellite estimates of the five products are integrated into fields of 0.25olat/lon and 3-hourly resolution and compared with the gauge-based analysis for the 3-year period. While our comparison covers a wide range of time and space scales, the focus of this work is the performance of the satellite products in depicting precipitation variations of daily and sub-daily time scales and their seasonality. Our preliminary results showed the following:
1) All of the five satellite products are capable of capturing the overall spatial distribution and temporal variations of precipitation reasonably well;
2) Performance of the satellite presents varies for different regions and different precipitation regimes, with better comparison statistics observed over wet regions and for warm seasons;
3) Diurnal cycle of precipitation derived from satellite estimates shows slightly different phase with that from the gauge observations; and
4) Satellite products present seasonally and regionally dependent biases.
Further work is underway to perform case studies and to examine the satellite products' capability to reproduce probability density function (PDF) of the precipitation events. Detailed results will be reported at the conference.
Session 7, Validation of Hydrometeorological Observations
Wednesday, 23 January 2008, 9:00 AM-10:00 AM, 223
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