Extended Abstract (136K)J1.9
Uncertainty in fine-scale MPA precipitation estimates and implications for hydrometeorological analysis and forecasting
George J. Huffman, NASA/GSFC and SSAI, Greenbelt, MD; and R. F. Adler, D. T. Bolvin, and E. J. Nelkin
The Multi-satellite Precipitation Analysis (MPA) system developed by the authors over the last three years provides 0.25°x0.25° 3-hourly precipitation estimates for the global latitude belt 50°N-50°S. Tropical Rainfall Measuring Mission (TRMM) observations are used to calibrate precipitation estimates from SSM/I and other passive microwave sensors, with the results then used to provide calibration coefficients for a variable-rainrate, threshold-matched infrared (IR) technique. All of these inter-calibrated estimates are combined to produce the final MPA product. A real-time MPA (RT-MPA) product has been computed and publicly posted on an on-going basis starting in February 2002, and a post-real-time research version was implemented in Version 6 of the TRMM data product 3B-42, eventually covering the period from January 1998 to the (delayed) present.
The RT-MPA has obvious potential for application to fine-scale hydrometeorological applications, but it is important to understand limitations imposed by uncertainties in the input data and algorithm. For example, the MPA estimates show a relatively high error variance at full resolution, but less so when averaging is carried out in space and/or time. At the same time, the histogram of rain rates estimated by the MPA over an area and/or at several times is relatively close to the rain rate histogram observed with gauges. Further, the MPA performs better in convective situations and in regions which are not strongly influenced by orography. This talk will review our current state of knowledge of MPA performance, then use that information to discuss ways that users can get the most value from the MPA precipitation estimates. For example, it might be helpful to interpret the full-resolution MPA estimates in a probablistic scheme pioneered in recent research on interpreting fine-scale numerical model estimates of precipitation.
Joint Session 1, Flash Flood Forecasting in the Urban Environment (Joint with the Symposium on Planning, Nowcasting and Forecasting in the Urban Zone and 18th Conf on Hydrology; Room 6E)
Monday, 12 January 2004, 1:30 PM-5:30 PM, Room 6E
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