Spatial Variability of Summer Florida Precipitation and Its Impact on Microwave Radiometer Rainfall-Measurement Systems

B. J. Turner McGill Radar Weather Observatory, McGill University, Montreal, Quebec, Canada

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G. L. Austin McGill Radar Weather Observatory, McGill University, Montreal, Quebec, Canada

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Abstract

Three-dimensional radar data for three summer Florida storm are used as input to a microwave radiative transfer model. The model simulates microwave brightness observations by a 19-GHz, nadir-pointing, satellite-borne microwave radiometer.

The statistical distribution of rainfall rates for the storms studied, and therefore the optimal conversion between microwave brightness temperatures and rainfall rates, was found to be highly sensitive to the spatial resolution at which 0bservations were made. The optimum relation between the two quantities was less sensitive to the details of the vertical profile of precipitation.

Rainfall retrievals were made for a range of microwave sensor footprint sizes. From these simulations spatial sampling-error estimates were made for microwave radiometers over a range of field-of-view sizes. The necessity of matching the spatial resolution of ground truth to radiometer footprint size is emphasized. A strategy for the combined use of raingages, ground-based radar, microwave, and visible-infrared (YIS-IR) satellite sensors is discussed.

Abstract

Three-dimensional radar data for three summer Florida storm are used as input to a microwave radiative transfer model. The model simulates microwave brightness observations by a 19-GHz, nadir-pointing, satellite-borne microwave radiometer.

The statistical distribution of rainfall rates for the storms studied, and therefore the optimal conversion between microwave brightness temperatures and rainfall rates, was found to be highly sensitive to the spatial resolution at which 0bservations were made. The optimum relation between the two quantities was less sensitive to the details of the vertical profile of precipitation.

Rainfall retrievals were made for a range of microwave sensor footprint sizes. From these simulations spatial sampling-error estimates were made for microwave radiometers over a range of field-of-view sizes. The necessity of matching the spatial resolution of ground truth to radiometer footprint size is emphasized. A strategy for the combined use of raingages, ground-based radar, microwave, and visible-infrared (YIS-IR) satellite sensors is discussed.

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