Abstract

Nimbus-7 Scanning Multichannel Microwave Radiometer (SMMR) normalized 37-GHz polarization differences P were compared with surface digital radar observations of oceanic precipitation made daring the Taiwan Area Mesoscale Experiment (TAMEX). Four cases were found for which SMMR and radar coverage of significant precipitation features were nearly simultaneous. These yielded 518 SMMR-radar data pairs, of which over half included precipitation. An empirical method was used to correct the radar data for range-dependent errors, and relationships were then sought between the corrected pixel-averaged radar rainfall parameters and the SMMR-observed microwave polarization P. Because of the small sample size and large statistical uncertainties associated with the direct comparisons, the latter were most useful as a means to validate and tune a theoretically derived relationship between 37-GHz P and radar reflectivity factor Z. This relationship in turn was used to generate a large set of simulated SMMR observations from all available TAMEX radar scans in order to produce histograms and mean values of pixel-averaged rain rate as a function of P. An Appendix also describes an attempt to compare SMMR estimates of integrated cloud liquid water with coincident aircraft data during TAMEX.

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