Eugene A. Mueller

Survey of Relationships Between Rainfall Rate and Radar Reflectivity in the Measurement of Precipitation

Abstract Numerous investigations have been made in the last two decades from both a direct measurement of the radar reflectivity and the rainfall amount, as well as indirect measurements of the raindrop size spectra. Calculations of the reflectivity factor and rainfall rate from these spectra can be made and the relationships determined. Both methods are discussed and a summary of the relationships presented. These relationships show differences in excess of 500% in rainfall rate at the same reflectivity. These large differences are primarily associated with differences in geographic locality. In addition, there are smaller differences on the order of 150% that can be attributed to different types of rain or different synoptic conditions. Some data are available which are indicative of the differences in the relationship on a given day, depending upon the location within the storm which is sampled. This is briefly described and in only one case out of 18 is there a significant difference. Estimates of the...

X-Band Attenuation and Liquid Water Content Estimation by a Dual-Wavelength Radar

Abstract Direct measurements of attenuation due to liquid water content (LWC) between two points in the common beam of a dual-wavelength radar system will be possible using a real-time digital processor of radar signals presently under construction. Precise measurements of attenuation are possible since accurate absolute calibration of the radars is not required. A resolution of 0.65 dB km−1 is possible in contiguous kilometer sections along the beam axis with an average over 32 independent values of echo power. In terms of LWC this is a resolution of ∼2 mg m−3 of precipitation using a new relation M = 2.23A0.787where M is the liquid water content (gm m−2) and A the attenuation rate (dB km−1) along the common beam.