THE ESTIMATION OF CLOUD PARAMETERS BY RADAR

Abstract

Although the radar-reflectivity factor Z = ?Nd6 is a function of the liquid-water content W, median volume diameter d0 (or other characteristic diameter), and breadth of the drop-size distribution, correlations of Z vs. W, and Z vs. d0, provide reasonable estimates of W and d0 from Z alone. If two of the latter three are known, considerably more reliable estimates of the third parameter are possible. Estimates may also be improved somewhat by an observation of cloud type. A theoretically feasible, though instrumentally complex method for measuring cloud water-content is also described. The possibility of using reflectivity measurements for warnings of icing severity is discussed. The reflectivity statistics indicate that natural clouds have a preference for drop-size spectra between the n = 2 (B) and 3 (C) distributions of the ?multi-cylinder? family.