Title

The effect of clustering on the uncertainty of differential reflectivity measurements

Authors

A. R. Jameson, RJH Scientific, Inc., El Cajon, California
A. B. Kostinski, Michigan Technological UniversityFollow

Document Type

Article

Publication Date

11-1-2008

Abstract

One of the most important avenues of recent meteorological radar research is the application of polarization techniques to improve radar rainfall estimation. A keystone in many of these methods is the so-called differential reflectivity Z_DR, the ratio of the reflectivity factor Z_H at horizontal polarization backscattered from a horizontally polarized transmission to that corresponding to a vertically polarized transmission Z_V. For such quantitative applications, it is important to understand the statistical accuracy of observations of Z_DR. The underlying assumption of all past estimations of meteorological radar uncertainties is that the signals obey Rayleigh statistics. It is now evident, however, that as a radar scans, the meteorological conditions no longer always satisfy the requirements for Rayleigh statistics. In this work, Z_DR is reconsidered, but this time within the new framework of non-Rayleigh signal statistics. Using Monte Carlo experiments, it is found that clustering of the scatterers multiplies the standard deviation of Z_DR beyond what is always calculated assuming Rayleigh statistics. The magnitude of this enhancement depends on the magnitudes of the clustering index and of the cross correlation between Z_Hand Z_V. Also, it does not depend upon the number of independent samples in an ensemble estimate. An example using real radar data in convective showers suggests that non-Rayleigh signal statistics should be taken into account in future implementations of polarization radar rainfall estimation techniques using Z_DR. At the very least, it is time to begin to document the prevalence and magnitude of the clustering index in a wide variety of meteorological conditions.

Publisher's Statement

© 2008 American Meteorological Society. Article deposited here in compliance with publisher policies. Publisher’s version of record: https://doi.org/10.1175/2008JAMC1860.1

Publication Title

Journal of Applied Meteorology and Climatology

Recommended Citation

Jameson, A. R., & Kostinski, A. B. (2008). The effect of clustering on the uncertainty of differential reflectivity measurements. Journal of Applied Meteorology and Climatology, 47(11), 2816-2827. http://doi.org/10.1175/2008JAMC1860.1
Retrieved from: https://digitalcommons.mtu.edu/physics-fp/219

Version

Publisher's PDF