Polarimetry for Weather Surveillance Radars

Scientific evidence accumulated over the last decade indicates that weather radar polarimetry has passed two important tests. First, as suggested by theory, polarimetric signals contain significant information about hydrometeor habits; and second, the information can be retrieved with sufficient accuracy to be useful. If it passes the cost effectiveness test, the technique should be adopted for operational applications. Although this could occur in less than 10 years, there is a large number of radar meteorologists that have not been exposed to radar polarimetry. Hence, the motivation for this paper is to present a simplified overview of the subject. Emphasized are applications to weather surveillance radars. We attempt a step in the direction well enunciated by Herzegh and Jameson (1992), who state: “While a number of significant inferences can be made from Z DR , LDR, and Z observations alone, the full impact of dual-polarization measurements will not be realized until analyses include a more complete set of simultaneous multiparameter radar observations.” To reach a broad audience, the paper touches aspects of polarimetry that are implicitly known to most radar meteorologists. Also, it provides examples of measurements obtained by the National Severe Storms Laboratory (NSSL) Cimarron polarimetric radar and speculates on future capabilities.