A review of multiparameter radar observations of precipitation

From the earliest years of radar meteorology, efforts have been devoted to multiparameter observations: the measurement of one or more signal properties, ordinarily in addition to the signal intensity, to give added information about the precipitation. Studies employing variable polarization or Doppler frequency measurement were among the first such techniques and over the years have proved fruitful in terms of the information provided. During the past decade there has been such an increase in the use of Doppler radar in meteorological research that radar-measured wind fields are becoming nearly as routine as reflectivity fields. Research has continued in variable polarization techniques, which appear to provide a means of distinguishing remotely between various precipitation types. Investigations of the correlation between the copolarized and cross-polarized components of the received signal have given new insight into the falling behavior of precipitation particles. A great deal of new information will evidently be made available by combining coherent signal processing techniques with variable polarization measurements.