Rain detection from ground-based radiometric measurements: Validation against rain sensor observations

The identification of rain contaminated ground-based radiometric measurements is addressed by means of two brightness temperature-based criteria, namely SSI, defined as the ratio of temperature at 30 and 23.8 GHz, and TB30 based on the 30-GHz temperature value alone. Threshold values of these criteria were chosen according to the rate of misclassification set by the experimenter after classification of a training subset of data on the basis of the atmospheric conditions as observed by a variety of rain sensors. A comparison of the discrimination performances indicates that SSI detects light rain events that are missed by both the rain-gauge and TB30 but it suffers from the intrinsic response time of the brightness temperature in the presence of rain. The analysis is referred to 1 year of measurements collected at the ARM SGP facility in Oklahoma.