Classification of hydrometeors using microwave brightness temperature data from AMSU-B over Iran

The Advanced Microwave Sounding Unit-B (AMSU-B) installed on the NOAA-15, 16, and 17 satellites, is the new generation of a series of microwave imagers/sounders that can sense atmospheric moisture and other hydrometeors through clouds. This paper demonstrates the potential of multi-frequency AMSU-B data for classifying different types of hydrometeors. Ten types of these hydrometers have been collected using meteorological data (synoptic reports, radiosonde data and infrared and water vapor images) over Iran. Co-located AMSU-B data were used to perform a quantitative classification of the hydrometers. Three main classes including heavy precipitating, moderate precipitating, and non-precipitating hydrometeors were found based on the multi-frequency brightness temperature signatures. The distinguishing criteria for this type of analysis are: (a) brightness temperature (BT) at 89 GHz frequency, (b) slopes of the BT between 89 and 150 GHz, and (c) crossover of BT curves between 89 and 183 GHz frequencies.