Assessing Global Precipitation Mission (GPM) data for use by the Aviation Community

The Forecast Impact and Quality Assessment Section (FIQAS) at NOAA/ESRL/GSD is using the Global Precipitation Mission (GPM) Dual-frequency Precipitation Radar (DPR) data to identify hazardous convection that impacts air traffic, specifically in regions outside of ground radar coverage.The consistency of GPM with other truth sets is evaluated through a comparison with ground radar products and routine surface reports (METARs) where observations overlap.

In this investigation, ground radar is remapped to the GPM swath. Results compare product fields, such as Vertically Integrated Liquid (VIL), an accepted aviation radar product, and Echo Top. Findings suggest GPM VIL values are lower than those observed by ground radar. In addition, METARs provide a present weather variable that includes weather types such as clear skies, light to heavy precipitation, and light to heavy thunderstorms. These reports are compared to radar, i.e. if a METAR is reporting rain/thunderstorm, it is expected that the GPM/ground radar should exhibit a non-zero VIL/Echo Top value in that location. The radar distributions associated with each present weather type will be discussed. Findings suggest GPM and ground radar are able to distinguish between METAR weather types. Results highlight the usefulness of the GPM product for aviation purposes, but stress the need to consider biases when making air-traffic decisions based on GPM.