Benjamin T. Johnson

JCET/UMBC & NASA/GSFC - Mesoscale Atmospheric Processes Lab

  The Global Precipitation Measurement (GPM) mission is an international network of satellites that provide the next-generation global observations of rain and snow.  Building upon the success of the Tropical Rainfall Measuring Mission (TRMM), the GPM concept centers on the deployment of a “Core” satellite carrying an advanced radar/radiometer system to measure precipitation from space and serve as a reference standard to unify precipitation measurements from a constellation of research and operational satellites.  The GPM core satellite consists of an active radar at Ku and Ka bands (14 & 35 GHz respectively), and a passive microwave radiometer with 13 channels operating from 10 GHz to 183.31 GHz.    The combination of active and passive microwave observations will provide us with the ability to reliably estimate precipitation rates as low as 0.5 mm/hr for both rain and snowfall near the surface.  

This talk will describe the efforts of our group and other collaborators to develop a state-of-the-art precipitation retrieval algorithm by leveraging existing knowledge from legacy observation platforms, such as TRMM and CloudSat, and through the use of synthetic data obtained from cloud resolving models (e.g., WRF).  A few specific areas of new research will be highlighted, such as the use of realistically shaped ice-phase hydrometeors in simulating snowfall events and the associated observable quantities, and a new land surface emissivity algorithm.