Data Assimilation & Prediction

(COMPLETED) Ensemble-based assimilation and downscaling of the GPM-like satellite precipitation information: Further development and improvements of WRF-EDAS

Project Period: April 1, 2013 to March 31, 2017
Principal Investigator(s): Milija Zupanski
Co-Principal Investigator(s): Sara Q. Zhang (NASA Goddard Space Flight Center)
Sponsor(s): National Aeronautics and Space Administration (NASA)


In this research we will further develop the NASA WRF-EDAS data assimilation system and increase its robustness and efficiency, in particular by addressing the insufficient number of degrees of freedom in ensemble error covariances and the precipitation-affected radiance bias correction. The focus of the proposed continued development of WRF-EDAS is methodology improvement that will eventually lead to maximizing the impact of GPM measurements and improved estimates of rainfall. Therefore, the main goal of the proposed research is to continue development of WRF-EDAS and produce an operation-ready assimilation/downscaling system for assimilation of GPM data. This will be achieved by:


  • Developing hybrid variational-ensemble capability, and
  • Developing bias correction scheme for precipitation-affected microwave radiances.

In parallel with the proposed research development, the WRF-EDAS components (e.g., WRF model, microphysics, Goddard-SDSU, GSI, and MLEF) will be periodically updated with the latest versions available. The WRF-EDAS analysis and forecast will initially be produced at 9 km and 3 km resolutions, eventually reaching 1 km resolution relevant for hydrological applications.


In addition to NOAA operational observations available through the GSI interface, we will assimilate currently available TRMM TMI, SSM/IS, MHS data, as well as GPM data when they become available after the launch in 2014. Targeted regions of our experiments will be Hydro-Meteorological Testbeds (HMTs) due to their relevance for ground validation of GPM data and eventual utilization of GPM products in NWP operations. We will also evaluate the system for tropical cyclone and flood events. Following a suggestion from a reviewer, we will validate downscaling of TRMM against other higher resolution products such as a ground-based radar.


We will also make steps towards utilization/validation of the downscaled precipitation analyses and forecasts by hydrological communities. The database produced by the proposed research will reside on NASA supercomputers. It will be made available to other GPM team members. It will be also posted to this research project webpage and to the GPM webpage.


Progress Report for Year-1 (2013-2014)