A Global Radial Wind Data Assimilation OSSE with the GFS

Nearly one thousand radars are registered in the World Meteorological Organization’s world radar database [Available online: http://wrd.mgm.gov.tr/Default.aspx?l=en]; however, none are leveraged for assimilating radial winds within NOAA’s Global Forecast System (GFS). Doppler radar radial velocities have been routinely assimilated into regional and convection-permitting model forecasts for over a decade, but the value of their assimilation is not well known for global modeling systems.

The Finite Volume model on the Cubed Sphere (FV3) is a state-of-the-art dynamic core and recently replaced the spectral dynamic core as part of the Next Generation Global Prediction System in the GFS. Eventually, global atmospheric models will advance toward convection-permitting resolutions and will likely assimilate radial wind observations. The assimilation of these observations at coarser resolutions (e.g., C768 or ~13-km) could also have impacts on the forecast. Research into how to best use these observations in a global paradigm is a necessary step toward this eventual, long term goal.

To facilitate testing of the assimilation of international radial wind observations, an observing system simulation experiment (OSSE) is adopted with the intent to evaluate if the global circulation can be estimated and informed from the assimilation of irregularly spaced, dense radar observing network. Results from this OSSE will be presented.