Observation Sensitivity Experiments with the Hourly Rapid Refresh Using Hybrid-Ensemble/Variational Data Assimilation

Data denial experiments have been carried out with the hourly updated Rapid Refresh for 10 different observation types including aircraft, raob, surface, GPS-IPW, atmospheric motion vectors, radar reflectivity, GOES, and others. The test period is for a 10-day period in May 2013 and using the hybrid ensemble-variational data assimilation capability within NOAA's Gridpoint Statistical Interpolation (GSI). Results show that aircraft reports are of highest importance for 3-6-9-12h forecasts from the Rapid Refresh for wind, temperature and relative humidity. Surface, GPS-IPW, rawinsonde and other observations contribute with positive impact also.