Assimilation of supplemental observations during tropical cyclones in the NCEP Hybrid Gridpoint Statistical Interpolation (GSI) scheme

Tropical cyclone (TC) synoptic surveillance missions from the NOAA Gulfstream-IV (G-IV) aircraft currently sample the atmosphere around the TC and upstream synoptic-scale features of interest with the goal of improving TC track forecasts for the issuance of Hurricane Watches and Warnings for the United States. The impact of assimilating these data using the NCEP 3D-Var data assimilation system and GFS model have been quantified over many years and in individual cases in previously published work.

In 2012, the NCEP global data assimilation system was upgraded to utilize a hybrid ensemble-variational scheme with characteristics of both a 3D-Var approach and an Ensemble Kalman Filter. Here, we will show preliminary results of the impact of TC synoptic surveillance data in the new hybrid GSI from cases during 2012 and 2013. In addition, the impact of these supplemental observations on GFS model forecasts of tropical cyclone track, intensity, and structure will be examined.

These preliminary results will help guide future studies and could lead to changes in how supplemental observations, including the G-IV, are deployed in tropical cyclone events.