An analysis of numerical weather prediction of the diabatic Rossby Vortex

• Main Author: Mckenzie, Matthew W.
• Other Authors: Moore, Richard W.
• Published: Monterey, California: Naval Postgraduate School 2014
• Online Access: http://hdl.handle.net/10945/42682

Approved for public release; distribution is unlimited === This work examines diabatic Rossby vortex (DRV) predictability through the examination of 12 cases of DRV genesis and evolution that undergo explosive deepening. An objective DRV identification script is created and applied to European Center for Medium Range Forecasting (ECMWF) ensemble data. The script is verified via an examination of the observed lifecycle of a DRV associated with recurving tropical cyclone Chaba. An assessment of the control forecast indicated significant uncertainty regarding the predictability of the DRV with no explosive deepening predicted. The evaluation of the 12 control forecasts identified two good forecasts, indicating generally poor performance. The DRV identification script was then applied to the ECMWF ensemble data. The analysis of the perturbed member forecasts exhibited similar characteristics to those of the 12 control forecasts and large uncertainty in the vicinity of the observed DRVs was found. The analysis of ensemble data in the selected cases is shown to provide valuable information. It is possible to quantify the uncertainty and to identify a subset of members that provide a disturbance genesis and evolution that is similar to the observed. Given the large initial condition uncertainty in such cases, it is apparent that a probabilistic approach should be incorporated when examining DRV predictability.