Ensemble Data Assimilation and Predictability of Tropical Cyclones

Abstract

LONG-TERM GOALSThe ultimate goal is to improve tropical cyclone track and intensity prediction through further development of ensemble-based data assimilation at the regional scale. More specifically, the objective is to make better use of in-situ and remotely-sensed observations in cloud-resolving models. In collaboration with scientists at the Naval Research Lab (NRL), we would like to develop an ensemblebased data assimilation system for the Coupled Ocean/Atmosphere Mesoscale Prediction System (COAMPS) that is capable of assimilating remotely sensed data, as well as observations from convential meteorological networks, to improve tropical cyclone prediction. This work will build upon a protype COAMPS-based ensemble Kalman filter (COAMPS-EnKF) that has been recently developed at NRL following the success of the ensemble data assimlation system developed at the Pennsylvania State University (PSU) for the Weather Research and Forecasting (WRF) model. OBJECTIVESThe primarily objectives of the proposed work are as follows:(1) Further develop the COAMPS-EnKF data assimilation system for tropical cyclone initialization capable of effectively assimilating airborne Doppler radar and satellite observations as well as data from conventional surface and sounding networks.(2) Implement a pseudo ensemble data assimilation (PEDA) system for COAMPS that is capable of ingesting flow-dependent background error covariance for tropical cyclone initialization without performing a computationally expensive online ensemble forecast. PEDA operates by sampling from a pre-constructed TC vortex library, given the intensity and size of the observed storm, and introducing the sample perturbations into a variational data assimilation system. For this task, the PEDA algorithm will be implemented with the COAMPS three-/four-dimensional variational (3D-/4D-Var) hybrid systems.(3) Explore the practical use of different observing strategies in predicting tropical cyclones, including the assimilation of droposondes, radar, airborne and spaceborne observations using the COAMPS-EnKF and COAMPS-PEDA systems. Report Documentation Page Form Approved OMB No. 0704-0188Public reporting burden for the collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing the collection of information. Send comments regarding this burden estimate or any other aspect of this collection of information, including suggestions for reducing this burden, to Washington Headquarters Services, Directorate for Information Operations and Reports, 1215 Jefferson Davis Highway, Suite 1204, Arlington VA 22202-4302. Respondents should be aware that notwithstanding any other provision of law, no person shall be subject to a penalty for failing to comply with a collection of information if it does not display a currently valid OMB control number.