Initialization of Tropical Cyclones in Numerical Prediction Systems

Initialization of tropical cyclones (TCs) is critical for TC predictions in operational numerical prediction systems, especially the intensity change. In this study a TC initialization scheme, identified as the TC dynamic initialization (TCDI) package, is developed that can be used in numerical prediction systems for TC predictions. The TCDI package includes two major components. The first part is the removal of the TC vortex in the initial field of the numerical model. The second part is a dynamic initialization of the TC vortex spun up with the full nonlinear dynamics and physics. During the spin-up period, the TC vortex is forced toward the best track estimated central minimum pressure. The dynamic and thermodynamic balanced TC vortex is then added back to the initial field. The TCDI initialization package was tested in the Navy COAMPS-TC system on a few TCS-08 storms and a larger sample of Atlantic storms. Preliminary results indicate that intensity errors and biases can be reduced at lead times of 0-48 h using this method. Detailed analysis of the TC vortex structure after the dynamic initialization will be presented. Further plans in this study include implementation of adjusting the heating in the vicinity of TCs to the satellite retrieved heating profiles during dynamic initialization, optimization of the TCDI package, and testing of the TCDI in an operational environment.