Impact of initial intensity error on simulated tropical cyclone track over the western North Pacific

In numerical modeling, uncertainties in the initial intensity of tropical cyclones (TCs) can lead to track errors. In this study, we analyzed the impact of initial intensity error on the simulated TC tracks based on 1128 simulations using the Weather Research and Forecasting (WRF) model for TCs in the western North Pacific between June and November from 2006 to 2018. Results show that the initial TC intensities were largely underestimated compared to observations. In TC cases with the initial intensity error below -10 m s- 1, the simulated track position errors (TPEs) were notably greater than TCs in other cases with smaller absolute initial intensity errors. To quantify the positive impact of the improved initial TC intensity on the track simulations, we conducted additional simulations with the dynamical initialization (DI) scheme to enhance the initial TC intensity. Compared to the simulations without the DI scheme, the simulations with the DI scheme performed better in simulating TC tracks, with a 20.3 % reduction in TPE at 72-h. The improvement was understood based on the potential vorticity tendency diagnostic analysis. Results show that the TC motion in the simulations with the DI scheme was controlled by both horizontal and vertical advections, while that without the DI scheme was dominated by horizontal advection only, especially in the early stage of simulations when the TC intensity was considerably underpredicted. The finding highlights the importance of improving the initial TC intensity to the TC track simulations/predictions.