Key ingredients in regional climate modeling for improving the representation of typhoon tracks and intensities
Abstract. There is evidence of an increased frequency of rapid intensification events of tropical cyclones (TCs) in global offshore regions. This will not only result in increased peak wind speeds but may lead to more intense heavy precipitation events, leading to flooding in coastal regions. Therefore, high impacts are expected for urban agglomerations in coastal regions such as the densely-populated Pearl River Delta (PRD) in China. Regional climate models (RCMs) such as the Weather Research and Forecasting (WRF) model are state-of-the-art tools commonly applied to predict TCs. However, typhoon simulations are connected with high uncertainties due to the high number of parameterization schemes of relevant physical processes (including possible interactions between the parameterization schemes) such as Cumulus (CU) and Micro Physics (MP), and other crucial model settings such as domain setup, initial times, and spectral nudging. Since previous studies mostly focus on either individual typhoon cases or individual parameterization schemes, in this study a more comprehensive analysis is provided by considering four different typhoons of different intensity categories with landfall near the PRD, i.e., Neoguri (2008), Hagupit (2008), Hato (2017), and Usagi (2013), as well as two different schemes for Cu and MP, respectively. Moreover, the impact of the model initialization and the driving data is studied by using three different initial times and two spectral nudging settings. Compared with the best-track reference data, the results show that four typhoons show some consistency. For track bias, nudging only horizontal wind has a positive effect on reducing the track distance error; for intensity, compared with a convective-permitting (CP; nudging potential temperature and horizontal wind; late initial time) model, using Kain-Fritsch scheme (KF; nudging only horizontal wind; early initial time) configuration shows relatively lower minimum sea level pressures and higher maximum wind speeds which means stronger typhoon intensity. Intensity shows less sensitivity to two MP schemes compared with the CP, nudging, and initial time settings. Furthermore, we found that compared with the CP, using the KF scheme shows a relatively larger latent heat flux and higher equivalent potential temperature, providing more energy to typhoon development and inducing stronger TC. This study could be used as a reference to configure WRF for historical and future TC simulations and also contributes to a better understanding of the model simulation performance of principal TC structures.
Qi Sun et al.
Status: open (until 08 Dec 2023)
Qi Sun et al.
Qi Sun et al.
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