Sensitivity to the Sundarbans’ vegetation of the Remal tropical cyclone's modelling with WRF-ARW

The Weather Research and Forecasting (WRF) model with the solver—Advanced Research WRF (ARW)—is commonly used in the meteorological community for forecasting tropical cyclones. However, it is well known that vegetation reduces the tangential wind velocity in a cyclonic storm. In this study, the reduction in wind during tropical cyclone (TC) Remal due to vegetation is calculated by using the difference between two WRF-ARW simulations of the event in the presence and absence, respectively, of the Sundarbans mangrove forest (SMF) within the simulated domain. It is found that, on average, the presence of SMF decreases the maximum surface wind of Remal by 5 ms⁻¹ and subsequently influences the spatial distribution of precipitation and upward moisture flux over the SMF area. In addition to that, it is shown that the reduction in drag force in the absence of this mangrove forest is connected with the increase in the small-scale ice water mixing ratio to a maximum value (0.010) of 77 nautical miles (NM) away from the coast through atmospheric teleconnection. Furthermore, the absence of the SMF is connected with the elimination of updraft after landfall, and the increase of wind flow from above 12.5 km height to 17.5 km height. Even though the absence of the SMF does not significantly change the track of the TC, TC centre speed, surface temperature, column-integrated water vapour mixing ratio and net radiation. The overall findings of this research suggest the importance of preserving and enhance the coverage of such forests in order to reduce coastal hazards’ risks, in agreement with previous studies.