Abstract
Typhoon (TY) Haiyan was one of the most intense and highly destructive tropical cyclones (TCs) to affect the Philippines. As such, it is regarded as a baseline for extreme TC hazards. Improving the simulation of such TCs will not only improve the forecasting of intense TCs but will also be essential in understanding the potential sensitivity of future intense TCs with climate change. In this study, we investigate the effects of model configuration in downscaling TY Haiyan using the Weather Research Forecasting (WRF) Model. Sensitivity experiments were conducted by systematically altering the choice of cumulus schemes, surface flux options, and spectral nudging. In addition to using the European Centre for Medium-Range Weather Forecasts Re-analysis 5th Generation (ERA5) single high resolution realization as initial and boundary conditions, we also used four of the ten lower resolution ERA5 Data Assimilation System (EDA) ensemble members as initial and boundary conditions. Results indicate a high level of sensitivity to cumulus schemes, with a trade-off between using Kain-Fritsch and Tiedtke schemes that have not been mentioned in past studies of TCs in the Philippines. The Tiedtke scheme simulates the track better (with a lower mean Direct Positional Error (DPE) of 33 km), while the Kain-Fritsch scheme produces stronger intensities (by 15 hPa minimum sea level pressure). Spectral nudging also resulted in a reduction in the mean DPE by 20 km and varying the surface flux options resulted in the improvement of the simulated maximum sustained winds by up to 10 ms−1. Simulations using the EDA members initial and boundary conditions revealed low sensitivity to the initial and boundary conditions, having less spread than the simulations using different parameterization schemes. We highlight the advantage of using an ensemble of cumulus parameterizations to take into account the uncertainty in the track and intensity of simulating intense tropical cyclones.
Highlights
30 As a country of 109 million people over more than 7,000 islands, the Philippines is considered one of the most natural hazardprone countries in the world (Brucal et al, 2020) and is ranked in the top five of all countries in terms of exposure to climaterelated risks (Eckstein et al, 2020)
3.1 Simulated track Fig. 2 shows the tracks obtained from the simulations of TY Haiyan for all experiments are in reasonably good correspondence with the best-track data
295 The results show that these three model settings individually lead to significant reductions in Direct Positional Error (DPE) values
Summary
30 As a country of 109 million people over more than 7,000 islands, the Philippines is considered one of the most natural hazardprone countries in the world (Brucal et al, 2020) and is ranked in the top five of all countries in terms of exposure to climaterelated risks (Eckstein et al, 2020). TY Haiyan was a category-5 super typhoon that claimed the lives of at least 7,300 people, most of them from drowning due to the devastating 5 to 7-meter-high storm surge 45 and coastal inundation (Soria et al, 2016) It affected more than 16 million people (NDRRMC, 2014) and caused an estimated USD 5–15 billion worth of damage in agriculture and critical infrastructure (Brucal et al, 2020). We investigate the effects of the different combinations of model cumulus convection schemes, spectral nudging and surface flux options on the TY Haiyan track, intensity and rainfall simulations. This study seeks to contribute to such studies with a particular focus on the Philippines by assessing the skill and sensitivity of a TC case study using a mesoscale numerical weather prediction model It aims to study the influence of the combination of cumulus convection scheme and the different surface flux options to the different TC characteristics. It is estimated to have caused between USD 5-15 billion worth of direct damages in agriculture and infrastructure (Brucal et al, 2020) and affected more than 16 million people (NDRRMC 2014)
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
