Modeling tropical cyclone wind hazard in the Philippines in present and future climates

The historical record of tropical cyclones (TCs) shows that the Philippines is amongst the most vulnerable countries to tropical cyclones and has endured some of the most disastrous storms on record. Prior work has applied a statistical-dynamical tropical cyclone hazard model, the Columbia HAZard model (CHAZ), to the Philippines downscaled from ERA5 reanalysis to provide a risk assessment using open-source methods to represent exposure and vulnerability (Baldwin et al. 2023). Since the historical TC record is limited in length and data quality, CHAZ provides a useful estimate for storms of return periods not captured in the historical record. In particular, CHAZ allows the simulation of storms in various climate change scenarios modeled in CMIP6. This study will extend Baldwin’s work by considering how climate change might impact the characteristics of tropical cyclones in the Philippines and the wind hazard and risk associated with them.

CHAZ uses environmental conditions forced stochastically to model the entire lifetime of a tropical cyclone including genesis, storm track, and intensity. Downscaling the CHAZ model from CMIP6 environmental conditions can provide insight into how tropical cyclone wind hazards in the Philippines will be affected by anthropogenic climate change. To provide a first-order estimate of TC hazard, one useful hazard metric is the return period of storms for a given storm intensity and location. We will present preliminary results on how this metric is simulated by CHAZ downscaled by CMIP6 historical and future climates when applied to the Philippines. Once the wind hazard analysis is completed, vulnerability and exposure for the Philippines will be added in order to perform the risk assessment and calculate potential economic losses.

In the future we hope that this study will lead to improvements in open-source modeling of TC risk at the country-level, potentially supporting the aid distribution and risk mitigation by NGOs and government entities.

Citations:

Baldwin, J. W., C.-Y. Lee, B. J. Walsh, S. J. Camargo, and A. H. Sobel, 2023: Vulnerability in a Tropical Cyclone Risk Model: Philippines Case Study. Weather, Climate and Society 15(3), 503-523. https://doi.org/10.1175/WCAS-D-22-0049.1