[A-AS07] Analyses and Prediction of Extreme Weather and Climate in Southeast Asia

[AAS07-P02] The Effects of the Topography of Mindanao Island on the Precipitation Distribution Associated with Typhoon Bopha (2012)

*Leia Pauline Sagisi Tonga¹, Lyndon Mark Olaguera^1,2 (1.Ateneo de Manila University, 2.Manila Observatory)

Keywords:Typhoon Bopha, Mindanao, topography, rainfall

In December 2012, Typhoon Bopha (Pablo) caused severe flooding and landslides in Mindanao Island, southern Philippines killing thousands and destroying infrastructures along its path. The devastation caused by such an extreme weather event highlights the need to understand its dynamics and to improve the performance of numerical weather prediction models to mitigate its impact. As a first step towards achieving this goal, this study investigates the impact of topography along the path of Typhoon Bopha on the spatial distribution of rainfall using the Weather Research and Forecasting (WRF) model. Model results were compared with weather stations from the Philippine Atmospheric Geophysical and Astronomical Services Administration (PAGASA) and Tropical Rainfall Measuring Mission (TRMM) 3B42v7. Sensitivity experiments to the Planetary Boundary Layer (PBL) and microphysics schemes were conducted first before the topography experiments. The results show that the Goddard-ACM2, microphysics-PBL combination captured the intensity of the simulated TC-induced rainfall well compared to the other combination of schemes.

Two experiments with the Diwata-Davao Oriental Mountains removed (NOTOPO) on the east coast of Mindanao Island and another experiment with twice the default height of the same mountains in the WRF model were conducted. The results show that the presence of the Diwata-Davao oriental mountains is crucial for the formation of intense rainfall on the windward side of the mountains. The NOTOPO experiment resulted in a more spread out and less intense rainfall distribution compared to the default experiment. The results of this study highlights the importance of topography in inducing heavy rainfall, as well as the potential of using the WRF model for future forecasting of extreme weather events associated with tropical cyclones over the Philippines.