[A-AS04] Extreme Events and Mesoscale Weather: Observations and Modeling

[AAS04-P09] Effect of Topography and Wind Direction on Convective Initiation and Precipitation Distribution in Bandung Basin, Indonesia

*Irfans Maulana Firdaus¹, Takeshi Yamazaki¹ (1.Graduate School of Science, Tohoku University)

Keywords:Topography, Wind direction, Convective initiation, Precipitation

A series of numerical sensitivity simulations is conducted to investigate the effect of topography and wind direction on convective initiation (CI) and precipitation distribution during a heavy rainfall case in Bandung Basin (107.35ºE-107.95ºE and 6.75ºS-7.25ºS), Indonesia which has mountain in the north, south, and east part of basin and makes concave-shape basin. CI is occurred at the mountain peak due to the orographic lifting and convergence. In the modified topography numerical simulation for terrain removed, the CI does not occur, indicating that mountain topography around Bandung basin is playing crucial role in CI mechanism. When the south or north mountain is removed, the CI remain occurs in the other mountain, and has a time-lag of CI compare than control run. The precipitation increases in the north basin, meanwhile the precipitation decreases in the south basin for terrain removed. These is due to the moisture transport from the south and west basin, which supplies the water vapor to that area. In the numerical simulations of wind directions, the CI occurs in the south mountain for all scenarios. The wind flow from south-west and south produces more precipitation in the Bandung basin, more area with precipitation >150 mm/day, and produce rainfall about 40 mm/day and 29 mm/day on area average, respectively.