B122-03
High-resolution rainfall mapping in tropical Island mountains

Wednesday, 16 December 2020: 10:06
Virtual
Lionel Benoit1, Matthew Lucas2, Han Tseng2, Yu-Fen Huang1, Yin-Phan Tsang1, Alison D Nugent3, Thomas W Giambelluca1 and Gregoire Mariethoz4, (1)University of Hawaii at Manoa, Honolulu, HI, United States, (2)University of Hawaii at Manoa, Department of Geography and Environment, Honolulu, HI, United States, (3)University of Hawaii at Manoa, Atmospheric Sciences, Honolulu, HI, United States, (4)Institute of Earth Surface Dynamics (IDYST), Faculty of Geosciences and Environment (FGSE), University of Lausanne, Lausanne, Switzerland
Abstract:
In the vicinity of orographic barriers, interactions between mountains and prevailing winds can enhance rainfall and generate strong precipitation gradients. Such orographic effects are prominent in tropical Islands because of the confluence of year-round trade-winds and steep Island slopes.

To investigate how rainfall gradients develop during rain storms in tropical Islands, we will present a new rain observation approach that combines high frequency rain gauge measurements with stochastic modeling in order to build 200 m x 1 min resolution space-time rain maps. The proposed framework will be presented in the form of a case study focusing on orographic rain gradients in Mānoa Valley, on the leeward side of the Island of Oʻahu, Hawaiʻi, USA.

The results will be used to highlight the tremendous variability of tropical orographic rainfall at the scale of a small headwater catchment, to stress the need for high density and high frequency rain gauge observations to capture orographic effects, and to investigate the observation errors that can arise when such a network is not available.

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