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Abstract

This paper describes the application of a coupled surge-wave model for simulating storm surge and wave along Taiwan coast. The simulations were conducted with an integrated surge-wave modeling system using a large coastal model domain wrapped around the island of Taiwan, with a grid resolution of 50-400 m. Simulations were made with tide only, with wind and tide, and with tide and wind and wave. The first part of the paper describes the hindcasting of historical typhoons. Hindcasting of Soudelor in 2015 revealed the significant effect of waves on storm surge when wave exceeded 11 m. Both the water level and wave were well simulated by the surge-wave model. The second part of the paper describes the forecasting of typhoons in 2016 With a focus on typhoon Napartak and Megi to examine the reliability, accuracy, and efficiency of the protopype forecasting system for Taiwan coast. The system uptime is estimated at 78% during the three months of operations. While the tide prediction has about 3-10% error (relative root-mean-square-error), the water level prediction error increases from 5.8-13.5% for now cast to 9.8-17.4% for 6-hour forecast, 11.4-18.2% for 12-hour forecast, and 20.3-31.4% for 24-hour forecast. The forecast error increases quickly for 24-hour forecast, due to the quick decline of typhoon track/intensity forecast accuracy beyond 24 hours. The forecasting system is run using an Intel-based PC with the Intel® Core™ i7-3770 CPU @ 3.40 Ghz (4 cores/8 threads) with 32GB RAM. Wall time varies between 0.8 and 1.8 hours.

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