The maximum significant wave height (Hsmax) induced by a tropical cyclone (TC) can be estimated from an empirical fetch formula using the TC’s size, maximum wind speed, and translation speed, in which larger, stronger, and faster-moving TCs generally have higher the Hsmax. In the formula, the radius of maximum wind (RMW) has been widely used as the TC size parameter under the assumption that Hsmax is mainly generated by strong winds near the RMW. This study investigates whether RMW is the optimal parameter for determining TC-induced Hsmax through extensive wave model simulations for North Atlantic hurricanes from 1988–2017. The correlation analysis between the estimated Hsmax and TC size parameters revealed that the radius of the 34-kt wind speed (R34, r = 0.84–0.95) was much higher than the widely used RMW (r = 0.33–0.58), which suggests that R34 is a more important TC size parameter for determining TC-induced Hsmax than RMW. This result can be explained by the fact that R34 showed a significantly higher correlation (r = 0.96) than RMW (r = 0.31) with cumulative TC wind speeds, which are closely related to Hsmax. These findings also indicate that the TC-induced Hsmax is more affected by the region containing moderately strong winds outside the TC than by the region of maximum wind speed near the RMW. Our paper provides additional insight into the mechanisms by which extreme wave heights, which cause severe damage during TC passage, occur.

Eleven Tropical Cyclone (TC) intensity guidance models in the western North Pacific have been validated over 2008~2014 based on various analysis methods according to the lead time of forecast, year, month, intensity, rapid intensity change, track, and geographical area with an additional focus on TCs that influenced the Korean peninsula. From the evaluation using mean absolute error and correlation coefficients for maximum wind speed forecasts up to 72 h, we found that the Hurricane Weather Research and Forecasting model (HWRF) outperforms all others overall although the Global Forecast System (GFS), the Typhoon Ensemble Prediction System of Japan Meteorological Agency (TEPS), and the Korean version of Weather and Weather Research and Forecasting model (KWRF) also shows a good performance in some lead times of forecast. In particular, HWRF shows the highest performance in predicting the intensity of strong TCs above Category 3, which may be attributed to its highest spatial resolution (~3 km). The Navy Operational Global Prediction Model (NOGAPS) and GFS were the most improved model during 2008~2014. For initial intensity error, two Japanese models, Japan Meteorological Agency Global Spectral Model (JGSM) and TEPS, had the smallest error. In track forecast, the European Centre for Medium-Range Weather Forecasts (ECMWF) and recent GFS model outperformed others. The present results has significant implications for providing basic information for operational forecasters as well as developing ensemble or consensus prediction systems.

In this study, we constructed a rapid refresh wave forecast model using sea winds from the Korea Local Analysis and Prediction System as input forcing data. The model evaluated the changes in forecast performance considering the influence of input wind–wave interaction, which is an important factor that determines forecast performance. The forecast performance was evaluated by comparing the forecast results of the wave model with the significant wave height, wave period, and wave direction provided by moored buoy observations. During the typhoon season, the model tended to underestimate the conditions, and the root mean square error (RMSE) was reduced by increasing the wind and wave interaction parameter. The best value of the interaction parameter that minimizes the RMSE was determined based on the results of the numerical experiments performed during the typhoon season. The forecast error in the typhoon season was higher than that observed in the analysis results of the non-typhoon season. This can be attributed to the variations of the wave energy caused by the relatively strong typhoon wind field considered in the wave model.