AbstractThe operational fishery sea seats forecast, issued by the Central Weather Bureau, is performed by introducing the relationship between the wind fields (in Beaufort scale) to the wave field. The forecasts for the near shore regions are provided with respect to individual civil district for the convenience. However, it is lack of observational or theoretic evidences to support the way of issuing the forecast. It is necessary to investigate whether it is appropriate or not to issue the forecasts with respect to civil parish based on the investigation of the homogeneity of wave climate around Taiwan.
Long-term sea states by both the numerical simulation and field observation are used to investigate the homogeneity of the seas climate Taiwan. The hybrid wave model proposed by Wen (1999) of 20 km resolution of the grid system is implemented in present study to simulate long term sea states. The calibration and tuning of the numerical model suggests that the combined upstream scheme and Lax-Wenderff scheme of differentiation are more appropriate to be adopted than the original scheme in the model, especially for the cases when sea-land boundaries are included in the computational domain.
Cluster Analysis (CA) and Principle Components Analysis are then applied to the data. The result indicates that the spatial distribution of wave climate is influenced by topography effects and whereas the swell plays an important role. Moreover, it is found that in the near-shore region, 11 zones along the coast of different wave climates would be identified if the field data from 12 near-shore observation stations are considered. The results imply the complexity spatial distribution of the wave climate in the near-shore region. Due to the complexity, more density of the field stations is required to obtain the further insight of the regional in-homogeneity in the coastal zones. Regarding to the offshore region, eight zones of homogeneity of regional wave climate over Taiwan water is yielded. In general, The division of the eight zones is similar to the present off-shore fishery forecasts areas, exclusive the area in the southern Taiwan Strait. These results provide the operational and theoretical background to support the current way of issuing the sea state forecast of Central Weather Bureau for fishery purpose.
|Date of Award||2002|
|Supervisor||Zsu-Hsin Chuang (Supervisor)|