Offshore winds in the Gulf of Thailand: Climatology, wind energy potential, stochastic persistence, tropical cyclone influence, and teleconnection

This study investigated various characteristics of ofshore winds at 100 m over the Gulf of Thailand (GOT) including its vicinity using JRA–55 reanalysis data during 1959–2018. The hierarchical clustering used yields six homogeneous clusters of wind speed in the GOT. Wind speed shows double peaks in December–January and July–August, refecting a signature of the two regional monsoons. In the wet season, the upper region of the GOT tends to receive southwest monsoonal winds more directly while, in the dry season, the lower region is more impacted by the northeast monsoonal winds. The degree of diurnal variation in wind speed is little and much lower than that of seasonality. Trends in wind speed are found to be of less concern because their magnitudes are relatively small and the areas close to the coasts do not show any signifcant change. A stochastic concept was proposed to account for the persistence and intermittency of wind speed using a transition matrix and a turbine power curve, fnding the degree of persistence of utilizable wind speed dominates in every case of region and season. Based on the developed threshold of 1,000 km as the distance from the tropical cyclone center, the upper subregions are the most impacted by tropical cyclones, especially during October−November. However, tropical cyclones do not signifcantly afect wind speed over the long term. Using the principal component and correlation analyses, it was found that the interannual variability of wet–season winds in the upper region is mainly associated with ENSO and PDO while dry–season winds in the lower region is mainly coupled with ENSO, in fair agreement with the wavelet coherence results.