The climatology of shamals in the Arabian SeaPart 2: Surface waves

摘要

The wave conditions in the Arabian Sea are mainly controlled by the SW/NE monsoon winds, the swells from the South Indian Ocean, and to some extent by the regional/local wind systems. The shamal winds are one of the important regional wind systems, which contribute to the wave characteristics in the Arabian Sea considerably. Previous studies explored the existence of shamal swells in the Arabian Sea, based on measurements and modelling during selected shamal events. The present study investigates the climatological features of the shamal waves in the Arabian Sea by analysing ERA-Interim significant wave heights (SWH) for the period 1987-2016. The ERA-Interim SWHs were validated against altimeter observations and available measurements in the Arabian Sea. Monthly and annual climatology of shamal and total waves were derived, the trends were estimated and discussed. The results indicate that the annual and monthly shamal SWHs (mean and 99th percentile) are significantly decreasing in most part of the Arabian Sea, while they are increasing in the Gulf of Oman. Significant increase in the 99th percentile total SWHs were estimated in the central Arabian Sea. The makran wind-induced waves were identified in the northern Arabian Sea for the first time.