On the sea breeze index at Yilan, Taiwan

  • 張 資凰

Student thesis: Master's Thesis


In recent years, tourism and leisure-water sports are thriving in Taiwan. The Northeast and Yilan Coast National Scenic Area has developed into an important district for sea sightseeing, leisure, fishing, yacht driving, wind surfing, and whale watching. In addition to waves and currents, wind is a determinant for water sports. Sea breeze is a specific meso-scale meteorological phenomenon in coastal areas. It affects the wind field and weather pattern over coastal areas, and bring about rainfall and air pollution which influence tourism and leisure-water sports. Hence it becomes an important issue for both research and activity promotion.
This study first reviewed domestic and international researches related to sea breeze. It was discovered that the definition of the sea breeze day is quite different and depend on spatial conditions and local weather type. Therefore, a selection algorithm of sea breeze day in Yilan, Taiwan was developed in this study, which excludes the days during monsoon season, typhoon periods, and frontal passages. An automated screening sequence and a manual assessment procedure were then taken into account in the algorithm to finally identify the cases which meet the criteria of sea breeze day.
Sea breeze index (SBI) is generally used to forecast sea breeze. The physical meaning of SBI expresses the relationship between the inertial force and buoyancy force under the circumstances without other special weather events. Inertial force is horizontal and caused by the wind force, and buoyancy force is the upward force caused by the temperature difference between land and sea water. The ratio of inertial force to buoyancy force can then be adopted to determine whether sea breeze may be formed. This study first examined the feasibility of applying SBI to sea breeze days, which are identified by the selection algorithm, between April and September 2009 to investigate the possible range values of sea breeze index in Yilan. Afterwards sample days of sea breeze in June, July, and August from 2007 to 2011 were scrutinized to find the threshold value of sea breeze index. It showed that the SBI values of summer season in Yilan fit a Dagum distribution and 95% of the sea breeze days will have index values smaller than 5.54. Hence we are 96% confident that all values of sea breeze index for sea breeze days are small than 6 to which the threshold value of sea breeze index is finally set.
Date of Award2013
Original languageEnglish
SupervisorZsu-Hsin Chuang (Supervisor)

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