Observational analysis of tidal effect on Sea breeze

Abstract:

The tidal effect on sea breeze was examined using a 4-year half-hourly database of wind profiles obtained from a 300-m tower at a coastal site in Boseong, South Korea. The study site is located in the bay facing the ocean with tidal flats on the southeast side. We selected sea breeze days during warm period from May to September for the period 2014-2017. Here, sea breeze day was defined as a day with both onset and cessation of sea breeze in a day. Sea breeze days were divided into four groups depending on tidal state and ambient flow direction. The tidal effect on sea breeze was tested at a significance level of 5% using two-sample t-test for onshore and offshore flows, respectively. For only offshore flow, tidal state results in significant difference in arrival time of sea breeze, showing earlier arrival for high tide group in the morning than low tide group in the morning. This could be explained by the shorter distance to the coast due to the movement of coastal boundary toward the station and stronger sea breeze forcing during high tide. For offshore flow, tidal effect on wind profile was examined. The results show that the tide state influences the time at which sea breeze intensity accelerates but not the daily maximum intensity of sea breeze.