A Long-Term Study of Sea-Breeze Characteristics: A Case Study of the Coastal City of Adelaide

Abstract

AbstractThe sea-breeze characteristics of the Adelaide, Australia, coastline have been studied by applying a sea-breeze detection algorithm to 3- and 6-hourly meteorological records of near-surface and upper-air data at Adelaide Airport from 1955 to 2007. The sea breeze is typically a westerly gulf breeze combined with a later-occurring southerly ocean breeze. Regression analysis showed a significant increasing trend in the intensity of sea breezes but not in their frequency. Over the 52-yr period, there was an average increase of 1 m s−1 in zonal and 0.7 m s−1 in meridional sea-breeze wind speed components. The annually and seasonally averaged maximum wind speeds on sea-breeze days increased significantly over the 52-yr period of the study by 0.65 m s−1 for the whole year, 0.48 m s−1 in spring, 1.02 m s−1 in summer, and 1.10 m s−1 in autumn. A comparison of hourly data for 1985–95 with those for 1996–2007 showed frequencies of sea-breeze onset times less than 4 h from sunrise increasing from 29% to 36%, durations greater than 8 h increasing from 51% to 59%, and times of maximum sea breeze between 2 and 6 h after sunrise increasing from 44% to 50%. The monthly frequency of sea breezes was found to increase by 2.8 percentage points for each degree Celsius rise in monthly average maximum air temperature at Adelaide Airport. The meridional ocean-breeze wind speed, unlike the gulf-breeze wind speed, is also correlated with maximum air temperature at Adelaide Airport.