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The Great South Australian Coastal Upwelling System is a seasonal upwelling system in the eastern Great Australian Bight, extending from Ceduna, South Australia, to Portland, Victoria, over a distance of about . Upwelling events occur in the austral summer (from November to May) when seasonal winds blow from the southeast. These winds blow parallel to the shoreline at certain areas of the coast, which forces coastal waters offshore via Ekman transport and draws up cold, nutrient-rich waters from the ocean floor.〔 Because the deep water carries abundant nutrients up from the ocean floor, the upwelling area differs from the rest of the Great Australian Bight, especially the areas offshore of Western Australia and the Nullabor in South Australia, which are generally nutrient-poor. Every summer, the upwelling sustains a bountiful ecosystem that attracts blue whales and supports rich fisheries.〔〔 The Great South Australian Coastal Upwelling System (GSACUS) is Australia's only deep-reaching coastal upwelling system, with nutrient-enriched water stemming from depths exceeding .〔Kämpf, J., 2010. On the preconditioning of coastal upwelling in the eastern Great Australian Bight. Journal of Geophysical Research – Oceans, VOL. 115, C12071, 11 pp., 〕 Recently, a new upwelling centre has been discovered on the western shelf of Tasmania.〔Kämpf, J., 2015. Phytoplankton blooms on the western shelf of Tasmania: evidence of a highly productive ecosystem, Ocean Sci., 11, 1-11. 〕 Since this new upwelling centre is located outside South Australian waters, the entire upwelling system should be rather called the Great Southern Australian Coastal Upwelling System. ==Oceanographic processes== During the austral summer, high-pressure systems over the Great Australian Bight cause southeasterly winds to blow over the coasts of Victoria and South Australia. When winds blow parallel to the shoreline, Ekman transport pushes water to the left of the wind direction (in the southern hemisphere), which in this case is westward and offshore. To replace the water moving offshore, cold waters from the ocean floor rise to the surface.〔 During upwelling events, local sea surface temperature drops by 2-3 degrees Celsius.〔 Key upwelling centres form in three different locations, described in the sub-sections below; the Kangaroo Island and Eyre Peninsula centres are linked by the same upwelling process.〔Butler, A. J., F. Althaus, D. M. Furlani, and K. R. Ridgway. (Assessment of the Conservation Values of the Bonney Upwelling Area: A Component of the Commonwealth Marine Conservation Assessment Program 2002-2004: Report to Environment Australia. ) Published by CSIRO Marine Research (now CSIRO Marine and Atmospheric Research) and Environment Australia, Dec. 2002. Accessed 12 July 2013.〕〔 Upwelling events occur nearly simultaneously across the three separate centres, appearing within a few days of each other, despite spanning a distance of approximately .〔 While the Bonney Upwelling, where the strongest and most reliable upwelling events occur, was reported and explored over 30 years ago,〔Lewis, R.K. 1981. Seasonal upwelling along the south-eastern coastline of South Australia. Australian Journal of Marine and Freshwater Research 32: 843-854.〕 the full extent of the upwelling system was discovered only as recently as 2004.〔Kämpf, J., M. Doubell, D. Griffin, R. L. Matthews & T. M. Ward, 2004. Evidence of a large seasonal coastal upwelling system along the Southern Shelf of Australia. Geophysical Research Letters, Vol. 31, L09310, 〕 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Great South Australian Coastal Upwelling System」の詳細全文を読む スポンサード リンク
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