科研之友
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摘要
Mean total (barotropic + baroclinie) mass transports of the oceanic top 1000 dbar are estimated for two regions of the South Atlantic between 18 degrees S and 47 degrees S. These transports are obtained by using Gravest Empirical Mode (GEM) fields calculated from historical hydrography with temperature and position data from quasi-isobaric subsurface floats deployed from 1992 through 2001. The float-GEM-estimated total mass transports reveal a Brazil Current with a southward flow of 20.9 Sv at 30 degrees S and 46 Sv at 35 degrees S (1 Sverdrup, Sv = 10(6) m(3) s(-1)). Two recirculation cells are identified in the southwest corner of the subtropical gyre north of 40 degrees S, one centered at 48 degrees W, 37 degrees S recirculating 28.5 Sv and another centered at 40 degrees W, 38 degrees S recirculating 13.9 Sv. The South Atlantic Current (SAC) flows eastward with 50 Sv at 30 degrees W and splits into two branches in the east, one north of 38 degrees S transporting 19 Sv and one south of 41 degrees S transporting 31 Sv. Of the 39.7 Sv of SAC transport that conies from the Malvinas Current/Antarctic Circumpolar Current (ACC) system in the western basin, only 8.7 Sv flow with the northern branch and the remaining 31 Sv flow as the southern branch out of the South Atlantic rejoining the ACC directly (20.6 Sv) or interacting with the Agulhas Current Retroflection (10.4 Sv). From the northern branch, only 4.7 Sv of Malvinas Current/ACC origin and 10.3 Sv of Brazil Current origin (a total of 15 Sv) stays in the South Atlantic forming the Benguela Current, recirculating within the subtropical gyre. The Agulhas Current Retroflection reaches westward as far as 10 E with a transport of 48 Sv. In terms of mean total transport, the cold-water route carries 4.7 Sv in the upper 1000 dbar whereas the warm-water route carries 8.5 Sv. However, considering the interaction between waters from both origins, there is a total of 19.1 Sv of waters entering the Cape Basin from the Pacific Ocean and 18.5 Sv from the Indian Ocean.
- 出版日期2010-11
