Antarctic Intermediate Water AAIW

Figure 13.2 Section of (A) nitrate versus depth and (B) nitrate versus potential density (sigma theta) using combined data from the 2003 (North Atlantic) and 2005 (South Atlantic) occupations of the A16 line. North Atlantic DeepWater (NADW), Antarctic Bottom Water (A ABW) and Antarctic Intermediate Water (AAIW) are indicated. Units pmol kg. ...

Nitrate-rich signatures of Antarctic Bottom Water (AABW) and Antarctic Intermediate Water (AAIW) extend northward, reflecting the high surface concentrations where these water masses are formed. These water masses are also evident in the zonal structure of the North and South Atlantic, and nitrate-rich (>30 iM) AAIW is evident in the South Atlantic (Fig. 13.3) at mid-depth, along with a hint of AABW with elevated nitrate concentrations in the deep western part of the basin. There is... 

A useful apphcation of preformed nutrient concentrations is that they are intrinsic to different water masses and sometimes can be used as conservative tracers. For example, the main sources of deep water in the Pacific Ocean are North Atlantic Deep Water (NADW), Antarctic Intermediate Water (AAIW) and Antarctic Bottom Water (AABW), all of which are at least partly homogenized in the Antarctic Circumpolar Water (AACW). It is not possible to determine how much of each of these sources contributes to Pacific deep water by using end member mixing of the conservative properties temperature and salinity because salinities of the end members are not sufficiently different. Since concentrations of DIP are well above detection limits in... 

Antarctic Intermediate Water (AAIW), and Antarctic Bottom Water (AABW). Note that 8Nd is -13.5 in NADW, and °Be/ Be is c. 0.5 x 10. In the southern circumpolar water is -9, and Be/ Be is 1 X 10. °Be/ Be, and in particular 8Nd mimic the shape of salinity. Incorporation of these tracers into the sediment at a given location potentially provides information on the distribution and mixing of water masses at this location back through time. 

AABW, Antarctic Bottom Water NADW, North Atlantic Deep Water MW, Mediterranean Water AAIW, Antarctic Intermediate Water T and S characteristics from Picard and Emery (1982) How rates are in Sverdrups (10 m s ). 

Fig. 3.2 (a) Simplified, schematic representation of oceanic deep water circulation (after Broecker 1997). (b) Water masses in theAtlantic (after Stowe 1979). AABW =Antarctic Bottom Water AAIW =Antarctic Intermediate Water AIW = Atlantic Intermediate Water med = Mediterranean Water NADW = North Atlantic DeepWater. 

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