Subtropical convergence

Within the main thermocline, relatively low-NOs waters of the southern subtropical gyre are separated from those rich in NOs in the monsoon gyre to the north and the sub-Antarctic zone to the south by the Hydrochemical Front and the Subtropical Convergence (STC), respectively (Fig. 14.IB). The maximum in NOs generally occurs in the 1-2 km depth range north of the STC, and at... 

The four different oceanic fronts crossed during this expedition are also marked in Figure 7.15. At the subtropical convergence the bioactivity, and therefore also the chlorophyll-fl concentration, were relatively low compared with the situation at the other oceanic fronts. In some cases, but not in all, peak concentrations of... 

Lee, C. M., Eriksen, C. C., 1996. The subinertial momentum balance of the North Atlantic Subtropical Convergence Zone. Journal of Physical Oceanography, 26, 1690-1704. 

Fig. 9-7 Global map of major ocean currents. AND, Antarctic divergence STC, subtropical convergence ARC, Arctic convergence.

We have used the size and trace element data by Cronblad Malmgren (1981) to make a rough assessment of the potential influences of size changes on Sr/Ca ratios (Fig. 9). Their Sites F49-19 in the central Subantarctic Indian Ocean (43°53.2 S and 90°06.0 E) and E48-22 in the subtropical convergence of the Indian Ocean (39°53.7 S... 

Be, a. W. H. DUPLESSY, J. C. 1976. Subtropical convergence fluctuations and Quaternary climates in the middle latitudes of the Indian Ocean. Science, 194, 419-422. 

Francois R, Altabet MA, Goericke R, McCorkle DC, Brunet C, Poisson A (1993) Changes in the d C surface water particulate organic matter across the subtropical convergence in the S.W. Indian Ocean. Glob Biogeochem Cycle 7 627-644... 

In the subtropics, where wind-stress is convergent, water tends to be forced downward from the surface ocean into the thermocline. This downwelling is an important process for ventilation of the thermocline, and for driving the shallow gyre circulation. Figure 8 shows the measured tritium-helium age as measured... 

The quasi-horizontal flow of a fluid toward a common destination from different directions. When waters of different origins come together at a point or along a line (convergence line), the denser water from one side sinks under the lighter water from other side. The ocean convergence lines are the polar, subtropical, tropical, and equatorial. Also see divergence. 

Trades Tropical easterly winds, northeast in the Northern Hemisphere and sontheast in the Sonthem, between the subtropical highs and the intertropical convergence. 

An important problem which remains to be elucidated is the evolution of CAM. Is it truly an example of convergent evolution The occurrence of CAM in the gymnosperm Welwitschia and in ferns suggests a positive answer to that question. If so, are the specific metabolic details of CAM in each family similar or are there distinctive differences which are representative of the taxonomic categories In this context, did these plants with the CAM photosynthetic pathway actually all develop in the tropics and then move into arid environments of the subtropics and deserts of the world ... 

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