distance (km)

tempe rature (;C)

computed current (ms"')

Figure 4.21 The distribution of (a) temperature (°C) and (b) salinity, plotted from measurements made in 1878 and 1914, for an east-west section in the narrowest part of the Straits of Florida, between Fowey Rocks, a short distance south of Miami, and Gun Cay, south of Bimini Islands (see Figure 4.20(b)). Note: Salinity values are effectively parts per thousand by weight, but for reasons explained later are usually given without units, (c) The velocity distribution as calculated from the temperature and salinity data, on the assumption that the current has decreased to zero by the depth of the 0-contour; and (d), the velocity distribution on the basis of direct measurements by Pillsbury.

Figure 4.22 Geostrophic current velocity (in m s-1) in the Gulf Stream off Cape Hatteras; the section is east-west so the blue shaded areas (with negative velocity values) represent flow with a southerly component (probably south-westerly). The horizontal scale is smaller than that in Figure 4.21.

Study Figure 4.21. then answer Question 4.10. bearing in mind that although the warmer water is also more saline, the ranges of temperature and salinity in the Straits of Florida are such that the density distribution is determined mainly by Trather than S. (If it were determined by salinity alone, the water column in the Straits of Florida would be unstable.)

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