Long description

Figure 14

This is a vertical profile of the Atlantic Ocean showing contours of salinity with depth and latitude.

There is a small inset map in the lower right corner. This map is centred on the Atlantic Ocean and spans all latitudes. There is a solid red line running more or less north-south through the middle of the Atlantic Ocean.

The horizontal axis of the main profile represents latitude, but is unlabelled. The axis scale goes from approximately 25° S to 65° N. There are tick marks at intervals of 10°, but numbered tick marks only at 20° intervals from 40° S to 60° N. The latitude of 0° is labelled as 'EQ'.

The vertical axis is labelled 'depth/m'. There are tick marks at intervals of 500 m but numbered only at intervals of 1000 m, from 0 m to 6000 m, with 0 m at the top of the axis.

There are horizontal and vertical gridlines at the numbered axes markers.

Along the bottom of the profile is a grey-coloured area, representing the ocean floor. The depth of the ocean floor starts shallow at 25° S and drops rapidly to below 5000 m at 30° S. It then undulates sharply up and down around the 5000 m depth with peaks at 40° S, EQ, 40° N and then it rises again to near surface at 66° N.

Contours of equal salinity are shown by labelled dashed or solid lines, ranging from 34 to 37 in intervals of 0.25. The labels are black and very small. The contour lines for salinities of 34, 35 and 36 are bold and the labels are white.

The salinity is also indicated by colour coding and this is indicated by the vertical colour key bar to the right of the profile. The key bar is labelled 'salinity' and is marked from 34 at the bottom to 37 at the top in intervals of 0.5. No units are indicated. The colour of the bar changes from purple at the bottom (low salinity) through blue, green, yellow, orange, red and then to pale red and orange again at the top (high salinity).

The general pattern of the profile shows the highest salinity along the surface and decreasing salinity with increasing depth.

Notable deviations from the general pattern are:

the narrow surface band of high salinity penetrates deeper into the ocean between 20° N and 40° N as evidenced by the bulge downwards of the orange-red colouration to depths of approximately 1500 m in these latitudes,

surface salinity is low between 25° S and 40° S with a finger of low salinity (blue) extending from 40° S to 10° N at a depth of 1000m, there is a band lower salinity (pale blue) along the ocean floor as it drops rapidly away from the surface at 15° S and as far north as the rise in the ocean floor at 40° S.