The Vertical Distribution of Temperature and Salinity in the Region of the East Greenland Polar Current.
It is remarkable how very similar the vertical distribution of temperature is in all regions of the Polar Current from the North Polar Basin and as far south as between Iceland and Jan Mayen, or even north-east of Iceland. And this similarity is striking, not only in the top layer of real Polar water, but also in the underlying warmer water.
In Fig. 92 we have drawn the vertical temperature curves for the Fram Stat. 23 (July 20-31, 1895), the Belgica Stats. 28 (July 21, 1905, 75° 55' N. Lat., 9° 0' W. Long.), 30 (July 22, 1905, 73° 39' N. Lat., 12° 0' W. Long.) and 49 (Aug. 16, 1905, 71° 20' N. Lat., 17° 25' W. Long.), and finally the Michael Sars Stat. 18 (Aug.6, 1900, 69° 9' N. Lat., 12° 0' W. Long.) and Stat. 13 (Sept. 1, 1903, 66° 55' N. La t., 8° 48' W . Long.)
The similarity of the curves of these several stations so far apart is striking. In the upper strata, between the surface and 100 metres, the curve of the Fram Stat. 23 shows lower temperatures than any of the other curves from stations farther south, as might be expected. But below 100 metres the curve of the Belgica Stat. 30 shows lower temperatures than the Fram curve, while the curve of the Belgica Stat. 28 shows higher temperatures. The Fram curve lies between the two Belgica curves, a circumstance which is in accordance with what was said above, the curve of Stat. 28 being from the current outside the continental slope, while Stat. 30 was within the edge of the continental shelf.
Down to a depth of about 800 metres there is a striking similarity between the curves of the Fram Stat. 23 and the Belgica Stat. 28, the main difference only being that the under side of the cold top layer was about 25 metres higher at the Belgica Station than at the Fram Station. Below 800 metres, the Belgica curve indicates lower temperatures than the Fram curve, which is in accordance with the fact that the bottom-water is colder in the Norwegian Sea than in the North Polar Basin , as was proved by N ansen [ 1902; 1906].
The curve of the Belgica stat. 49, in the Polar Current between Greenland and Jan Mayen, is very like the curve of the Belgica Stat. 28, four degrees and a half farther to the north. In the upper part, above 150 metres. the two curves are nearly indentical; but below that level the southern curve (stat. 49) shows lower temperatures than the northern (Stat. 28).
Fig. 92. Temperature-Curves, at Stations from different Parts of Polar
The Michael Sars Stat. 18 was between Jan Mayen and Iceland, and was not really in the Polar Current. The curve of this station shows that the top layer of cold Polar water has become warmer than at any of the above-mentioned stations farther north. It is covered by a surface-layer of warmer water about 25 metres thick; but its lower boundary ( the isotherm of 0°C.) is very nearly at the same level as at the Belgica Stats. 49 an d 28. The underly ing warmer water is still colder than the Belgica Stat. 49 (except at 600 m.), but upon the whole the curve shows a great similarity to that of the last-named station. The curve of the Micael Sars Stat. 13, north-east of Iceland, has still the characteristic features of the above curves; but the Polar water has become still warmer and is covered by thiker layer of warmer water. Its lower boundary is deeper, however, and the underlying water considerably colder than at stat.18.
The vertical distribution of salinity and density in the Polar water and underlying warmer water also shows a great similarity in the different Latitudes of the East Greenland Polar Current as also in the North Polar Basin . The similarity in the salinity and density is seen from the above table (pp. 274 -275, 279. The determinations of the salinities of the North Polar Basin are unfortunately not sufficiently accurate to show the details of this similarity; but the great features are clear. We shall not enter into further particulars on this point.
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Continue to Chapter IX.3 Course and Extent of the East Greenland Polar Current.