78 FRIDTJOF NANSEN. M.-N. Kl. 
cold Polar water which has a temperature-minimum at about 60 metres. 
No melting of the ice near the surface, worth mentioning, can be caused 
by conduction of heat through the water from the underlying warmer 
water; for in this manner, it would require about one year to melt a 
centimetre of ice, provided that the rise of temperature be as much as 
2° C. per 100 metres from the under-surface of the ice downwards, 
The melting thus caused is consequently a negligeable quantity. The 
heating of the overlying cold strata by the warmer under-current is to 
a much greater extent caused by the intermixture between the two 
waters. But even in this manner only an extremely slow heating can be 
produced, because the overlying layers are so much lighter, that the inter- 
mixture between them will proceed extremely slowlyl, It is, therefore, 
found that the temperature as well as the salinity of the cold surface 
layers of Polar water very slowly rise on the way southwards along the 
Greenland coast. And furthermore, it is found that in the East Green- 
land Polar Current there is, at least in the summer, a temperature-mini- 
mum at 60 to 80 metres?, and this minimum would naturally soon be 
washed away if such an active intermixture occurred as would be ne- 
cessary to cause any appreciable melting of ice near the surface, by 
heating from below, 
1 As the sea-surface is covered by ice, the wind will have little opportunity to stir the 
waters, and where the density rapidly increases downwards, the lighter layers will 
glide over the heavier ones with very little friction, and without causing vertical move- 
ments of any great extent. 
? At Amdrup’s Station III (4p. II), near the eastern margin of the East Greenland Polar 
Current, the minimum (—r'45? C.) lies somewhat higher, at about 30 metres, and 
there may be a more appreciable heating from below, though even here it cannot be 
considerable; for at 40 metres there is —ı'4°C. and at 60 metres —ı'o5°C. The 
temperature of —0'05? C., and salinity of 33.10 °/,, at 50 metres is of course erronous, 
the water-bottle has obviously been closed near the water-surface. 
At Ryder's Station XII (R XII) there may also be a slight heating from below. At 
these Stations it is therefore possible that some slight melting might be caused by 
heating from the underlying warmer water. 
3 Prof. Otto Pettersson might perhaps object that this minimum is due to melting 
of the lower part of the great hummocks reaching down to depths of 50 and 60 metres 
or more. But howsoever this may be, it is at least certain that there is much more 
ice nearer the surface and consequently much more melting is going on there. But in 
spite of this the temperature rises towards the surface during the summer, by being 
heated from above, to much above its freezing point; and it is, therefore, clear that 
the melting of ice in this water is chiefly, or almost exclusively, due to the direct heat 
of the sun, which melts the ice on the surface, and heats the water in which it floats. 
It is of course impossible that water overlying a temperature-minimum can be heated 
from strata underlying this minimum, for as long as this stratum with a minimum tem- 
perature exists, it must naturally have a cooling effect upon the overlying strata. 
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