334 PETTEMSSON, SIBERIAN SEA. 



The Kära Sea. 



Ten years have scarcely elapsed since the Kära Sea was 

 opened anew to the investigations of science as well as to 

 traffic and trade by the expeditions of Nordenskiöld in 1875 

 tfe 1876. In order to ensure the interests and lessen the risks 

 of the Siberian trade, nothing could be rnore desirable than a 

 thorough knowledge of the hydrographic conformation of the 

 ice and the water-strata of this sea. I hope, that the present 

 paper will contribute to prove the importance of fnrther in- 

 vestigations on this subject. For, as I will try to show in 

 the following, there are reasons to suppose, that the possibil- 

 ity of safe navigation in this sea depends not only npon the 

 mere changes of wind and Aveather or upon the influence of a 

 warmer or colder summer, but also upon the conformation of 

 its deeper strata. Little as we know at present of this subject, 

 we can not fail to recognize the prevailing difference in salt- 

 ness and temperature between the upper and lower layers of 

 the Kära Sea as the most characteristic feature of its hydro- 

 graphic constitution. In the summer months a thin layer of 

 warm and relatively fresh water covers the surface of the 

 Kära Sea, while a few metres below there is found a stratum 

 of salt water, cooled unto (and in some cases even heyond) its 

 freézing point. I have already alluded to this fact in the 

 introductory chapter of the foregoing paper. 



In the eastern and northern parts of the Kära Sea this 

 difference is greatest on account of the masses of fresh and 

 warm water emerging from the testuaries of the Obi and 

 Yenisei rivers. On the hydrographic map [plate 24] I have 

 inserted some temperatures observed by Captain Mack, one 

 of the first explorers of the Kära Sea in 1871, showing that 

 the influence of these rivers still prevails at the latitudes of 

 Cape Nassavi and the Oranie Islands. According to Mack, 

 Johannesen a. O. the water here is so fresh as to be almost 

 drinkable, whenever the sea is calm and unruffled by tempest, 

 which however soon mingles the water of the thin superficial 

 stratum with the ice-cold water from below. As for the eastern 

 part of the sea, I can refer to the observations of the Vega- 

 expedition from the 10'^'' to the 19*^ of August, 1878. The tem- 

 perature of the surface, which was + 8° or + 9° at Port Dick- 

 son, gradually diminished and at last sunk below 0° C north 



