28 MARION EXPEDITION TO DAVIS STRAIT AND BAFFIN BAY 



frequently washed ashore alonjj: the eastern and southern parts of the 

 Greeidand coast. 



The total amount of observational data collected to date is so small 

 that no complete and reliable account can yet be given of the move- 

 ment of the ice in the polar cap. Nearly all of the data, as can be 

 seen, pertain to the Siberian sector, and practically no satisfactory in- 

 formation is available for the American side of the <i:reat interior. 

 Tlie known indraft of Avater throu<»;li Berin*:; Strait and the well-rec- 

 o<>;nized (liscliar<j.e of ice throu«ih (Treenland Strait, when considered 

 in conjunction with the above records of drifts, just mentioned, defi- 

 nitely establish, however, a westerly movement of the ice on the 

 Siberian side. Since the course of the ice can be traced with reason- 

 able assurance from Point Barrow around the Siberian continental 

 shelf, and finally out into the Greenland Sea, it is logical to believe 

 that the American margin assists in feeding what would otherwise 

 become ice-deficient regions immediately to the west. All of the 

 drifts that have l)een recorded were from east toward west, except 

 Peary's, and the route over which he traveled toward the pole un- 

 doubtedly lay within the area of active drainage to the Xorth Atlantic. 

 It seems, therefore, difficult to escape the conclusion that the outer 

 margin of the polar cap ice, on the Siberian side at least, participates 

 in a slow, but definite, anticyclonic movement.^'^ 



Cum sole motion in the Xortliern Hemisphere is, however, not in 

 harmony with the theory which, as Nansen points out, holds that 

 gi'adient currents tlow as a ride with the land on their right hand. 

 Why should tlie Arctic Ocean ice drift in a dii-ection opposite to the 

 current? The drift of fiat ice, as proved by observations in many 

 parts of the world is well known to be largely controlled f rictionally 

 by the wind and in a region of weak gradient currents, such as the 

 north polar basin; the wind is probably dominant.^' 



Two different types of circulation, belonging to the planetary wind 

 system, affect nortli polar regions. A central |)()lar dome of residual 

 high atmospheric })ressure causes anticyclonic Avinds around the pole. 

 But the southern margin of the Arctic extends into the belt of cy- 

 clonic westerlies, and as modified by the distribution of land and 

 water and by the seasonal cycle, these prevailing conditions are often 

 interrupted. The polar cap of high atmospheric pressure must tend 

 to give a westerly and northwesterly drift to the ice, and the sub- 

 arctic westerlies would tend to im])art an east and southeasterly com- 

 ponent to the fields while the congestion in various parts of the cover, 

 as noted by Sverdrup. must exert a third modifying effect. Until 

 Ave secure a greater amount of meteorological, ice, and oceanographi- 

 cal data from these regions aac shall be unable to state conclusively 

 the actual movement of the polar ice cap and to explain its causes. 



The accepted vieAA's that the general drift of the ice is anticyclonic 

 does not necessarily contradict the theory of gradient currents for 

 the Northern Hemisphere because the winds or various conditions 

 Avithin the pack itself may constitute the deciding factor. All the 



'« AA'e sliould not lose sight of Amundsen's unsuccessful attempt to be canied from east 

 to west across the polar basin in the Maud, 1918-1'.»:.*."'>. The early part of the drift began 

 auspiciously and the vessel was carried as far as the New Silwrian Islands, but whether 

 owing to unfavorable local conditions, or actually to some temporary suspension of the 

 normal east to west movement of the ice. no further headway was made. 



"On the Siberian shelf the winds, according to Sverdrup (1928. p. 45) are the main 

 control. Avith the ice drifting approximately 3:^° to the right of the wind. These conclu- 

 sions are based on a wealth of observational data obtained during the drift of the Maud 

 with the recorded winds in the Siberian sector. (See Sverdrup 1928, 1929.) 



