28 MARION EXPEDITION TO DAVIS STBAIT AND BAFFIN BAY 



frequently washed ashore alon<r the eastern and southern parts of the 

 Greenhmd coast. 



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

 that no comj>lete and relial)le account can yet be tjiven of the move- 

 ment of the ice in the ])olar cap. Xearly all of the data, as can be 

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

 formation is available for the Amei'ican side of the orreat interior. 

 The known indraft of water throu«i;h Bering Strait and the well-rec- 

 ognized discharge of ice through Greenland 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 I 

 siielf. 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 been 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 North 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 Northern Hemisphere is, however, not in 

 harmony with the theory which, as Xansen points out. holds that 

 gradient currents flow as a rule with the land on their right hand. 

 Why should the Arctic Ocean ice drift in a direction opposite to the i 

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

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

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

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



Two different types of circulation, belonging to the planetary windi 

 system, affect north polar regions. A central polar dome of residual 

 high atmospheric pressure causes anticyclonic winds 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 oftein 

 interrupted. The polar cap of high atmospheric pressiu-e nuist tend' 

 to give a westerly and northwesterly drift to the ice, and the siil)-' 

 arctic westerlies would tend to impart an east and soutliea.sterly com- 

 ponent to the fields wiiile the congestion in various parts of the cover.' 

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

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

 cal data from these regions w^e shall be unable to state conclusively 

 the actual movement of the polar ice caj) and to explain its causes. • 



The accei)te(l views tliat the general drift of the ice is anticvdonif 

 does not necessarily contradict the theory of gradient currents foi 

 the Northern Hemisphere because the winds or various conchtionM 

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



'0 Wp should not lose si^hf of Aiiuiii(istMi"s unsiicoossful attempt to be carried from oust 

 to west atM-oss the polar liasiii in the M<iti<l. I'.ilS-liiU.-.. Tli.' early part of the dritt iwm 

 auspiciously and the vessel was carried as f;ir as tin- Xew Silierian Islands, tint w'>''""'1* 

 owiii};' to linfavorahle loc.il condilions. or actually to some tenipor.iry suspension of tlu'| 

 normal <'ast to west movement of the ice. mi further headway was made. \ 



"On the Siherian shelf the winds. acc(»rdinK to Sverdrup (T.rjs, p. 4.'.) are the niflHi^ 

 control, with the ice driftini; approximately .•{:{" to the riuht i>f the wind. Tlie.se coiiclih 

 .sions are based on a we.ilth of observational data obtained durini; the drift ot the il(i«<'i 

 with tile recorded winds in the Siberian sector. t See Sverdrup lOl'S. IKl'lt.) L, 



