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17(1
bagcvendcnde atlantiske Vand, mod Vest af Grønland,
sa’tter den grønlandske Polarstrom mod SS W forbi Jan
Maven og senere, med mere vestlig Retning, ind i den
nordlige Del af Danmarkstaedet, Hastigbeden er størst ved
Isgrændsen og aftager efterhaanden henimod Grønlands
Kvst, hvor den er mindst. Østenfor Jan Maven gaar
Hastigheden op til 15 Kvm. (0.32 m), hengere Nord, under
75» Bredde. 0» Lgd.. til 7 Kvm. (0.15 mi. Under
Grenlands Kyst gaar Hastigheden ned til 4 Kvm. (0.09 m).
De samvirkende Factorer ere her den større Vindhastighed
ved Isgrændsen og den ringere specifiske Vægt af Vandet
ved Kysten. Det er interessant at sammenligne disse
Resultater af Beregningerne med den Skildring, som den
erfarne og intelligente Polarfarer, Capt. Koldewey, giver af
dell Grønlandske Polarstroni i folgende Old1:
■’Ved Vdcrkanten af Isen og i Drivisen selv. indtil
lie Flak. der befinde sig længere indenfor Isbarrieren.
findes, mellem Bredderne 7ll°og 75". en bestandig sydgaaende
Strømning af gjennemsnitlig 8 til 1(1 Kvartmiles Fart i
24 Timer, hvilken imidlertid efter Vindene og den deraf
følgende Isdrift ofte bliver merkelig afbøjet mod Øst eller
Vest. Inge ved Kysten er dog — omend i Almindelighed, det
er i Middel for Aaret, en Flytning af Isen og Vandet mod
Syd ikke kan ganske oversees (den gjennemsnitlige
Hastigbed af det Isflak, hvorpaa Hansa-Mændene drev, beløb sig
til 4.li Kvm. i Dognel s — denne svagere end ved dell ydre
Isgrændse".
De Drifter i Isen, som Scoresby anfører*, give, mellem
74» og sil" N, 2°—III" W. Hastigheder af 8.5, 12—13,
14 og 2(1 Kvm. i Døgnet. Capt. C. Bruun har observeret
med sit Skib en Drift vestenom Jan Mayen ned mod
Limganes paa Island med en Fart af 10 Kvm.-pr. Døgn.
Fli Del al Polarstrommen fortsætter sin Vej ned
mod Island. Den overvejende Del folger Grenlands Kyst
gjennem Danmarkstrædet og videre til Grønlands Sydspids,
hvor den gaar ind i Davisstriedet.
Strømningerne omkring Island ere meget interessante.
Deres Lob er allerede for mange Aar siden beskrevet af
Admiral Irminger». De omkredse Island i anticyclonisk
Retning. De nordlige Landes Klimatologi lærer, at ilet er
Forholdene om Vinteren, der give Aaret dets
gjennemsnitlige Character. Fastlandets Afkjøling i Modsætning til
det varmere Hav fremkalder et Maximum af Lufttryk over
Landet, med Landvinde, der, afbøjede til højre, omkredse
Kysten i anticyclonisk Retning. Endvidere ville Elvenes
Vand forhøje Vandspejlet ved Kysten, og begge disse
Aarsager frembringe en Strøm i Retning af de herskende
’ Zweite Deutsche Nol-di.olfohrt. Jtetenmli.gie Ull.l
Hy.ii-n-gi-njihie, S. ni:;.
1 An Account of ille Arctic. Regions. I. S. -2C1 17.
■ Stroiiiiiinger ngls.llift veil Islnn-I. Tids«ltrift forSoviesen, lslll.
bounded by the Atlantic water returning towards the south,
on the west by Greenland, the Greenland Polar current sets
SSW. past Jan Mayen, and then, taking a more westerly
direction, flows into the northern part of Denmark Strait.
The velocity is greatest at. the ice-limit, gradually
diminishing towards the coast of Greenland, where it is least. East
of .Tan Mayen, the velocity, reaches 15 nautical miles (0.32 ni.),
farther north — lat, 75» N. long. I)» — it is 7 naut. miles
(0.15 m.). Off the coast of Greenland, the velocity
diminishes to 4 naut. miles (0.09 m.). The co-operating factors
are hero the comparatively great wind-velocity at the ie.-limit
and the low specific gravity of the water at the coast. It is
interesting to compare these results of the computations
with the account given by Capt. Koldewey, the experienced
and intelligent Arctic navigator, of the Greenland Polar
current, in the following words1: —
■’At the outer limit of the ice, and in the drift-ice
itself, as far as the fields which lie at a greater distanc’
from the ice-barrier, there is, between lat. 70» and 75",
a steady south-setting current, averaging from 8 to 111
nautical miles in 24 hours, which, however, according to
the winds and the ice-drift resulting from them, often
deviates remarkably towards the east or the west.
Meanwhile. in immediate proximity to the coast — though as a
rule. i. e., iu the mean for the year, wo cannot quito
overlook that both ice and water are moving southward
(the average rate of the ice-floe on which the Hansa-men
drifted, was 4.(i nautical miles in 24 hours) — this movement
is less rapid than at the outer ice-limit."
The various ice-drifts mentioned by Scoresby» give,
between lat. 74»—80" N and long. 2°—III» W, velocities
of 8.5, 12—13, 14, and 20 nautical miles iu 24 hours.
Capt. C. Bruun observed with bis ship a drift setting from
the sea west of Jau Mayeil towards Laiigaues, Iceland, at
the rate ol’ 10 nautical miles in 24 hours.
Part of the Polar current continues its course towards
Iceland. By far the greater part Hows along the coast ol’
Greenland, through Denmark Strait, and thence farther on
to the southern extremity of Greenland, where it passes
into Davis’ Strait.
The currents round Iceland arc highly interesting.
Their course was many years since described by Admiral
Irminger.3 They encircle Iceland, taking an antieyclonic
direction. Tho climatology of the northern countries
teach us that it is winter that gives to the year its
prevailing character. The cooling-down of the continent
as contrasted with the higher temperature of the sea,
gives rise to a maximum of atmospheric pressure over the
land, with land-winds, which, deviating to tin- right,
encircle the coast in an antieyclonic direction. Moreover,
the water of the rivers will raise the level of the sea
• Zweite Deutsche Nordjxilfahrt. .Mctoorologio mid Hydro,
graphic, p. 1113.
- An Account ol’ the Arctic Regions, 1, p. -’i:; -JIT.
» Stramninger og Isdrift veil Island. Tidsskrift foi-Sovæsen, isiil.
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