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101
vigelse af en enkelt Observation fra det normale Medium
er + 1°.7. Den absolute Maxinmmsafvigelse er 2°.o. Ved
Observation af Havoverfladens Temperatur i
Sommermaa-nederne, reduceret til Midten af August, maa man altsaa
i vort Nordhav være belavet paa at finde den indtil et Par
Grader linjere eller lavere end den normale. For at bringe
den sandsynlige Fejl af Normalinediet ned til + 0°. 1
udfordres Observationer fra 81 Aar.
Til Construction af Kartet for Havoverfladens normale
Temperatur i Marts foreligger, for Strækningen fra
Nordsoen forbi Shetland til Jan Mayen og Grønlandshavet
nor-denfor denne 0, 19 Aars Observationer (1807—85) fra norske
Sælfangere. Blandt disse have især været virksomme
Cap-tejnerne Carsten Bruun, Jacob Melsom, Axel
Kref-ting, L. Grønvold og L. H. Castberg, der have
indsendt sine Iagttagelser til det norske meteorologiske Institut.
Disse Observationer har jeg, for Marts Maaned, da
Variationen er ringe, afsat udenReduction til Midten af Maaneden,
paa et Kart, og tegnet Isothermer efter dannede
Gruppemedia.
For at kunne fortsætte disse Isothermer op til
Spidsbergen har jeg paa den ene Side benyttet de Iagttagelser,
der ere gjorte i Dybet i Magdalene Bay,
Nordvest-Spidsbergen, og paa den anden Side de Iagttagelser, som gjordes
under "Alberts" Rejse til Spidsbergen i November og
December 1872.
I Dybet af Magdalene Bay fandt Charles Martins,
Medlem af Expeditionen med "La Recherche", i August 1839
Temperaturer fra —1°.7 til—l°.9l. Sammesteds fandt jeg
i August 1878 Temperaturer fra —1°.8 til — 2°.l. Disse
låve Temperaturer maa hidrøre fra Vinterkulden i
Overfladen, og jeg sætter derfor Temperaturen i den koldeste
Maaned, Marts, ved Nordvest-Spidsbergen til —2°.
Efter Meddelelse fra Capt. Carsten Bruun, der i 20
Aar har drevet Sælfangst ved Jan Mayen, gaar den
midlere Isgrændse (Pakisen) om Vinteren fra et Punkt 3°
østenfor Jan Mayen mod NNE til 75° N. Br., 0° Længde, hvor
den danner det saakaldte Is-Nes. Idet den her pludselig
vender sig mod YVN W, danner den en stor Bugt, der
væsentlig hidrører fra vedholdende østlige Vinde. Den inderste
Vig af denne Bugt ligger mellem 76° og 77° N. Br. og fra
5° til 10° vestlig Længde. Bugtens nordlige Bred dannes
af Isgrændsen, eier løber mod ENE hen til Spidsbergen.
Efter denne Isgrændse har jeg trukket Isothermen for —2°
for Marts fra Jan Mayen til Nordvest-Spidsbergen.
Paa Rejsen til Spidsbergen fandt Capt. Otto2 den
24. November 1872 i Sydvest for Spidsbergens Sydkap,
1 Voyages en Scandiiiavio, en Laponio et au Spitzborg de la
corvette La Recherche — Géographie physique, II, p. I!41).
2 Alberts Expedition til Spidsbergen i November og December
1872 og dens videnskabelige Resultater. Christiania
Videnskabs-Selskabs Forhandlinger for 1873.
imum-deviation of a single observation from the normal
mean, is + l°.7. The.absolute maximum-deviation is 2°.5.
When measuring the temperature of the sea-surface during
the summer-months, reduced to the middle of August, we
must, therefore, be prepared to find it in the Norwegian Sea
some two or three degrees higher or lower than the normal.
In order to bring down the probable error to + 0°. 1,
observations are required extending over a period of 81 years.
For constructing a map that shows the normal
temperature of the sea-surface in March, we have for the tract
from the North Sea past Shetland to Jan Mayen and the
Greenland Sea north of the latter island, 19 year’s observations
(1867 — 1885), furnished by Norwegian sealers. Amongst
the captains distinguished as specially energetic, we can
mention Carsten Bruun, Jacob Melsom, Axel Krefting, L.
Grønvold, and L. H. Castberg, who sent in their journals to the
Norwegian Meteorological Institute. These observations I have
set down for the month of March, without reduction to the
middle of that month, the variation being inconsiderable,
on a map, and have drawn the isotherms from the means
of collected groups.
In order to extend these isotherms as far north as
Spitzbergen, I have, on the one hand, made use of the
observations taken throughout the depths of Magdalena Bay,
north-west coast of Spitzbergen, and, on the other, those
made during the cruise of the "Albert" to Spitzbergen, in
November and December 1872.
In the depths of Magdalena Bay, M. Charles Martins,
member of the Expedition with "La Recherche," found,
during the month of August 1839, a temperature ranging
from —1°.7 to —1°.9. 1 Throughout the same locality, in
August 1878, I registered a temperature varying from
—1°.8 to —2°.l. These low temperatures must obviously
originate in the winter-cold of the surface; and hence I
put the temperature on the north-west coast of Spitzbergen
during March, the coldest month of the year, at —2°.
According to a statement communicated by Capt.
Carsten Bruun, who, during the space of 20 years, has been
engaged in the seal-fishery off Jan-Mayen, the mean ice-limit
(of the pack) in winter extends from a point 3° east of Jan
Mayen towards the NNE, as far as lat. 75° N, long. 0°,
where it forms the so-called ice-cape. Here, diverging
suddenly towards the WNW. it constitutes a large bay,
chiefly the result of continuous easterly winds. The inmost
creek of this bay lies between lat. 76° and lat. 77° N and
long. 5° to long. 10° W. The northern shore of the bay is
formed by the ice-limit, which, passing ENE, reaches up to
Spitzbergen. Along the tracts of the ice-limit, I have drawn
the isotherm for —2°, in March, from Jan-Mayen to the
north-west coast of Spitzbergen.
On his voyage to Spitzbergen, Capt. Otto- found on
the 24th of November 1872, to the south-west of South
1 Voyages en Scandinavie, en Laponie et au Spitzborg de la
corvette La Recherche — Oéographie physique, II, p. IMS).
2 Pctermanns Gcographischc Mittheilungeu f. 1873. Ocean
Highways, June 1873, p. 104.
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