Fróðskaparrit - 01.01.1993, Page 147

151
Measurements ofsea bottom temperatures
between the Faroe Islands and Iceland and
between the Faroe Islands and Shetland
1906-1962 using telegraph cables
Vagn Erik Michelsen
Úrtak
I greinini eru mátingar av el-mótstøðuni í telegrafkaðal-
um á havbotninum millum Tórshavn og Seyðisfjørð og
millum Tórshavn og Burwick. Fyri seinna heimsbar-
daga vórðu mátingarnar gjørdar eina ferð um mánaðin,
seinni eina ferð hvønn ársfjórðing. Saman við upplýs-
ingum um samanbindingar eftir kaðalbrot ber til at
brúka mótstøðuna til at frnna miðalhitan í sjónum uttan
um kaðalamar. Langtíðarbroytingamar í hitanum skulu
takast við fyrivami, tí lop eru í, sum m.a. kunnu hava við
kaðalbrot at gera. Hitabroytingarnar við árstíðini eru
meiri álítandi og kunnu vera liður í tulkingum av óvan-
ligum viðurskiftum í økinum millum ísland og Hetland.
Abstract
Resistance measurements are reported from a cable be-
tween Tórshavn in the Faroe Islands and Seyðisfjørð on
eastem Iceland and a cable between Tórshavn and Bur-
wick in Shetland. The measurements were performed at
monthly intervals until the second world war and quar-
terannually after that. When combined with information
on splicings after cable breaks the resistances may be
used to determine average bottom temperatures of the
water along the cable tracks. The long-term variations of
annual mean temperatures may be doubtful due to occa-
sional offsets, possibly associated with cable breaks; but
the seasonal variation appears more reliable and exhibits
interesting features that may shed light on the behaviour
of anomalous periods (Great Salinity Anomalies) in the
Iceland-Shetland region.
Introduction
In 1906 the Great Northem Telegraph
Company (Det Store Nordiske Telegraf-
Selskab A/S, København) hereafter re-
ferred to as “SNTS” established two sea-
cables, one between Tórshavn in the Faroe
Islands and Seyðisfjørð in Iceland (here-
after referred to as the “Iceland-cable”) and
the other one between Tórshavn and Bur-
wick in Shetland (hereafter referred to as
the “Shetland-cable”). Both cables started
operation in August 1906 and were in oper-
ation until 1962 although with occasional
gaps. In this period the cable resistance was
measured and archived regularly and as the
resistance depends upon the temperature of
the surrounding seawater these measure-
ments may yield information on the aver-
age bottom temperatures along the cable
tracks.
With the large interest in the role of the
ocean in the climate system a time series of
bottom temperatures between Iceland and
Scotland should be of large interest; but to
use this information two sets of problems
Fróðskaparrit 41. bók. 1994(1993); 151-163