Download This paper not to be cited without prior refernce to the

This paper not to be cited withou t prior refernc e to the authors
Intern ationa l counci l for
C.M .. l984/G en:l5
the Explor ation of the sea
Mini-Sy mposium
CLIMATIC VARIATIONS IN THE BARENTS SEA DURING THE 1970'S .
by
Harald Loeng and Lars Midttu n
Institu te of Marine Researc h
Bergen , Norway
2
~·
Recently three small reports were presented by members of the
viz: Midttun, Nakken and
Institute of Marine research
Raknes
(1981), Loeng, Nakken and Raknes
(1983) and
s~tersdal
and Loeng {1934) all describing biological reactions to
climatic variations in the Barets Sea. The biological reactions
in the two larger fish stocks of the area, the
Arctic Cod and the Barents Sea Cape1in. It is of considerable
interest to study the nature of the biological reaction
were
and equally important is it to try to understand
the mechanisms causing the climatic variations. The latter
is however beyond the scope of this paper which is merely
proc~sses,
of climatic variations observed in the
Barents Sea in the period 1970-1983. The paper may be seen
to the two papers dealing with some
as an
biological variables observed in Capelin (Gj~s~ter and Loeng
just a
1984) and Cod (Nakken and Raknes 1984) during recent years.
in the Barents Sea.
2. Climat
The Barents Sea is in the north and east covered with Arctic
water masses, where ice is formed in winter and melts again
during the surruner
season~
In the south and west the inflowing
Norwegian Coastal Current and the Barents Sea branch of the
Atlantic Current form the Sub-Arctic water masses bordered
(Fig. l) The climatic
from the Arctic area by the Polar Front
conditions in the Barents Sea are therefore determined both by
effects from variation in the inflow from the west and by
processes
place in the sea itself.
Several authors have studied the climatic conditions of the
Barents Sea, among others He11and-Hans en and Nansen (1909),
Lee
(1963), Kislyakov (1964), Midttun (19691, Dickson, Midttun
and Mukhin
(1981),
(1970)Q Buchkov (1976)
(1983
1984)
r
B1indhe.im and Loeng
Dickson and Blindheim (1984).
- 3 -
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68°
so
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10°
,ig. 1.
15°
' 20°
50°
Location of the four sections A, B, K, and C seen in relation to the
circulatio n pattern of the Barents Sea.---->
: Atlantic water,
- - - -> : Arctic water,
••••••> : Coastal water. The polar front is
indicated by a broken line.
A general conclusi on is that the climatic conditio ns of the
Barents Sea depend mainly on the activity and property in the
inflowin g water from the west. Climatic variatio ns can therefor e
be recorded in the sections crossing the inflowin g water masses.
3. Variatio ns in standard sections
The location s of the standard sections dealt with below are
shown in Fig 1. The three sections A, B, and C have been observed by Norwegia n reserach vessels since the early 1950's,
ar observa tions have been taken in
since 1953. From 1977 the sections
but at
late
(1981),
(section A: 6 times, section B:
Blindhei rn and Loeng
s yearly)
Loeng (1984) have studied the
in
and salinity in the three sections ,
ions of the sections containi ng the
are more
4
the) Se
reflecti ng the Atlantic influenc e.
sal
shows the location of the famous
of the two neriods 1906-20 and
Kola.
are recorded back to 1900
for the depth layer 0-200 m between
been made availab le to the Institut e
1941-44 ,
70°30 N clrtd
the Knipowic h Polar Research
s and Oceanog- raphy, Murmans k.
(1981} have calculat ed monthly
of Mar:'ine
Insti tt:li:e
Midttun
for the periods 1921-198 0 and
mean values have been calculat ed for
up to 1983. The complete series
60
anomali
the whole
in a paper by
of artoma1
S~tersdal
and Loeng
crossing the eastward flowing current
·tempera ture, therefor e t.he Kola
(1984) "
at
exactly the same waterma sses as the
. But as is shown below,
seed: ion
in all the series.
1970 - 1983.
4. Var
Ficr
2.
and salinity variatio ns in
shows
the~three
Norweqia n sections A, B and C and the correspo nding tempera ture
the Kola
The curves
in late
, the latter taken from Anon. (1983).
mean values in the layer 50-200 m, observed
each vear.
The 9al
A, B
C
ini
imilar trends in all the three secti.ons
is gradual ly decreasi ng from 127Q until
5
S%o
35.2
35.1
35.0
34.8
Fig. 2.
Tempera ture (left) and salinity (right) of the 50-200 m layer in the
three sections A, B, C and tempera ture in 50-200 m in the Kola section.
August-S eptembe r, 1970-198 3.
1978-19 79 when
values are observ ed. Later on the
salini ties are genera lly increas ing up to normal values in 1983.
The variati ons are greate st Ln the east (sectio n CJ where the
standa rd deviati on for the perLod 1964-19 83 is 0.07 compar ed
to 0.05 in the west (sectio n A)
e
Also the temper ature curves show parall ell trends , most pronounce d is the cold period 1977-1 981, which in the Kola section
is the longes t period with negativ e anomal ies observ ed after
1920s
The curves of Fige 2 are all based on only one observ ation per
year and may therefo re be encumb ered with accide ntal short term
variati onss Since 1977 the section s A, B and C have been more
freque ntly observ ed In order to elimin ate the season al
change s anomal ies have been calcula ted for the period 19771983. (Fig 3-5)_0
The thres curve sets show the same trends in the climat ic
variati ons as was describ ed aboveo The salinit y was decrea sing
- 6 -·
t.12.lLL 7B 1 79
1s
80 1 B1 j__Jg_j_fu
0.15
0.1
1\/\ .}\f
!\! vv"
0
'<!-
Vl
<l
Fig. 3. Anomalies in temperature (left) and salinity (right) in the depth layer
50-200 m in section A (71°30' - 73°30'N)in the period 1977-83.
ti9771 78
I 82
79 1 80 1 81 1 82 1 83 1
1
1
83 I
1.5
1.0
rv
05\
u
0
+<!
0
-0.5
0.10
t·'\ . .I
~
I'
I
\A
I
I
·v
I'JI' I
\!
.
IA
/
0.05
j\1
0
0~
Vl
<l
0
/
-0.05
-1.0
-0.10
-1.5
-0.15
Fig. 4. Anomalies in t.emperature (left) and salinity (right) in the depth layer
50-200 m in section B (72°15' - 74°15'N)in the period 1977-83.
- 7 -
t19771 78
1
5~
1.0
1
79
1
80
81
L1277 I
82 I 83 I
78
1
0.15
I
0.10
os
0.05
79
80
1
81
82
83
'\
\
0
~
L.J
~
V1
<J
<J
0
-0.5
-0.05
-10
-0.10
-1.5
-0.15
Fig. 5. Anomalies in temperature (left) and salinity (right) in the depth layer
50-200 m in section C (71°15' - 72°45'N) in the period 1977-83.
1.0
10
I
I
I
I
I
I
I
/ ¥
0.5
I
I
I
n
1"11
w
z
..._
<J
~
X
-0.5
-5
-1.0
-10
-1.5
\
I
I
-15
\~
Fig. 6.
Temperature anomalies of the 0-200 m layer in the Kola section
(continuous line) together with the ice index (broken line) .
- 8 -
in the beginning of this period until lowest value in 1978-1979.
Later on the salinity have been increasing. There seems to be
a lag in the alteration from west to east as would be expected.
The relative high salinity value in section C observed in
August 1981 is difficult to explain. The temperature curves
as well have similar trends. The lowest values were observed
in 1978-1979, some warming through 1980, but again lower
values in 1981. Since early 1982 the temperature has generally
been
increasing~
The best description of the climatic variations in the period
1970-1983 is presented in Fig. 6 which shows the temperature
anomalies observed in the Kola section (section K) . The
normal in the 0-200 m layer are monthly means for the period
1921-1980
In the same figure is also indicated the variation
in the ice coverage in the Barents Sea taken from
s~tersdal
and
Loeng (1984).
s. Concluding remarks.
Large variations have been observed in the climatic conditions
in the Barents Sea during the 1970's. The second half of the
decade was characterized by low temperature, low salinity anq
large ice coverage. Through the beginning of the 1980's
temperature and salinity are generally increasing and the ice
coverage becomes smaller.
The climatic variations are mainly determined by variation in
the Atlantic inflow to the Barents Sea.
- 9 -
Refere nces
Anon. 1983
Prelim inary repor t of the Intern ationa l 0-grou p
fish survey in the Baren ts Sea and adjace nt waters in
Augus t-Sept ember 1983. Coun. Meet. Int Coun. Explo r.
Sea, 1983 (G 35): 1-27. (Mimeo .)
Blindh eim, J. and Loeng , H 1981. On the varia bility of
Atlan tic influe nces in the Norwe gian and Baren ts
Seas
Fisk. biro Skr. Ser. HavUn ders. 17: 161-18 9.
Buchk ov, Yu.A. 1976. On the effec t of solar activ ity of variou
s
perio dicity on the terma l regime of the Barets Sea.
Coun Meet. Int. Coun. Explo r. Sea, 1976. (C 2) :l-19.
(Mimeo .)
Dickso n, R.,Mi dttun, L. and Mukhi n, A. 1970. The hydro graphi
c
condi tions in the Baren ts Sea in Augus t-Sept ember
1965-1 968 in Drage sund, 0. (Ed.) Intern ationa l
0-grou p survey in the Baren ts Sea 1965-1 968.
ICES Coope rativ Resea rch Repor t A (18).
Dickso n, R. and Blindh eim, J. 1984. On the abnorm al hydro graph ic condi tions in the Europe an Arctic during the
1970' s. Jens Smed Volum e, Rapoo rts et
p~oces-Verbeaux.
(In press ).
Hellan d-Han sen, B
and Nanse n, F. 1909. The Norwe gian Sea.
Fisk. Dir. Skr. Ser. HavUn ders. 2 (2): 1-360 .
Kislya kov, A.G. 1964. Horiz ontal circu lation of water on the
Water shed of the Norwe gian and Baren ts Sea. Trudy
polya r. nauch no-iss led. Inst. morsk . ryb. khoz.
Okean ogr 16 : 215-22 5. (In russia nJ .
Lee, A. 1963. The hydrog raphy of the Europ ean Arctic and
Subar ctic Seas. Ocean ogr. Mar.!!! _ Biol. , 1: 47-76.
- 10 -
Loeng, H. 1983
Climatic variations in three hydrographic
sections in the Barets Sea during the period
1977-1982
Fisken Hav. 1983
(3) : 5-21.
(In Norwegian,
abstract in English) .
Loeng, H. 1984. The climate in the Barets Sea in 1983.
Fisken Hav. 1984
(1): 9-15.
(In Norwegian, abstract
in English) .
Loeng, H , Nakken, 0. and Raknes, A. 1983. The distribution
of capelin in the Barents Sea in relation to the
water temperature in the period 1974-1982, Fisken
Hav.,
198~
(1): 1-17
(In Norwegian, abstract in
English o)
Midttun, L. 1969. Variability of temnerature and salinity
at some localities off the coast of Norway.
Prog Oceanogr. 5: 41-54.
Midttun, L.
Nakken,
o.
and Raknes, A. 1981. Variations in
the geographical distribution of cod in the Barents
If
Sea in the period 1977-1981. Fisken Hav., 1981 (4):
1-16
(In Norwegian, abstract in English.)
S~tersdal,
G. and Loeng H. 1984. Ecological adaption of
reproduction in Arctic Cod. P. 13-35 in
God~,
O.R.
and Tilseth, S. ed. Proc. of the Soviet-Norwegian
Symp
Re?roduction and Recruiternent of Arctic Cod,
Leningrad, 26-30. September 1983. Institute of
Marine Research, Bergen 1984.