TO IN

AC'I.A UMVERTiITATIS DERGENSIS . _SERIES MATIIEMATICA R"ERUMQITE NATURALIUM

ARBOK FOR UNIVERSITETET I ^BERGEN . MAT..NATURV.

^SERIE

1963 No ¹⁵

THE "CONRAD ^{HOLMBOE'O EXPEDITION}

TO EAST GREENLAND WATERS IN ¹⁹²³

By

TOR KVINGE

r 963

NORWBGIAN

UNIVERSITIES

^PRESS BERGEN . OSLO

ÅRB. UNIV.

BERGEN 1963

MAT.-NATURV. SERIE

No

¹⁵

Printed with a grant from Norges almenvitenskapelige forskningsråd Received for publication February 27th 1963

Distribution office

:

Karl Johans gt. ⁴⁷ , ^Oslo

OSCAR EDLUIVD lB92

-1959

The Swedish meteorologist Oscar Edlund was born

in

1892. After graduating Irom the University of Uppsala and after two years of practice as a meteorologist

in

Stockholm, he went to Norway

in

^1920. Here he spent the years up

to

1926,

from the autumn

oI

1922 as head

of

the division of weather forecasting

of

the Geophysical Institute in Tromsø.

In

1923 he participated in the "Conrad Holmboe"

expedition, the oceanographical results oI which are presented on the following pages.

After Edlunds return to Sweden

little

time was left for his scientific work, and be{ore his death on

1l

February, 1959 he expressed to his wife the hope that the

work

might be

fulfilled at

the Geophysical Institute of Bergen.

Due to the Polar ice the sea-area outside the east coast of Greenland is dif{i- cult oi access; very few oceanographical data had been collected before 1923, and not many more are available to-day. As most oI the data from the "Conrad Holm- boe" expedition are of a good quality,

it

was felt that they should be published, although they can

only very

modestly contribute

to the

understanding

of

the East Greenland Current.

For similar

reasons

the

meteorological observations have been included.

Bergen

in

February 1963.

Håkon Mosbv

CONTENTS

Abstract

⁵

Theexpedition..

.

⁵

Material of

observations

⁷

Sections "Conrad ^Holmboe

I"

and

"Sotra".

¹⁵

Section

"Veiding"

¹⁹

Sections "Conrad llolmboe"

II, III

^and

IV

²⁰

Characteristic water

masses

²²

Dynamical

computations

²³

Transport

²⁶

Comparison

²⁷

Acknowledgement

²⁹

Literature

²⁹

Explanation of

tables

³⁰

Hydrographic stations :

Table

I:

"Conrad Holmboe", st.

l-36, 1923.

^3l

Table

II:

"Veiding", st. ^185-196,

1931.

³⁵

Table

III:

"Sotra",

st.204-211,1930.

³⁷

Meteorological observations :

Table

IV:

"Conrad llolmboe", ^1923.

.

³⁸

ABSTRACT

The present paper is based on the hydrographical observations collected during the "Con- rad Holmboe" expedition to Jan Mayen and East Greenland in 1923, supplemented by ^some stations talen by s/s "Sotra"

in

1930, and by s/s "Veiding"

in

^1931.

Dynamical computatiorur relative to the 200 decibar surlace show that the East Greenland Current flows in a south-westerly direction nearly parallel to the isobaths.

-

The highest current components, about 8 cm/sec, are lound on the shelf near the slope, and also close to the border between Atlantic and Polar water.

-

^{The total} water transport in the East Greenland Current is estimated to about 0.6 mill ^m3/sec, towards the south-west. The following water types are found

in the East Greenland Current: Surface water, Polar water and Atlantic water. The Atlantic water meeting the Polar water is characterized by S

:

35.010/00, and T

:

2.65o, Due to admix- ture of water formed by local convection in winter, the Polar water in the East Greenland Current can not be considered as a well defined water t)?e.

The expedition.

A

preliminary report

on

the "Conrad Holmboe" expedition was published by Oscen Eor-uNo

(1924).In

the present paper, a brief summary

will

be given, based on abstracts from Eor,uxo's paper, on letters, telegrams and the journal from the "Conrad Holmboe".

The "Conrad

Holmboe",

a

former sealer

oI

127 br.reg. tons was

built

of wood, and equipped

with

sail and an auxiliary motor. The ship belonged to the Geofysisk

Institutt in

Tromsø, and she was sent out

in

order to transfer crew and equipment to the stations Jan ^Mayen and Myggbukta, and to carry out oceano- graphical and meteorological investigations.

On

July

^{19, 1923, the ship left Tromsø}

with

a crew

of

19, of which B were to winter on Greenland and Jan Mayen. The master on board was JoHAN ^N.æss, and the scientific leader Oscan Elr-uxo.

"Conrad Holmboe" arrived atJan Mayen

onJuly

25, ^and 3 days later, after the wintering crew and equipment had been brought ashore, she sailed for Green- land.

To

begin

with,

the main course was north-north-west,

later

more westerly, and, after the ice was met, very irregular. As the ship approached the coast of Greenland, the ice grew more and more compact. About 30 miles off Gael Hamke Bay,

the

ice conditions made any

further

movement impossible.

This

was on August 6, and from then on the "Conrad Homboe" was stuck

in

the ice,

drifting

TOR KVINGE Mat.-Naturv. serie

along the south-east Coast of Greenland, and following a rather irregular path.

During this part of the

expedition, oceanographical observations were taken as

far

south as

72"30'N. The

ice-activity, however, increased, and on August 28,

it

was feared that the ship would be ground down by the ice. Three lileboats

with

supplies

and

equipment were therefore placed

on the ice

alongside the ship. Later on "Conrad Holmboe" was lifted up by the ice and suffered a minor leakage. By this time the situation was considered very critical, and a telegram was transmitted to Tromsø, asking for help. On September 13 the sealer "Polar-

ulv"

departed

from

Tromsø

in

order

to

relieve "Conrad Holmboe".

An air

rescue-expedition was also considered,

but

this had

to

be given up due

to

impossible landing conditions.

The

action

of

the ice decreased,

but

the situation was

still

critical, as may be illustrated by an extract from the logbook.

"september

15.

The pumps are working continually, and as long ^as the ^{leakage does} not'increase ,

it

seems possible to ^keep the ship afloat.

But "Conrad Holmboe" is

strained so

badly, that

she

is

leaking everywhere."

The first

radio contact

with "Polarulv"

was established

on

September ^17.

The next day very severe ice-activity gave "Conrad Holmboe" a ^{30o starboard} list, which made the situation even more critical. On October 3 a slight ^decrease in the pressure of the ice occured, and this made it possible for "Conrad Holmboe"

to

force her way towards the open sea. Next day, an open lane was seen, but owing

to a

storm from east-north-east,

further

movement was impossible. The wind packed the ^ice-floes together, and the ship was once again stuck

in

the ice.

The

weather conditions

improved slowly, and on

October

9 the

"Conrad Holmboe" was quite close

to

the ice border,

but

owing

to

heavy swell had to go back

into

the ice again. The situation was now very critical, and "Polarulv"

was requested to come as soon as possible.

At

this time there were neither radio tubes nor rockets left on the "Conrad Holmboe", and communication had to be maintained

by light

^signals.

Next

morning

the "Polarulv"

appeared close

to the ice

border

within

^a

distance

of

about

4

miles.

The "Conrad Holmboe"

^succeeded

in

forcing her way towards the open ^sea and

"Polarulv",

simultaneously working from the out- side, made a lane

in

the ^ice.

It

was found unadvisable to cross directly

to

Norway, because the ^o'Conrad Holmboe" was

in

a very bad state.

It

was therefore decided to go to Isafjord on Iceland. The following message was then transmitted

to

director

O.

Knocxæss

at

Geolysisk

Institutt in

Tromsø.

"Position

at 6 pm.

approximately 67o29'

N,

25"06'

W,

Heading for Isafjord assisted

by

Ulv.

Edlund."

No 15, 1963 THE "coNRAD HoLMBoE" ExPEDITIoN

rN

1923

,'Conrad Holmboe" had suffered badly during her

drift in

the ice. ^{She was} leaking heavily, but steamed at

full

speed towards Isafjord,

in

order to reach the harbour before

a

new storm blew

up.

The leakage increased and the dunnage gave away every time the bow rammed into the waves. But at midnight on Octo-

ber

l

l "Conrad

Holmboe" reached Isafjord

and

dropped anchor

in

Pollen.

The ship had then ^been in a situation of ^{distress since} August 28, i.e. for a period

of

more than 6 weeks.

The next alternoon, after the official examination of the ship, all equipment and samples were brought ashore and shipped

for

Norway. The water samples were sent to the Geofysisk

Institutt in

Bergen, and the rest of the equipment to Tromsø or to the lenders. "Conrad Holmboe" ^{was then beached so} that a closer examination of the underwater ^damage could be made. The underkeel ^was found to be missing, and the main keel was broken

for

a length

of

^{15 feet.}

The maritime

inquiry

was held

in

the Norwegian Viceconsulate on October 16. The declaration ^showed that a repair of "Conrad Holmboe" was considered unadviseable. She was therefore declared condemned, and all equipment of any value was

brought

ashore.

Later on "Conrad Holmboe"

^was

filled up

with stones and sunk

in

order

to

serve as

a

quay.

Material of obseraations.

A total number ^of

4l

hydrostations were taken during the "Conrad Holmboe"

expedition,

but

13 of these consist

of

surface samples

or

depth soundings only.

Serial measurements were made at the remaining ^stations.

The

observations include depth soundings, temperature measurements and water samples,

from

which salinity, oxygen content and hydroxyl-ion concen-

tration

were determined.

6

ordinary Nansen bottles were available

for

water sampling, each

of them

^equipped

with one

reversing thermometer. Depth sounding were carried

out by

means

of a

Lucas sounding machine.

At

the deeper stations observations were taken

at

ordinary standard ^depths only,

but in

the shallow waters additional observations were included.

On

section

I,

from Tromsø to

Jan

Mayen, observations were taken down to 2800 m depth,

in

section

II, fromJan

Mayen to Gael Hamke Bay, to ⁶⁰⁰ m. On section

IV,

along the coast of Greenland, the deepest haul was 400 m.

In

order

to

gain a better knowledge of the ice-drift, some velocity ^measure- ments were carried out by means of a special method. A number of drift-velocities

were also determined

by

making use

of

the ship's changing position.

The meteorological observations and ^notes on ice-conditions are ^presented

in

Table

IV.

A

few sections from other expeditions have ^also been included

below:

One from

Jan

^{Mayen to Harstad,}

run by

the S/S

"Sotra" in

^1930, and one section

from

Greenland

to

Svalbard taken

by

S/S

"Veiding" in

^1931.

TOR KVINGE Mat. Natunr. serie

Fig.

l.

^The sections.

"Veiding" ^and "Sotra"

^{were fishing vessels chartered}

by the Ministry

of Fisheries

in

order

to

carry

out

research

in

the northern Norwegian Sea. These ships worked

in

Denmark

Strait

and

in

the regions around

Jan

^{Mayen. Most} of the observations were published by Trron fvnnsnn (1936)

with

the exception

of the

stations

from the

cross-sailing; these are therefore given below, Tables

II

^and

III.

Position.

In

the open sea the positions had

to

be determined

by

means of astronomical observations, depth soundings and dead reckoning.

In

fair weather, this enables positions to be determined to the nearest nautical mile. Considerable errors, however, may often have occurred, due

to

frequent fog, mist and rain.

Near the coast

of

Greenland, the positions are probably quite reliable, due to bearings

on

land.

THE "coNRAD HoLMBoE" ExpEDrrroN

rN

1923

Fig.

2.

Track of the t'Conrad Holmboe" from Jur ^{Mayen to Iceland.}

I

lrr"

I

I I

?t%s

* rtÅ

nr%

\_2% JAN ^MAYEN

._30Å

rW

^.7oo

I

%o

Y,o {

!%o

25o 2oo r5o

I

roo

IC

^E

L A N D''

4o,

AOOø \

eø

Ø s>.t

l{

_soqr

t.oo'

---\JOOo

oo o

Øo, 2,

JAN MAYEN

24'w

Tz

10 TOR KVINGE Mat.-Naturv. serie

Fig.

3.

^('Conrad Holmboe" stations 9-41, surface current component between the stations.

Temperature. Each Nansenbottle was equipped

with

one thermometer only.

In

one of them the auxiliary thermometer was broken, and the corrections were therefore based on the auxiliary temperature for the neighbouring thermometers

in

the rack. This probably caused no noticeable error, since special precautions were taken

to

read the thermometers under

unilorm

conditions.

The thermometers were borrowed from the Geofysisk fnstitutt, Bergen, where zero-point corrections had been made

by

Professor Hnr,r,aNo-HANSEN. After the expedition the thermometers were re-corrected by Eor.uNo, but no diflerences were found. The temperatures should therefore be reliable

within

the customary

limit

NO 15, 1068 THE ^((CONRAD HOLIBOB'' EXPEDITION IN 1923 ^I I

of

accuracy, which is estimated

at +

0.015"

for

the thermometer types which were used (Hrlr,eNo-HaNsBn and

Korronn

^1909).

Salinit2.

The

salinities are based upon one single

titration of

each sample, carried out at the Geofysisk Institutt, Bergen. And there ^{is reason} to believe that

the

salinities

from "Conrad llolmboe" are

determined

with the

customary accuracy, wich is estimated

at f

^{0.015 o/os.}

Ox2gen. Samples

for

determination of oxygen content were collected

up

to station 15. The samples were

titrated at

the Geofysisk

Institutt,

Bergen, about 5 months later.

A

storage period of this order makes the reliability of the results

very

doubdul,

and

the values have therefore been omitted

in the

tables.

H1droxyt.

Hydroxyl-ion

concentrations

were

determined

from the

water samples up to st. B. Later measurements were

not

taken into account due to in- accurate indicators. The determinations are ^based upon a colorimetric method,

27.2 I | ,l ^{-1 I} 34'8 '9 35'O 'l ^o/oo

tl '2-t 1'

6'

0

30

10

00

7/]4

/,,r7;,

/ ^s/

t,

' ,/ ,'/'oo,'

/ ^,)'/.,/'

^,

tt il

>/

,f/l/

t100 2e Ootl20N

Fig. 4. ^ttConrad Holmboe" st. 4.

r2

s oÅ" gt.z 0 m

TOR KVINGE

4 6oc

( iilr .6 -6 ',20.0bi

Mat.-Natuw. serie

Fig. 5.

(tConrad Holmboe"

st. B.

Fig. 6.

"Conrad Holmboe"

st. 12.

v

I I

i-b l.f

No 16, 1908 THE "coNRAD HoLMBoE" ExpEDrrroN

rN

1923 r3

,' -t I _27-O lll .2

o'

I I 33-0 .6 I 'bll

32.4 26 0 m

-2'I .2rl

.6

-r'

I

.1tl

.E

2'c

'6 'A

.c ' 3o.o ^{I 2e} -09

I 35.0 ^o/oo

Jo

2

t'

0

-l

8 350-2

Fig. 7. ('Conrad Hoknboe" st. 15.

applying phenolphthalein and c-naphthalein as indicators. The margin of error

by

this method is estimated

to 10-l5o/o

(Geenonn 1917).

Geenonn suggests expressing

the

hydroxyl-ion concentrations

by a :

l0z Css-, where Co"- are equivalents hydroryl-ions per

litre;

a is generally referred to as the hydroxyl number.

Interpretation of the

OH-

conditions is considered to be beyond the intention

of this

paper.

The hydroxyl

numbers

are

therefore presented

in

tables only

Table I.

Values

of

71ø,

the

specific volume anomaly, were computed

for

st.

9-21

at the following depths: 0,

l,

5, 10, 20,

30,40,50,

60, 70, 80, 90, 100, I25, 150, L75 and 200 meters. Missing values have been interpolated.

Most of the stations were taken in several hauls, and a time interval amounting

to 2-3

hours between the observations may therefore occur. This has probably caused no

eror in

samples from the deeper layers,

but

a considerable variation may have taken place

in

the upper layer during the

time

mentioned.

The vertical

distribution

of

observed

and

computed elements are plotted on diagrams for each station together

with

a

T-S

curve.

A

few of the diagrams

will

be discussed here, each showing the distinctive feature

of

one area.

L4 TOR KVINGE

.6 34-0

Mat. Naturv. serie

-2 -l o lt'c ^n'0

4

2e.0 {

.1 0

m

/ t50 100 100

'/"'

/

,600 I

"oI

'l

Fig.

8.

'Veiding" st. ^186.

At

st. 4, Fig. 4, the upper layer consists of Atlantic water down to 600-700 m, where the transition layer between Atlantic and Deep \Mater is found. The Deep water is nearly homohaline below 1000 m, and from 2000 m it is also homothermal.

The low temperature and salinity at st. B, Fig. 5, indicate that a new water type has been encountered. The salinity increases rapidly

with

the depth, while

the

temperature decreases,

particularly in the upper

100-200

m. The

result

is an

extremely stable surface layer.

The hydrographical features

in

the waters north-west of Jan Mayen are

illu-

strated by the curyes for st. ^12, Fig. 6. The surlace layer ^consists mainly of Polar water, characterized

by low

temperature and salinity.

The

lowest temperature

will

generally

be found 20-30 m

below

the

surface.

Then the

temperature increases

until

reaching

a

maximum value

at

depths between 150 and 200 m.

Below

this

depth

the

temperature decreases slowly towards

the

bottom. The salinity ^reaches its maximum value at the same depth ^as the maximum tempera- ture is found. The deeper layers are approximately homoline.

St.

15,

Fig.

7, is situated

in

the shallow waters

on

the shelf.

The

hydrographical conditions are similar to those at st. 12,

but

the covering Polar water layer is heavier at st. 15,

and the maximum values are found below 200 m. The

"Veiding"

^{st. 186 is situ-} ated

on the

slope, about 280 miles north-west

of "Conrad Holmboe" st.

^12.

The temperature and salinity curyes at these two stations are very similar, indi- cating closely related hydrographical conditions.

At st.

186, Fig. B,

an

intermediated layer of

Atlantic

water is encountered,

"l i tao

./i

rt ,ll

_ls/

/b/

I

No 15, 1963 THE "coNRAD HoLMBoE" ExpEDrrroN

rN

1923

giving

maximum temperature and salinity

at

about 200

m

depth.

The T-S

curve consists of two nearly straight lines, which intersect at the point of maxi- mum values; 35.010/oo and 2.65'.

A T-S

curve of this form indicates an

initial

stage

in

mixing,

or

an area where two water types encounter a

third, (Stocr- u,rx

1946).

A

^more extensive discussion

will

be given

in the

chapter dealing

with

characteristic water masses.

Sections "Conrad Holmboe"

I

^and "Sotra".

Section "Conrad Holmboe"

L

Fig. 9, is based upon observations at the stations

1-8,

carried

out during

the crossailing

from

Norway to

Jan

^Mayen.

St. I

^is

situated on the slope 25 miles off the coast of Norway. St. ^B was taken

4/2

days later about ¹⁵ miles east of Jan Mayen, giving the section a total length of more

than

480 miles.

The

nearly homohaline Deep water may be considered

limited in

the east

by the 34.900/00 isohaline. The isohaline is encountered at an approximate depth

oI

¹⁰⁰⁰

^{m, and}

^coincides

with the

Oo-isotherm

from the

coast

of Norway

to beyond st.

6 at lol9'W,

where both isohaline and isotherm bend towards the surface.

Above the 34.900/oo isohaline we find mainly Atlantic water, defined as water of salinity above 35.00 ^0/00. The 35.000i00 isohaline roughly coincides

with

the ^3o isotherm, indicating

that

the

Atlantic

water

in

this region is warmer

than

^3o.

In

the west an entirely different water type is encountered above the 34.880/oo

isohaline. This is probably a branch of the Jan Mayen Polar Current, character- ized

by

low temperature and salinity.

The

strong horizontal temperature and salinity gradients between st. 6 and 7 indicate a very sharp border between the two water types, and form the western

limit

of the Atlantic water

in

this region.

Section "Sntra", Fig. 10, is based on observations from the B stationsr

204-21I,

taken on the cross-sailing from

Jan

^Mayen

to

Norway

in

August 1930. St. 204 is situated about 50 miles south-east of

Jan

Mayen, and

st.2l1,

¹⁰ miles north ol Bleik, Andøya. Consequently this section is taken

15-20

miles south oI section

"Conrad Holmboe"

I,

being nearly parallel

to

it.

The

characteristic upper layer

of Atlantic

water

is

present

mainly on

the east side. The 35.00 ^0/oo isohaline follows the

3'

isotherm at depths between 300

and ll00 m.

Below these isohalines, temperature

and salinity both

^decrease

downwards slowly

until

reaching the values which characterize the Deep water.

The

limit

between Atlantic and Polar water is not seen

in

Fig. 10, but

at

st. 204 strong horizontal gradients indicated

a

neighbouring

cold water front.

This

front is

probably situated

35-40

miles farther west than

in

section "Conrad

Holmboe" I.

Qgite unexpexted conditions appear at st. 207.

At

the surface the salinity is

below 35.180/00 and the temperature slightly above 5o. But the transition layer

15

t6

JAN MAYEN

0

TOR KVINGE Mat.-Natury. serie

TROMSg

500 n. m.

st.

0m

35.r0

.00 t. \--

34.88

\\

\\

\ \ \ \ \

\-

\

----}34'90

\--o'-:

N. MILES

\

Fig.

9.

^Section "Conrad lfolmboe"

I,

Irom Tromsø to Jan ^Mayen. July ^1923.

between

Atlantic

and Deep water bends downwards, sinking about 500 m. The

4o isotherm and the 34.14 ^oloo isohaline are found

at

1000 m, and a ^nearLy homo- geneous layer extends from this depth to the surface. As no unprotected thermo- meters were available, there is no possibility of controlling the observation depths.

The

sampling was carried

out in 4

hauls,

but all

observations

fit

nicely into smooth curves, and there seems

to

be no reason

for

suspecting

that

the water- bottles have reversed

at

wrong depths.

Sections carried

out in the

same area

by the R/V

<Helland-Hansen>> in 1958, 1959 and 1960 show no similar features.

Cornparison. According

to

Hnr-r.nro-HaNsnx and NeNssn (1909) the upper water layer in the east consists mainly of Atlantic water with salinity above 35 ^o/oo.

Thus, to the west of Lofoten the 35 ^0/oo isohaline is found at 450 to 900 m depth,

No 15, 1963

JAN MAYEN

0

5t. 201I

0 m _1..

THE "coNRAD HoLMBoE" ExpEDrrroN

rN

1923

35.20

3t,'92

lrl

NAUT. MILES 200

I

207

r7

H A RSTAD 100 n. miles

2ll

r-lr-

35.00

Fig. 10. Section "Sotra", fromJan ^{Mayen to} llarstad, August 1930.

in

most cases at 700 to 800 m. The average temperature for the month of May is estimated

to

be 6.43'

at

the sur{ace, 5.92o

at

50

m,

and 5.01o

at

200

m

depth.

As mentioned above the 350/oo isohaline was found at about 700 m at the "Conrad Holmboe" st. 5,

4

and 3.

The few observations from "Conrad Holmboe" ^and

"Sotra"

^give no reliable average temperature, but the single observations show slightly higher values than those given

by

Har-r-eNo-Hanrsnu and Nensru. However,

the latter

are based

on observations from May, while the ^6'Conrad Holmboe" and

"Sotra"

^stations were taken

in July

^{and August.}

The

Deep water

in

the Norwegian Sea is known

to

be very nearly homo- haline and homothermal. Hpr,r,eNo-HANsEN and NeNsnx (1909) have estimated

the salinity

as slightly above 34.90 ^0/00

and the

temperature

at a little

below

-

^1.00"._Mosnv (1959) has computed mean values from deep water observations

in

1936. He found an average salinity

oI

^{34.917 0/oo} and an average temperature

IB Mat.-Naturv. serie 200 n. mites

V"

3t'?0 34'30

100

Fig.

ll.

section "conrad }rolmboe" II, fromJan Mayen to East Greenland,July-August 1923,

of

-1.001'.

These values seem to agree fairly well

with

the results from ,,Conrad Holmboe" and,,Sotrat'.

According to Hrr,r.eNn-Hansnw and Nensnx (lg0g) _the Atlantic water flows northwards along

the

coast

of

Norway,

following the

continental slope.

on

meeting

the

Helgeland Plateau

it

turns north-west towards

Jan

^Mayen.

In

^a

section

from

Lofoten to

Jan

^{Mayen the}

^Atlantic

^water

will,

therefore, appear as more extended than would

be the

case

in a

section

at right

angles

to

the current.

No 15, f963 THE "coNRAD HoLMBoE" ExpEDrrroN

rN

1923

NeNsnN (1901) states

that

the

Atlantic

water

in the

Norwegian Sea flows north-westward between 67' and 69"

N

latitude.

At

about

5'W

the current turns more easterly again. NaNsnn also believed

that this

westgoing

current

^drags the Coast water

to

the west as

well. In the "Conrad

Holmboe"

and

"Sotra"

sections this water appears as a tonguelike surface layer with salinity below 35 ^o/oo extending westward from the coast.

The

Coast water is of Baltic origin,

but

its properties are influenced

by local and

meteorological conditions.

The characteristics of the Polar water ^{are due} to fresh water from the Siberian and North-American rivers, and to ^ice freezing during the winter (NeNsnN 1902).

This ^gives a surface layer

in

the Polar basin of salinities about 34oloo, and temper- atures close

to

the corresponding freezing temperature

-1.85'.

Some of this water ^crosses the Nansen ridge, flowing south-wards along the eastern side

oI

Greenland. This current is known as the East Greenland Polar Current, but its waters ^are not only of polar origin.

fn

section "Conrad Holmboe"

II

^(Fig.

ll)

^a warm and saline water layer is ^seen to appear between the Polar water and the Deep water. This feature of the East Greenland Current was first demonstrated

by

Rvor,n

in lB9l.

Later Hnr,r,eNn-Hexsex and NeNsr,N pointed

out that

the intermediate layer is of

Atlantic

origin, being

part of

the current flowing northwards along the coast of Svalbard.

At

about

77'N

part of the water turns west

and

thereafter south-west, owing

to its

higher density

forming

an intermediate layer. The following section

will

elucidate these conditions.

Section "Veiding".

Section"Veiding", Fig. 12 starts at st. 186 on the Greenland shelf at 77"40'N, 6o30'W,

it

then ^crosses the basin and terminates at st. ¹⁹⁶ on the Svalbard shelf about 30 miles south-west of Isfjord (Fig. 1).

In

this section the 35 ^0/oo isohaline, together

with

the 2o isotherm, forms the

limit

oI a continuous layer o{ Atlantic water, extending from Svalbard to the shelf of Greenland.

19

GREENLAND 0

sr. r85 186 187

r---r.t>--

---t

SVALBARD 250 n. miles r94 t95 t96

Fig. 12.

Section "Veidiog", from East Greenland to Svalbard,

August 1931.

05'

Irttl

20 TOR KVINGE Mat.-Naturv. serie

This layer is thick near the slopes on both sides, but in the middle of the section

it

is present only as a

thin

upper layer. This may be interpreted ^as

follows: In

the northern hemisphere the lightest water

of a

current

will

be present

to

the

right. The

section dealt

with is

probably crossing the basin near the latitudes where part of the Atlantic water turns to the west. Both north- and southflowing water may therefore be present

in

this section.

The thinner layer encountered

in

the middle of the section is probably the

left

side of the westgoing current.

Sections "Conrad Holmboe"

IL III

^{ønd IV.}

Section "Conrad Holrnboe"

/d

^Fig. 3 starts at st. 9, 40 miles north-west off Jan Mayen, running north-westward to st. 14, 74"10'N, 15o10'

W;

here

it

bends west and then south-westerly to Gael Hamke Bay. As mentioned above, the configu- ration of isotherms and isohalines found at

"Veiding"

^{st. 186 is also} encountered at the slope in section "Conrad Holmboe"

II.

On the shelf a thick layer of Polar water

is

seen extending immediately below

the

Surface water.

The

Atlantic water occurs as

a

small intermediate layer, particularly

at

the slope,

but

^also

in

the

part

on the shelf and

in

the deep trenches.

Section "Conrad Holrnboe"

III,

st. 14,

17,lB

and 20, is a supplementary section,

0t020 ³⁰ 10 ^{s0 60}

+ | l's I I'l I

^I

^{'i^ i!"}

---o-c-2---;;;i":--

jL'?o t'5. '^{o z'}

å\_

a

A 3 A

t

:l eil a

t

e

t

e

t

34.50

X

6

Cs

A C EA A E A E

€s

FiS. 13. Section "Conrad Holmboe"

III,

^{August 1923.}

No 15, 1963 THE "coNRAD HoLMBOE" ExpEDrrIoN

IN

1923

Fig. 14. Section ,.Conrad Holmboe" IV, August 1923.

used

for

dynamical computations

in

order

to

facilitate the construction

of

the isovel map.

This section is situated on the shelf, and the masses consist mainly

of

Polar water and Surface water (Fig.

l3).

The temperature along the bottom, however, increases rapidly from st. lB

to

17, indicating mixing

with

Atlantic water which intrudes over the shelf. For the rest, the isohaline and the isotherms have a form similar

to that

found

on

the shelf

in

section ,,Conrad

Holmboe" fI.

The border between

Atlantic

and Polar water has a configuration which is closely related

to

the current conditions. This

will

be discussed later.

Section "Conrad Holmboe"

IV,

Fig. 14 includes st. 19 and all succeeding stations.

This section follows a rather irregular course (Fig. 3), and the stations are very dissimilar.

At

a few stations only a few observations were taken. The main fea- tures are clearly seen, however, the water masses on the shelf consist mainly of Polar water, but Atlantic water is also present

in

the deeper trenches. The deep trench off Foster Bay is thus nearly

filled with

water warmer than ^0o.

Maximum temperature, 1.56", is found at st. 35

at

300

m

depth.

The Surface water is characterized by low temperature and salinity. A temper- ature minimum is generally encountered at about B0 m depth, while the salinity increases continuously towards the bottom. This gives very stable water masses,

especially

in

the upper layers.

Before discussing the current conditions, let us consider the bottom topography.

In

the map given byJerHnr.r.N (1936a), depth soundings taken on the,.Conrad

2l

22 TOR KVINGE Mat.-Naturv. serie

Holmboe" expedition were included.

This

map has therefore been taken into account

in

discussing details of bottom topography, (Figs. 3 and

t6). A

contour map has been prepared

at

the Institute

of

Marine Research of the Directorate

of

Fisheries, Bergen

(Fig. l). The

depth along section "Conrad Holmboe"

II

(Fig. 3) is more than 2000 m up to st. 14, where the steep slope is encountered about 90 miles off shore.

A

number of narrow trenches cut

into

the continental slope, forming ^a very irregular contour. The shelf is about 200 m deep, and fairly smooth.

Characteristic water møsses

The following water types are present

in

the East Greenland Current: Sur- Iace water, Polar water and

Atlantic

water. The Deep water is not

part

of the current.

The

properties

of the

Surface water are variable, depending on local

and

seasonal conditions.

The

salinity

is found to be 30 to

32.5 o/oo,

and

the temperature

-1.6o

^{to 0.7".}

^With

the exception of the uppermost layer, the Sur- face water is extremely stable, mainly due

to

the strong downwards ^increase of salinity. This applies

to

the summer situation. When the ice starts forming, the salinity must increase rapidly, because sea ice has a very low salinity and there is no run off from land. The water masses

will

then ^become unstable, and vertical convection may occur.

It

can be shown that the formation of one meter of ice is sufficient to increase the salinity from the summer level to values so high as to give vertical convection down

to

the depth

of

the temperature minimum

in the

Polar water. Some of this water

will

probably be found,

in

varying quantities, during the rest of the year.

The

Polar water should therefore

not

be considered as

a

uniform water type, and no

T-S

^relation can be given

for "pure"

Polar water

in

this area.

The minimum temperature is very near to the corresponding freezing tempera- ture, especially at the stations near the coast. In section "Conrad Holmboe"

IV

the minimum temperature was between 0.0o and 0. 10'above freezing temperature;

the average was 0.06o. The difference between actual and freezing temperature had a minimum value

at

the minimum temperature. This water had probably

not

been mixed

with

other water types, and there is reason

to

believe

that

the water had been formed

in

this area

or in

the neighbourhood.

According

to SrocrueN

(19a6)

T-S

relations

lor

intermediate

water

in

its

original state can be found, provided

that

the upper and the lower water layers are homogeneous and unlimited relative

to

the intermediate layer. The tangents touching the

T-S

curve at the characteristic points for upper and lower water

will

intersect at the

T-S

point for intermediate water in its original state.

Applying this method to the

T-S

diagram

for "Veiding"

^st. 186 (Fig. B),

it

is seen

that

the tangents nearly coincide

with

the curye, indicating that st. 186 is situated very close to the area where Atlantic water encounters the Polar water.

The tangents intersect

at

the point where

T :

2.65' and S

:

35.01 ^0/q6 which

THE "coNRAD HoLMBoE" ExPEDrrroN

rN

1923

.6 I 340 2 '4

Fig. 15.

T-S

plotting diagram, "Conrad Holmboe"

No 15, 1963 23

33 2'l.. 68

st. ¹⁰

-

^19.

are the values for Atlantic water ^before the mixing with Polar water. The

Srocr- uex

^{method has not been} applied to the single "Conrad Holmboe" ^{stations, due} to the irregular

T-S

^curves.

^A

^common

T-S

diagram ^has therefore been made

(Fig.

15), and the method applied on this curve. According

to

this figure, the intermediate water

in

its original state has

a

temperature

of

2.65" and salinity 35.0 ^o/00, before meeting the Polar water. This agrees well

with

the results from

,,Veiding" st.

186,

and

supports

the

conclusion concerning

the

Intermediate water.

It

^has been mentioned before

that

Srocxuex's method presupposes that

the

upper and lower watermasses are homogeneous and unlimited relative to the intermediate layer. But ^these conditions are not

fulllilled

here, and the values stated, should therefore be considered

with

reservation.

As mentioned above, the Deep water is nearly homogeneous, and so exten- sive

that

application

of this

method can be justi{ied. _However,

the

extent of Polar water is nearly the ^{same as} that of the Intermediate water, and the Polar water ^is neither a homogeneous nor a uniform water type. The

T-S

curve (Fig.

l5),

nevertheless, is

fairly

smooth and even, and there is reason

to

believe that the values stated are

fairly

accurate.

Dlnamical computations

The

geostrophic current comPonents have been computed

by

means oI the formula given by HoLr-INo-HANSEN (1905), which neglects acceleration, friction and tidalforces. The ^sections taken into account consist of stations 9 to 21. Very few stations are ^deeper than 200 m, and the 200 m decibar surface has therefore

2+ TOR KVINGE Mat.-Naturv. serie

been chosen as reference depth. Stations

lB,

19, 20 and

2l

are, however, ^less than 200 m deep, and the dynamic depths at these stations have been determined

by

means of the following formula given

by

Hrr-r.ewo-HANsEN (193a):

[adp:["al+S"ap

where index

I

^denotes the bottom curve from the reference surface to the station vertical, and index

II

the station vertical.

Neglecting acceleration and V,*-terms

in

the equation of motion, we obtain according

to

S^ær.rw (1959),

for the

differential

of

dynamic depth

gdz: dp-2øsingV,dy

The y-axis is parallel

to

the section, the r-axis vertical

to

the section. This

formula

shows

that

Hnr-r,aNn-HeNsnx's statement

is

correct

only if V, :

O at the bottom (or

if it

has a very unlikely distribution along the bottom). The

Aø

distribution

at the

bottom

is not

uniform, and consequently

the

integral [a dp not unique, but dependent on the path of integration.

Dynamic depths determined

by

this method should therefore be ^considered

only in

connection

with the

section along

which the

integrations have been performed.

A

trench more than 300

m

deep extends eastward

from

Gael Hamke Bay, separating st. 20 from the previous stations. There are, however, no observations

from

this trench and the differences

of

dynamic depth between

st.

18

(or

19)

and 20 have therefore been determined

in

the following

way: The

integration la ^{dp has been} performed along a straight line connecting the point of intersection between the station vertical at st.

lB

(or 19) and the bottom

with

the correspond-

ing point at

st. 20, and

from

there vertically

to the

surface. This procedure is equivalent

to

Hor,r.nqo-HeNsnr's method of integrating along the bottom line, and is of course subject to the same limitations, mentioned above. The dynamic depth

at

st. 20 is computed relative

to

the depth

at

st. 21, being 177

m

deep.

The bottom has been taken as reference surface between these two stations.

Geostrophic

current

components

are then

computed, applying

the

above mentioned methods and formulae.

It

should be emphasized that the components are all relative to those at the reference surface. There ^is no reason to believe that the current components at the reference surface are equal in the different sections, and the components are therefore not directly comparable. The surface velocity components are shown

in

the maps Figs.

3 and

16. The isovels

in

the vertical section "Conrad Holmboe"

II

are presented

in Fig.

17.

Fig. 3 shows a weak surface current towards south-west

in

the eastern part of section "Conrad Holmboe"

II. In

the deeper layer between st.

9 and 1l

a

minor

north-easterly current

is

seen, probably

due to

the

Jan

^{Mayen Polar} current, (Hnr,r,aNo-HANsEN and NeNsEN 1909). The currents on, and near, the shelf are quite irregular and complicated (Figs.

3,

¹⁶

and

^17).

No 15, f963 THE "coNRAD HoLMBoE" ExpEDrrIoN

IN

lg2g 25

Fig. 16. Geostrophic surface current components, . Conrad lfolmboe', st. 14-21.

Fig. 17. Section "Conrad Ffolmboe"

II,

current components vertical to the section incm.sec.-l

on

the continental slope, between

st.

12

and

14, relatively strong current components are present, directed parallel to the isobaths. Strong current compo- nents are also found

in the

sections between the stations

17-20, lB-20,

and

19-20.

The sections

st. 14-15,

st.

14-17

and

st. L7-lB,

are situated on the slope, running more

or

^less parallel

to

the isobaths. The corresponding current components are

all

relatively weak.

The

strongest current components are found

on

the shelf

in

the section st.

+5+4 +l +2

r1

^f

As es 4 :l 4

26 TOR KVINGE Mat.-Naturv. serie

15-16,

amounting

to

8.2 cm/sec.

in the

surface layer.

Fig. 1l

shows

that

at these stations

the

section

is

crossing

the

border between

Atlantic and

Polar waters.

The

lines ^seem

to

be nearly parallel

to

the interface between the two watermasses. Consequently, the geostrophic current is closely related to the ^steep inclination of the border separating the water ^masses. We may therefore conclude as follows:

Current conditions are closely related to the bottom topography and to bor- ders between the water masses.

On

the

right

side,

the

current approximately follows the slope.

On

the shelf, however, the direction of the current is parallel to the border ^between the two water masses; here the highest velocities are found.

The

components

are

computed

from the

available observations,

and

the conclusions are given on the assumption that the components are approximately reliable. The smaller components are, however, doubtful, because minor errors of observation may have a relatively great effect of these values.

Neither tidal nor frictional

forces are taken

into

account.

Friction at

the bottom is probably most important on the shallow shelf. The areas dealt with are

partly

covered

by

ice floes, and

friction at

the ice cover may therefore ^also be of importance.

The

effect

of tidal

^forces is probably more significant

in

the narrow, deep trenches.

On

the basis oI the present data, however, a closer ana- lysis

ol

such ellects is

not

^possible.

Transport.

The transport ^values given below, are volume transport values, i.e. the volume oI water which, due to geostrophic current, flows through a vertical section per

unit

time.

Section.

st. l0- 9: llTT0mssec-l

Section.

st. 17-14:

67290m3sec-1

st. 1l-10:

-25230 ^st. 18-17:

¹⁵⁶⁸⁰⁰

st. l2-l

^t

: 67420

^st.

20-18:

²³²⁸⁸⁰

st. 14--12: 224890

^st.

20-17:

³⁸⁸²⁷⁰

st. 15-14: 24870 ^st. 20-19:

¹⁹¹⁰³⁰

st. 16-15: 256600

^st.

2l-20:

¹⁰⁴⁸⁶⁰

st. 19-16:

³⁵⁰⁶⁰

Transport towards south

is

considered positive.

The isotransport diagram Fig. lB shows a large transport through the ^sections st.

12-14

and st.

15-16.

A conspicuous feature is the negative transport extend- ing from the reference level to about 90 m depth between st. ¹⁴ and 15. Negative transport is also encountered

at

about

73'N

latitude

in

the section st.

9-l

^1.

This is probably due

to

the above mentioned

Jan

^Mayen Polar current.

The net

transport through the section

"Conrad

Holmboe"

II

^st.

9-19

^is

estimated to about 0.6

mill.

mssec-1.

No 15, 1968 THE "coNRAD HoLMBoE" ExpEDITToN

rN

1923 27

Fig. lB. Section "Conrad llolmboe"

II,

isotransport curves and transport histogram; mssec-l.

Compaison.

As very few expeditions have previously worked

in

these areas,

only

a few observations are available

for

comparison. Observations carried

out on _"Nat- horst" in

lB9B,

"Frithjof" in

^{1900 and}

"Fram" in

^1910, indicate a west-going current

of Atlantic

water

at

about

77"40'N to

7Bo

N.

HBr,r,eNr-HeNsnN and NaNsew (1912) conclude

that the

Svalbard-Atlantic

current

splits

into

two branches. One continues north-wards

into

the Polar basin, the other bends to the west

at

77"-7Bo

N

latitude, forming an intermediate layer under the Polar water

in

the East-Greenland current.

In

the horizontal sections from the

"Fram"

it

is seen

that

the isohalines have

a

tongue-like extension west-ward along the 78"

N

latitude. The 35.00 ^0/oo isohaline thus reaches 100 m depth ^as far west as

beyond 4o

W. In

the

"Veiding"

section the 35.00 ^0/oo isohaline reaches 5o30' W, situated

at

about 200

m

depth.

In

this area (between

st.

186

and

lB7) the

At-

lantic water becomes an intermediate layer

in the

East-Greenland current.

Al-

together, the observations from

"Veiding"

^{obviously agree well}

^with

^{those from}

the previous expeditions.

Before the observations on the "Conrad Holmboe" ^{sections are} discussed,

it will

be convenient to examine an intermediate section carried out on "Belgica"

in

1905 (Hnr.r.lNo-HexsnN and Konrono 1909). The "Belgica" ^{section st.}

30-25

^runs

in

a north-westerly direction from 75o39'

N,

12'00'W to 76'00' N, 3o55'W, alter having ^crossed the continental ^slope. The warm layer, limited by the 1o isotherm,

02550

NAUI. l,ltLEs

28 TOR KVINGE Mat.-Naturv. ^serie

has a configuration similar to that lound in the section "Conrad Holmboe"

II,

but in

a less developed form. The

q

curves incline steeply, indicating current at the slope.

On the "Polarbjørn" expedition in 193 I and l932 a few sections were carried out

in the

areas close

to

"Conrad Holmboe" ^section

II

and

III (Jernnu.N

^1936a).

According

to

these observations, the core of

Atlantic

water is characterized by a salinity o134.97 ^o/oo and a temperature of 2.10'.JAKHELLN ^suggests that ^these values are very high, as previous investigations do not show temperatures above 1.50' and salinities above 34.95 _oioo. Maximum values

in "Conrad

Holmboe"

sections are found at st. 12

at

¹⁵⁰ m depth, where the temperature is 1.90o, and the salinity 34.95 ^0/oo. Polar water in its original state is, according to Jernnr-r.N, characterized by the salinity 3+.07 ^oloo and the temperature

-1.85'.

^{The lowest}

minimum

temperature

found on the "Polarbjørn"

expedition

is

-1.80o

^and the corresponding salinity 33.55 ^0/oo. These values agree

well with

those from

"Conrad Holmboe" ^section

II,

where lowest minimum temperature is

-1.85'

and the salinity 3+.0201oo found

at

100

m

depth.

As mentioned above, the Polar water in the East Greenland current ^is probably

not

a

well

defined and uniform water type. Consequently,

to

speak

of a

well- defined

T-S

relation

for

Polar water

in

its original state is meaningsless. Based upon observations from the "Belgica" ^{and the} "Polarbjørn" expeditions, current components and water transport have been determined

by

dynamical compu- tations. According to

Jerunr,lN

^no components above 14 cm/sec are present on the

"Polarbjørn"

^{sections. He suggests}

that

the

total

current

in

the section st.

26

to

27 is about 20 cm/sec

at

the surface.

The current velocities

in

the northern areas have been estimated

to 25-30

cm/sec

at the

surface (Hnr.r-eNu-HANsEN

and Korrono

1909).

In the

above mentioned computations the 200

db

surface has been used as reference depth.

The

transport through the section "Belgica" ^{st. B23}

to

836 is estimated to 1.6

mill.

m3/sec (Jernnr.r.n, 1936a).

By applying the method suggested by

Jernrlr-N

^(1936b), the transport ^east of "Polarbjørn" ^{st. 20,1932, is} determined ^{as 1.32} mill. m3/sec (Jexnnr.r.N 1936b).

This

transport has, however, been computed

by

using

the

300

db

surface as

reference depth.

The above mentioned current and transport values are about twice ^as high as those

in the

"Conrad Holmboe" ^sections. Most

of the

"Conrad Holmboe"

sections were, however, situated on the slope, running more

or

^less parallel to the isobaths and consequently also parallel

to

the current.

The values

from

"Conrad Holmboe" should therefore be considered

in

re- lation to the bottom topography, and to the direction of the sections.

The "Conrad Holmboe" expedition ^was carried out late in the summer season,

and the ice had already started to form. This may have had an influence on cur- rent conditions as well. Considerable current and transport may also be present

off the

shelf.