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Interaction of waters from the Arctic Ocean with those from the Atlantic and Pacific
TRANSLATIONS FROM OKEANOLOGIYA This section contains a group of edited translations from the Russian Journal Okeanologiya. It is expected that the publication of these will prove of value to scientists engaged on similar work in other parts of the world. Note--All references to articles from Russian journals etc. are in Russian.
Publisher's announcement--The publication of translations from Okeanologiya has fallen behind schedule because of the conflict between the amount of space available and the large proportion o f the Russian articles which the Editors have felt to be of interest to some readers. In future, the Editors will select for publication only those articles of the widest interest. This issue contains those articles selected from Okeanologiya, Volume 3, Number 4, the remainder being listed by title and author only. No articles from Volume 2, Number 2 to Volume 3, Number 4 will be published, but translations from these and subsequent issues may be obtained on a cost-sharing basis on application to the following address • Custom Translation Service, Pergamon Press Limited, Headington Hill Hall, Oxford, England. A list of papers from Okeanologiya translated by Pergamon Press, or translated and published elsewhere, will be published in Deep-Sea Research, Volume 11, No. 3.
Interaction of waters from the Arctic Ocean with those from the Atlantic and Pacific V. T. TIMOFEYEV Arctic and Antarctic Scientific Research Institute
Okeanologiya, 1963. 3 (4): 569-578 TI~ hydrological conditions of the Arctic Ocean are to some extent governed by Atlantic and Pacific currents as well as by fresh water run-off. They all bring to the Arctic Ocean waters of different physico-chemical properties. A quantitative calculation o f the balance of water and heat from these sources is o f great scientific and practical interest, for, without knowing their income and outlay, no valid conclusions can be drawn about their influence upon water conditions of the Arctic Ocean.
Entry of Atlantic water into the Arctic Ocean and its transformation in the seas of this ocean The influence of the intensity of warm water entry through the Faroe-Shetland channel upon
the hydrological conditions o f European seas and upon the'European climate was noticed and has long been studied. Most o f the warm waters brought by the Atlantic current to the Arctic Ocean flow through the channel between the Faroes and Shetlands [12]. A. V. Yanesyi has now done some work using the results obtained by various earlier authors, chiefly by Chaplygin [20] from 1902 to 1937 and by Tait [23] from 1927 to 1952, as well as other data from 1938 to 1959. On the grounds of these data the deliveries o f water in the Faroe-Shetland channel were calculated by one method. The number o f profiles used in the Faroe-Shetland channel during the 33-yr period from 1902 to 1959 is given in Table 1. It is evident from this table that the traversing was done most irregularly in the course o f the year. The maximum falls on the summer months, and the minimum on the winter months, so any computation from these observations o f the yearly and even multi-yearly discharge can only be approximate. The results o f these calculations are given in Table 2. As this data is the most complete, we shall use it in further calculations. 265
266
v . T . Tmlol~vEv
Table 1. Number of traverses made monthly in the Faroe-Shetland channel from 1902 to 1959 Months
No. of traverses
lI Ili IV V VI VII VIII IX X XI XII
2 2 2 7 16 16 9 13 3 2 5 2
Total
79
l
Tab~ 2. Mean multi-year discharge of Atlantic water and heat brought by the Atlantic current into the Arctic Ocean from 1902 to 1959
Months I
1I III IV V VI VII VIII IX X XI XII
Year
Discharge of water (km s × 103)
Discharge of heat (kcal × 10is)
33-4 18-8 17"0 23-8 27.1 25-0 19.6 23"8 22.9 28-1 29.6 29.8
248 134 141 117 137 147 112 177 181 189 165 174
298
1922
Table 3. Mean discharge 0[" Atlantic water and heat in the Arctic basin through the Barentsburg-ice barrier section, 1933-1960. 18 profiles used Discharge of water (kin s x 103)
Discharge of heat (kcal × 1015)
1I III IV V VI VII VIII IX X XI XII
13"18 12"14 10"36 7-67 7"22 8"07 9'64 11 '07 11 "69 12"72 12"58 12"78
18"54 13"05 10"36 7"17 8"66 15"66 22"34 27"25 28"99 29"67 26"44 22"60
Year
129.12
230-73
Months I
Interaction of waters from the Arctic Ocean with those from the Atlantic and Pacific
267
Entry o f Atlantic water into the Arctic basin Flowing through the Greenland Sea from the Atlantic into the Arctic basin are warm Atlantic waters. And here the chief outflow from the Arctic basin of cold waters brought by the East Greenland current is directed towards the Greenland Sea. So it is most important to get the absolute or near absolute properties of at least one of these two currents. Much is already known about the Spitsbergen current. Analysis of these data make it possible to ascertain the seasonal variation in the strength o f this current and get a qualitative idea of the complete or near complete volumes o f Atlantic water being brought by this current into the Arctic basin. We have previously considered this problem [I 5], but only the relative (for the 1000db surface) discharge of water and heat was given. Now we have obtained the complete or near complete discharge of water and heat entering the Arctic basin from the Greenland Sea (Table 3). Entt3, o f Atlantic water into the Barents Sea Atlantic waters enter the Barents Sea chiefly between North Cape and Bear Island and also, though in much smaller volume, between Bear Island and South Cape. The flow o f water and heat passing between North Cape and Bear Island was determined previously [12] on twelve traverses; that between Bear Island and South Cape was ascertained on five. By 1950 the Arctic Institute had gathered and processed a considerable amount of data, to wit : fifty profiles along the line North Cape-Bear Island and sixteen along the line Bear Island-South Cape [24]. Uralov [18] has processed data from 1931 to 1956 for 78 North Cape-Bear Island traverses and 22 Bear Island-South Cape traverses. As a result the author computed that in a year the North Cape current proper brought in 31.081 km 3 of Atlantic water and 196 x 10~5 kcal o f heat, and the Norwegian coastal current 25.912 km -~o f water and 200 x 1015kcal of heat. In this connection Uralov calculated the flow of heat at a temperature of t "8", and not at one of 0 ~. To compare his heat discharge with the others, it has to be decreased by 56'993 km 3 x 1-8° = 103 x 10~5 kcal. Then Uralov's total discharge of heat over the North Cape-Bear Island section will be 293 x I0 ~5 kcal per annum. The Arctic and Antarctic Institute has gathered and processed considerably more data : 131 North Cape-Bear Island traverses and forty-five Bear Island-South Cape traverses. The North Cape-Bear Island section has been traversed regularly for 28 years (1930 to 1961). But, during the year, it was traversed rnost irregularly (Table 4). The Bear Island-South Cape section was traversed most irregularly during the year (Table 5), which made it very hard to determine the mean multi-year discharge of water and heat. From those profiles traversed from 1930 to 1960 the discharge of water and heat was calculated by N. V. Ovchinnikov, while in 1961, for the North Cape-Bear Islandsection, traversed six times, we calculated the water and heat flow from the same profiles. In the calculation o f the water and heat flow on the Cape North-Bear Island profile its sectional area was divided into two parts. In the northern part (near Bear Island) there is a permanent current going from the Barents into the Norwegian Sea. Passing through the other part of the profile is a permanent current from the Norwegian into the Barents Sea, called the North Cape branch of the Table 4. Number o f traverses made along the line North Cape-Bear lsland]rom 1930 to 1961 Months I 11 III IV V VI VII VIII IX X XI XII Tota/
No. o f traverses 8 11 13 13 13 12 13 8 9 11 6 14 131
268
V.T. TIMOVEVEV Table 5. Number of traverses .made along the !ine Bear Island-South Cape ]rom 1931 to 1960 Months
No. of traverses
I 1I 11I 1V V VI VII VIII IX X XI XII
8 11 5 2 2
Total
45
1 1 1
2 6 6
Atlantic current. The discharges of water and heat of these two opposing currents were calculated separately. Also calculated separately for east and west were the discharges of water and heat on the Bear Island-South Cape traverse.
Table 6. Monthly discharges of water and heat entering the Barents Sea through the North Cape-Bear Island section according to observations "rom 1930 to 1961 Discharge of water (kin 3 x 103)
Discharge of heat (kcal x 103)
I II III IV V VI VII VIII IX X XI XII
4.07 3.95 4.12 4-55 3.57 3-33 3-75 4.25 4.69 5.06 5.10 5"26
19.11 18.10 17.93 19.20 16.28 14.58 21.77 25.75 25'65 30.41 27"79 27"37
Year
51.70
263'96
Months
Table 7. Menthly discharges of water and heat entering the Barents Sea through the Bear Island-South Cape section according to observations from 1931 to 1960 Discharge of water (kin 3 x 103)
Discharge of heat (kcal × 1015)
I II III IV V VI VII VIII IX X XI XII
0"14 0'63 1"11 0.89 1"59 0.61 0.84 0.75 0.49 0.49 0-53 0-47
0.24 1-90 3.57 2.43 4.19 2.04 2'98 2.52 2"31 1 '69 1-90 1-24
Year
8.54
27.01
Month
Interaction o f waters from the Arctic Ocean with those from the Atlantic and Pacific
269
The mean multi-year water and heat discharge of the North Cape branch of the Atlantic current, entering the Barents Sea through the North Cape-Bear Island section, is given in Table 6, while Table 7 presents information about the inflow of Atlantic water and heat into the Barents Sea through the Bear Island-South Cape section. Thus, according to data for the North Cape-Bear Island and Bear Island-South Cape sections, 60.24 x 103 km 3 of Atlantic water enters the Barents Sea during the year, bringing with it 290.95 × 1015 kcal of heat. Comparing the inflow of Atlantic water and the heat brought with it into the Norwegian Sea to the inflow of this water with its heat into the Arctic basin and Barents Sea, the following should be noted. I. During the year 298 × 103 km 3 of Atlantic water enters the Norwegian Sea. From the Norwegian and Greenland Seas .129.12 × 103 km 3 pours into the Arctic basin during the year, and 60.24 x 103 km 3 runs into the Barents Sea. Consequently, within the Norwegian and Greenland Seas 108-64 x 103 km 3 of Atlantic water is transformed in one year, which amounts to about 36% of its inflow. The quantity of such water entering the Barents Sea and Arctic basin respectively comes to 2 0 ~ and 4 0 ~ of the total amount of Atlantic water received by the Arctic Ocean. 2. The annual inflow of heat brought by Atlantic water into the Norwegian Sea through the Faroe-Shetland channel amounts to 1922 × 1015kcal. From the Norwegian and Greenland Seas, Atlantic water brings 230.73 x 1015 kcal into the Arctic basin and 290.95 × 1015 kcal into the Barcnts Sea. Thus, being transformed in the Norwegian and Greenland Sea, Atlantic water loses 1410 × 10 ~5 kcal of heat--73 ~ of the yearly amount of heat entering these seas with Atlantic water. The remaining heat is brought with Atlantic water into the Barents Sea (15 ~ ) and the Arctic basin (12 %). It is now possible to estimate how much heat is expended by Atlantic water during its transformation in the Norwegian and Greenland Seas in convective turbulent heat-exchange, evaporation, radiation and mixing with other colder waters. When determining the heat balance of the Norwegian and Greenland Seas, Zaitsev [4] got a yearly sum of 415 x 10~5 kcal for heat crossing the sea surface, 770 x i@ 5 kcal for that lost in evaporation and 615 x 1015 kcal for that lost in convective turbulent heat-exchange. If in the Norwegian and Greenland Seas 1410 x 10~5kcal of the heat entering with Atlantic water is lost on its transformation during the year, and 415 x 1015kcal crosses the surface of these seas, the annual loss o f heat in the Norwegian and Greenland Seas will total 1825 x 10is kcal. Of this amount 42 ~ is consumed in evaporation, and 35 ~ in convective turbulent heat-exchange. So 405 x 1015 kcal a year, or 23 ~ of the heat, is lost by Atlantic water on mixing with other colder waters in the Norwegian and Greenland Seas.
Transformation of Atlantic water in the Barents Sea As shown above, the Barents Sea receives during the year 60.24 x 103 km 3 of Atlantic water containing 290"95 x 1015kcal o f heat. According to data for the Bear Island-South Cape section, the mean annual volume of water, entering the Greenland Sea from the Barents and bringing with it 16.56 x 10TM kcal of heat a year, amounted to 5'06 x 103 krn 3. The Cape Zhelaniye (Novaya Zemlya)- Salm Island (Franz Josef Land) profile was traversed eight times from 1932 to 1960. The discharge of water entering the Kara Sea from the Barents, calculated from this traverse, was 17.13 x 103 km 3 per annum; the heat discharge amounted to 14'87 x 10 kcal. According to Uralov's data [18], the resulting loss from the Barents Sea to the Kara through the Karskiye Vorota comes to 1-24 x 103 km 3 of water and 25-87 x 1015 kcal of heat per annum; through the Yugorskii Shar it comprises 0.40 x 103 km 3 of water and 0-46 x 1015 kcal a year. According to calculations by Timonov and Kuz'min [11], the flow of heat from the Barents Sea into the White is 11.025 x 1015 kcal a year. The exchange of water and heat across the Spitsbergen-Franz Josef Land section has only been determined on one traverse. Over it, the Barents Sea does not consume heat but gets 0.83 x 10~5 kcal a year from the Arctic basin. Thus, in exchanging water with nearby basins through the sections and channels indicated above, the Barents Sea loses (16.55 ÷ 25.87 ÷ 0'46 ÷ 11.025) x 1015 = 52.915 x 1015 kcal of heat a year, which forms only 1 8 ~ of the annual heat inflow into this sea as a result of water-exchange(290.95 -t- 0.83) x 101~kcal. It is hence clear that most of the Atlantic waters coming from the Norwegian into the Barents Sea are transformed within the latter. From what has been said, the credit side of the Barents Sea's heat balance is made up of 291.78 x 10:5 kcal (32~) of heat which enters with Atlantic and Arctic waters. It was found pre-
270
V.T. "I-IMOFEYEV
viously [13] that the heat of radiation equalled 451.26 × 1015 kcal (52~/o), with 142'29 × 101~kcal (16 ~ ) of it being given off in a year during ice formation. The debit side of this sea's balance is made up of 427.40 × 1015 kcal (49~) of heat exchanged between the sea and atmosphere per annurn, 222.89 ×, 10X~kcal (25~/o) due to evaporation, 142.30 × 1015kcal (16~) due to i:e melting and 53.91 × 1@5 kcal ( 6 ~ ) due to the exchange of water with nearby basins. So 20"83 x 10~skcal (4 ~ ) is annually expended during the mixing of warmer and cold waters. This heat ultimately enters the atmosphere during the exchange of heat between water and air through ice. However, these data were obtained about twenty years ago. Naturally enough, during this time much work devoted to a determination of this sea's heat balance has been published, and its outcome should be considered. In 1951 Sheremet'yevskaya [9] estimated the rnain components o f the heat balance of the surface of the Barents Sea. She found that tl~e inflow of heat from solar radiation equalled 70 % of the total received, while the heat brought in Atlantic waters came to about 27~,~. The expenditure of heat, according to her estimates, was 46~,~ in effective radiation, 32°0 in evaporation and 22~o in heat exchange with the atmosphere. In 1955 Konoplev [6] determined the heat balance for the surface of the south-western Barents Sea. It should be noted that, according to Konoplev's and SheremeCyevskaya's calculations the inflow of heat with Atlantic water for the same squares of the sea amounts to 50"~ and 25°~ respectively of the total heat receixed. In 1957 Mileiko [9] estimated the total heat loss from the Barents Sea's surface, with the same results as Sheremet'yevskaya, since they used the same Sverdrup-Kuz'min formulae. In 1958 Dcnisov [3], as a result of comparing the local and advective factors, concluded that for the North Cape current the advective factor averaged only 17 ?/o of all the heat coming into the Barents Sea. In 1961 Seryakov determined the heat balance of the surface of the unfrozen part of the Barents Sea, and f3und that the heat exchange with the underlying water layers (intra-water convection of heat) was 69.1 kcal/cm z a year. These reports on the heat balance of the Barents Sea are contradictory, apart from the inconsistency in the estimation of the indiGdual compor, ents of the heat balance, which is due both to the different methods of calculation and to the fact that separate parts of the sea, and not the whole area, were considered. Thus, the data obtained by these various authors cannot actually be compared. Moreover, they all calculated the heat balance of the sea surface, deriving the advective component not directly from their observatiors but by equating the credit and debit items ol the heat balance as its remainder term. So all the errors and inaccuracies in the d~.termination of the components of the sea's heat balance went into the remainder term of this balance's equation, i.e. into its advective component. Consequently, we can compare our value of 263'94 × 10J5 kcala year for the advection of hcat entering the Barents Sea through the North Cape-Bear Island section only with that obtained by N. S. Uralov for the same section, which comes to 291.26 > 10~ kcal a year. This comparison for the advection o f heat into the Barents Sea across the North Cape-Bear Island section happens to be fairly close. The relatively srnall discrepancy in the advection values appears to b: due partly to the different method of calculation as well as to the fact that our data were obtained on a considerably larger number of sections. ErltO' o f Pacific water into the Arctic Ocean Ratmanov [10] was the first to try to determine the water balance of Bering Strait. Next, a more thorough attempt by Maksimov [8] calculated that the annual amount of water brought by the Pacific current into the Chukchi Sea was 30.35 × 10-~km 3. Recalculating I. V. Maksimov's data with allowance for the wind conditions in the Bering Strait, N. A. Volkov obtained a figure of 20-22 × 10~ kmL N. N. Zubov took the yearly discharge of the Pacific current into the Chukchi Sea to be roughly 20 × 103 km 3 [3]. A. K. Leonov got a yearly discharge of 44.03 x 103 km 3 [7]. G. A. Baskakov found the flow of water and heat in the Bering Strait to be 36 >~" 103 km 3 and 33.49 x 10 ~5kcal a year respectively. In the Arctic and Antarctic Scientific Research Institute, Fedorova and Yankina [19] processed all the Bering Strait observations for 21 years (1941 to 1961), getting mean multi-year data for the water and heat flow which are given in Table 8. This information is at present the most complete, so we have taken it in further calculations. Further observations on the Bering Strait current at times of different wind speeds, directions and periods, and especially those carried out in winter, make it possible to revise the water and heat flow in this channel.
Interaction of waters from the Arctic Ocean with those from the Atlantic and Pacific
271
Influence o/" Atlantic and Pacific currents upon the water conditions of the Arctic Ocean To consider the relative role of these currents in the conditions of the Arctic Ocean, we have to compare the flow o f water and heat brought by them into the ocean. From a comparison of the annual flow o f water passing through the Faroe-Shetland (298 × 103 kin31 and Bering (30 × 10~ km 3) channels, it follows that the inflow of Atlantic water into the Arctic Ocean is ten times as much as that from the Pacific. The annual discharge o f water entering the Arctic balance across the Barentsburg-ice barrier section totals 129.12 x 103 km 3. Passing each year from the Norwegian and Greenland Seas throogh the North Cape-Bear Island and Bear Island-South Cape sections into the Barents Sea is 60.24 x 103 km 3 of water. Crossing the same sections from the Barents Sea into the Greenland and Norwegian Seas is 29.61 x 103 km 3 of water. According to calculations by Timonov and Kuz'min [11], the resultant yearly flow from the White Sea into the Barents amounts to 200 km 3.
Table 8. Mean monthly discharge of water and heat entering the Chukchi Sea through the Bering Strait
Months
Discharge of water (kin 3 x 103)
Discharge of heat (kcal x 1015)
1 "59 1"33 1 "22
1I III IV V V1 VII VIII IX X XI XIII
1'56 2"24 3"31 4"17 4'32 3'61 2"65 2"15 1"80
-- 2-87 - - 2'40 -- 2.20 - - 2.81 -- 3.43 -- 0'66 8'76 14.70 14.40 4"77 0.11 3 '24
Year
29'99
26.45
1
Hence it follows that during the year 30"83 × l03 km s df water enters the Arctic basin from the Barents Sea through the Novaya Zemlya channels and those between Franz Joseph Land. Therefore a total o f 152-96 x 103 km 3 of water flows each year into the Arctic basin through the SpitsbergenGreenland and Noyaya Zemlya-Franz Josef Land channels as well as through the Novaya Zemlya passages. Comparing this value with the yearly flow of water coming in through the Bering Strait (30 × 103 km3), the Arctic basin apparently receives five times as much water from the North European basin as from the Pacific. It is interesting, too, to compare the amounts o f heat brought in by the currents. Comparing information about the quantity of heat entering the Arctic Ocean with the Pacific current through the Bering Strait (26.45 x 1015 kcal) to that coming in with the Atlantic current through the Far6eShetland channel (1922 x 1015 kcal), we can see that the Atlantic current brings seventy-three times as much heat into the Arctic Ocean as the Pacific current. However, as shown above, most o f the heat (1701 x 1015 kcal or about 88 ~ ) brought by the Atlantic current into the Arctic Ocean is still consumed in the Norwegian, Greenland and Barents Seas; only 1 2 ~ (230"73 × 1015kcal) o f the heat flowing into the Arctic Ocean with the Atlantic current is left for the Arctic basin. We should thereby stress that the Atlantic current only brings ten times as much heat to the Arctic basin as the Pacific current. Though the role o f Pacific waters in the exchange of water and heat with the Arctic basin is substantial, their direct influence upon the hydrology o f this basin is limited to the Chukchi Sea, the south-east o f the East Siberian Sea and the west of the Beaufort Sea. The behaviour and spread of Pacific waters into the Arctic basin were first studied by Treshnikov [16, 17]. He showed that these waters with their peculiar physico-chemical characteristics could be traced in separate years (in the 50-100 m layer) as far as the pole. The conditions of Pacific waters in the Arctic basin were also considered at length by Coachman and Barnes [22].
272
V . T . TrMOFEYEV
Approxhnate water balance for the Arctic Ocean To draw up the balance for the Arctic Ocean waters, the chief components of their income and outlay were taken into account. The basic credit items of the Arctic Ocean's water balance are the entry of waters from the Atlantic and Pacific Oceans, the influx of continental waters and precipitation. The basic debit items are the loss of water and ice from the Arctic Ocean, chiefly by the East Greenland current, and through evaporation. When approximately determining the water balance, we may equate precipitation and evaporation which have yet to be estimated. Such an assumption is justified since in determining the water balance of the Arctic Ocean these items will be of slight importance compared with other factors. The entry through the Faroe-Shetland channel into the Arctic Ocean of waters borne by the Atlantic current was considered above. To compute this ocean's water balance, the overall exchange of water with the Atlantic Ocean which occurs between Sogne Fiord, the Faroes, Iceland and Greenland must be taken into account. On the Sogne Fiord Iceland profile most of the water is exchanged through the Faroe-Shetland channel [12]. Ye. 1. Chaplygin showed that in the Faroe-Shetland channel there were two opposing permanent currents : in the east part of the channel the current sets northwards, in the west southwards. The average multiycar inflow of water from the Atlantic Ocean into the Arctic through the eastern part of the channel has been calculated from A. V. Yanesyi's observations between 1901 and 1959 as 297.84 × l0 skm s a year. The outflow through the eastern part of the channel is 165.56 × 103 km 3 a year. Thus, the net annual inflow of water into the Arctic across the Faroe-Shetland channel equals 132.28 ;< 10skm s. To further determine the amount of water received by the Arctic Ocean, the land run-off into the Arctic basin must be considered. The yearly run-off into the Arctic Ocean, according to V. S. Antonov's calculations, is 4-39 x l0 skm s. With this figure being by no means small, river waters markedly influence the hydrological and ice conditions of Arctic seas [1, 2]. As a result, the water entering the Arctic Ocean through the Faroe-Shetland and Bering channels with that flowing off the land amounts during the year to : (132-28 ÷ 30-00 -+- 4"39) × 103
~
166"67 × 103 km s
The same quantity o f water can be presumed to flow out of the Arctic Ocean through the Denmark Strait and the numerous passages of the Canadian Arctic archipelago, where the hydrology has not been sufficiently studied. As a result, the rough water balance of the Arctic Ocean obtained previously [14, 24] may now be defined (Table 9).
Table 9. Yearly water balance of the Arctic Ocean (km s x l0 s) Chief items of the water balance Faroe-Shetland channel Bering Strait Land run-off Denmark Strait Passages of the Canadian archipelago Water balance
Total inflow of water 297"84 30"00 4"39
Total outflow
Net inflow
165-56
132"28 30.00 4'39
Net outflow
126.67 332-23
t
40.00 332.23
166.67
166"67
The hydrology of the Denmark Strait has not been sufficiently studied for a determination the water exchange through it. From the information available the water conditions appear to be very complex. In it there are countercurrents : from the north the cold East Greenland current usually flows into the western part o f the strait, and from the south the warm Irminger current generally enters its eastern half. In the Denmark Strait, from 1949 to 1954, foreign ships regularly carried out traverses, but, unfortunately, these did not extend into the Greenland coast and, consequently, failed to intersect the full flow of the East Greenland current. The only exception is four profiles, but from these it is difficult to deduce the mean annual discharge of water since it varies from 1.64 km 3 x 103 (in August 1933) to 57.92 km s x 103 (in March 1933). Thus, it was impossible to determine reliably by indirect means the exchange o f water through the Denmark Strait.
Interaction of waters from the Arctic Ocean with those from the Atlantic and Pacific
273
Therefore, comparing all the data for the inflow and outflow of water and not forgetting that according to direct observations the total annual discharge through the Canadian Arctic archipelago comes to 40 × 103 km 3 [21], the rest of the water (126-67 ,< 103 km 3) must run out through the Denmark Strait. This figure proved to be 34.33 /. 103 km 3 a year lower compared with the former value (161.00 × 103), due to a revision of the inflow of Atlantic water (its inflow was found to be 19.72 "~: 103 km -~a year) and Pacific water (6.00 × 103 km 3 a year less) and a correction for the outflow through the passages of the Canadian archipelago (8.6 × 10-~km 3 a year more). Bearing in mind nevertheless the low accuracy of some values, especially for the Denmark Strait, as data roughly depicts the relative role of various items in the water balance of this ocean and gives a general quantitative idea of the chief factors which influence the hydrology of the Arctic Ocean. Moreover, they make it possible to ascertain the role of Atlantic and Pacific currents in the water and heat balances of basins in this ocean. REFERENCES [I]
ANTONOV,V. S, and V. YA. MOROZOVA(1957) Total land run-off into Arctic seas. Coll. River hydrology of the Soviet Arctic (Sh. Gidrologiya rek Sovetskoi Arktiki), Trans. Arct. Inst., Leningr. (2) 208. ]21 ANTONOV,V. S. (1958) Role of land run-off in the behaviour of Arctic currents. Probl. Severa, (l/, lzd. Akad. Nauk, SSSR. [31 DENJSOV,A. S. (1958) Method for studying the thermics of warm currents. Probl. Arct., (3). [41r ZArrSEV,G. N. (1960~ Heat balance of the Norwegian and Greenland Seas and its component factors. Soviet fishing research in the seas of northern Europe (Sovetskiye rybokhozyaistvennyye issledovaniya v moryakh Yevropeyskogo severa), lzd. Vses. Nauch.-lssled. Inst.
Morsk. R.vbn. Khoz. Okeanogr. Polyarn. Nauch.-Issled. Inst. Morsk. Rybn. Khoz. Okeanogr., [5] [6] [7] [8] [9] [10] [11] [12] [13] [14] [15]
Moscow. Ztmov, N. N. (1945) Arctic ice (L'dy Arktiki), lzd. Glavsevmorputi, Moscow. KONOeLEV,N. P. (1955) Trial research on multiyear variations of the heat balance by means of shipboard observations in the Barents Sea. Trud. Gos. Okeanogr. Inst., (22). LEONOV,A. K. (1947) Trial quantitative calculation of the water, heat and salt brought by Atlantic and Pacific currents into the Arctic basin. Met. Gidrol. Nabl. (5). MAKStMOV,I. V. (1944) Determining the ordinal value of the annual flow from the Pacific to the Arctic through the Bering Strait. Probl. Arkt., (2). MILEIKO,G. N. (1957) Estimate of the heat lost by the Barents Sea surface for determining the water and ice-barrier temperature. Trud. Tsent. Inst. prognoza, (57). RATMANOV,G. YE. (1937) Water exchange through the Bering Strait. Issled. Morei SSSR, (25). TIMONOV, V. V. and P. P. KtJZ'MIN (1939) Rough trial determination of the heat balance of the White Sea. Trud. Gos. Gidrol. Inst., (8), Gidrometeoizdat, Leningrad and Moscow. TIMOFEVEV,V. T. (1944) Water masses of the Norwegian and Greenland Seas and their dynamics. Trud. Arct. Inst., (183), Moscow and Leningrad. TIraOFEVEV,V. T. (1945) Rough trial determination of the heat balance of the Barents Sea. Dokl. yubileinoi sessii, Izd. Glavsevmorputi, Moscow and Leningrad. TIMOFEVEV,V. T. (1956) Annual water balance of the Arctic Ocean. Priroda, (7), Moscow. TIr~OFEYEV,V. T. (1961) Entry of Atlantic water and heat into the Arctic basin. Okeanologiya,
1 (3). [16] TRESHNtKOV,A. F. (1959) Surface waters of the Arctic basin. Probl. Arct. (7). [17] TRESHN~KOV,A. F. (1960) The Arctic reveals its secrets. New data on the bottom topography and waters of the Arctic basin. Priroda, (2). [18] URALOV,N. S. (1961) Advective component of the heat balance of the southern half of the Barents Sea. Trud. Gos. Okeanogr. Inst., (55), Leningrad. [19] FEDOROVA,Z. P. and Z. S. YANKINA(1963) Entry of Pacific waters through the Bering Strait into the Chukchi Sea. Okeanologiya, 3 (4). [20] CHAPLYGIN,YE. I. (1949) Northwards flow of Atlantic waters through the Faroe-Shetland channel (Postupleniye atlanticheskikh cod cherez Farero-Shetlandskii proliv na sever). Avtoref Kand. Diss., Leningrad. [21] COLLIN,A. E. (1960) Oceanographic observations in the Canadian Arctic and the adjacent Arctic Ocean, Arctic, 13, (3).
274
V.T. TIMOFEYEV
[22] COACHMAN,L. K. and C. A. BARNES (1961) The contribution of Bering sea water to the Arctic Ocean. Arctic, 14 (3). TAIT, J. B. (1957) Hydrography of the Faloe-Shetland Channel, 1927-1952. Mar. Res., (2), Edinburgh. [24] TIMOFEYEV,V. T. (1961) Water masses o f the Arctic Basin. Dept. of Oceanography, University of Washington, Seattle.
[2!t]
Publisher's announcement--The publication of translations from Okeanologiya has fallen behind schedule because of the conflict between the amount of space available and the large proportion o f the Russian articles which the Editors have felt to be of interest to some readers. In future, the Editors will select for publication only those articles of the widest interest. This issue contains those articles selected from Okeanologiya, Volume 3, Number 4, the remainder being listed by title and author only. No articles from Volume 2, Number 2 to Volume 3, Number 4 will be published, but translations from these and subsequent issues may be obtained on a cost-sharing basis on application to the following address • Custom Translation Service, Pergamon Press Limited, Headington Hill Hall, Oxford, England. A list of papers from Okeanologiya translated by Pergamon Press, or translated and published elsewhere, will be published in Deep-Sea Research, Volume 11, No. 3.
Interaction of waters from the Arctic Ocean with those from the Atlantic and Pacific V. T. TIMOFEYEV Arctic and Antarctic Scientific Research Institute
Okeanologiya, 1963. 3 (4): 569-578 TI~ hydrological conditions of the Arctic Ocean are to some extent governed by Atlantic and Pacific currents as well as by fresh water run-off. They all bring to the Arctic Ocean waters of different physico-chemical properties. A quantitative calculation o f the balance of water and heat from these sources is o f great scientific and practical interest, for, without knowing their income and outlay, no valid conclusions can be drawn about their influence upon water conditions of the Arctic Ocean.
Entry of Atlantic water into the Arctic Ocean and its transformation in the seas of this ocean The influence of the intensity of warm water entry through the Faroe-Shetland channel upon
the hydrological conditions o f European seas and upon the'European climate was noticed and has long been studied. Most o f the warm waters brought by the Atlantic current to the Arctic Ocean flow through the channel between the Faroes and Shetlands [12]. A. V. Yanesyi has now done some work using the results obtained by various earlier authors, chiefly by Chaplygin [20] from 1902 to 1937 and by Tait [23] from 1927 to 1952, as well as other data from 1938 to 1959. On the grounds of these data the deliveries o f water in the Faroe-Shetland channel were calculated by one method. The number o f profiles used in the Faroe-Shetland channel during the 33-yr period from 1902 to 1959 is given in Table 1. It is evident from this table that the traversing was done most irregularly in the course o f the year. The maximum falls on the summer months, and the minimum on the winter months, so any computation from these observations o f the yearly and even multi-yearly discharge can only be approximate. The results o f these calculations are given in Table 2. As this data is the most complete, we shall use it in further calculations. 265
266
v . T . Tmlol~vEv
Table 1. Number of traverses made monthly in the Faroe-Shetland channel from 1902 to 1959 Months
No. of traverses
lI Ili IV V VI VII VIII IX X XI XII
2 2 2 7 16 16 9 13 3 2 5 2
Total
79
l
Tab~ 2. Mean multi-year discharge of Atlantic water and heat brought by the Atlantic current into the Arctic Ocean from 1902 to 1959
Months I
1I III IV V VI VII VIII IX X XI XII
Year
Discharge of water (km s × 103)
Discharge of heat (kcal × 10is)
33-4 18-8 17"0 23-8 27.1 25-0 19.6 23"8 22.9 28-1 29.6 29.8
248 134 141 117 137 147 112 177 181 189 165 174
298
1922
Table 3. Mean discharge 0[" Atlantic water and heat in the Arctic basin through the Barentsburg-ice barrier section, 1933-1960. 18 profiles used Discharge of water (kin s x 103)
Discharge of heat (kcal × 1015)
1I III IV V VI VII VIII IX X XI XII
13"18 12"14 10"36 7-67 7"22 8"07 9'64 11 '07 11 "69 12"72 12"58 12"78
18"54 13"05 10"36 7"17 8"66 15"66 22"34 27"25 28"99 29"67 26"44 22"60
Year
129.12
230-73
Months I
Interaction of waters from the Arctic Ocean with those from the Atlantic and Pacific
267
Entry o f Atlantic water into the Arctic basin Flowing through the Greenland Sea from the Atlantic into the Arctic basin are warm Atlantic waters. And here the chief outflow from the Arctic basin of cold waters brought by the East Greenland current is directed towards the Greenland Sea. So it is most important to get the absolute or near absolute properties of at least one of these two currents. Much is already known about the Spitsbergen current. Analysis of these data make it possible to ascertain the seasonal variation in the strength o f this current and get a qualitative idea of the complete or near complete volumes o f Atlantic water being brought by this current into the Arctic basin. We have previously considered this problem [I 5], but only the relative (for the 1000db surface) discharge of water and heat was given. Now we have obtained the complete or near complete discharge of water and heat entering the Arctic basin from the Greenland Sea (Table 3). Entt3, o f Atlantic water into the Barents Sea Atlantic waters enter the Barents Sea chiefly between North Cape and Bear Island and also, though in much smaller volume, between Bear Island and South Cape. The flow o f water and heat passing between North Cape and Bear Island was determined previously [12] on twelve traverses; that between Bear Island and South Cape was ascertained on five. By 1950 the Arctic Institute had gathered and processed a considerable amount of data, to wit : fifty profiles along the line North Cape-Bear Island and sixteen along the line Bear Island-South Cape [24]. Uralov [18] has processed data from 1931 to 1956 for 78 North Cape-Bear Island traverses and 22 Bear Island-South Cape traverses. As a result the author computed that in a year the North Cape current proper brought in 31.081 km 3 of Atlantic water and 196 x 10~5 kcal o f heat, and the Norwegian coastal current 25.912 km -~o f water and 200 x 1015kcal of heat. In this connection Uralov calculated the flow of heat at a temperature of t "8", and not at one of 0 ~. To compare his heat discharge with the others, it has to be decreased by 56'993 km 3 x 1-8° = 103 x 10~5 kcal. Then Uralov's total discharge of heat over the North Cape-Bear Island section will be 293 x I0 ~5 kcal per annum. The Arctic and Antarctic Institute has gathered and processed considerably more data : 131 North Cape-Bear Island traverses and forty-five Bear Island-South Cape traverses. The North Cape-Bear Island section has been traversed regularly for 28 years (1930 to 1961). But, during the year, it was traversed rnost irregularly (Table 4). The Bear Island-South Cape section was traversed most irregularly during the year (Table 5), which made it very hard to determine the mean multi-year discharge of water and heat. From those profiles traversed from 1930 to 1960 the discharge of water and heat was calculated by N. V. Ovchinnikov, while in 1961, for the North Cape-Bear Islandsection, traversed six times, we calculated the water and heat flow from the same profiles. In the calculation o f the water and heat flow on the Cape North-Bear Island profile its sectional area was divided into two parts. In the northern part (near Bear Island) there is a permanent current going from the Barents into the Norwegian Sea. Passing through the other part of the profile is a permanent current from the Norwegian into the Barents Sea, called the North Cape branch of the Table 4. Number o f traverses made along the line North Cape-Bear lsland]rom 1930 to 1961 Months I 11 III IV V VI VII VIII IX X XI XII Tota/
No. o f traverses 8 11 13 13 13 12 13 8 9 11 6 14 131
268
V.T. TIMOVEVEV Table 5. Number of traverses .made along the !ine Bear Island-South Cape ]rom 1931 to 1960 Months
No. of traverses
I 1I 11I 1V V VI VII VIII IX X XI XII
8 11 5 2 2
Total
45
1 1 1
2 6 6
Atlantic current. The discharges of water and heat of these two opposing currents were calculated separately. Also calculated separately for east and west were the discharges of water and heat on the Bear Island-South Cape traverse.
Table 6. Monthly discharges of water and heat entering the Barents Sea through the North Cape-Bear Island section according to observations "rom 1930 to 1961 Discharge of water (kin 3 x 103)
Discharge of heat (kcal x 103)
I II III IV V VI VII VIII IX X XI XII
4.07 3.95 4.12 4-55 3.57 3-33 3-75 4.25 4.69 5.06 5.10 5"26
19.11 18.10 17.93 19.20 16.28 14.58 21.77 25.75 25'65 30.41 27"79 27"37
Year
51.70
263'96
Months
Table 7. Menthly discharges of water and heat entering the Barents Sea through the Bear Island-South Cape section according to observations from 1931 to 1960 Discharge of water (kin 3 x 103)
Discharge of heat (kcal × 1015)
I II III IV V VI VII VIII IX X XI XII
0"14 0'63 1"11 0.89 1"59 0.61 0.84 0.75 0.49 0.49 0-53 0-47
0.24 1-90 3.57 2.43 4.19 2.04 2'98 2.52 2"31 1 '69 1-90 1-24
Year
8.54
27.01
Month
Interaction o f waters from the Arctic Ocean with those from the Atlantic and Pacific
269
The mean multi-year water and heat discharge of the North Cape branch of the Atlantic current, entering the Barents Sea through the North Cape-Bear Island section, is given in Table 6, while Table 7 presents information about the inflow of Atlantic water and heat into the Barents Sea through the Bear Island-South Cape section. Thus, according to data for the North Cape-Bear Island and Bear Island-South Cape sections, 60.24 x 103 km 3 of Atlantic water enters the Barents Sea during the year, bringing with it 290.95 × 1015 kcal of heat. Comparing the inflow of Atlantic water and the heat brought with it into the Norwegian Sea to the inflow of this water with its heat into the Arctic basin and Barents Sea, the following should be noted. I. During the year 298 × 103 km 3 of Atlantic water enters the Norwegian Sea. From the Norwegian and Greenland Seas .129.12 × 103 km 3 pours into the Arctic basin during the year, and 60.24 x 103 km 3 runs into the Barents Sea. Consequently, within the Norwegian and Greenland Seas 108-64 x 103 km 3 of Atlantic water is transformed in one year, which amounts to about 36% of its inflow. The quantity of such water entering the Barents Sea and Arctic basin respectively comes to 2 0 ~ and 4 0 ~ of the total amount of Atlantic water received by the Arctic Ocean. 2. The annual inflow of heat brought by Atlantic water into the Norwegian Sea through the Faroe-Shetland channel amounts to 1922 × 1015kcal. From the Norwegian and Greenland Seas, Atlantic water brings 230.73 x 1015 kcal into the Arctic basin and 290.95 × 1015 kcal into the Barcnts Sea. Thus, being transformed in the Norwegian and Greenland Sea, Atlantic water loses 1410 × 10 ~5 kcal of heat--73 ~ of the yearly amount of heat entering these seas with Atlantic water. The remaining heat is brought with Atlantic water into the Barents Sea (15 ~ ) and the Arctic basin (12 %). It is now possible to estimate how much heat is expended by Atlantic water during its transformation in the Norwegian and Greenland Seas in convective turbulent heat-exchange, evaporation, radiation and mixing with other colder waters. When determining the heat balance of the Norwegian and Greenland Seas, Zaitsev [4] got a yearly sum of 415 x 10~5 kcal for heat crossing the sea surface, 770 x i@ 5 kcal for that lost in evaporation and 615 x 1015 kcal for that lost in convective turbulent heat-exchange. If in the Norwegian and Greenland Seas 1410 x 10~5kcal of the heat entering with Atlantic water is lost on its transformation during the year, and 415 x 1015kcal crosses the surface of these seas, the annual loss o f heat in the Norwegian and Greenland Seas will total 1825 x 10is kcal. Of this amount 42 ~ is consumed in evaporation, and 35 ~ in convective turbulent heat-exchange. So 405 x 1015 kcal a year, or 23 ~ of the heat, is lost by Atlantic water on mixing with other colder waters in the Norwegian and Greenland Seas.
Transformation of Atlantic water in the Barents Sea As shown above, the Barents Sea receives during the year 60.24 x 103 km 3 of Atlantic water containing 290"95 x 1015kcal o f heat. According to data for the Bear Island-South Cape section, the mean annual volume of water, entering the Greenland Sea from the Barents and bringing with it 16.56 x 10TM kcal of heat a year, amounted to 5'06 x 103 krn 3. The Cape Zhelaniye (Novaya Zemlya)- Salm Island (Franz Josef Land) profile was traversed eight times from 1932 to 1960. The discharge of water entering the Kara Sea from the Barents, calculated from this traverse, was 17.13 x 103 km 3 per annum; the heat discharge amounted to 14'87 x 10 kcal. According to Uralov's data [18], the resulting loss from the Barents Sea to the Kara through the Karskiye Vorota comes to 1-24 x 103 km 3 of water and 25-87 x 1015 kcal of heat per annum; through the Yugorskii Shar it comprises 0.40 x 103 km 3 of water and 0-46 x 1015 kcal a year. According to calculations by Timonov and Kuz'min [11], the flow of heat from the Barents Sea into the White is 11.025 x 1015 kcal a year. The exchange of water and heat across the Spitsbergen-Franz Josef Land section has only been determined on one traverse. Over it, the Barents Sea does not consume heat but gets 0.83 x 10~5 kcal a year from the Arctic basin. Thus, in exchanging water with nearby basins through the sections and channels indicated above, the Barents Sea loses (16.55 ÷ 25.87 ÷ 0'46 ÷ 11.025) x 1015 = 52.915 x 1015 kcal of heat a year, which forms only 1 8 ~ of the annual heat inflow into this sea as a result of water-exchange(290.95 -t- 0.83) x 101~kcal. It is hence clear that most of the Atlantic waters coming from the Norwegian into the Barents Sea are transformed within the latter. From what has been said, the credit side of the Barents Sea's heat balance is made up of 291.78 x 10:5 kcal (32~) of heat which enters with Atlantic and Arctic waters. It was found pre-
270
V.T. "I-IMOFEYEV
viously [13] that the heat of radiation equalled 451.26 × 1015 kcal (52~/o), with 142'29 × 101~kcal (16 ~ ) of it being given off in a year during ice formation. The debit side of this sea's balance is made up of 427.40 × 1015 kcal (49~) of heat exchanged between the sea and atmosphere per annurn, 222.89 ×, 10X~kcal (25~/o) due to evaporation, 142.30 × 1015kcal (16~) due to i:e melting and 53.91 × 1@5 kcal ( 6 ~ ) due to the exchange of water with nearby basins. So 20"83 x 10~skcal (4 ~ ) is annually expended during the mixing of warmer and cold waters. This heat ultimately enters the atmosphere during the exchange of heat between water and air through ice. However, these data were obtained about twenty years ago. Naturally enough, during this time much work devoted to a determination of this sea's heat balance has been published, and its outcome should be considered. In 1951 Sheremet'yevskaya [9] estimated the rnain components o f the heat balance of the surface of the Barents Sea. She found that tl~e inflow of heat from solar radiation equalled 70 % of the total received, while the heat brought in Atlantic waters came to about 27~,~. The expenditure of heat, according to her estimates, was 46~,~ in effective radiation, 32°0 in evaporation and 22~o in heat exchange with the atmosphere. In 1955 Konoplev [6] determined the heat balance for the surface of the south-western Barents Sea. It should be noted that, according to Konoplev's and SheremeCyevskaya's calculations the inflow of heat with Atlantic water for the same squares of the sea amounts to 50"~ and 25°~ respectively of the total heat receixed. In 1957 Mileiko [9] estimated the total heat loss from the Barents Sea's surface, with the same results as Sheremet'yevskaya, since they used the same Sverdrup-Kuz'min formulae. In 1958 Dcnisov [3], as a result of comparing the local and advective factors, concluded that for the North Cape current the advective factor averaged only 17 ?/o of all the heat coming into the Barents Sea. In 1961 Seryakov determined the heat balance of the surface of the unfrozen part of the Barents Sea, and f3und that the heat exchange with the underlying water layers (intra-water convection of heat) was 69.1 kcal/cm z a year. These reports on the heat balance of the Barents Sea are contradictory, apart from the inconsistency in the estimation of the indiGdual compor, ents of the heat balance, which is due both to the different methods of calculation and to the fact that separate parts of the sea, and not the whole area, were considered. Thus, the data obtained by these various authors cannot actually be compared. Moreover, they all calculated the heat balance of the sea surface, deriving the advective component not directly from their observatiors but by equating the credit and debit items ol the heat balance as its remainder term. So all the errors and inaccuracies in the d~.termination of the components of the sea's heat balance went into the remainder term of this balance's equation, i.e. into its advective component. Consequently, we can compare our value of 263'94 × 10J5 kcala year for the advection of hcat entering the Barents Sea through the North Cape-Bear Island section only with that obtained by N. S. Uralov for the same section, which comes to 291.26 > 10~ kcal a year. This comparison for the advection o f heat into the Barents Sea across the North Cape-Bear Island section happens to be fairly close. The relatively srnall discrepancy in the advection values appears to b: due partly to the different method of calculation as well as to the fact that our data were obtained on a considerably larger number of sections. ErltO' o f Pacific water into the Arctic Ocean Ratmanov [10] was the first to try to determine the water balance of Bering Strait. Next, a more thorough attempt by Maksimov [8] calculated that the annual amount of water brought by the Pacific current into the Chukchi Sea was 30.35 × 10-~km 3. Recalculating I. V. Maksimov's data with allowance for the wind conditions in the Bering Strait, N. A. Volkov obtained a figure of 20-22 × 10~ kmL N. N. Zubov took the yearly discharge of the Pacific current into the Chukchi Sea to be roughly 20 × 103 km 3 [3]. A. K. Leonov got a yearly discharge of 44.03 x 103 km 3 [7]. G. A. Baskakov found the flow of water and heat in the Bering Strait to be 36 >~" 103 km 3 and 33.49 x 10 ~5kcal a year respectively. In the Arctic and Antarctic Scientific Research Institute, Fedorova and Yankina [19] processed all the Bering Strait observations for 21 years (1941 to 1961), getting mean multi-year data for the water and heat flow which are given in Table 8. This information is at present the most complete, so we have taken it in further calculations. Further observations on the Bering Strait current at times of different wind speeds, directions and periods, and especially those carried out in winter, make it possible to revise the water and heat flow in this channel.
Interaction of waters from the Arctic Ocean with those from the Atlantic and Pacific
271
Influence o/" Atlantic and Pacific currents upon the water conditions of the Arctic Ocean To consider the relative role of these currents in the conditions of the Arctic Ocean, we have to compare the flow o f water and heat brought by them into the ocean. From a comparison of the annual flow o f water passing through the Faroe-Shetland (298 × 103 kin31 and Bering (30 × 10~ km 3) channels, it follows that the inflow of Atlantic water into the Arctic Ocean is ten times as much as that from the Pacific. The annual discharge o f water entering the Arctic balance across the Barentsburg-ice barrier section totals 129.12 x 103 km 3. Passing each year from the Norwegian and Greenland Seas throogh the North Cape-Bear Island and Bear Island-South Cape sections into the Barents Sea is 60.24 x 103 km 3 of water. Crossing the same sections from the Barents Sea into the Greenland and Norwegian Seas is 29.61 x 103 km 3 of water. According to calculations by Timonov and Kuz'min [11], the resultant yearly flow from the White Sea into the Barents amounts to 200 km 3.
Table 8. Mean monthly discharge of water and heat entering the Chukchi Sea through the Bering Strait
Months
Discharge of water (kin 3 x 103)
Discharge of heat (kcal x 1015)
1 "59 1"33 1 "22
1I III IV V V1 VII VIII IX X XI XIII
1'56 2"24 3"31 4"17 4'32 3'61 2"65 2"15 1"80
-- 2-87 - - 2'40 -- 2.20 - - 2.81 -- 3.43 -- 0'66 8'76 14.70 14.40 4"77 0.11 3 '24
Year
29'99
26.45
1
Hence it follows that during the year 30"83 × l03 km s df water enters the Arctic basin from the Barents Sea through the Novaya Zemlya channels and those between Franz Joseph Land. Therefore a total o f 152-96 x 103 km 3 of water flows each year into the Arctic basin through the SpitsbergenGreenland and Noyaya Zemlya-Franz Josef Land channels as well as through the Novaya Zemlya passages. Comparing this value with the yearly flow of water coming in through the Bering Strait (30 × 103 km3), the Arctic basin apparently receives five times as much water from the North European basin as from the Pacific. It is interesting, too, to compare the amounts o f heat brought in by the currents. Comparing information about the quantity of heat entering the Arctic Ocean with the Pacific current through the Bering Strait (26.45 x 1015 kcal) to that coming in with the Atlantic current through the Far6eShetland channel (1922 x 1015 kcal), we can see that the Atlantic current brings seventy-three times as much heat into the Arctic Ocean as the Pacific current. However, as shown above, most o f the heat (1701 x 1015 kcal or about 88 ~ ) brought by the Atlantic current into the Arctic Ocean is still consumed in the Norwegian, Greenland and Barents Seas; only 1 2 ~ (230"73 × 1015kcal) o f the heat flowing into the Arctic Ocean with the Atlantic current is left for the Arctic basin. We should thereby stress that the Atlantic current only brings ten times as much heat to the Arctic basin as the Pacific current. Though the role o f Pacific waters in the exchange of water and heat with the Arctic basin is substantial, their direct influence upon the hydrology o f this basin is limited to the Chukchi Sea, the south-east o f the East Siberian Sea and the west of the Beaufort Sea. The behaviour and spread of Pacific waters into the Arctic basin were first studied by Treshnikov [16, 17]. He showed that these waters with their peculiar physico-chemical characteristics could be traced in separate years (in the 50-100 m layer) as far as the pole. The conditions of Pacific waters in the Arctic basin were also considered at length by Coachman and Barnes [22].
272
V . T . TrMOFEYEV
Approxhnate water balance for the Arctic Ocean To draw up the balance for the Arctic Ocean waters, the chief components of their income and outlay were taken into account. The basic credit items of the Arctic Ocean's water balance are the entry of waters from the Atlantic and Pacific Oceans, the influx of continental waters and precipitation. The basic debit items are the loss of water and ice from the Arctic Ocean, chiefly by the East Greenland current, and through evaporation. When approximately determining the water balance, we may equate precipitation and evaporation which have yet to be estimated. Such an assumption is justified since in determining the water balance of the Arctic Ocean these items will be of slight importance compared with other factors. The entry through the Faroe-Shetland channel into the Arctic Ocean of waters borne by the Atlantic current was considered above. To compute this ocean's water balance, the overall exchange of water with the Atlantic Ocean which occurs between Sogne Fiord, the Faroes, Iceland and Greenland must be taken into account. On the Sogne Fiord Iceland profile most of the water is exchanged through the Faroe-Shetland channel [12]. Ye. 1. Chaplygin showed that in the Faroe-Shetland channel there were two opposing permanent currents : in the east part of the channel the current sets northwards, in the west southwards. The average multiycar inflow of water from the Atlantic Ocean into the Arctic through the eastern part of the channel has been calculated from A. V. Yanesyi's observations between 1901 and 1959 as 297.84 × l0 skm s a year. The outflow through the eastern part of the channel is 165.56 × 103 km 3 a year. Thus, the net annual inflow of water into the Arctic across the Faroe-Shetland channel equals 132.28 ;< 10skm s. To further determine the amount of water received by the Arctic Ocean, the land run-off into the Arctic basin must be considered. The yearly run-off into the Arctic Ocean, according to V. S. Antonov's calculations, is 4-39 x l0 skm s. With this figure being by no means small, river waters markedly influence the hydrological and ice conditions of Arctic seas [1, 2]. As a result, the water entering the Arctic Ocean through the Faroe-Shetland and Bering channels with that flowing off the land amounts during the year to : (132-28 ÷ 30-00 -+- 4"39) × 103
~
166"67 × 103 km s
The same quantity o f water can be presumed to flow out of the Arctic Ocean through the Denmark Strait and the numerous passages of the Canadian Arctic archipelago, where the hydrology has not been sufficiently studied. As a result, the rough water balance of the Arctic Ocean obtained previously [14, 24] may now be defined (Table 9).
Table 9. Yearly water balance of the Arctic Ocean (km s x l0 s) Chief items of the water balance Faroe-Shetland channel Bering Strait Land run-off Denmark Strait Passages of the Canadian archipelago Water balance
Total inflow of water 297"84 30"00 4"39
Total outflow
Net inflow
165-56
132"28 30.00 4'39
Net outflow
126.67 332-23
t
40.00 332.23
166.67
166"67
The hydrology of the Denmark Strait has not been sufficiently studied for a determination the water exchange through it. From the information available the water conditions appear to be very complex. In it there are countercurrents : from the north the cold East Greenland current usually flows into the western part o f the strait, and from the south the warm Irminger current generally enters its eastern half. In the Denmark Strait, from 1949 to 1954, foreign ships regularly carried out traverses, but, unfortunately, these did not extend into the Greenland coast and, consequently, failed to intersect the full flow of the East Greenland current. The only exception is four profiles, but from these it is difficult to deduce the mean annual discharge of water since it varies from 1.64 km 3 x 103 (in August 1933) to 57.92 km s x 103 (in March 1933). Thus, it was impossible to determine reliably by indirect means the exchange o f water through the Denmark Strait.
Interaction of waters from the Arctic Ocean with those from the Atlantic and Pacific
273
Therefore, comparing all the data for the inflow and outflow of water and not forgetting that according to direct observations the total annual discharge through the Canadian Arctic archipelago comes to 40 × 103 km 3 [21], the rest of the water (126-67 ,< 103 km 3) must run out through the Denmark Strait. This figure proved to be 34.33 /. 103 km 3 a year lower compared with the former value (161.00 × 103), due to a revision of the inflow of Atlantic water (its inflow was found to be 19.72 "~: 103 km -~a year) and Pacific water (6.00 × 103 km 3 a year less) and a correction for the outflow through the passages of the Canadian archipelago (8.6 × 10-~km 3 a year more). Bearing in mind nevertheless the low accuracy of some values, especially for the Denmark Strait, as data roughly depicts the relative role of various items in the water balance of this ocean and gives a general quantitative idea of the chief factors which influence the hydrology of the Arctic Ocean. Moreover, they make it possible to ascertain the role of Atlantic and Pacific currents in the water and heat balances of basins in this ocean. REFERENCES [I]
ANTONOV,V. S, and V. YA. MOROZOVA(1957) Total land run-off into Arctic seas. Coll. River hydrology of the Soviet Arctic (Sh. Gidrologiya rek Sovetskoi Arktiki), Trans. Arct. Inst., Leningr. (2) 208. ]21 ANTONOV,V. S. (1958) Role of land run-off in the behaviour of Arctic currents. Probl. Severa, (l/, lzd. Akad. Nauk, SSSR. [31 DENJSOV,A. S. (1958) Method for studying the thermics of warm currents. Probl. Arct., (3). [41r ZArrSEV,G. N. (1960~ Heat balance of the Norwegian and Greenland Seas and its component factors. Soviet fishing research in the seas of northern Europe (Sovetskiye rybokhozyaistvennyye issledovaniya v moryakh Yevropeyskogo severa), lzd. Vses. Nauch.-lssled. Inst.
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