DEOE-, 1922. MONTHLY WEA4THER REVIEW.
SOME METEOROLOGICAL ASPECTS OF THE ICE PATROL WORK IN THE NORTH ATLANTIC.
By Lieut. (Junior Grade) EDWARD H. S Y ~H .
pJ. S. Coast Guard, Cambridge, Mass., Jan. 10,lQZl
629
Next spring will complete 10 years of ice patrol service in the north Atlantic. During this period scientific investigation of the ice regions has been carried 011 with the object of increasing our general howledge of these regions, and also of securing a more effective mana e- ment of the patrol. Up to within a few gears the te- havior of ice in the Atlantic was a inatter of conjecture. To-day charts are available showing the drift of bergs from the time of leaving the Labrador coast, the courses followed by these bergs being as carefully plotted as the track of a ship. Conditions are subject to inucli varia- tion from year to year. Some years produce large quan- tities of ice; other ears bring scarcely n a y . In some
drifts far south. Until now little time has been devoted to this aspect of the problem. The causes oE rnriations in oceanic circulation, and similarly the behavior of ice from year to year, may be attributed to several factors. The meteorological aspects affecting the movements of ice dl be considered later, but before takin u that matter a brief description of the Internationltl %e Satrol Service ma be interesting.
constitutes a groat menace to steamships plying between Europe and the United States. In the days of slow steamers most of the vessels followed a rent circle
them throu h the ice zone a lar e portion of the penr.
agreements have been entered into whereby definite routes have been established to the southwnrd of the normal ice zone.
If the ice zone were Cued nothing further would be required to assure reasonable safety along the routes, but, as reviously indicated, the limits of the ice fields
season, and consequently a vessel might sail on a course that was clear at the tune of her departure but collide with ice which had drifted into her path when she reached the vicinity of the Newfoundland Banks.
The establishment of the ice patrol followed directly the Titanic disaster, when the then largest shi afloat was sunk on the night of April 14, 1912, by strging an iceberg off the tail of the Great Bank of Newfoundland. In November, 1913, an international convention met at London, and amon other subjects discussed the prac-
to esta t lish a permanent International Ice Patrol Service and the United States Government was in- vited to undertake the management of the service; the expense to be divided among the signatory powers in proportion to the amounts of thew respective ship tonnages.
The work has two aspects: First, and of the utmost importance, is the determination of the variable limiting lines of menacing ice, and the dissemination of the information for the guidance of ship ing; secondly, and
ographical and meteorological observatlons as will de- tarrmne the causa of these variations, thereby increas- ing our knowledge to insure means of greater safety for life at sea.
years the ice is he1 B up in high latitudes: in others it
Ice whic K drifts south. into the. Atlantic el-erv spring
course between the two continental ports, w a ich carried
Since the a d vent of the large and f ast passenger steamers
and the i ergs vary considerably in location as well as in
ticabilit of patrol k mg the ice regions. It was agreed
coordinately with the first,js the ma El ng of such ocean-
with the southern, eastern, and western limits of ice as they vary in position throughout the season, and to broadcast this information to all approachin ships.
that a thorough knowledge of ice movements is abso- lutely nec,essary. In conjunction with its scouting. duty, the ice patrol secures scientific observations relatmg to the area. Daily reports also are foiwarded to the United States Weather Bureau. Previous scientific investigation of the vicinity of the Newfoundland Banks
is negligible, except for the Murray and Hjort expedi- tion on the Michael Sars, 1912, and the Scotia cruise,
1813, Mttthews. Vessels logs possess a large amount of data, but it is not easily accessible and is limited to the ocean surface. No true picture of oceanographicd conditions can be obtained without consideration of the subsurface. The three great ocean currents in the northwest Atlantic are well known, viz, the East Greenland, the Labrador, and the Gulf Stream. The East Greenland current is an overflow from the north polar basin of an accumulated mass of fresh water which has been discharged from northern Eurasian rivers and augmented during the summer by the water from melted ocean ice. The escape is southward past Jan Mayen along the east coast of Greenland, where the current bears. great masses of sea ice. The number of bergs is comparatively smal heavy , due to the scarcity of glaciers along the east coast. The East Greenland Current rounds Cape Farewell and continues northward along the west coast of Greenland to 65 N., where it begins to throw off branches west- ward to the Labrador Current. From 70 N. a northerly current is found alon the coast as far as Cape York,
southerly current. The polar drift, which has its source north of Smiths Sound, is made up of two branches, an eastern branch, consisting of the current just described, and a western branch which flows southward close to the American coast, being augmented by tributaries from Lancaster Sound, Jones Sound, etc. In Davis Strait the east and west branches join, forming the Labrador Current. Tracin the Labrador Current in its southern extension we fin % it floods the northern part of the Great New- foundland Bank, a small branch esca es to the westward
Greater uantities s read eastward in expansive surface layers, w ?I ile the mi dle branch continues its flow along the east slope of the Great Bank. When the polar cur-
rents are swelled, arctic water spreads in over the Bank and across the southern end,. otherwise the area over the Bank resents a characteristic identity that is at no time
engulzd by either Labrador Current or Gulf Stream.
The Labrador Current flows southwesterly around the
I t can be seen froni this duty as brie f f y described
where it turns sharpy B south in the east branch of a
through the Gully under the Ne wp oundland headland.
630 MONTHLY WEATHER REVIEW. DEGEMBEB, 1922
Tail of the Bank and im in es on the Gulf Stream which ZS flowing east ast the Faif. The Gulf Stream, after it passes the Ban!, spreads out in fan shape into several swirling bands and ex ansive ocean drifts. Upon meet-
arrested, then turned in toward the Stream, and lastly pulled along in an easterl flow parallel with the Stream,
water at the Tail of the Bank in t e form of varied
mixing eddies. The statement that the Labrador Current is. arrested in its flow and turned back parallel to the Gulf Stream is at variance with the views of many authorities who claim that the Labrador Current sweeps southwesterly across the Great Bank and continues as a cold current with a set down the east coast of the United States as far as Cape Hatteras. Another fact which has been brou h t out by the oceanographical work of the ice
the Labrador Current upon meeting the Gulf Stream dives beneath the latter, emerging to the southward. The evidence gathered by the patrol forbids such a view. On the contrary, the tendency of the polar water to spread out on the surface is quite pronounced. One ocean current may dive beneath another at some places in the world, but such is not the case here. In the consideration of ice, it is necessary to make a
distinction between field ice and berg ice. Field ice, formed by frozen Arctic sea water, is under the con- trol of the winds and the surface currents. I t is the first ice to drift south, puttin in an appearanc.e as early
covers the entire area between the Newfoundland coast and the 43d In March and Axil it is noted
In low latitudes it is quickly melted and is by no means as dangerous as icebergs. eat source of icebergs is the laciers on the west
When released by the breaking up of the field ice in summer the bergs are drifted around by ocean currents until they succeed in entering the Labrador Current. They first a pear during March, drifting south along the
June, bergs constitute a menace to steamships in this vicinity.
As stated above, the oceanic circulation and niove- ments of ice are subject to continual variations which are attributed to several underlying factors, viz: (a) Meteorological conditions over the north Atlantic and Arctic regions, (6) the hydrodynamics of the Atlantic and Arctic basins, Cc) variations in solar energy. In re-
viewin some of the literature upon the subject, there is
potential possessed by large bodies of water of similar character. The theory, briefly stated, is that the basic principle of oceanic circulation originates in the physical changes in water which manifests themselves in move- ments of a certain kind of a water mass from the region in which it abounds to the region where it is scarce. The volume and velocity of the induced current thus established will be governed by the supply and demand. Meteorological changes are factors in oceanic circulation which cause variations according as they increase or
ing the Gulf Stream, t K e Labrador Current is frictionally
with a consequent inter d igitation of olar and tropical
f
patro 5 is the lack of evidence to support the belief that
as January and February. !i t the latter date it often
most frequent P y on the southern part of t L e Great Bank.
coast o Y Greenland, from the region o !? Disko northward.
east side o P the Great Bank. During April, May, and
arallel.
The
a mo 8; ern tendency to stress the importance of the
1 Sandstrom W.: Canadian Fisherics Expeditim. 1914-1915. pp. 221-291.
Pettemxm 0.: Connection bet\veen Hydrograp:licaI and h;etoornlogical Phe-
Dlclsdm, E. N.: 86The &mlatlon Gf th<Su&re Waters of the North Atlantic,
B~&II~s,*V.% K .: t l D ~ Meteorology and Hydrography, Carnegie Instltiite,
nomena Q w t Jour Ro Met. Soe luly l9P pp. 123-191.
Phll Tram R Scc London. 1900. vol. 196-A.
Wwhhgton, 1810-11. Pu No 88.
decrease dynamic forces. An axam le of this is a pre-
m$ course, but if this meteorological phenomenon be removed, normal positions are resumed. In the northwest Atlantic probably the underlying
cause of the Labrador Current is hydrodynamic condi- t.ions. Seasonal melting of the ice in northern regions causes an escess accumulation of cold fresh water to flood the surface between Greenland and North America. It seeks escape in a southward expansion on the warm saline water of the lower latitudes. The variations in movements of the surface water are greatly influenced by the circulation of the atmos- phere. They follow directly from the seasonal changes. The wind control is determined by the position, form,  and intensity of the whole north Atlantic high-pressure area and by the cyclonic area to the northward. If the Icclandic ininimuiii lie to the westward in the Greenland region, during the months of December, January, and February, the priocl when the field ice breaks loose, it will cause revailing southwesterly winds which will re
tard the Lsrador Current and tend to hold the ice in the higher lititudes. On the other hand, wind possessing a strong northerly coni onent will tend to augment the
greater quantity than otherwise. The normal seasonal increase in size and intensity of the north Atlantic high during suininer causes strong southwesterly winds which speed up the Gulf Stream. A great amount of warm water is accumulatecl in the eastern Atlantic basin which escapes to the nort.hemt, even entering the polar basin. The reports recently received froiii Spitzbergen telling of unusually mild weather ancl open water where it is nor- mally covered with ice may, if they are reliable, be attrib- uted to a conibination of favorable conditions, one of the individual factors being 6he atmospheric circulation over the north Atlantic. Another matter of direct importance to the patrol is t,he probable relation existing between the distribution of the two kinds of ice in the lower latitudes during a given year ancl the meteorological conditions in northern re- gions during the previous year. Some work in this line has been done by Dr. Ludwig Mecking (1907)2 and the conclusions reached are extremely interesting. In brief, these may be stated as follows: The amount of field ice appearing durinu the season off the Newfoundland Banks is compared witk the mean barometric pressure gradient for December, January, and February, connecting two points whieh lie across the Labrador Current in the vicin- ity of the Labrador coast. The agreement is astonish- ingly good. The ex lanatioii is simple if we assume that
that the gradient is a measure of the amount of off-shore wind which breaks the ice loose and permits it to drift southward. The number of icebergs in any year in the north Atlantic is determined by the barometric gradient over the birthplace of the bergs in.west Greenland durin the previous summer. The assumption is that offa % ore winds will drive a great number of bergs westward into the southerly current, thus reparing for a ear unusu-
on the other hand, tend to cause a poor ice year. An attempt is being made, using the much more amur- ate data re arding icebergs in the vicinit of the New-
vailin off-shore wind across the G up f Stream that tends to us 5 the surface layers of the Stream, from their nor-
Labrador Current an B drift the ice south faster and in
the great source of t f e field ice is the Labrador coast, and
ally rich in bergs in lower s atitudea. Onatore winds,
foundland % anks, to determine a possib { e relation Ire-
1 Y e a L.: Die T d M ~n n ~ bel Neuhmdhd, humleu d. Hydro., Berlin, ld , PP. 348-396.
DECEMBER, 1922. MONTHLY WEATHER REVIEW. 631
tween the ice and the meteorological conditions based upon the last 10 years of the ice patrol work. Difficulty has been experienced in securing meteorological records from critical points on the Greenland and North American
coasts.
It is unfortunate that there are not several ear-round
advantage which might be derived from their records, as just inhcated, they might also serve as ice observation posts. If a station could be located somewhere along the side of the arctic drift where it swee s in close to the
serve the double pufpose of a meteorological station and an ice observation post. The situation may be likened to that of a river. Flotsam observed upstream in the current will later appear a t the river mouth. In this case the Labrador Current is the river whose mouth is in the vicinity of the Great Bank of Newfound- land; the flotsam is the icebergs. It takes approximately five months for a ber passin Cape Dyer to appear
of bere, with dates of passing Cape D er were h o r n to the ice patrol and the Hydrographic &ce, long range of ice conditions m the North Atlantic would tin% pro ably be possible. It would prepare us to meet and deal with a situation &bout which to-day we lack advance information.
meteorological stations in northern regions. ii esides the
shore, for instance at Cape Dyer, Ba fin Land, it could
south of the 45th pard f el. If t f e record of the number
POLAR ICE-DRIFT AND SUN SPOTS.
By GEORGE NICOLAS IFFT, American Coned.
[Bergen, Norway, Dec. 6,1922.1
An interview with Dr. Adolf Hoel expressing doubt of the ossibility of Amundsen's plan for drifting over the Nor% Pole in the ~Uaad with the supposed drift of the polar ice is attracting much attention throughout Nor- way and causing considerable discussion in the Nor- wegian press. Doctor Hoel, who is lecturer on geology
known sun-spot periods. Doctor Hoel states that the fact of the ice drift from
the northern coasts of Asia and America across the ole to the strait between Spitzbergen and Greenland and t 7l en south along the east coast of Greenland has been shown by the drift of the Jeanette and other vessels. Amundsen's esperience last year, however, seemed to indicate that the ice drift is subject to variations. At all events, the Maud did not succeed in getting into the drift because of unfavorable ice conditions and Doctor Hoel argues that it is reasonable to assume, either, that the exceptionally favorable ice conditions now prevailing at Spitzbergen are due to the fact that the polar current is weak and that the unfavorable ice conditions on the Asian and American north coasts are due to such cause or, that the ice in those regions actual1 moves in an o posite direc- tion from that in which it z as been believe B to move. Dr. H. T. Hesselbe , director of the Norwegian Mete- orolo ical Institute, fcus!inf such suggestion, states
in the
regard to a relation between olar ice conditions and sun-spot periods, he said that t e influence of sun spots is felt in so many conditions, among them atmospheric conditions, that it is not im ossible that they also play
interest, as he is thorou hly familiar with conditions in that section of the world!
that 5 t ere can hardy be talh o a 10 or 11 year ice
to a t K orough investigation and without a thorou
their art in ice conditions a E out the pole. At the s m
time, i e considers Doctor Hoel's statement of the utmost
olar seas without having submitted such
study of the comparatively scanty material a t
A REVIEW OF GEOPHYSICAL MEMOIRS NO. 19.'
B~ALFREU J. HENRY.
[Weather Bureau. Washlagton, D. C.. Dec. 28,192%]
The latest MemoiT of the British Meteorological Office The Memoir includes, in addition to the material col- lected by Mrs. Newnham, an introduction by Sir Napier Shaw, to which reference will be made later, and a short discussion by Dr. Harold Jeffreys on " Theories on the Ori in of Tropical Cyclones." 'J%e observational material is presented in four sec- tions, each one dealing with those portions of the eat oceans which are subject to visitation by tropicfcy- clones. These are: (1) North Atlantic: A. West Indian Hurricanes. B. S ualls and Tornadoes of
(2) Indian Ocean: A. Cyclones of the Ba of Ben- gal and the Aragian Sea. B. Cyclones of the South In- dian Ocean. (3) Pacific Ocean: A. Typhoons of the North Pa- cific. B. Revolvin Storms of the
resented in great detail with many rather full extracts rOm the original pa em. Thirty-three full page plates with numerous mserts i lustrate the paper.
b e s t Africa.
South 5 acific.
.p
accomplished this difficult task may be seen by a perusal of the 102 closely packed quarto pages of text and charts.
1 Hurricanes and Tropical Revolving Storms b Yrs E. V. Newnham M. Sc. With lntrodnctim 011 The Birth and Deatqof Ck6nes.' By Sir Napier h w , F. R. 6.
pp.vl. 323illaS. H.M.S. O., 1922. Pncel .tM.
The material is
P
31311-2-2