. t ~~ .,.-•*.- - •• .. - ;- OCTOBER 1965 EDITOR: JAN HAHN Circulation: Priscilla Cummings Published quarterly and distributed to the Associates, to Marine libraries and universities around the world, to other educational institutions, to major city public- libraries and to other organizations and publications. Library of Congress Catalogue Card Number: 59-34518 HENRY B. BIGELOW founder Chairman NOEL B. McLEAN Chairman, Board of Trustee* PAUL M. FYE President and Director COLUMBUS O'D. ISELIN H B. Bigelow Oceanographer BOSTWICK H. KETCHUM Associate Director for Biology and Chemistry The Woods Hole Oceanographic Institution • Woods Hole, Massachusetts VOL. XII, No. 1, October 1965 • ' * %-^-vfc- -•^ • • . ' .->_*•' it ^/L"^* (_A\\d Qod made tf»e {i/tmament, anc( divided tfie u/ate/tg wdicli u/e/te iWe/i tde jftom tfce ti/ate/ts u/liicli n/e/te aboi/e tde ji/tmament, and it u/as 20. TT HAT is this scene doing on the cover of Oceanus? Well, they are water buffalo aren't they? And to have water they need rain. And to have rain they need the monsoon. And to have a monsoon they need the interaction between the ocean and the atmosphere: and it is so. COVER PHOTO BY: MUNNS v The Monsoons *>. VOL. XII, No. 1, October 1965 0 U) z UJ Q Dropped from our aircraft the parachute of the radio-sonde is beginning to open. This is a reversal of the more usual radio- sonde procedure when a sounding is made by launching the apparatus from the ground attached to a balloon. The observed temperatures show the cool- ing accomplished by passage of the air over 300 or 400 kilometers of cold water. The values given are degrees absolute. Potential temperatures are used to elimi- nate the effect of pressure changes with height in the atmosphere. 500 600 - 700 - . POTENTIAL TEMPERATURE, °K 1 -o s 800 - 900 - 1000 - 1100 200 100 0 100 200 300 400 500 600 700 800 900 1000 DISTANCE, KILOMETERS DOPPLEFt RADAR WINDS 4000 3500 - The diagram presents the wind speed ob- served at many heights from close to the water to a height of four kilometers. The effect of the horizontal temperature gra- dient upon the height variation of the wind speed is very apparent with the wind at 1,000 meters reaching a speed of 25 meters per second (± 50 mph). The strong, low level wind jet (arrow) is caused by the cold upwelling waters off the Somali coast. 10 15 20 25 WIND SPEED, M/ SEC JO D.R.V. 'ALVIN' 12 I N June and July 1965, the Deep Re- search Vehicle 'Alvin' made her first deep dives off the Bahamas. Leaving the pleasant anchorage at Coral Harbour, New Providence Island, the small craft (called "ocarina-shaped" by the Wall Street Journal) first was lowered gingerly on a polypropylene line from her at- tendant catamaran to a depth of about 2340 meters, (7700 feet), and retrieved during a long day's work. The up-and down speed was about ten meters per minute. A series of successively deeper dives, without a line, ended on July 20th, when the 'Alvin' made a free dive to her de- signed depth of some 1825 meters (6000 feet), with pilots W. Rainnie and M. McCamis on board. The three pilots who made the series of deep dives, including V. Wilson, con- centrated on the vehicle's performance, although they did have an opportunity to observe rugged cliffs, plant and animal life. Mariners may well have rubbed their eyes seeing the catamaran, a cross be- tween a houseboat and a dredge. When the 'Alvin' surfaces she is attended by aqualung swimmers who guide the craft between the floats of the mothership until the 'Alvin' is lifted out of the water on a cradle. The photograph at bottom left, taken during the hoisting procedure, clearly shows the two maneuvering pro- pellers and the large driving-steering propeller. o H o I Q_ Z UJ 5 o Deep Research Vehicle A/v/n Two kilometers down! 13 ITUT FUR MEERESKUNDE The Meteor* in th. Indian Ocean by P. KOSKE ON DECEMBER 16, 1964, we left the port of Aden bound for Mombasa, Kenya, with about thirty days of work ahead in the region of the Somali current off the coast of East Africa. We, that is, the F. S. 'Meteor' (with a length of 82 meters and a displacement of 2700 tons, comparable to the 'Atlantis IF), a crew of 55 (including a group of nine scien- tists and technicians who are on the boat continuously), and 25 scientists from nine different universities with Prof. G. Dietrich from Kiel University as chief scientist. All with much enthusiasm, not all with the same amount of experience with the element, and everyone con- vinced, as is the rule with sea-going scientists, that his field is the most im- portant one of the whole cruise. We had spent the last four weeks in the Red Sea, mainly in the southern part of it, doing current measurements in the Straits of Bab el Mandeb, the "gate of tears", while a team of eight biologists stayed ashore for a fortnight, on Sarad Sarso, an uninhabited island of the Farsan group (Saudi Arabia), for littoral work. During this time, which was sort of a shake-down cruise we had started to like our new bucket. She is big enough for many different aspects of basic re- search in oceanography, the individual labs are well placed around the main working-deck, and because of their spe- cial suspended construction they are free from vibration which made it possible even to make micro-photographs while under way. Apart from the working fa- 14 cilities we started to reflect on the long tour of sea-duty ahead of us, working around the clock, and having the unusual feeling on this new ship — of not being uncomfortable at sea. On December 24 we were at 7°.50' North, 52°.02' East, about 120 miles off the coast of Somalia, 'Meteor' Station 112, at a depth of 5070 meters. Work — work — work Contrary to the former days with northeast winds of force 6-7 it was rather calm. We started off with the "Bathysonde", our in-situ instrument for the measurement of conductivity, tem- perature and pressure. While it was lowered down to 2000 meters, the plank- ton people did their shallow cast with 5 liter bottles to study productivity and routine vertical hauls with the Indian Ocean Standard Net. At noontime some- one mentioned Christmas. It was a strange feeling. At home Christmas means icy winds, snow and long dark nights and here we were in shorts without shirts and the temperature outside was as high as 28°C. After two hydro casts, a shallow one and deep one, the chem- ists lowered their oxygen-sonde down to 500 meters and finally our geology group worked with a small bottom-grab. We stopped working at 17.00. At dinner time in the messroom there was a real Christmas tree with lighted candles and we had a quiet meal. Prof. Dietrich said a few words and read a chapter from the Bible. Some received telegrams from home. Later in the evening, in our quarters, we played some tapes with Christmas music and celebrated with a bottle of wine. It is at such moments that even tough, bearded oceanographers feel somewhat uncomfortable and want to be at home. At midnight we went back to work again. On December 3 1 we got a telephone call via Norddeich Radio from our local newspaper "Kieler Nachrichten". They were sending best wishes for the New Year. We had just finished our hydrographic section 4 and were steaming to the start- ing point of section 5. About 200 miles to go with only a few under-way instru- ments working: the echo-sounder, the counter for gamma-radiation, the re- corder for surface temperature, salinity and transparency, two thermopiles for long and short wave radiation and the magnetometer. So everything was set for a big party and it sure became wild dur- ing this night. Next morning only 14 people out of 80 asked for breakfast, the absolute minimum for the whole cruise. The more we approached the Equator the more our meteorology team became excited. We were in the region of the jet-stream. Two daily balloon ascents were part of their routine work, at 12.00 GMT and 24.00 GMT. These balloons with their "radio-sondes" were tracked automatically by the wind-weather-radar, sometimes to heights of 30.000 meters and more. And while one could follow every movement of the balloon on the dials of an analogue computer the sonde was transmitting information about tem- perature, humidity, and air-pressure. Apparently the results were really excit- ing because during these days there were only happy faces around the meteorology lab. Land — at last Then finally after more than thirty days at sea and after a big initiation ceremony on the line with 58 dirty pollywogs and only 22 honorable shellbacks, we ap- proached Mombasa on January 16. The white beaches with palm trees and the beautiful tropical vegetation seemed to us like a paradise. The work at the Somali coast during the time of the northeast-monsoon lay behind us. 15 V .z 'o New Sources of Seafood Ai .MERICAN scientists have discov- ered two more areas of the Indian Ocean that may be rich sources of seafood for the oftentimes hungry peoples of parts of Asia and Africa, according to a recent announcement of the National Science Foundation. The researchers, who operated from the Foundation's R.V. 'Anton Bruun', said that "indications of the presence of fishery resources available to trawling" were found off Delgoa Bay, Mozambique, and off Formosa Bay, Kenya, north of the Mozambique Channel. This was the second announcement regarding the possible presence of un- tapped fishery resources in the Indian Ocean. The first report, also from scientists aboard the 'Anton Bruun' was made in May, 1964. Fisheries experts from the Bureau of Commercial Fisher- ies (BCF) of the U.S. Fish and Wildlife Service then found evidence suggesting the existence of a fishery perhaps several hundred miles in extent off the coast of the protectorates of Muscat and Oman in eastern Arabia. The evidence indi- cated a fishery containing a large con- centration of bottom fish and crabs. The presence of the new fishery re- sources consisted of large quantities of market-size red shrimp and lobster from Delgoa Bay and very large shrimp from the vicinity of Formosa Bay. Mr. Springer, also of the BCF, was chief scientist aboard the 'Anton Bruun' during the latest discovery. The shrimp from near Delgoa Bay, he said, were a small, red, relatively soft-fleshed variety of the type now fished off the coast of Argentina and to a lesser extent, off Florida. A deep-water type (1350 feet), they need refrigeration and special hand- ling in order to be marketable. The shrimp from the Formosa Bay area were from shallower water (about 750 feet) and were especially large, running about six or eight shrimp per pound. "There would be no problem in marketing these," Mr. Springer said. Though the extent of the two fisheries is not known, Mr. Springer pointed out, the catch rates for the hauls from the 'Anton Bruun' suggest fisheries of com- mercial concentration. "If we could do this well on a ship not designed for the purpose, a properly rigged commercial boat could do much better." Existence of the fisheries would be of great importance to the peoples of countries bordering the Indian Ocean. Large populations in the area suffer from chronic food shortages and from health problems due to protein-poor diets. The cruises of the 'Anton Bruun' were part of the International Indian Ocean Expedition, an investigation involving some 40 ships and 28 nations. The field investigations, carried out in the spirit of the International Cooperation Year re- cently announced by President Lyndon B. Johnson, were largely completed in 1964, though some additional work will be done in 1965. Scientists involved in the HOE are expanding the presently scanty knowledge of the Indian Ocean, a body of water covering 28 million square miles. The National Science Foundation has planned and coordinated the U.S. parti- cipation in the IIOE. The U.S. biological program is headed by Dr. J. H. Ryther of our staff. As far as we know the 'Anton Bruun' was the only foreign based ship to remain in the Indian Ocean during the entire program. When the expedition ends, some 15 ships and five aircraft of the United States will have participated in the program. 16 c^ 0 We had a rather unusual visit at Woods Hole in October. Two newly built research vessels both destined for the v/est coast came alongside, prior to their shakedown cruises. The ships are the last of a class of ten AGOR-type vessels built by the U.S. Navy. The 'Thomas Washington' is for the use of the Scripps Institution of Oceanog- raphy, University of California, while the 'Thomas G. Thompson' (naturally) is oper- ated by the University of Washington's Department of Oceanography. The 209' vessels both will make observations in the Caribbean area prior to sailing for fheir homeports. Co-incidentally both chief sci- entists, Dr. F. A. Richards and M. Silverman, are old Woods Hole hands. — -meanwhile the R.V. 'Atlantis II' visited our Scripps friends and is on the final leg of her circumnavigation. She is expected at Woods Hole in November. in z z D t 17 10 MIL. TON/SEC , 5 NIL. TON/SEC K-KUROSHIO N-N. PACIFIC C. T-TSUSHIMA C. 0-OYASHIO 1 20° E-N. EQUATORIAL C. C-EQ. COUNTER C. - PF-POLAR FRONT by T. ICHIYE E 130° 130° 140 150° 170° 180° The Kuroshio System The 'Atlantis IT has just taken part in an international survey of the Kuroshio before continuing on her circumnaviga- tion. The Pacific counterpart of the Gulf Stream influences the climate and fisher- ies of Japan. DR. ICHIYE is Physical Oceanographer on the staff of the Lamont Geological Observatory, Palisades, N.Y. He was at our Institution for a year or two when he first arrived in the U.S.A. J. HE name Kuroshio (Kuro = black, Shio=current) appeared first in the 13th century in some Japanese historical stor- ies of the struggles between the two largest military families in which the current of this name was described near an island colony for political exiles about 150 miles south of Tokyo. The name is due to the extraordinary transparency of the water which makes it look black. The first scientific report on the current might be that of the French 'navigator De Tessan who cruised in the North Pacific on board the corvette 'La Venus' be- tween 1836 and 1839. Thus for some time in western countries, the current was known as Tessan's current, a name which was gradually forgotten due to the lack of continuing studies by the French. A more detailed study was made by Lt. S. Bent who participated in Commodore Perry's expedition to the Far East in 1853-54. He noticed the warm current in the western North Pacific from surface water temperatures and named it the Japan current. In his paper read in 1856 before the American Geographical So- ciety Lt. Bent said: "The Japanese are well aware of this current and have given it the name of Kuro-Siwo or Black Stream, which is undoubtedly from the deep blue color of its water". In 1873 18 Schrenck also described the current sys- tem in the western north Pacific from surface water temperatures collected by Russian warships between 1857 to 1867. His nomenclature, such as Tshushima Current, Liman Current and Kurile Current still is in use. Large scale oceanographic exploration in the area were initiated by the 'Chal- lenger' in 1875 and by the Russian 'Vityaz' from 1886-1889. In the 20th century the R.V. 'Carnegie' occupied extensive hydrographic stations during her 1928-29 cruise in the North Pacific. Ships of the Japanese Hydrographic Office, including the 'Manshu1, the 'Kom- ahashi' and the 'Koshu' started extensive surveys of the entire Kuroshio system in 1930, although most of these data were classified and not available until after the war. Research vessels of the Japanese fishery stations including the 'Soyo' made simultaneous surveys near Japan during every summer from 1933 to 1940, occuping hydrographic stations on ten or more transects across the Kuroshio be- tween Longitude 130° East and 150° East. Some of these results were dis- cussed in comparison with the Gulf Stream in a paper by Wust (1936). Since 1950 the area south and east of Japan was surveyed almost synoptically at least four times a year by five to eight vessels from the Japanese Meteorological Agency and the Japanese Hydrographic Office. Seasonal and year to year changes of the Kuroshio have been obtained from these studies. In the summer of 1955 an international survey was carried out with seventeen ships from the United States, Japan and Canada to obtain an overall picture of the circulation in the North Pacific Ocean. (Operation Norpac). The System The Kuroshio is the counterpart of the Gulf Stream in the Pacific Ocean. Wust in 1936 applied the name "Kuroshio System" to the western and northern parts of the clockwise gyre in the North Pacific. The system consists of three major divi- sions. From east of Luzon in the Philip- pines the Kuroshio proper flows north- ward, turns to the northeast from north of Taiwan and runs close to Japan as far as 35° North where it turns nearly east to form the Kuroshio Extension. The North Pacific Current continues from the Exten- sion, flowing eastward as far as 1 50° West. The Tsushima Current which has no counterpart in the Gulf Stream System, is a branch of the Kuroshio which enters the Japan Sea and flows west of the Japanese islands to the north. Rice Crops Catastrophies of an economic nature often have stimulated scientific research. The failure of the rice crops throughout northern Japan in 1931 and 1934 and changes in the fisheries stimulated co- operative surveys of the Kuroshio. A cold eddy some 300 kilometers long, which has appeared and disappeared since 1934 and changed the course of the current also added to the eagerness to study the current in detail and con- tinuously. Our knowledge about the fluctuations of ocean currents and their relationship to changes in climate and weather is still fragmentary. Years of expensive and careful observations are needed to produce only an approximate description of such fluctuations. The source region of the Kuroshio is east of Luzon where a part of the North Equatorial Current turns to the north close to the Philippine Islands. This area was not surveyed until recently, but the information obtained between 1932 and 1936 suggested that the current east of Luzon runs at about one to three knots with a width of about 150 km. with one or two clockwise eddies to the right hand side of the current. Japanese ocean- ographers estimate that some 20 to 30 million tons of water per second — from one half to three quarters of the 40 million tons of water per second trans- ported in the North Equatorial Current —becomes the source of the Kuroshio. Just south of Japan the volume of water transported by the Kuroshio is fifty mil- lion tons per second so that from 20 to 30 million tons must have been entrained from the Philippine Sea east of the current, a counterpart of the Sargasso Sea. The water mass of the Kuroshio con- sists of Western North Pacific Central 19 Kuroshio Water. In the upper 200 meters this water mass has a temperature above 20°C. and a salinity of 34.8 to 35%o. At depths from 200 to 600 meters the temperatures range from 20°C. to 8°C. and salinities from 34.8 to 34.1%o. Still lower from 1000 to 2000 meters the temperatures are from 4° to 2°C. with salinities of 34.6 to 34.3%o. Like the Gulf Stream the Kuroshio in not a "river of warm water" but is situated on the edge of the warm central water and is distinguished by a sharp rise of isotherms from the right to the left, looking in the direction of the flow. One conspicuous difference is that the Kuroshio, as I re- ported in 1963, contains intermediate water from the cold Oyashio Current which flows southward like the Labrador current. The Oyashio water with a low salinity of 33.8 to 34. %o spreads to the south below the warm, saline water of the Kuroshio between 400 and 1000 meters. As the Kuroshio reaches the southern coast of Japan its surface velocity in- creases. The average velocities measured at the axis of the current with the G.E.K.* from the southern coast of Japan until the current bends offshore are from 2.6 to 3.7 knots. The width of the current in this area, defined as the flow with a surface speed of more than one knot, is about 100 kilometers. At a depth of 1000 meters the current flows in the same direction as at the surface with a speed of 9% or 30% of the surface velocity, depending upon whether one uses a reference level of "no motion" at depths of 1200 meters or 3000 meters. Seasonal changes and meanders The total volume of water passing Japan in the Kuroshio has been calcu- lated as from 30 to 60 millions tons of water per second with the maximum transport in the spring and fall and the minimum in winter and early summer. This is in contrast to the seasonal changes in the Gulf Stream between Long Island and Bermuda which Iselin computed to change from 60 to 75 million tons per second, with the maximum in the sum- mer and the minimum in the fall and early spring. It must be understood that the oceanographer calculates geostrophic currents from the density field, which in turn, has been obtained from measure- ments of temperature and salinity — both vertically and horizontally — taken at hy- drographic stations. Meteorologist com- pute winds aloft from observed density fields but they have the advantage of sitting at the bottom of the pressure field. Oceanographers rely upon an arbitrary choice of the "level of no motion". This is meant by the "1000 meter (or 2000 meter, etc.) reference level". The smaller mass transport of the Kuroshio, compared with the Gulf Stream may be due to the choice of the shallower reference level. The Kuroshio changes its course from northeast to due east at about 142° East, separating from the coast of Japan and the narrow shelf around it, unlike the Gulf Stream which roughly follows the bathymetry of the continental shelf as far as the Grand Banks. After leaving the coast, the current shows multiple struc- ture and meanderings like the Gulf Stream. Also, to the north of the Kuro- shio there are clockwise eddies of warm water and counterclockwise eddies of cold water with dimensions of 100 to 200 kilometers and lifetimes of a few months to nearly one year. The warm eddies seem to be cut-off meanders of the Kuroshio and the cold ones may be of Oyashio origin. Large fluctuation Another feature of the Kuroshio which has no counterpart in the Gulf Stream is its detour around a counterclockwise eddy of cold water to the south of Japan between 136° and 140° East. This eddy lasted for several years while its shape and extent changed considerably. The eddy first appeared in the fall of 1934 with it center at about 32.5° North and 136° East and a major diameter of 200 kilometers. By the spring of 1938 the eddy had reached its maximum extent of 300 kilometers with the center at 32° North and 137° East. The eddy diminished in size and moved eastward suddenly after 1941 and completely dis- appeared in 1947. Then it appeared again from 1954 through 1955, disap- peared again in 1956, returned during the summer of 1959 and has continued since with a slight weakening in 1963. 20 There are many speculations on the cause of this eddy and the detour of the Kuroshio around it. The detour of the current may be due to a topographic effect of the Bonin Ridge which lies across the path of the Kuroshio just downstream of the detour. Growth and decay of the eddy seems to have a period of eight to ten years, while the amplitude of the first northward ridge of the mean- ders, east of 142° East, fluctuated with a period of four to five years. The fre- quent surveys of the area south of Japan from May 10 to June 9, 1959 showed the process of growth of the detour which started west of 133° East and within a month became steady between 135° and 137° East. The Tsushima Current The Tsushima current, a branch of the Kuroshio, has no counterpart in the Gulf Stream system. This current is believed to separate from the Kuroshio, southwest of Japan at about 30° North but is not recognized as a strong current until it reaches the Japan Sea, where it flows close to the western Japanese coast with a maximum speed of one to one and a half knots and has a width of 50 to 100 kilometers. The greater part of the Tsushima flows into the Pacific through the Tsugaru Strait, the remaining part flowing further north is dissipated by mixing with cold water. Two or three eddies, a few hun- dred kilometers across are usually present on the offshore edge of the current be- tween 35° and 40° North. The current is about 300 meters deep. Below that depth the water is cold (0°-1°C.), fresh (34-34. 1%0) and almost homogenous. It remains an enigma how such water is formed. 39° 38° r- 37° I 34° 40 ' 35° 1 I I 1950 I 135 140 145°E 150°E The location of the northern limit (N.) of the first meander east of Japan fluctuates over a period of 4?/2 to 5 years, while the location of the southern limit (S.) shows fluctuations of about eleven years due to the generation of a counterclockwise eddy off Japan. 40 35 I I T 1955 I 135° 140L 145°E 150°E The northern limit (dotted line) and the southern limit (solid line) of the Kuroshio, as shown in the above drawings, move toward or away from each other over a period of about eleven years. The farthest separation started in 1959. Northern Limit / N I I / V 1935 1940 YEAR 1945 1950 1956 1959 21 Looking while listening T, HAT the Antarctic seal Leptonychotes weddelli (Lesson) 1826 produces a var- iety of calls underwater has been known at least since E. A. Wilson's account published in 1907. He described the calls graphically, recounted hearing the seals calling beneath the ship as well as be- neath the ice, and supposed that the calls were communicative. Unfortunately his observations have been missed by later workers. More recent observers have seemed reluctant to consider that the calls were made underwater, and pre- sumed that the seals were calling in air trapped under the ice. A. A. Lindsey recorded the in-air calls phonographi- cally in November, 1934; his record was not published, but he has generously supplied copies of it to interested stu- dents. In October and November, 1963, underwater recordings were made at McMurdo Sound in the Ross Sea by Dr. Carleton Ray of the New York Zoological Society and Lt. David Lavallee, USN.* *From: Schevill, W. E., and W. A. Watkins. Underwater calls of Leptonychotes (Weddell seal). Zoologica, 50, 1 pp. 45-47. by W. A. WATKINS I N October and November 1964 we went to the Antarctic to study the under- water sounds produced by the Weddell Seal, Leptonychotes weddelli. These seals live most of their lives under the sea ice. They occasionally are seen when they poke their heads out of a breathing hole or when they come out on the ice to bask in the sun, - - the rest of their existence is in the water under the ice, out of sight. In 1963 a New York Zoological So- ciety party made a recording of the underwater sounds of these seals at McMurdo. We analyzed the sounds for publication and as a result Mr. W. Schevill and I made preparations to go to the Antarctic in a joint operation with the New York Zoological Society group headed by Dr. Carleton Ray. This trip was made possible through a grant from the National Science Foundation. Their United States Antarctic Research Pro- gram arranged transportation and cloth- ing for McMurdo Sound and provided food as well as excellent logistic support in the field. Ice chamber During the planning of the trip W. Schevill suggested a sub-ice observation chamber to take advantage of the unusual transparency of the water - - 200 feet or better. The idea was presented to the USARP offices of the National Science Foundation, and both Schevill and Lt. D. Lavallee of the U.S. Navy submitted sketch designs. With USARP support, a chamber was built by Alpine Geophysical Associates. It is still at McMurdo Sound in the Antarctic according to plan, and was a very successful tool during this trip. The sub-ice observation chamber was the outgrowth of an interest that has existed here at the Woods Hole Oceano- graphic Institution ever since the war. 22 "inside-out aquarium" to study Weddell Seas below the Antarctic ice. The** inside temperature of the chamber was at the freezing point. •i CL z o K Ld J CE \V. Schevill, A. Vine and others have been interested in direct visual under- water observation. Many designs have been sketched for observation chambers to be used on submarines, on surface ships and independently. There has, however, been little success in getting them built until (with the support of several others) the bow chamber of 'Atlantis IT resulted. The 'Alvin' with its observation capabilities is another step in the same direction. And now we have the Antarctic sub-ice observation chamber, which Schevill calls an "inside- out aquarium". The chamber turned out well worth- while. It permitted underwater observa- tion by the hour, instead of by the minute, as with divers. Moreover, unlike scuba divers, it made no noise to inter- fere with sound recording, and, once in place, it did not disturb the seals much more than a duck blind disturbs ducks. It became a part of the underwater land- scape, and it enabled us to match ob- served seal behavior with the sounds heard. Transparency The extraordinary underwater visibility during the Antarctic springtime permitted us to see seals nearly 65 meters away. As the season wore on, the accelerating plankton growth made the water less transparent, and a few weeks after we left (about Christmas time), the visibility had deteriorated, we are told, to about 10 meters. We did not heat the chamber, so that we had almost no trouble from conden- sation inside. With a loose lid on top, for darkness and warmth, the internal temperature stayed near 0°C. (the water outside was --1.9°C). No forced ventila- tion was necessary. An observer would stay a couple of hours at a time. Mr. Watkins surrounded by listening and recording gear in a shack built on the ice. Curious seals occasionally came up through a hole in the shack to inspect his works. CARLETON RAY 23 Look-listen The builders did not entirely follow our plans, so that the chamber turned out smaller and longer than intended. We had hoped to have two observers in it together, but there was room for only one. We had planned internal ballast; the builders fitted outside ballast on a long extension, so that the total assembly was awkward to handle. The next one should be larger and shorter, with inside ballast, so that there would be more room for cameras and a second observer, and to make the chamber easier to handle from a ship or from the ice. The chamber was held in place by three arms from which cables extended through the ice to toggled stops. The observer's head was about 2 meters under the ice (about 4 meters below the water surface). There were outside lights for photogra- phy. Instrumentation A fairly complicated instrumentation system accompanied the use of the under- ice chamber and was remarkable con- sidering the logistics required for any Antarctic work. A hydrophone array was lowered with units at 300 meters (10 meters off the bottom), 150 meters, and 10 meters, plus a fourth unit used intermittently at 30 to 45 meters. Run- ning voice commentary of visual obser- vations from the recording shack as well as from inside the chamber was recorded on tape along with the hydrophone information. Two high-fidelity monitor- ing systems capable of listening to any of the hydrophone channels were located in the chamber and in the recording shack. An intercommunication system was maintained between the chamber and the recording shack. A visual moni- tor utilizing variable filters and a cathode- ray-tube read-out was used for receiving frequencies above and below the audio spectrum. Two large laboratory-type tape recorders (Modified Crown Series 800) were used for recording the signals and these machines as well as the port- able equipment were synchronized to- gether with a high-frequency precision timing system. A high-frequency echo sounder with a trainable multiple head was used in a number of frustrated at- tempts to follow seals acoustically as they came and went, and did give a good MR. WATKINS is in our Department of Geophysics and works with Mr. Schevill on the recording and analyzing of sea- sounds. map of the local bottom conditions. Maintenance tools, equipment, and spare parts helped to fill up the left-over space in the recording shack. A shock-mounted gasoline generator provided the heavy- load power and was located 150 meters away to keep noise levels to a minimum; battery stacks provided power for really silent listening. A four-foot hole cut through the ice occupied one end of the recording shack. It was through this hole that hydrophone cables and echo-sounder heads passed, and it was through this hole that many good observations of seal reactions were made. On several occasions the curiosity of the seals actually brought them up into the hole tor a long look at the world of electronics. It was also into this hole that we continually reminded ourselves not to step! It was 310 meters to the bottom! Three holes There were three holes cut in the ice, some 20 metric tons of ice, all moved by hand. One hole was for the sub-ice observation chamber, another hole was for the instruments and a third hole was for the seals. The seals began to use their hole even before we had completed our installation. The acoustic observations from this "cruise" included over 42.700 meters of sound on tape. Analyzing this promises to occupy much of this winter's effort. Besides a complete physical description of the sounds of the Weddell seals, we'd like to know how depth affects their calls, what significance the different calls have, and what sort of echo-ranging abilities, if any, they possess. The coordinated combination of good visual as well as good acoustic observa- tion provided a clear glimpse into part of the daily routine of the Antarctic Weddell seal. Looking while listening increased the chances of learning many- fold. 24 lilH 17ZI1 Associates of the Woods Hole Oceanographic Institution Ti [IE ASSOCIATES of the Woods Hole Oceanographic Institution are a group of individuals, corporations and other organizations who, because of their love for the sea and interest in science and education, support and encourage the research and related activities of the Institution. Membership dues in the Associates are as follows: Member $50 Contributing Member $100 Club Membership $100 Patron $500 Life Member $1,000 Corporate Member $1,000 Sustaining Corporate Member $5,000 or more. All contributions and dues are tax deductible to the extent provided by law. President Secretary Executive Assistant HOMER H. EWING JOHN A. GIFFORD RONALD A. VEEDER EXECUTIVE COMMITTEE DEVELOPMENT COMMITTEE CHARLES F. ADAMS WINSLOW CARLTON W. VAN ALAN CLARK PRINCE S. CROWELL F. HAROLD DANIELS JOHN A. GIFFORD PAUL HAMMOND NOEL B. McLEAN HENRY S. MORGAN MALCOLM S. PARK GERARD SWOPE, JR. THOMAS J. WATSON, JR. JAMES H. WICKERSHAM PAUL HAMMOND, Chairman HOMER E. EWING, Vice Chairman BRUCE BRED1N DONALD F. CARPENTER FRANK B. JEWETT, JR. HOWARD C. JOHNSON J. SEWARD JOHNSON EDWIN A. LINK JOSEPH V. McKEE, JR. HENRY A. MORSS, JR. R. CARTER NICHOLAS JOHN C. PICKARD ROBERT W. SELLE M. MICHAEL WALLER ALFRED M. WILSON EX-OFFICIO NOEL B. McLEAN, Chairman PAUL M. FYE, President and Director EDWIN D. BROOKS, JR.., Treasurer INDUSTRIAL COMMITTEE Chairman: CHARLES F. ADAMS Chairman, Raytheon Company ROBERT M. AKIN, JR. President, Hudson Wire Company PAUL HAMMOND President, The Hammond-Kennedy Company F. L. LaQUE Vice President, The International Nickel Company, Inc. WILLIAM T. SCHWENDLER Senior Vice-President, Grumman Aircraft Engineering Corporation D. D. STROHMEIER Vice President, Bethlehem Steel Co. MILES F. YORK President, The Atlantic Companies Contents Articles THE SOMALI CURRENT fay 8. Warren INTERACTION BETWEEN THE SUMMER MONSOON AND THE INDIAN OCEAN by A. F. Bunker THE 'METEOR' IN THE INDIAN OCEAN Features MONSOONS SHIPS' NAMES THE 'ALVIN' THE KUROSHIO by P. Koike by 1. Ichiye NEW SOURCES OF SEAFOOD AGOR 9 AND TO LOOKING WHILE LISTENING bx W. A. Watkins Published by the WOODS HOLE o< EANOGRAPHK: INSTITUTION WOODS HOLE, MASSACHUSETTS