The Arctic regions have been under investigation for the past 400 years, first by sailing ships, steamships, and icebreakers, and more recently by submarines. The obvious questions are: Why do people want to explore these desolate regions, and what discoveries are being made?
Man has shown a special interest in reaching the North Pole. This desire to find a particular geographic position on the earth is hard to explain because the place looks essentially the same as thousands of others near it. (In actual fact, its surface appearance continually changes as the ice moves past.)
Many countries, principally Denmark, Britain, and Norway sent explorers to seek a northwest passage over the top of North America from Europe to China. Many of these expeditions tried to get to the North Pole.
The first person accredited with actually reaching the North Pole was Robert Peary on 6 April 1909. Peary’s party traveled by means of a ship to northern Greenland and then by dog sleds the rest of the way. On 9 May 1926, Byrd and Bennett crossed the Pole by airplane. A few days later, Amundsen and Ellsworth made the trip by dirigible.
One of the first U. S. endeavors to accomplish this feat was made by the U. S. Navy in 1879 using the Arctic steamer, Jeanette. She went up the Pacific through the Bering Sea into the Chukchi Sea and then attempted to reach Greenland through the ice. Unfortunately, the ship was crushed by the ice. The few who reached safety made their way home by ice, water, and land through Siberia. A significant result of this expedition was that parts of the crushed ship were later found on the coast of Greenland. This led Nansen, a Norwegian explorer, to construct a ship which would not be crushed by the ice, and to repeat the path of the drift of the wreckage of Jeanette. So, in 1893, Nansen’s ship, Fram, was allowed to lodge in the ice off northern Siberia. It drifted with the shifting ice, generally towards the Pole, and after three years emerged in the Atlantic Ocean.
Later, Amundsen wanted to repeat this feat. He constructed a ship similar to Fram and called her Maud. He and Dr. Harold Sverdrup, former director of the Scripps Institution of Oceanography, and others aboard the ship tried to enter the drifting ice, but failed to do so. They drifted in circles just north of the Bering Strait. After seven years, they abandoned the attempt.
Icebreakers have also been used to explore the Arctic Ocean. By accident, the Russians lodged an icebreaker in the ice and more or less repeated the cruise of Fram. Our icebreakers have not been so bold, but nearly every summer since the war, they have operated in the ice fringes of the Chukchi and Beaufort Seas north of Alaska and Canada, respectively.
Conventional Submarines
Probably the most farsighted Arctic explorer of all was the Australian, Sir Hubert Wilkins. Thirty years ago he believed that a submarine could reach the North Pole by traveling under the polar ice cap. Laboriously he raised money wherever he could. He leased a surplus World War I submarine from the U. S. Navy for the sum of one dollar per year and modified it for Arctic operations. By removing the sail, or superstructure, and mounting large steel sled runners on the top, he proposed to slide on the underside of the ice. He added a hydraulic ram on the bow to ease head-on collisions with submerged ice pinnacles. For safety, he had a “cathead” rotary cutter with which he planned to bore holes through as much as fifteen feet of overhead ice. The holes could be used for escape or for snorkeling.
Wilkins’s expedition was intended, first, to demonstrate the feasibility of operating a submarine under the Arctic ice pack as a means of reaching the North Pole and, second, to make a scientific study of the Arctic. Dr. Sverdrup and a group of scientists were on board to study magnetic variations, ambient light, underwater spectrographic properties, depth of water by acoustic means, and the chemical and physical properties of the water and ice. Water samples were obtained by lowering water bottles through a trap door in the bottom of the submarine. When the submarine was at or near the surface, the air pressure in a forward room was increased to equal that of outside water pressure, and the trap door opened for direct access to the open sea below.
The first objective, to travel under the ice and surface in polynyas, was not achieved, because on arrival at the edge of the Arctic pack the diving planes were missing. The submarine did, however, push for five miles under the ice fringes bumping the overhead ice until it became too rough; she then surfaced in a polynya.
The scientific program, necessarily confined to the ice fringes, was more successful. Periodic depth soundings showed that the sea floor northwest of Spitzbergen was extremely irregular. Determinations of the physical and chemical properties of the water, though not numerous, were still highly significant, since they were the first of their kind in this particular region.
The idea of a submarine running under the Arctic ice pack was made a reality by Dr. Waldo Lyon of the U. S. Navy Electronics Laboratory. After World War II, Lyon, Leighton Morse, Eric Baltzly, Ted Saur, and others conducted several under-ice expeditions by submarines and collected oceanographic data in the ice fringes of the Chukchi and Beaufort Seas. Their technique was to install a winch in the forward torpedo room and lead a wire rope up through the forward hatch and hold it over-side by an A-frame. To the wire were attached water bottles, nets, and other instruments which could be lowered into the sea for sampling. This technique worked satisfactorily in openings in the ice around the ice fringes. However, the ice frequently interfered with the wire and bottles as the ship drifted against it and also as the ice blocks drifted against the ship on the windward or sampling side. Ice sometimes had to be fended off with a pole.
With over-side wire, it takes upwards of an hour to retrieve the wire from a deep operation. If the ship drifts into the ice, the equipment is endangered. The officers are usually concerned about their ship drifting in and being surrounded by ice, but in broken ice, the problem is not serious.
Nuclear Submarines
With the advent of nuclear-powered submarines, a major breakthrough was made in the techniques of Arctic exploration and oceanographic research. The 1957 cruise of USS Nautilus, the 1958 cruises of USS Nautilus and USS Skate, and the 1959 cruise of USS Skate to the Arctic Ocean clearly demonstrated this. In 1958, Nautilus made the epic cruise from the Chukchi Sea to the North Sea under ice in 96 hours. Skate, with the author on board, afterwards entered the Arctic from the Atlantic side where the water is deeper, ran to the North Pole, and zigzagged in order to cover more area.
Both ships carried on oceanographic studies. Neither ship had a winch for over-side sampling as in previous cruises. In Skate, the technique was to move the submarine up and down, leveling off at fifty-foot intervals for sampling. In this way, water samples were collected in a series with the same result as a vertical cast.
Ice Thickness:
In the Arctic, the thickness of ice cover is probably the most significant oceanographic parameter, and it is most easily measured from submarines, since most of the ice is below the surface.
Visual observation of the ice (periscope, television) is not satisfactory because of the distances from the ice at which the submarine must operate for safety, and because the information obtained is qualitative.
On Skate, echo sounders were mounted on the deck and directed upward, a technique developed by Dr. Lyon. An example of an echogram is given below. The tape shows depth or vertical distance as the ordinate and time or distance as the abscissa. With this acoustic instrument, the sea surface or water- air interface gives a strong echo or dark trace on the tape, whereas ice gives a weak echo from a lesser distance than that of the water surface.
In the echogram, the ice protrudes downward nearly 25 feet in one place. This echogram also demonstrates how rough the underside of the ice really is (the vertical scale on this representation is greatly exaggerated). The thickness of the ice fluctuates widely even over distances of only a few hundred feet. (We did know that the upper ice surface is rough and that ice protrudes downward 5-9 times its height above the water, so the rough underside was not surprising.) The average thickness of flat ice in summer is about three meters, being generally thicker in the central part of the ocean. In summer, more than 90 per cent of the central Arctic basin is covered with ice. In the open water between ice floes, the height of surface waves can be studied by the upward echo sounder, and from the results, an estimate of wind speed can also be derived.
Characteristics of the ice above the surface can also be studied with submarines. In summer, some openings, or polynyas, in the ice are large enough for a submarine to surface. In winter, it is even possible for a submarine to break through newly formed ice.
Polynyas:
After surfacing in a polynya, it was fairly easy to get out of the submarine, inflate a rubber boat, and go ashore. It was found that the ice on one side or other of the polynya was usually rafted. The uneven wind stress, along with the surface drainage, are factors in creating a polynya. On the ice, we sampled ice and water puddles, collected plankton samples, made temperature measurements, and recorded the weather.
In the summer, the surface ice and snow melt and form puddles which drain into the polynyas. Since the water is relatively warm, about 34°F, and relatively fresh, about 3 parts per thousand of salt, it floats on top of the normal seawater. There is a sharp boundary at about ten feet, at approximately the bottom of the flat ice, at which the temperature and salinity change abruptly. Since the salinity increases and the temperature decreases, a large density discontinuity is created, below which the temperature is about 30°F and the salinity about 33 parts per thousand.
Another summer characteristic is the undercutting by erosion or melting of the ice at its boundary with the water. The water in a polynya (and the Arctic Ocean in general) is unusually clear. In most cases, objects are visible down to at least fifty feet. Old crops of plankton are frequently found on the ice, as shown by the dark area.
Ambient Light:
The ambient light meter used consisted of a photocell enclosed in a glass-covered, watertight housing. It was mounted on the deck and directed upward. The current created by light falling on the photocell was amplified and then recorded on tape.
The ice crystals, brine cells, and detritus of old sea ice greatly reduce the transmission of light from the sun and sky. Even the relative thickness of the ice is approximated by small changes in light intensity below the ice. Under small openings through the ice, the ambient light increases in proportion to the size of the openings. Light from two closely spaced openings sometimes merges.
Water openings can be easily distinguished from ice because of the opaque quality of the ice and the remarkable clarity of Arctic water. As the submarine comes out from under the ice, traveling at a constant depth, the ambient light is not only increased by the direct rays from sun and sky but also by reflections from the vertical sides of the near-surface ice. Under completely open water, the light intensity increased from ten to twenty times compared to that under the normal ice thickness.
Light Attenuation:
Measurements of water transparency were made by means of a hydrophotometer. This instrument consisted of a standard light source in a watertight housing which transmitted a focused light beam from a glass port, through one meter of water, and into another housing containing a Weston photocell. Ambient light was excluded by means of a baffle arrangement which, however, allowed free flooding and exchange of water in the path of the light beam.
The sensing element was mounted on the hull, and measurements made periodically at cruising depth and also at fifty-foot intervals on vertical excursions. The results showed exceedingly clear water near the ice and still clearer water below.
In addition, some visual observations were made by means of the periscope and television. A few coelenterates were observed at shallow depth in polynyas. An optically different layer at the fresh water-salt water interface was observed to display “shimmer.”
Light Scattering:
Light scattering coefficients were obtained by means of a nephelometer especially developed for use with seawater. The nephelometer directed a light beam through a light filter into a column of water. A photo-multiplying cell faced towards the light beam at an angle of 135°, and detected only light scattered by particles in the water.
Water samples were taken routinely every six hours at cruising depth and at three to five levels during vertical excursions. These samples were drawn from the sea-water suction line in the engine room. They were allowed to come to room temperature and then inserted into the chamber of the nephelometer. Readings of light scattering were made using filtered light of three different wavelengths.
The light scattering found was generally low. Blue was scattered about 50 per cent more than red and about 25 per cent more than green. Scattering usually decreased with depth. Water near the surface in polynyas exhibited about ten times the scattering of deeper waters, but the scattering still was not as great as that observed in water from lower latitudes at this season.
Since the shorter wavelengths (blue) were scattered more than the longer (red) ones, the particles suspended in Arctic water must be very fine. In polynyas, however, the green scattering values were highest; this would indicate that simple Rayleigh scattering did not predominate there.
Biological Populations:
Biological populations in the Arctic, from our observations, were extremely sparse. Plankton samples were collected by filtering seawater through a small, 1-inch diameter piece of bolting silk with mesh opening of 0.076 mm. The bolting silk was held in place by a metal clamp attached to a funnel. Large samples were collected by running a stream of water through the filter directly from the sea suction line in the engine room.
No acoustic scattering layers, as commonly observed in other oceans and attributed to marine organisms, were found on the echo sounder trace. The diurnal light changes in summer (and winter) were very small, and thus a phototropic migration would be negligible. The clarity of the water and the scarcity of plankton further substantiate the non-existence of sufficient organisms to create a scattering layer. Even larger discrete scattered were virtually absent, as shown by the excellent Precision Depth
Recorder tapes.
Most plankton was found at the bottom of pools or on the shallow subsurface shelves of polynyas. At these locations, increased light by reflection from the ice shelf and the vertical sides of the ice, together with slightly higher temperatures, was conducive to phytoplankton production. Older, retarded, green algae spores, sometimes in large concentrations, were found in and on the ice, undoubtedly the results of the freezing of polynyas and the melting of surface ice which gradually work this material to the surface. As far as large animals are concerned, there were a few seals in one polynya, a polar bear in another, and fresh tracks in still another.
Temperature and Salinity:
Temperature, conductivity, and sound velocity were measured by elements mounted on the hull. Short electrical leads through the hull make this procedure appreciably simpler than with a surface ship.
In addition, water samples were drawn from sea suction lines in the engine room as the submarine cruised at constant depth or made vertical excursions. Thermometer buckets held in a strong stream gave in situ readings of outside conditions. The excess water from these operations was drained into the bilge and periodically ejected.
The temperature and salinity measurements revealed that the water became slightly warmer with greater depth, whereas the salinity increased with depth. The shallow layers are warmer and more saline on the Atlantic side than on the Pacific side of the Arctic basin. The water mass boundaries are largely controlled by the current circulation patterns and bottom topography.
Bottom Topography:
One of the most important measurements obtained from Skate and Nautilus was a continuous profile of the sea floor made by means of an echo sounder directed downward. The bathymetry of the Arctic basin is known largely from the Russians, especially from single soundings made over a wide area by plane landings.
On the basis of these earlier soundings plus those of Nautilus and Skate, Dr. R. S. Dietz of the U. S. Navy Electronics Laboratory has divided the Arctic basin into geomorphic provinces. Proceeding from the western hemisphere to the eastern hemisphere, the first province is the Continental Rise off Alaska. This falls concavely into the second province, the Canadian-Arctic Basin, with a very flat floor, 2,080 fathoms in depth. The third province is the Central Arctic Rise, a deep and broad plateau with localized irregular relief (averaging 500 fathoms in depth) which probably extends all the way across the “Great” Arctic Basin (see Inset a, p. 95). This is followed by the relatively small, flat Central Arctic Basin at 2,150 fathoms, about seventy fathoms deeper than the Canadian-Arctic Basin (see Inset b). Following this is a main feature, the Lomonosov Ridge, which appears to extend from the New Siberian Islands nearly to Ellesmere Island. The typical depth of the central part of this flattop ridge is about 700 fathoms. The next province is the abyssal plain of the large Eurasian-Arctic Basin. It slopes from north to south, about one fathom per mile. The North Pole is situated at about 2,300 fathoms over the north edge of the floor of the Eurasian Basin. This large basin terminates in a province of sharp peaks protruding through the flat terrain (see Inset c). These peaks or possibly seamounts continue up to Nansen Ridge, about 500 fathoms deep, and the east end of the “Great” Arctic Basin.
Summary
It is evident that nuclear submarines are extremely useful vehicles from which to carry out oceanographic research. Some specialized instrumentation and compact laboratory arrangements are still needed. However, a great deal has been accomplished in Arctic oceanography.
Still greater use of submarines for exploration and in situ oceanographic studies is anticipated in all oceans. In the Arctic, oceanographic information is needed for an accurate prediction of open water conditions.
With the current development of other deep-diving vehicles, such as the bathyscaph, mesoscaph, and deeper diving submarines, our ways of studying the sea will undoubtedly be modified. New techniques, such as diagonally directed up-and-down paths, could be adopted for two-dimensional coverage. Specialized electronic equipment will be mounted to sense continuously the various oceanographic properties of the water. Even plummeted or buoyed sensing casts could be made. With various types of submarines we will soon study the many features of the Arctic and other oceans in situ.
Dr. LaFond is Head of the Marine Environmental Studies Branch, U. S. Navy Electronics Laboratory, San Diego, and has taken part in five arctic oceanographic expeditions during the past eleven years. He achieved worldwide recognition for his pioneering studies of the oceanography of the Indian Ocean in 1952-53 and 1955-56. During those periods, while on Fulbright awards, he made 47 oceanographic cruises in the Bay of Bengal. His achievements in India led to his receiving the honor of a Doctor of Science degree from Andhra University, Waltair, India. This is the first such degree the university has ever awarded to a U. S. citizen.
“To see what is right and not to do it is want of courage.”
Confucius