第16次南極地域観測隊夏隊(1974-1975)報告

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The icebreaker FUJI, under the command of Captain Mamoru MORITA with a crew of 181, left Tokyo on November 25, 1974 on a mission of transportation of members and cargos of the 16th Japanese Antarctic Research Expedition. The expedition consisting of 40 members was led by Dr. Takao HOSHIAI. Ten of the 40 men, 7 scientists and 3 technicians, constituted the summer party led by the author as a deputy leader. Dr. HOSHIAI also led the wintering party of 16 scientists and 14 technicians. In addition to the expedition personnel, three observers joined the summer party. Dr. Tetsuo TOMIYAMA, former chancellor of the Tokyo University of Fisheries and councilor for the National Institute of Polar Research, made inspection on summer activities, as an observer sent from the Promoting Headquarters of the Antarctic Research. Mr. Yuki KOBAYASHI, technician from the Ship Research Institute of Ministry of Transport, participated in the 16th JARE to make research on the navigation of the FUJI for the development of an icebreaker as a trading vessel. Mr. Tadaaki WATANABE, ranger of the Nature Conservation Bureau of Environment Agency, also joined the expedition to collect basic information on wildlife in the Antarctic region so as to consider the administrative measures for wildlife conservation in Antarctica. The present report outlines scientific and logistic activities of the 16th JARE during the austral summer season, between the departure from Fremantle, Australia on December 16, 1974 and the arrival at Cape Town, South Africa on March 7, 1975. The scientific programme of the 16th JARE was made by the Specialists Committee of National Institute of Polar Research as a part of the long-term annual plans. The programme comprised many items in various disciplines as listed in Table 1, and emphasis was laid on environmental sciences such as biology, medical science, chemistry, and on earth sciences. During the summer season several field surveys were schemed in areas around Liitzow-Holm Bay, and stations for oceanographic observation were scheduled along the course of the FUJI from Fremantle via Syowa Station to Gape Town. A new all-sky camera, an automatic developper, an ionosonde, an echo-sounder for submarine stratigraphy, an aero-camera, a continuous analyser for atmospheric NO-Nox, etc. were added to the observation facilities of Syowa Station. The station was also replenished with a KC-20 and a SM-15-S oversnow vehicles, two Yamaha snow mobiles, a TCM STD-25 tractor shovel, materials of a hut for transmitter, etc. Transported cargos amounted to 470 tons, of which 345 tons were fuel and lubricating oil. The itinerary of the FUJI was determined to be almost the same as that of the previous navigation. When the plan for the summer operation in the Antarctic was being discussed at Tokyo, the U. S. Antarctic Research Program suddenly requested the FUJI to escort the drilling ship GLOMAR CHALLENGER during drilling at the edge of the continental shelf off the Liiser-Larsen Peninsula. The operation plan of the 16th JARE was adjusted to satisfy the request as far as possible. Unfortunately, the FUJI and the GLOMAR CHALLENGER could not agree on the period of drilling. The FUJI left Fremantle for Antarctica on December 16, 1974 and sailed southward along longitudes between 110° and 95° East. On December 27 she encountered the first pack ice off the Amery Ice Shelf at 63°54'S and 67°45' E, and two days later she made a thrust into the pack ice zone at 65°23. 7' S and 44°35'E. Pack ice was so heavily concentrated (7/10〜10/10) that it took four extra days before the ship reached the edge of the fast ice area. It seems that weak blizzard of December 25 and 26 made pack close and snow accumulation on floe during the blizzard prevented ice from melting. The first flight of a Sikorsky-69A helicopter to Syowa Station was made on January 4, 1975 from the point 36 nautical miles north-north-west of Syowa Station. The FUJI started air transportation on a full scale from January 6, trying to approach to the station by charging at fast ice. But the ice was so hard to break that the FUJI was forced to conduct air transportation from the position about 28 nautical miles north-north-west of the station. The weather was fairly fine untill the end of January, and 470 tons of cargos were transported smoothly by air before January 29. Construction work was started on January 4. A pre-fabricated transmitter hut of 72m^2 in area was built within 16 days by hand only, because ice melting prevented a crane truck from getting near the site. Reconstruction of ,a dark-room, exchange of a refrigerating machine, exchange of engines of generators, etc. were performed as prearranged. Thus the 16th wintering members took charge of all scientific and logistic routine works at Syowa Station on February 1, relieving the 15th wintering members. On the other hand, field surveys during the summer season were conducted in parallel with transportation and construction works. Two members were sent to a depot on the continental ice 18km east of Syowa Station on January 6 with other four (three 16th personnel and one 15th personnel) supporting staffs for deep drilling of ice sheet at Mizuho Camp 300 km south of Syowa Station. They joined four 15th members who had started drilling work at the beginning of December of 1974. Four supporting staffs returned to Syowa Station on January 17, together with the 15th JARE traverse party who made a trip to the Yamato Mountains, collecting snow samples at various places for geochemical study. The field surveys in the ice-free areas along the coast were rather intensive than those on the previous occasions. Four biologists and one chemist stayed in the Langhovde ice-free area from 13th to 20th of January. They made an ecological study of lichens and mosses and a limnological study of lakes. One of the results is the discovery of one species of moss (Bryum argenteum) which was not reported in the Liitzow-Holm Bay region till then. From January 27 to February 2, the Skarvsnes area, the largest ice-free area on the Prince Harald and Prince Olav Coasts, was visited by field scientists consisting of four biologists, two geochemists, two geologists, and one geomorphologist. Items of observation were detailed geological mapping of bedrock, coastal geomorphology, limnological study of both saline and fresh-water lakes, and ecological study of lichens and mosses. Living flagellate algae were found in the highly saline water of Lake Hunazoko. The water is also rich in chlorophyll-a. A new moss (Tortula sp.) was discovered from the Liitzow-Holm Bay region, and a kind of Bryum in connexum was found to have adapted itself to shallow fresh-water lakes. In addition, rather extensive surveys including ground surveying were carried out by eleven scientists in the Akarui Point ice-free area between 6th and 8th of February. Traverse surveying, basic surveying, and astronomical observation were also conducted by eight members from January 23 to February 2 in Padda Island, Austhovde Rock, and the Rundvagskollane ice-free area. Aerial Photography of the coastal areas was made by a Cessna 185. The above-mentioned field surveys were conducted by the joint party of the 16th and 15th JARE personnel under the supervision of the author. The author also had several occasions to make reconnaissance observation on ice conditions of sea ice and glaciers by helicopter and Cessna flights. It gave us information on the fluctuation of the snout on the ice-tongue of the Shirase Glacier and on the distribution of ice-shelf-like floating tongues on the west coast of Liitzow-Holm Bay. The FUJI left the transportation position on February 12 just after evacuating the drilling staff members of Mizuho Camp from the depot, and began to cruise north for the margin of pack ice zone. However, she was stuck with heavily concentrated ice at the point 53 nautical miles north-north-west of Syowa Station. She was beset for one week and drifted 40 nautical miles westward with the surrounding pack ice. On February 18 the ice condition began to change and fractures developed in the hammocked pack around the ship. The weather became fine on February 19, and the reconnaissance long-distance flight revealed that the ship could sail to the west if she could break ice 300 m ahead the bow. Explosion of ice set the FUJI free from the beset state and she moved slowly forward to the west. On February 21 she was able to reach the edge of the pack ice zone through large open water off the Liiser-Larsen Peninsula. On account of the delayed arrival at the pack ice margin, oceanographic observation stations had to be reduced compared with the original plan. Moreover, oceanographers gave up the observation between March 3 and 7, because a member of the crew was seized with acute attack of appendicitis. To rush the patient to the hospital the FUJI made the best of her cruise and entered the harbour of Cape Town on March 7, two days earlier than scheduled.
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第16次南極地域観測隊夏隊(1974-1975)報告

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