ヒンパツ スル ナンキョク リュツォ・ホルム ワン ノ カイヒョウ リュウシュツ 1980ネン ～ 2003ネン ノ カイヒョウ ジョウキョウ カラ

南極リュツォ・ホルム湾で発生した海氷流出の事例を,1980年から2003年までの間について調べた.事例によって流出の面積や持続期間に差異はあるが,過去24年間の内,計19年で流出が認められた.大半の流出が湾の中央北部から東部に至る,ほぼ同一箇所で発生しており,流出は秋季に始まることが多い.1997年厳寒期に発生した広域流出は,翌1998年冬季まで継続し,流出面積・期間共に最大規模となった.その後,2003年までの間は秋季から初冬に亘る流出が毎年継続している.頻発している海氷流出の要因について,南寄りの風,少雪年の継続,暖冬の影響との関連から考察した.The history of sea-ice breakup in Lutzow-Holmbukta, Antarctica, has been investigated for the period 1980-2003. Though spatial and temporal scales for breakups are different among each event, breakup phenomena have occurred at least 19 times. The geographical sites of breakups are almost the same in the bay and commencement is usually in autumn. In particular, the 1997/1998 event covered a wide area and was of long duration. Since then, autumn to early winter breakup has continued until winter 2003. It is suggested that a southerly wind field, small snow depth and mild winter prior to the breakup are factors which favor breakup events

ダイ49ジ ナンキョク チイキ カンソクタイ エットウ ホウコク 2008-2009

第49次南極地域観測越冬隊(第49次越冬隊)は29名で構成され,南極地域観測第VII期計画および国際極年2007-2008(IPY2007-2008)の2年次として越冬観測を実施した.昭和基地とその周辺域において,定常観測およびモニタリング研究観測を継続すると共に,宙空圏から大気圏,海洋圏にわたる分野横断的な重点プロジェクト研究,生物圏および地圏に関する一般プロジェクト研究,さらに将来の大型大気レーダー計画に関わる萌芽研究観測を行った.2008年2月1日に第48次越冬隊から昭和基地の運営を引き継ぎ,基地を維持しつつ,科学観測データ取得のために安全を第一に心がけ,総力を上げて取り組んだ.従来と比べてやや少人数の越冬隊であったため,特に野外旅行隊の編成では旅行計画や準備はもちろん,基地在住者がさらに減じる期間中の業務代行および非常時対策を十分に検討した.日々の基地運営や基地内外における活動の際には,危険予知と安全対策を綿密に行い,各種講習・訓練を通じて知識と技術を向上させると共に,危険箇所や行動に関する情報や経験を共有して,事故の再発防止に努めた.越冬終盤では,度重なるブリザードのために,除雪作業に難渋することもあったが,2009年1月の第50次隊の基地到着後は,例年より短期間で観測・設営業務の引き継ぎを進め,同年1月29日の越冬交代を完了し,第49次隊による越冬活動を終えた.本報告に越冬活動の概要を記す.The wintering party of the 49th Japanese Antarctic Research Expedition (JARE-49), consisting of 29 members, was conducted as the second year of the 7th four-year plan of JARE and the second half of the International Polar Year 2007-2008 (IPY2007-2008) at Syowa Station and its surrounding areas. JARE-49 took over management of the station facilities and functions from JARE-48 on February 1, 2008, and performed scientific observations and logistic duties. Though it was a little smaller in terms of number of wintering personnel than previous teams, it was well prepared to perform station management and research activities. To maintain safety and active field work, personnel knowledge and skill were improved through training courses, and information and experience concerning search and rescue were shared. Snow removal work was hard because there were also many blizzards through spring and summer. The observations and related work were successful, and JARE-49 handed the station over to JARE-50 on January 29, 2009. This report gives an outline of JARE-49 wintering activity in and around Syowa Station

Evaluation of water flushing effect on icebreaking operation of “Shirase” by analysis of Japanese Antarctic Research Expedition voyage data

The Tenth Symposium on Polar Science/Ordinary sessions: [OM] Polar Meteorology and Glaciology, Thu. 5 Dec. / 2F Auditorium , National Institute of Polar Researc

Land-fast ice variation in Lutzow-Holm Bay, Antarctica, since 1930s

第2回極域科学シンポジウム/第34回気水圏シンポジウム 11月17日（木） 統計数理研究所 3階リフレッシュフロ

ナンキョク リーセル・ラルセン ハントウ ノ ポリニア ノ スイオン コウゾウ

昭和基地の西北西約200 km,南緯68度30分,東経35度00分周辺のリーセル・ラルセン半島沖に形成されるポリニア(海氷域内の開水面または疎氷域)において,海面状態と水温構造を把握するために,2000年3月から2001年1月までの間,航空機による海洋観測を行った.厳寒期のポリニア域では海氷生産が目視で確認された.AXBT(航空機投下式水温プロファイラー)による観測の結果,結氷温度に達した冬季対流混合層の深さは250-300 mであり,昭和基地北方沖ポリニアにおける混合層の深さ(約400 m)と比べて小さかった.Satellite images have suggested the presence of winter open water, or a polynya, off the Riiser-Larsen Peninsula (around 68.5°S, 35.0°E) in East Dronning Maud Land, Antarctica. To ascertain evidence for polynya formation and to survey thermal structures, the 41st Japanese Antarctic Research Expedition executed aircraft observations in 2000-2001. The observations have verified that the polynya appeared and sea ice formed in the cold season. In the polynya region, water temperature profiles were measured using an Airborne-XBT device. It is found that the winter convective-mixed layer which cooled to its freezing point reached the depth of about 250 to 300 m. The mixed layer was thinner than that of another polynya located over the shelf break around 68.5°S, 39.0°E

ナンタイヨウ インドヨウ ク オヨビ リュツォ・ホルムワン オキ ノ カイヒョウ ショウチョウ ノ トクチョウ

1970年代以降の衛星データを用いて,南大洋インド洋区及びその中のリュツォ・ホルム湾沖における海氷消長の特徴を調べた.インド洋区で海氷域面積が最大値に達する時期は10月で,他の海域と比べて1カ月遅い.この遅れの一因として,インド洋区の西に位置するウェッデル海区から沖合流氷が東に輸送されることが寄与していると考えられる.海氷融解期の11-12月の面積減少率はインド洋区で最も大きいことも示された.リュツォ・ホルム湾沖の海氷消長については,東経40度線上の海氷縁位置の変化に着目した.その結果,秋～初冬の海氷域拡大期には氷縁の北上開始が他の海域よりも1-2カ月遅れること,春の海氷域縮小期には急速に氷縁が後退する傾向が顕著であることがわかった.この東経40度付近の海氷消長はインド洋区の中でも顕著な特徴であり,同海域におけるコスモノートポリニアの形成との関連が示唆される.Characteristics of sea ice variations in the Indian Ocean sector and off Lutzow-Holmbukta, Antarctica, have been described with satellite data archived since the 1970s. In the Indian Ocean sector, the period of maximum ice extent is generally reached in October, a month later than in other sectors. The probable reason for the delay is eastward sea-ice drift from the Weddell Sea sector west of the Indian Ocean sector. During the ice melt season, the highest rate of ice retreat from November to December appears in the Indian Ocean sector. Also, the ice edge along 40 degrees east longitude off Lutzow-Holmbukta shows a remarkable delay pattern at the beginning of autumn ice extent season and rapid retreat of the ice edge in the spring melt season. These features are qualitatively explainable due to Cosmonaut Polynya formation

Satellite observation of melting and break-up of fast ice in Lutzow-Holm Bay, East Antarctica

Lutzow-Holm Bay, East Antarctica is covered entirely by multi-year fast ice, almost every year, but this fast ice breaks up periodically, with several years between break up events. A large break-up started in March 1997, and reached its maximum at the end of March 1998. Two thirds of the fast ice in the bay was blown out. Melting features in the fast ice and surrounding ice sheet slope were observed by high resolution ADEOS AVNIR visible data in 1997.Since there are periodic break ups of the fast ice in Lützow-Holm Bay, warmer climate conditions and an increase in melting are investigated and compared with the occurrences of fast ice break up. The interannual variation of melting in the coastal zone was estimated by using the passive microwave brightness temperature. The gradient ratio of horizontal channels of 18/19 GHz to 37 GHz of SMMR and SSM/I was used to detect the melting duration of each summer from 1978/79 to 1998/99. A long melting period was estimated to have occurred in summer 1996/97 before the large break up; similar relationships were observed in the previous break-ups. The fast ice area has large variability in the number of melting days compared to the ice sheet slope zone, and it will be sensitive to the air temperature change in the coastal zone