海面更正気圧 (SLP) により定義されるシベリア高気圧の季節変化を半旬を単位として明らかにし,上空の気圧配置および気温分布との関係を明らかにした. 1980年から1992年までの13年平均データを用い,シベリア高気圧の中心部 (50～55°N, 90～95°E) とウラル山脈北部(60～65°N,70～75°E)のSLPの3半旬平均の差により,季節変化のステージ分けを行った.その結果, 1年をステージ1(第39～53半旬),ステージ2(第54～57半旬),ステージ3(第58～64半旬),ステージ4(第65～72半旬),ステージ5(第73～3半旬),ステージ6(第4～7半旬:最盛期),ステージ7(第8～12半旬),ステージ8(第13～15半旬),ステージ9(第16～38半旬)に分割することができ,シベリア高気圧の形成・発達・衰退・消滅に至る時期およびその出現位置をとらえることができた.
さらに,上空の気圧配置,気温分布,気温の鉛直構造を考察した.この結果, 500hPa面高度で130°E付近の強いトラフと, 50°Eのトラフ, 80°Eのリッジが強くなっている時に,シベリア高気圧の中心が強まっていることがわかった.すなわち,シベリア高気圧の中心部分が発達・衰弱する時には,上層の気圧配置の影響が見られる.また,バイカル湖周辺がシベリア高気圧の中心となっており,気温の鉛直方向の逆転はステージ6のみで見られる.その西部および北東部では下層の寒気により高気圧が形成される.西部のウラル山脈北部では,シベリア高気圧形成時と衰退時に高気圧の中心になり,北東部のヤクーツク付近では,シ球リア高気庄が発達している時に,地上気温が大陸上で最も低くなるため高気圧が張り出す.シベリア高気圧は,これらの3地域を中心として,強さと形が季節変化することが示された.

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本研究では，GNIPデータからNAO指数と降水の安定同位体比の間に負の相関があるレイキャビクと正の相関があるエスポーを抽出し，両地点の変動要因の違いを明らかにした。その結果，降水のδ¹⁸Oに与える温度効果の影響はレイキャビクでは30%以下なのに対し，エスポーでは85%以上となった。また，同位体大気大循環モデルの長期データから，降水のδ¹⁸Oの分布や大気循環場のコンポジット解析を行った。さらに，NAO指数が高い年と低い年に分けて，水蒸気フラックスの違いについて解析した。その結果，レイキャビクではNAO指数が高い（低い）年には，西（南）からの低い（高い）水蒸気フラックスによって降水のδ¹⁸Oは低く（高く）なる。一方，エスポーではNAO指数が高い（低い）年には北緯50°～60°付近に偏西風が強く（弱く），大西洋からの同位体比の高い水蒸気フラックスが多い（少ない）ため，降水のδ¹⁸Oは高く（低く）なる。

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Climate variabilities in characterictics of typhoon, annual precipitation and SST are investigated in connection with the indecies of atomospher- ocean interaction such as MEI, PDO, NAO and AO. Spectra of annual time serries of the climate indecies were analyed to find a relationship between the climate change and the indecies of ocean-atmosphere interaction. A five-year variation in an annual mean minimum pressure of typhoon is found to have the same period of MEI and about one year time lag. The other climate indecies are found to change with the indecies of large-scale atmosphere-ocean interaction, such as MEI and PDO. The activity of typhoon and climate valiations are estimated employing linear system analysis with the impulse response functions and are compared with the measured climate data.

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 The Arctic Oscillation (AO; Northern hemisphere annular mode), which is the most dominant mode of climate variability in the Northern extratropics, is reviewed. The AO is a seesaw pattern between the Arctic region and the mid-latitude regions. It is an atmospheric internal mode caused by interaction between mean flows and eddies. In winter, it extends to the stratosphere, and the tropospheric AO interacts with the stratospheric AO. Since the mid-20^th century, the AO has shown an increasing trend in winter and summer. Climate models predict a future positive trend due to global warming. Recent sea ice loss in the Arctic Ocean is also discussed. The decline of the Arctic sea ice cover in late summer has accelerated recently and a record-low ice cover was observed in September 2007. The rate of decrease is much faster than climate model predictions, and it might pass a tipping point.

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From the 18^th to 19^th century, the atmosphere in Rome was observed by several artists from abroad. J. M. W. Turner, English painter left many sketches and paintings of landscape. When we see the sky, the color effect for optical view is composed of the layer of whole atmosphere and the outer space. For the purpose to analyze the relationship between optical sky and character of atmospheric environment in Rome, global and regional environment were observed. This paper aims to elucidate the main factor of vertical atmospheric layers using the photographs of sky and surface climatic data collected from 6^th to 11^th September 1999. In this research period, the sky showed varied phenomena of the climate transition from the typical dry summer to wet Autumn season. A distinctive feature was the influence of wind direction on diurnal range of temperature and humidity. Also it could be possible to define the transportation of desert dust mass originated in Sahara desert over Mediterranean basin is a stable element of atmosphere in Rome. The analysis of environmental character conduces to understand “the idea of the space and place” which inspires the human imagination.

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Research on factors of climate variations on a seasonal to multi-decadal timescale is surveyed. However, it is difficult to fully cover wide-ranging research on climate systems including the latest results. This paper focuses on phenomena such as QBO that interact with the other factors. Oceans, which have a close relationship with climate change, are considered. Although there is overlapping with dissertations in another chapter, the main contents are as follows 1) ENSO is a quasi-periodic air-sea interaction, which has been studied closely. If evolvement of ENSO is predicted, it will make seasonal weather forecasts more precise. 2) The effects of stratospheric QBO on climate systems in the troposphere might have been exercised as grave cool damage that occurs in summers when QBO was in the W-phase, and some correlations have been found. QBO probably holds a significant key explaining climate variations. Therefore, elucidation of the QBO mechanism that influences the troposphere can be expected. 3) The relationship between solar activities and climate remains obscure. However, some influences of solar activities on the tropospheric circulation have been felt through sea surface temperature or interaction with stratospheric QBO. 4) In the air-sea interaction the ocean responds to solar radiation more slowly than the atmosphere, so the ocean seems to play a dominant role in long-lived teleconnections such as PDO. In addition, regime shifts of oceans sometimes have major effects on climate. We cannot discuss climate change without referring to oceans. 5) Global warming is in progress. As a result, shifts in general circulation might lead to abnormal weather, which means increased danger of frequent developments of the Okhotsk high, which is responsible for cool summer damage. 6) It is important to evaluate which factors contribute greatly to climate change. Understanding the mechanisms of weather fluctuations ranging from a few months to several years is a pressing matter to prevent recurrence of meteorological disasters.

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 Structure (regime) of the global environmental system composed of atmosphere, oceans and marine ecosystems has repeatedly shifted from one state to the other on an interdecadal timescale, which is called “regime shift” (RS). The RS was first discovered in 1983 with synchronous fluctuations in biomass of three distantly separated sardine populations in the Pacific, which were closely linked to the global air temperatures, and the synchronized occurrences of an alternation between the sardine and anchovy in different areas were also observed. Similar synchronized variations have been detected thereafter in a wide range of taxa and ecosystems. Since the late 1980s, the RS has been reported about the ocean climate in the North Pacific Ocean as well as in the Atlantic. Studies in these different areas have been merged, creating a new interdisciplinary study area. The concept of the RS has had an effect on the traditional management regime of marine living resources and the UN Convention on the Law of the Sea has to be re-examined. Global warming and overfishing could disrupt the normal processes of the RS.

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国際協力事業団 (JICA) のメキシコ沙漠地域農業開発プロジェクトの紹介を通じ, メキシコの乾燥地と農業の現状を紹介した。まず, 古代から現在に至るまでのメキシコ農業の変遷を示し, 近年断行された農業大改革によってメキシコ農業は急速な勢いで輸出指向型農業に転換されつつあることを紹介する。つぎに, メキシコの国土のほぼ半分を占める北部三大沙漠地域の気候およびそこで展開されている農業について紹介する。最後に, プロジェクトの概要を, 発足の経緯, 組織構成, 立地条件, 周辺の農業事情, 活動概況の順に説明し, 今後は農業開発だけではなく環境保全も含めた国際協力を実施していく必要があることを示唆した。

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オホーツク海の海氷面積は冬季の大気循環により変動するが, 逆に海氷変動は大気循環に影響を与える.本研究では1-2月平均の大気場と海氷面積との間のラグを含む相関解析により, 海氷と大気循環の関係を調べた.
海氷はオホーツク海で西風が吹き気温が低下する時に拡大するという結論を得た.オホーツク海周辺の大気場と1月初めの海氷面積から十分な精度で1-2月の海氷面積を予測する回帰式を作ることができる.また東北地方以南の日本ではオホーツク海の海氷面積が広いと気温が高くなる相関が得られ, 海氷が日本の気候に与える影響を示唆する.半球規模の循環との関係では北大西洋振動/北極振動や西太平洋パターンと良い相関がある.
海氷が大気に及ぼすシグナルを取り出すために500hPa高度を用いた指標を定義し相関を調べた.日本～北米の4地点の指標と海氷はほぼ同時かやや指標が早いときに最大の相関がある.ところがアラスカ・北米のみで指標をつくると, 海氷が1ヶ月早いときに最大の相関となる.このことからオホーツク海の海氷はアラスカ・北米の大気循環に影響を及ぼしていると考えられる.
オホーツク海の海氷面積と冬季の北半球大気循環との相互作用をラグを含む相関解析によって調べた.

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サハラ砂漠西端部に分布する砂丘列に含まれる孤立砂丘の形態をもとに，当該地域で砂丘形態に影響を与えている季節風の角度変化量・相対強度の推定を試み，既存の評価方法では決定することのできなかった，ふたつの流れの強度の差が大きい二方向の風からなる風況の存在を確認した．
モーリタニア西部の都市・Port-Étienne (現 Nouadhibou) での年間の風況が，Breed et al. (1979) に報告されている．Breed らは RDP/DP ^* という指標を用いてその風況を評価し，一方向性が強い風況であることを示した．しかし，サハラ砂漠西部では，北大西洋に中心を持つ及び夏季にサハラ砂漠上に発達するサハラ高気圧と，南方に位置する ITCZ との影響を受け，一般には北～北東の風と北東～東の風の二方向の風からなる季節風が存在するとされている．
筆者らの水路実験により，交互二方向流下で発達する孤立砂丘地形について，その形態から砂丘形成に影響を与えた二方向流の「角度変化量」及び「相対強度」を推定する方法が示された (谷口ら, 2008)．角度変化量（θ）は流向変化時に起きる地形上のクレストラインの変化過程を支配するパラメータで，二方向流を繰り返し受けることで発達する地形の種類を決定する．二つの流れの強度比（α. 二次風のDP 値を一時風のDP値で割った値として定義）は，地形の種類には基本的に影響しない．角度変化量が75~90° の場合と180° の場合には，地形の分裂を伴う特殊な地形が，流れの強度比に依存して形成される．この解析方法には，従来用いられてきたRDP/DPを用いた相図(Wasson and Hyde, 1983) と比較して，『二方向流の条件を重複なく決定できる』 『ふたつの流れの強度が著しく異なる場合にも適用できる』などの利点がある．本研究では，この利点を活かし，従来の評価方法では判別が困難であった第2の流れの影響が小さい二方向流の影響を，砂丘形態から読み取ることを試みた．
モーリタニア西部・西サハラ南部の大西洋岸地域の衛星写真を用いた分析では，αの値は小さい（つまり，2次風の影響が相対的に小さい）が，北東～東寄りの2次風の影響が確認できる．たとえばPort-Étienne の北東120 km に位置する砂丘群では，θが60～90°，α が0.33以下の条件で見られる諸地形が観察された（右図）．このことから，この地域においても二つの高気圧とITCZ の影響による二方向性の風況が示唆される．この地域の二次風のように，影響の小さい流れ成分は，通常の気象観測ではイレギュラーな風に紛れやすい．砂丘地形を用いた風況推定では，そうしたノイズの中から，実際に地形に影響を与えている（つまり，数十年というスケールで繰り返し作用し続けている）二つの風向を指摘することができる．
^* DP (Drift potential, その方角からの風により年間に移動する砂の量に比例する) をもとにした流れの一方向性の指標．全方位のDP の和の絶対値を，全方位のDPの絶対値の和で除算した値．RDP/DP値が1に近いほど流れの一方向性が強い．

文献
谷口圭輔・遠藤徳孝・関口秀雄, 2008. 「角度変動量によって異なる二方向流下の孤立砂丘発達」，2008. 日本地理学会発表要旨集, 74, 125.
Breed, C. S., Fryberger, S. G., Andrews, S., McCauley, C., Lennartz, F., Gebel, D., Horstman, K., 1979. Regional studies of sand seas, using LANDSAT (ERTS) imagery. In: McKee, E. D. (Ed.), A study of Global Sand Seas. USGS Professional Paper 1052, pp. 305-397.
Wasson, R. J. and Hyde, R. 1983. Factors determining desert dune type. Nature 304 : 337-339

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This paper describes past climate and environmental changes during the past 101 to 105 year time scale obtained by recent studies on ice cores from Arctic and Antarctica. Shallow ice cores from Greenland and Svalbard show clear North Atlantic Oscillation (NAO) signals and explosive volcanic activities in the Northern Hemisphere and the equatorial regions. A deep ice core drilled to 2503 m at Dome Fuji, Antarctica covers the past 320 ka, which includes 3 glacial-interglacial cycles with Milankovitch cycles of about 20, 40, and 100 ka. Major chemical compositions and microparticle flux show high concentrations in glacials and low concentrations in interglain high-middle latitudes during glacial-interglacial cycles. The Dome Fuji deep ice core contains 25 visible tephra layers. An analysis of the chemical compositions shows the possible source volcanoes in and around the Antarctica.

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Across circumpolar region many wild reindeer populations are declining coincidently, and global warming is considered one of primary causes of this phenomenon. Various environmental factors induce by global warming may affect reindeer population dynamics. In this paper major factors regulating reindeer population are reviewed, and their influences to reindeer herding are examined. Climatic change influences local reindeer populations directly through absolute/relative forage availability, and indirectly through acceleration of human activities. Absolute forage availability includes biomass and quality of reindeers’ diet. Climatic variables influence vegetation, its nutritive value and phenology, then they affect reindeer physical condition, productivity and calf survival. Relative forage availability is based on absolute forage availability and accessibility to them, and includes snow depth and hardness, insect harassment. In winter much snow and ice layer disturb reindeer from grazing. Meanwhile in summer reindeer run away for a long time to avoid insect harassment and cannot forage sufficiently. Both of them lead shortage of energy needs and excessive energy cost, and may influence reindeer physical condition. Due to global warming accessibility of the Arctic regions for human activities are increasing, and many of them may disturb reindeer forage and spoil their habitat. They includes “line corridors” (roads, railways, oil pipe lines and so on), development projects (forestry, mining and so on) and recreational activities. These limiting factors similarly affect local reindeer herding. However there are some unique characteristics peculiarly in reindeer herding. First, as coat color of domestic reindeer is highly variable, it may accelerate insect harassment. Second, as pastures of domestic reindeer are relatively limited, damage of habitat are severer than wild reindeer. Third, as population traits of domestic reindeer may differ from wild one, sensitivity to environmental change also may be different. Through these factors and their multiple effects, global warming may economically influence reindeer herding.

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