中緯度の山脈と乾燥した気候

S Manabe, A J Broccoli

Science (New York, N.Y.)

|January 12, 1990

まとめ

山々は北半球における乾燥した気候の形成に重要な役割を果たしています. 気候モデルでオログラフィーを削除すると,かなり湿度の高い条件が生まれ,山が示されます.

科学分野:

気候学気候学
大気科学大気科学
ジオモルフォロジージオモルフォロジー

背景:

北半球の中央緯度では,広範囲にわたる乾燥した気候が表れています.
地形的な特徴,特に山脈が地域の乾燥に及ぼす影響は,完全に理解されていません.
以前の古気候データによると,主要な山の上昇前に干ばつの減少が示唆されています.

研究の目的:

北半球の中緯度における乾燥した気候を維持する上で山の役割 (オログラフィ) を調査する.
シミュレートされた気候条件をオログラフィー付きとオログラフィーなしで比較し,降水量と大気循環への影響を理解する.

主な方法:

オーログラフィーの有無でシミュレーションを実行するために,グローバル気候モデルを利用した.
シミュレートされた大気循環パターン,嵐の発生,水分輸送を分析した.
モデルの出力を観測された気候データと古気候の証拠と比較した.

主要な成果:

オーログラフィーのシミュレーションでは,中央アジアと北米西部で観測された乾燥した気候を再現しました.
オーログラフィーの欠如により,これらの地域ではシミュレートされた湿気気候が生まれました.
オーログラフィは沈下を誘導し,上流の嵐の発生を制限し,下流の嵐の発生を強化し,大陸の内部への水分輸送を減少させることが判明しました.

結論:

山は,大陸内部の乾燥状態を確立し維持する重要な要因です.
このメカニズムは,オログラフィ的に誘発された大気循環パターンを含み,一部の地域で降雨を抑制し,水分輸送に影響を与えます.
これらの発見は,山の上昇と干ばつの増加との関連を示唆する古気候の証拠と一致しています.

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