まとめ
1988年の米国における干ばつの原因は主に,大気循環に影響を与えたエルニーニョを含む太平洋の熱帯変動によるものでした. 地表のプロセスが干ばつを悪化させたのかもしれない.
科学分野:
- 気候学 気候学
- 大気科学 大気科学
- 海洋学 海洋学 海洋学
背景:
- 1988年のアメリカ合衆国の夏の干ばつが,例外的に広範囲にわたるものでした.
- 干ばつの発生と地域的な影響は,米国全体で様々でした.
- 前年のエルニーニョ (1986年−1987年) は,西海岸の干ばつと一致した.
研究 の 目的:
- 1988年の米国における干ばつの原因を調査する.
- 熱帯太平洋と大気間の相互作用の役割を決定する.
- 大気循環の異常の影響を評価する.
主な方法:
- 干ばつ発生と地域差の分析.
- 大気循環パターン (ジェットストリーム,アンチサイクロン条件) の調査.
- 安定状態の惑星波大気モデルを利用した.
主要な成果:
- 米国中北部の干ばつと,記録的な低雨量 (1988年4月~6月) が関連している.
- 移動したジェットストリームを含む観測された大気異常は,熱帯太平洋から発生しました.
- モデルの結果は,北米の波動列車に強制的に移動した熱帯間の収束地帯 (ITCZ) の加熱異常を示した.
結論:
- 熱帯太平洋における大気と海洋の結合システムにおける変動が,1988年の干ばつの主な原因であった.
- 移動したITCZに関連した異常な大気熱は,重要な循環パターンを生成することができます.
- 陸地表面のプロセスが干ばつの重度と期間を悪化させた可能性が高い.
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