トロピカルサイクロンでは,風速が高い場合のレーザー抵抗係数が低下します
Mark D Powell1, Peter J Vickery, Timothy A Reinhold
1National Oceanic and Atmospheric Administration, Atlantic Oceanographic and Meteorological Laboratory, Hurricane Research Division, Miami, Florida 33149, USA. Mark.Powell@noaa.gov
Nature
|March 21, 2003
まとめ
極端な風の下での海洋と大気間のモメンタム転送は,現在のモデルに反して,表面フルースの平準化を示しています. この発見は,ハリケーン予測とリスク評価に影響を及ぼします.
科学分野:
- 大気科学 大気科学
- 海洋学 海洋学とは
- 地質物理学 地質物理学とは地質物理学です.
背景:
- 大気と海洋の運動量移転は,天気と気候の鍵です.
- 直接的な測定は低風速に限られており,極端な状況では抽象化が必要である.
- 熱帯サイクロンは,海洋境界層のダイナミクスを理解するためのユニークな課題を提示します.
研究 の 目的:
- GPS探査データを用いて,熱帯サイクロンにおける風のプロファイルとモメンタム転送を分析する.
- ハリケーン・フォースの風の下での表面運動量流動の振る舞いを調査するために.
- 気候モデルで使用されている既存の表面流量パラメータ化と発見を比較する.
主な方法:
- 海洋境界層における風速プロフィールを測定するために,グローバルポジショニングシステム (GPS) の探査機を使用した.
- 1997年以降のデータを分析し,熱帯サイクロンの状況に焦点を当てました.
- 表面張力,粗さ長さ,中性安定阻力係数を決定する.
主要な成果:
- 高さ200mまでの風速の対数値増加が観察されました.
- 確認された最大風速は500mで,3kmまで徐々に弱くなります.
- 風速がハリケーン・フォースを超えると,表面モモントム・フクスレベルが低下することを発見した.
結論:
- 気候およびリスク評価モデルで使用されている現在の表面流量パラメータ化は,極端な風の条件では不正確である可能性があります.
- モモントムフルースの平準化は,大気と海洋の相互作用に関する既存のモデルに挑戦しています.
- この研究は,ハリケーンモデリングと予測の精度を向上させるために重要なデータを提供します.
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