水同位体比D/H,18O/16O,17O/16Oは,雲の中と外で,脱水経路を地図化しています
Christopher R Webster1, Andrew J Heymsfield
1Earth and Space Sciences Division, Jet Propulsion Laboratory (JPL), California Institute of Technology, Pasadena, CA 91109, USA. chris.r.webster@jpl.nasa.gov
Science (New York, N.Y.)
|December 6, 2003
まとめ
サールス雲の同位体分析は,上部トロポスフィアの有意な水蒸気枯渇を明らかにする. これは,様々な脱水過程を示し,氷粒子は水運搬において重要な役割を果たしている.
科学分野:
- 大気科学 大気科学
- クラウド物理学 クラウド物理
- イソトープ地球化学 イソトープ地球化学
背景:
- サールス雲は,地球の放射線バランスと水循環にとって極めて重要です.
- トロポスフィアの上部の水蒸気同位体組成を理解することは,気候モデリングに不可欠です.
- 以前の研究では,亜熱帯のシラス雲内の同位体比に関するデータが限られていた.
研究 の 目的:
- 亜熱帯のシラス雲の内外における水の同位体比を測定する.
- トロポスフィアの上部の水蒸気の起源と脱水メカニズムを調査する.
- 地元で形成された氷粒子を,より低い高度から持ち上げられたものから区別するために.
主な方法:
- レーザー吸収スペクトロスコピーは,水の同位体比を測定するために使用されました.
- 局所測定は,シラス雲の中で行われました.
- 分析は水蒸気と氷粒子の同位体シグネチャーに焦点を当てた.
主要な成果:
- 熱帯および亜熱帯の上部熱帯圏水蒸気で,これまでに記録されていない広範囲の同位体枯渇が観察されました.
- この枯渇に寄与するコンベクティブおよび漸進的な脱水メカニズムの両方を特定しました.
- 採取した上層熱帯圏水の25%が氷の粒子であり,形成過程を示す明確な同位体シグネチャーを持つことを決定しました.
結論:
- サブ熱帯の上層熱帯圏の水蒸気は,複数の経路を通って重要な脱水を経験します.
- サーラス雲の氷粒子は,大気中の水の輸送と処理のための重要なトレーサーです.
- 同位体分析は,雲の形成と熱帯圏上部の水循環に関する重要な洞察を提供します.
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