天王星と海王星におけるジェットストリームの大気収束

Yohai Kaspi¹, Adam P Showman, William B Hubbard

¹Department for Environmental Sciences and Center for Planetary Science, Weizmann Institute of Science, Rehovot 76100, Israel. yohai.kaspi@weizmann.ac.il

Nature

|May 17, 2013

まとめ

天王星と海王星の大気動態は,1000km未満の薄い気象層に限定されています. 重力場測定は,これらの強力なジェットストリームが,これらのガス巨人の最も外側の層から発生することを明らかにしています.

科学分野:

惑星科学は惑星科学である.
大気ダイナミクス大気ダイナミクス
地質物理学地質物理学とは地質物理学です.

背景:

外側の惑星は,雲のレベルで強い東西ジェットストリームを示しています.
これらの大気動力の深さは,惑星の内部とエネルギーを理解するために重要です.
2つの仮説が存在します:浅い大気中のプロセスと深い内部ダイナミクス.

研究の目的:

天王星と海王星の大気動力の深さを決定するために.
惑星のジェットストリームの駆動機構に関する仮説を検証する.
大気モデルを制約するために重力場測定を用いる.

主な方法:

天王星と海王星の4次重力ハーモニック (J4) の分析.
惑星の質量と大気深さの分布に関する重力場データ.
観測上の制約を,大気循環の理論的モデルと比較する.

主要な成果:

重力場の測定は,天王星の質量の最も外側の0.15%にダイナミクスを制限します.
重力場測定は,ダイナミクスを,海王星の質量の最も外側の0.2%に制限しています.
これは,大気動力学が,深さ約1,000kmの浅い気象層に限定されていることを示しています.

結論:

ジェットストリーム生成の深層内部ダイナミクス仮説は,天王星と海王星ではありそうにない.
これらの氷の巨人の大気動態は,薄い表面層に限定されています.
重力ハーモニックは,巨大な惑星の内部構造と動態を調査するための強力なツールです.

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