地球の自転の変動について

W E Carter, D S Robertson, J E Pettey

Science (New York, N.Y.)

|June 1, 1984

まとめ

地球の自転速度は,大気中の角運動量交換によって変動する. これらの変動は,ラジオ干渉計と衛星レーザーレンジングで追跡され,特にエルニーニョのイベントの間,昼間の長さに大きく影響します.

科学分野:

地質物理学地質物理学とは地質物理学です.
天文学 (astronomy) 天文学 (astronomy) とは,天文学 (astronomy) とは,天文学 (astronomy) とは,天文学 (astronomy) とは
大気科学大気科学

背景:

地球の自転は,宇宙時間1 (UT1) のミリ秒未満の変動を含む複雑な変動を示しています.
これらの変化を追跡することは,地球システムの動態を理解し,正確なタイムキーピングを維持するために不可欠です.

研究の目的:

地球の自転と日の長さの短期的な変動の原因を調査する.
地球のスピンレートに及ぼす大気過程の影響を定量化するために.

主な方法:

天文学的なラジオ干渉計を用いた地球の自転のミリ秒未満の精度測定.
レーザーはLAGEOS衛星まで幅を広げ,正確な地質測定を行う.
観測された地球の自転の変化と,地球大気における角度運動量データを比較する.

主要な成果:

観測されたUT1の変動は,数週間で最大5ミリ秒に達した.
昼間の長さの変化と,地球大気における角度運動量の変化との間に強い相関が認められた.
大気と固体地球 (マントル) の間の角運動量交換は,週間から複数年の時間スケールでのスピンレート変化の支配的な原動力として特定されています.

結論:

大気の角運動量交換は,様々な時間スケールで地球のスピン速度の変動に影響を与える主要な要因です.
昼間の長さの顕著なピークを含む地球の自転の変化は,1982-1983年の激しいエルニーニョ現象と関連付けられました.
これらの発見は,地球の大気と固体の相互接続性が,その自転を調節することを強調しています.

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