UHの科学者が土星で大規模なエネルギー不均衡を発見(UH Scientists Discover Massive Energy Imbalance on Saturn)

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2024-06-18 ヒューストン大学(UH)

ヒューストン大学の研究者が、土星の大規模なエネルギー不均衡を発見し、惑星科学と進化に新たな光を当てました。この発見は、土星の季節的エネルギー不均衡が初めて観測されたもので、既存のガス巨星の気候モデルに挑戦するものです。カッシーニ探査機のデータを使用して、土星の大きな軌道離心率が吸収される太陽エネルギーの季節変動を引き起こし、エネルギー不均衡が巨大な嵐の発生に重要な役割を果たしていることが判明しました。この研究は、ガス巨星の気候モデルの再評価を必要とする発見であり、次は天王星など他のガス巨星の調査を目指しています。

<関連情報>

カッシーニ探査機、土星の地球規模のエネルギー不均衡を発見 Cassini spacecraft reveals global energy imbalance of saturn

Xinyue Wang,Liming Li,Xun Jiang,Patrick M. Fry,Robert A. West,Conor A. Nixon,Larry Guan,Thishan D. Karandana G,Ronald Albright,Joshua E. Colwell,Tristan Guillot,Mark D. Hofstadter,Matthew E. Kenyon,Anthony Mallama,Santiago Perez-Hoyos,Agustin Sanchez-Lavega,Amy A. Simon,Daniel Wenkert & Xi Zhang
Nature Communications  Published:18 June 2024
DOI:https://doi.org/10.1038/s41467-024-48969-9

UHの科学者が土星で大規模なエネルギー不均衡を発見(UH Scientists Discover Massive Energy Imbalance on Saturn)

Abstract

The global energy budget is pivotal to understanding planetary evolution and climate behaviors. Assessing the energy budget of giant planets, particularly those with large seasonal cycles, however, remains a challenge without long-term observations. Evolution models of Saturn cannot explain its estimated Bond albedo and internal heat flux, mainly because previous estimates were based on limited observations. Here, we analyze the long-term observations recorded by the Cassini spacecraft and find notably higher Bond albedo (0.41 ± 0.02) and internal heat flux (2.84 ± 0.20 Wm−2) values than previous estimates. Furthermore, Saturn’s global energy budget is not in a steady state and exhibits significant dynamical imbalances. The global radiant energy deficit at the top of the atmosphere, indicative of the planetary cooling of Saturn, reveals remarkable seasonal fluctuations with a magnitude of 16.0 ± 4.2%. Further analysis of the energy budget of the upper atmosphere including the internal heat suggests seasonal energy imbalances at both global and hemispheric scales, contributing to the development of giant convective storms on Saturn. Similar seasonal variabilities of planetary cooling and energy imbalance exist in other giant planets within and beyond the Solar System, a prospect currently overlooked in existing evolutional and atmospheric models.

1701物理及び化学
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