2022-05-10 カリフォルニア大学バークレー校(UCB)
Image of clouds generated by the underwater eruption of the Hunga Tonga-Hunga Ha’apai volcano on Jan. 15, 2022, captured by the GOES-17 satellite. Crescent-shaped bow shock waves and numerous lighting strikes are also visible. (Image credit: Joshua Stevens, using GOES imagery courtesy of NOAA and NESDIS)
その影響は宇宙にまで及び、高度60マイル以上、地表から約190マイル上空の電離層の電流に影響を及ぼしたことが、現在科学者たちの間で報告されている。
この噴火による電離層への影響は、カリフォルニア大学バークレー校の物理学者が設計・運用するNASAのIonospheric Connection Explorer（ICON）と欧州宇宙機関のSwarm衛星の2つの衛星によって宇宙の果てまで検出されました。
1月15日の火山噴火により、ハリケーン級の強風と電離層（宇宙の果てにある地球の電気を帯びた上層大気層）に異常な電流が発生したことは、本日発行の学術誌「Geophysical Research Letters」で報告されています。ICONの主な目的は、嵐やその他の大気擾乱の、宇宙の果てまでの上層大気への影響を研究することです。
＜関連情報＞
- https://news.berkeley.edu/2022/05/10/effects-of-januarys-tonga-eruption-felt-at-the-edge-of-space/
- https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2022GL098577
2022年1月トンガ火山噴火の電離層ダイナモへの影響。ICON-MIGHTIと群発観測による極端な中立風と流れの観測 Impacts of the January 2022 Tonga Volcanic Eruption on the Ionospheric Dynamo: ICON-MIGHTI and Swarm Observations of Extreme Neutral Winds and Currents
Brian J. Harding,Yen-Jung Joanne Wu,Patrick Alken,Yosuke Yamazaki,Colin C. Triplett,Thomas J. Immel,L. Claire Gasque,Stephen B. Mende,Chao Xiong
Geophysical Research Letters Published: 10 May 2022
https://doi.org/10.1029/2022GL098577
Abstract
The eruption of the Hunga Tonga-Hunga Ha’apai volcano on 15 January 2022 triggered atmospheric waves at all altitudes. The National Aeronautics and Space Administration Ionospheric Connection Explorer (ICON) and European Space Agency Swarm satellites were well placed to observe its impact on the ionospheric wind dynamo. After the Lamb wave entered the dayside, Swarm A observed an eastward and then westward equatorial electrojet (EEJ) on two consecutive orbits, each with magnitudes exceeding the 99.9th percentile of typically observed values. ICON simultaneously observed the neutral wind (90–300 km altitude) at approximately the same distance from Tonga. The observed neutral winds were also extreme (>99.9th percentile at some altitudes). The covariation of EEJ and winds is consistent with recent theoretical and observational results, indicating that the westward electrojet is driven by strong westward winds in the Pedersen region (∼120–150 km). These observations imply that the dynamo is a key mechanism in the ionospheric response to the Tonga disturbance.
