X-Raying Neutral Density Disturbances in the Mesosphere and Lower Thermosphere induced by the 2022 Hunga-Tonga Volcano Eruption-Explosion

TL;DR

This study uses X-ray observations from the Insight-HXMT satellite to analyze atmospheric density disturbances caused by the 2022 Hunga Tonga eruption, revealing significant depletions and wave structures in the mesosphere and lower thermosphere.

Contribution

First detection of neutral density disturbances in the mesosphere and lower thermosphere caused by a volcanic eruption using X-ray occultation data.

Findings

Severe density depletion up to 1,000 km from eruption site

Weak depletion extending up to 7,000 km for over 8 hours

Wavy structures indicating Lamb or gravity waves

Abstract

We present X-ray observations of the upper atmospheric density disturbance caused by the explosive eruption of the Hunga Tonga-Hunga Ha'apai (HTHH) volcano on 15 January 2022. From 14 January to 16 January, the Chinese X-ray astronomy satellite, Insight-HXMT, was observing the supernova remnant Cassiopeia A. The X-ray data obtained during Earth's atmospheric occultations allowed us to measure neutral densities in the altitude range of ~90-150 km. The density profiles above 110 km altitude obtained before the major eruption are in reasonable agreement with expectations by both GAIA and NRLMSIS 2.0 models. In contrast, after the HTHH eruption, a severe density depletion was found up to ~1,000 km away from the epicenter, and a relatively weak depletion extending up to ~7,000 km for over 8 hr after the eruption. In addition, density profiles showed wavy structures with a typical length scale of either ~20 km (vertical) or ~1,000 km (horizontal). This may be caused by Lamb waves or gravity waves triggered by the volcanic eruption.