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Abstract The Hunga‐Tonga Hunga‐Ha'apai volcano underwent a series of large‐magnitude eruptions that generated broad spectra of mechanical waves in the atmosphere. We investigate the spatial and temporal evolutions of fluctuations driven by atmospheric acoustic‐gravity waves (AGWs) and, in particular, the Lamb wave modes in high spatial resolution data sets measured over the Continental United States (CONUS), complemented with data over the Americas and the Pacific. Along with >800 barometer sites, tropospheric observations, and Total Electron Content data from >3,000 receivers, we report detections of volcano‐induced AGWs in mesopause and ionosphere‐thermosphere airglow imagery and Fabry‐Perot interferometry. We also report unique AGW signatures in the ionospheric D‐region, measured using Long‐Range Navigation pulsed low‐frequency transmitter signals. Although we observed fluctuations over a wide range of periods and speeds, we identify Lamb wave modes exhibiting 295–345 m s−1phase front velocities with correlated spatial variability of their amplitudes from the Earth's surface to the ionosphere. Results suggest that the Lamb wave modes, tracked by our ray‐tracing modeling results, were accompanied by deep fluctuation fields coupled throughout the atmosphere, and were all largely consistent in arrival times with the sequence of eruptions over 8 hr. The ray results also highlight the importance of winds in reducing wave amplitudes at CONUS midlatitudes. The ability to identify and interpret Lamb wave modes and accompanying fluctuations on the basis of arrival times and speeds, despite complexity in their spectra and modulations by the inhomogeneous atmosphere, suggests opportunities for analysis and modeling to understand their signals to constrain features of hazardous events.
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This content will become publicly available on June 11, 2025
Atmospheric and Ionospheric Responses to Orographic Gravity Waves Prior to the December 2022 Cold Air Outbreak
Abstract Mountain waves are known sources of fluctuations in the upper atmosphere. However, their effects over the Continental United States (CONUS) are considered modest as compared to hot spots such as the Southern Andes. Here, we present an observation‐guided case study examining the dynamics of gravity waves (GWs) and their impacts on the ionosphere over the CONUS prior to the cold air outbreak in December 2022, which resulted from a significant distortion of the tropospheric polar vortex. The investigation relies on MERRA‐2 and ERA5 reanalysis data sets for the climatological contextualization, analysis of GWs based on National Aeronautics and Space Administration Aqua satellite's Atmospheric Infrared Sounder, 557.7 and 630.0 nm airglow emission observations, and the measurements of ionospheric disturbances retrieved from Global Navigation Satellite System signal‐based total electron content (TEC) and Super Dual Auroral Radar Network observations. We demonstrate that the tropospheric polar jet stream shifted toward the Rocky Mountains, generated large amplitude GWs (up to 11 K of brightness temperature), which, aided by winter‐time winds over mid‐latitudes, could propagate to mesospheric heights. The breaking of GWs plausibly led to the generation of a plethora of secondary acoustic and GWs that eventually emerged as the sources of extensive ionospheric fluctuations of ∼3–30 min periods and up to 0.7 TECu, observed across the entire CONUS for several days. This case offers a valuable demonstration of the interplay between tropospheric circulation and the ionosphere over CONUS, pointing to the need for a better understanding of wave‐driven deep‐atmosphere coupled dynamics.
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- PAR ID:
- 10514172
- Publisher / Repository:
- DOI PREFIX: 10.1029
- Date Published:
- Journal Name:
- Journal of Geophysical Research: Space Physics
- Volume:
- 129
- Issue:
- 6
- ISSN:
- 2169-9380
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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