Space Weather & Heliophysics

Earth’s Mesosphere During Possible Encounters With Massive Interstellar Clouds 2 and 7 Million Years Ago

By Keith Cowing

Status Report

astro-ph.EP

September 12, 2024

Filed under astro-ph.EP, astrochemistry, atmosphere, Earth, geophysics, Interstellar, interstellar cloud, Local Bubble, Local Lynx of Cold Cloud, mesosphere, noctilucent cloud, Ozone, space weather

Earth’s Mesosphere During Possible Encounters With Massive Interstellar Clouds 2 and 7 Million Years Ago — Equatorial cuts from MHD simulations (Opher et al., 2024, 2024, accepted) showing the compression of the heliosphere by interstellar clouds with densities of a) 3000 cm−3 and b) 900 cm−3 , where the color contours show neutral hydrogen density. These events may have occurred 2 and 7 Myr ago as our solar system collided with the LxCC and the edge of the Local Bubble, respectively. The red circle shows Earth’s orbit. One can see that Earth experiences densities up to 6000 cm−3 in case (a) and 1500 cm−3 in case (b). — astro-ph.EP

Our solar system’s path has recently been shown to potentially intersect dense interstellar clouds 2 and 7 million years ago: the Local Lynx of Cold Cloud and the edge of the Local Bubble.

These clouds compressed the heliosphere, directly exposing Earth to the interstellar medium. Previous studies that examined climate effects of these encounters argued for an induced ice age due to the formation of global noctilucent clouds (NLCs).

Here, we revisit such studies with a modern 2D atmospheric chemistry model using parameters of global heliospheric magnetohydrodynamic models as input. We show that NLCs remain confined to polar latitudes and short seasonal lifetimes during these dense cloud crossings lasting ∼105 years. Polar mesospheric ozone becomes significantly depleted, but the total ozone column broadly increases.

Furthermore, we show that the densest NLCs lessen the amount of sunlight reaching the surface instantaneously by up to 7% while halving outgoing longwave radiation.

Altitude-latitude plots of the percentage change in ozone concentration between the control case and that of the LxCC (a, b) and that of the Local Bubble (LB) wall (c, d). Panels (a) and (c) are taken on day 42 of the final year, and panels (b) and (d) are taken on day 212. Panel (e) is the percentage change in the total column density of ozone in the LxCC simulation. — astro-ph.EP

Jesse A. Miller, Merav Opher, Maria Hatzaki, Kyriakoula Papachristopoulou, Brian C. Thomas

Comments: 12 pages, 4 figures
Subjects: Earth and Planetary Astrophysics (astro-ph.EP); Astrophysics of Galaxies (astro-ph.GA); Atmospheric and Oceanic Physics (physics.ao-ph)
Cite as: arXiv:2409.06832 [astro-ph.EP] (or arXiv:2409.06832v1 [astro-ph.EP] for this version)
https://doi.org/10.48550/arXiv.2409.06832
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Journal reference: Geophysical Research Letters, volume 51, issue 17, id e2024GL110174 (7 September 2024)
Related DOI:
https://doi.org/10.1029/2024GL110174
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Submission history
From: Jesse Miller
[v1] Tue, 10 Sep 2024 19:18:13 UTC (1,702 KB)
https://arxiv.org/abs/2409.06832
Astrobiology, Space Weather,

Keith Cowing

Explorers Club Fellow, ex-NASA Space Station Payload manager/space biologist, Away Teams, Journalist, Lapsed climber, Synaesthete, Na’Vi-Jedi-Freman-Buddhist-mix, ASL, Devon Island and Everest Base Camp veteran, (he/him) 🖖🏻

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