Mittlere Atmosphäre, solare Variabilität, und Klimawechselwirkungen

Die mittlere Atmosphäre ist der Höhenbereich zwischen etwa 10 km und 120 km und stellt einen Übergangsbereich dar zwischen der unteren Atmosphäre und dem erdnahen Weltraum. Sie wird stark beeinflusst sowohl durch externe Einflüsse (solare Variabilität), als auch durch die untere Atmosphäre (Wettersysteme, atmosphärische Wellen, Vulkanausbrüche, starke Wildfeuer). Die Zirkulation der mittleren Atmosphäre kann Einfluss auf das Wettergeschehen in der unteren Atmosphäre haben, und solare Signale, die durch die mittlere Atmosphäre nach unten transportiert werden, sind ein Teil der natürlichen Variabilität des Klimasystems. Unser Verständnis der solar-terrestrischen Wechselwirkungen können ebenfalls dazu beitragen, die Atmosphären von erdähnlichen (Gesteins-) Exoplaneten in stellaren Systemen mit sehr aktiven Sternen zu verstehen. 

Photo of a Pyrocumulonimbus cloud NWS Albuquerque
Wechselwirkung von mittlerer und unterer Atmosphäre:
Aurora seen from the ISS, @ESA, CC BY-SA 3.0 IGO ESA, Space_Aurora.jpg, CC BY-SA 3.0 IGO
Sonnenvariabilität und die Erdatmosphäre:
Pale blue dot NASA/JPL - Caltech / Space Science Team
Stellare Aktivität und Exoplaneten-Atmosphären:

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Fluxes of precipitating electrons and the corresponding atmospheric ionizationCC BY
Ring current electron precipitation

Electrons from the ring currents and radiation belts accelerated to hundreds of keV precipitate into the atmosphere during geomagnetic storms. This precipitating flux and the ensuing atmospheric ionization are modelled here with a magnetospheric model, considering different acceleration mechanism within the ring currents.

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A CME of December 2003 seen by different instruments on SOHOSOHO (ESA & NASA)
Towards improved solar forcing for chemistry-climate model experiments

Solar variability is part of the natural forcing of the climate system. For climate model experiments, forcing data of the spectral irradiance and particle fluxes of high precission are necessary over many decades. The forcing data provided for the Coupled Model Intercomparison Project CMIP6 were extensively used for scientific studies and tested in intercomparison experiments; here, a roadmap is discussed for an improved forcing data-set for the upcoming CMIP7. 

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Theoretical transit spectra of Trappist-1e considering different types of Earth-likes atmospheres, with and without stellar particle events. From Herbst et al, 2023:
What impact does stellar activity have on observable spectral features of Earth-like exoplanets?

M-stars like Trappist can be much more active than the sun. But how does that affect possible atmospheres of planets in orbit around such starts? And, will that have an impact on the detectability of biosignatures like ozone?

This is explored in a recent publications exemplarily for the exoplanet Trappist 1e.

Draft of the paper on arxiv:
Ozone loss due to the "Halloween" solar storm of October 2003 compared to the AD774/775 extreme eventLarge solar particle events and the impact of chlorine ion chemistry

How does a once-per-millenia solar storm compare to the well-known "Halloween" solar storm of October 2003, and does the anthropogenic chlorine loading of the early 20th century increase the impact on stratospheric ozone?


For a short summary, see the EGU blog here

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Modelled change of UV index after a once-per-millenia solar extreme eventWhat would an extreme solar event do to the atmosphere?

Even the largest solar proton events of the last 70 years had a relatively small impact on the atmosphere below 30 km altitude. But what would happen if a much larger solar event as occurred, e.g., in paleonucleid records in AD774/775? We investigated the impact on atmospheric composition and the change in UV radiation at the surface.

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Aurora seen from ISSOnline-seminar on magnetospheric electron precipitation

Want to learn more about the impact of electron precipitation from the radiation belts? Watch recent online-seminar from Miriam Sinnhuber:

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Daily mean NOx from MIPAS at 68 km, 14/12/2009Exceptional electron precipitation observed by balloon

Exceptionally electron precipitation was observed by a research balloon on December 14, 2009, in magnetic mid-latitudes. Trace gas observations confirm that precipitation in midlatitudes probably took place, despite low geomagnetic activity. 

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NO in the mesosphere and lower thermosphere: MIPAS observations versus model resultsResults of Heppa III intercomparison experiment published

New results from round III of the international High Energetic Particle Precipitation into the  Atmosphere (HEPPA) intercomparison experiment published in JGR space physics recently, with focus on mesospheric NO formation during a geomagnetic storm in April 2010.

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