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| Format: | Preprint |
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2026
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| Online Access: | https://arxiv.org/abs/2602.22987 |
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| _version_ | 1866911533803503616 |
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| author | Pereira, Luiz Augusto Stuani Anjos, Rita C. |
| author_facet | Pereira, Luiz Augusto Stuani Anjos, Rita C. |
| contents | We present a Monte Carlo study of galactic cosmic-ray (GCR) energy deposition and its implications for stratospheric chemistry, performed with the Geant4 toolkit. Primary nuclei (protons, $α$, CNO, and Si) were propagated through an atmosphere modeled from 0 to 120~g~cm$^{-2}$, considering both Polar ($R_{\mathrm{c}}=0.1$~GV) and Equatorial ($R_{\mathrm{c}}=15$~GV) geomagnetic cutoff conditions. The simulations resolve the variation of energy deposition with altitude for primary and secondary particles, revealing that $\sim$~96\% of the stratospheric energy budget arises from cascade secondaries within the 15--35~km domain. By converting layer-resolved energy deposition into ion pair production rates, we quantify the resulting formation of odd nitrogen (NO$_{\rm x}$) and odd hydrogen (HO$_{\rm x}$) radicals, which catalyze the destruction of ozone. The modeled production rates peak between 18 and 22~km altitude, leading to an estimated fractional ozone decrease of order $10^{-3}$--$10^{-2}$ under average GCR fluxes, consistent with observed background modulation over the solar cycle. These results establish a physically consistent link between cosmic-ray induced energy deposition and ozone chemistry, providing a benchmark framework for coupling high-energy particle transport to atmospheric photochemical models. |
| format | Preprint |
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arxiv_https___arxiv_org_abs_2602_22987 |
| institution | arXiv |
| publishDate | 2026 |
| record_format | arxiv |
| spellingShingle | Energy Deposition by Galactic Cosmic Rays and Implications for Ozone Chemistry Pereira, Luiz Augusto Stuani Anjos, Rita C. High Energy Astrophysical Phenomena We present a Monte Carlo study of galactic cosmic-ray (GCR) energy deposition and its implications for stratospheric chemistry, performed with the Geant4 toolkit. Primary nuclei (protons, $α$, CNO, and Si) were propagated through an atmosphere modeled from 0 to 120~g~cm$^{-2}$, considering both Polar ($R_{\mathrm{c}}=0.1$~GV) and Equatorial ($R_{\mathrm{c}}=15$~GV) geomagnetic cutoff conditions. The simulations resolve the variation of energy deposition with altitude for primary and secondary particles, revealing that $\sim$~96\% of the stratospheric energy budget arises from cascade secondaries within the 15--35~km domain. By converting layer-resolved energy deposition into ion pair production rates, we quantify the resulting formation of odd nitrogen (NO$_{\rm x}$) and odd hydrogen (HO$_{\rm x}$) radicals, which catalyze the destruction of ozone. The modeled production rates peak between 18 and 22~km altitude, leading to an estimated fractional ozone decrease of order $10^{-3}$--$10^{-2}$ under average GCR fluxes, consistent with observed background modulation over the solar cycle. These results establish a physically consistent link between cosmic-ray induced energy deposition and ozone chemistry, providing a benchmark framework for coupling high-energy particle transport to atmospheric photochemical models. |
| title | Energy Deposition by Galactic Cosmic Rays and Implications for Ozone Chemistry |
| topic | High Energy Astrophysical Phenomena |
| url | https://arxiv.org/abs/2602.22987 |