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Title: Atmospheric changes caused by galactic cosmic rays over the period 1960–2010

The Specified Dynamics version of the Whole Atmosphere Community Climate Model (SD-WACCM) and the Goddard Space Flight Center two-dimensional (GSFC 2-D) models are used to investigate the effect of galactic cosmic rays (GCRs) on the atmosphere over the 1960–2010 time period. The Nowcast of Atmospheric Ionizing Radiation for Aviation Safety (NAIRAS) computation of the GCR-caused ionization rates are used in these simulations. GCR-caused maximum NOx increases of 4–15 % are computed in the Southern polar troposphere with associated ozone increases of 1–2 %. NOx increases of ~1–6 % are calculated for the lower stratosphere with associated ozone decreases of 0.2–1 %. The primary impact of GCRs on ozone was due to their production of NOx. The impact of GCRs varies with the atmospheric chlorine loading, sulfate aerosol loading, and solar cycle variation. Because of the interference between the NOx and ClOx ozone loss cycles (e.g., the ClO + NO2+ M → ClONO2+ M reaction) and the change in the importance of ClOx in the ozone budget, GCRs cause larger atmospheric impacts with less chlorine loading. GCRs also cause larger atmospheric impacts with less sulfate aerosol loading and for years closer to solar minimum. GCR-caused decreases of annual average global totalmore » ozone (AAGTO) were computed to be 0.2 % or less with GCR-caused column ozone increases between 1000 and 100 hPa of 0.08 % or less and GCR-caused column ozone decreases between 100 and 1 hPa of 0.23 % or less. Although these computed ozone impacts are small, GCRs provide a natural influence on ozone and need to be quantified over long time periods. This result serves as a lower limit because of the use of the ionization model NAIRAS/HZETRN which underestimates the ion production by neglecting electromagnetic and muon branches of the cosmic ray induced cascade. Furthermore, this will be corrected in future works.« less
 [1] ;  [2] ;  [2] ;  [3] ;  [4]
  1. NASA Goddard Space Flight Center, Greenbelt, MD (United States)
  2. National Center for Atmospheric Research, Boulder, CO (United States)
  3. NASA Langley Research Center, Hampton, VA (United States)
  4. NASA Goddard Space Flight Center, Greenbelt, MD (United States); Science Systems and Applications Inc., Lanham, MD (United States)
Publication Date:
OSTI Identifier:
Accepted Manuscript
Journal Name:
Atmospheric Chemistry and Physics (Online)
Additional Journal Information:
Journal Name: Atmospheric Chemistry and Physics (Online); Journal Volume: 16; Journal Issue: 9; Journal ID: ISSN 1680-7324
European Geosciences Union
Research Org:
NASA Goddard Space Flight Center (GSFC), Greenbelt, MD (United States)
Sponsoring Org:
USDOE Office of Science (SC); NASA Headquarters Atmospheric Composition Modeling and Analysis Program; National Science Foundation (NSF)
Country of Publication:
United States
79 ASTRONOMY AND ASTROPHYSICS; 54 ENVIRONMENTAL SCIENCES; solar proton events; middle atmosphere; odd nitrogen; 2-dimensional model; particle-precipitation; chemical-composition; space exploration; ozone depletion; stratosphere; radiation