Submitting Campus
Daytona Beach
Department
Physical Sciences
Document Type
Article
Publication/Presentation Date
3-9-2012
Abstract/Description
High precision observations during Solar Cycle 23 using the Wisconsin H‐alpha Mapper (WHAM) Fabry‐Perot quantify a factor of 1.5 ± 0.15 higher Balmer α column emission intensity during near‐solar‐maximum than during solar minimum conditions. An unresolved question is how does the observed solar cycle variation in the hydrogen column emission compare with that calculated from the hydrogen distribution in atmospheric models? We have compared WHAM solar minimum and near‐solar‐maximum column intensity observations with calculations using the thermospheric hydrogen density profile and background thermospheric conditions from the Mass Spectrometer Incoherent Scatter (NRLMSISE‐00) empirical model extended to exospheric altitudes using the analytic exosphere model of Bishop (1991). Using this distribution, we apply the lyao_rt global resonance radiative transfer code of Bishop (1999) to calculate expected intensities that would be observed from the ground for the viewing conditions of the observations. The observed intensities are brighter than those calculated for the corresponding conditions, indicating that when MSIS is used as the thermospheric hydrogen distribution the derived intensities are too low. Additionally, both the observed and calculated WHAM hydrogen column emission intensities are higher for near‐solar‐maximum than for solar minimum conditions. There is better agreement between observations and intensities calculated using the evaporative analytic exosphere model at solar maximum, suggesting an underestimation of modeled satellite atoms at high altitudes. This result is consistent with sensitivity studies using the option for a quasi‐exobase for satellite atoms to account for the creation of satellite orbits from charge exchange collisions.
Publication Title
Journal of Geophysical Research
DOI
https://doi.org/10.1029/2011JA017074
Publisher
American Geophysical Union
Grant or Award Name
National Science Foundation ATM-0334611, ATM-0836367, and AST-9619424
Scholarly Commons Citation
Nossal, S. M., E. J. Mierkiewicz, and F. L. Roesler (2012), Observed and modeled solar cycle variation in geocoronal hydrogen using NRLMSISE-00 thermosphere conditions and the Bishop analytic exosphere model, J. Geophys. Res., 117, A03311, doi:10.1029/2011JA017074.
Additional Information
Dr. Mierkiewicz was not affiliated with Embry-Riddle Aeronautical University at the time this paper was published.