Thermospheric atomic hydrogen densities and fluxes from dayside Lyman /α measurements

摘要: Abstract Knowledge of the atomic hydrogen density profile ([H]( z )) in upper atmosphere is important both for studies mesospheric–lower thermospheric (MLT) chemistry and determining thermospheric–lower exospheric densities needed realistic modeling geocoronal ballistic flux distributions. Early work reviewed sparseness relevant data on variation [H] with altitude emphasized. While optical measurements (e.g., Lyman α ) constitute most practical approach currently available, analysis requires radiative transport (RT) [H]( retrieval effectively limited to obtaining values a small number parameters. The key physical parameters interest are exobase c , photochemically initiated upward φ at mesospheric peak . This paper discusses RT-modeling dayside disk–to–limb scanning intensity (4π I couched terms these parameters, aided by use physically motivated parametric model overcoming MSIS limitations MLT altitudes. Illustrative sensitivity study results under solar maximum conditions presented. directly impacts 4π profiles over wide range zenith angles such conditions. mild difficulties unraveling efforts may arise, 4 π expected from several future satellite FUV instruments should permit determination much dayside.