Multiple Scattering Effects in the Interplanetary Medium: Evaluation Using SOHO SWAN and MAVEN EUVM Lyman α Measurements. Issue 6 (20th June 2019)

• Record Type: Journal Article
• Authors: Quémerais, Eric; Thiemann, Edward; Snow, Martin; Ferron, Stéphane; Schmidt, Walter
• Is Part Of: Journal of geophysical research. Volume 124:Issue 6(2019)
• Page Start: 3949
• Page End: 3960
• Publication Date: 2019-06-20
• Subjects: interplanetary background -- UV solar irradiance -- radiative transfer; Magnetospheric physics -- Periodicals; Space environment -- Periodicals; Cosmic physics -- Periodicals; Planets -- Atmospheres -- Periodicals; Heliosphere (Astrophysics) -- Periodicals; Geophysics -- Periodicals; 523.01
• DOI: 10.1029/2019JA026674
• Languages: English
• ISSNs: 2169-9380

Abstract

Abstract: Interplanetary background measurements can be used to derive the solar flux that is illuminating the atoms in the interplanetary medium. We present a new algorithm combining measurements from the Solar Wind ANisotropies (SWAN)‐Solar Heliospheric Observatory (SOHO) Lyman α photometer with Earth‐based solar flux measurements to derive the solar illuminating flux at Lyman α in any direction along the ecliptic plane. The modulations of the solar flux and the interplanetary background intensity are proportional. The proportionality coefficient is a direct measurement of the fraction of the interplanetary brightness that is due to single scattering in the interplanetary medium. We find that for an observer at 1 AU from the Sun, single scattering photons represent roughly 70% of the total brightness. This new algorithm is tested by a comparison with actual measurements from the Extreme Ultraviolet Monitor (EUVM)‐Mars Atmosphere and Volatile EvolutioN (MAVEN) solar monitor in orbit around Mars since 2014. Key Points: We present a new method to evaluate the solar flux toward any object in the solar system We evaluate the contribution of multiple scattering to the interplanetary ultraviolet emission