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Observations of the Sun's surface suggest a nonuniform radiated flux asrelated to the presence of bright active regions and darker coronal holes. Thevariations of the FUV/EUV source radiation can be expected to affect theLyman-alpha backscatter glow measured by spaceborne instruments. In particular,inferring the heliolatitudinal structure of the solar wind from helioglowvariations in the sky can be quite challenging if the heliolatitudinalstructure of the solar FUV/EUV radiation is not properly included in themodeling of the heliospheric glow. We present results of analysis of theheliolatitudinal structure of the solar Lyman-alpha radiation as inferred fromcomparison of SOHO/SWAN satellite observations of the helioglow intensity withmodeling results obtained from the recently-developed WawHelioGlow model. Wefind that in addition to time-dependent heliolatitudinal anisotropy of thesolar wind, also time-dependent heliolatitudinal variations of the intensity ofthe solar Lyman-alpha and photoionizing emissions must be taken into account toreproduce the observed helioglow modulation in the sky. We present a particularlatitudinal and temporal dependence of the solar Lyman-alpha flux obtained as aresult of our analysis. We analyze also differences between polar-equatorialanisotropies close to the solar surface and seen by an observer located farfrom the Sun. We discuss the implications of these findings for theinterpretation of heliospheric-glow observations.

Influence of Heliolatitudinal Anisotropy of Solar FUV/EUV Emissions on Lyman-alpha Helioglow: SOHO/SWAN Observations and WawHelioGlow Modeling