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Latitudinal distribution of solar wind as deduced from Lyman alpha measurements: An improved method

Abstract : In this work we examine the possibility of deducing the latitudinal distribution of the solar ionization rate using Prognoz 6 Lyman alpha data in a more general and flexible way than previously examined. Using so‐called hot model for the hydrogen distribution and the optically thin model for the resonance scattering, theoretical Lyman alpha intensity for the interstellar hydrogen is calculated and compared with the intensity data measured by Prognoz 6. Varying the latitudinal dependence of the ionization rate, the distributions, which produce the best fit with the data, are analyzed for four different measuring sessions. As a result, we get four ionization rate distributions that have two common features. The ionization rate is enhanced near the solar equator, and large broad plateaus exist around heliographic latitudes ±30° to ±70°. The latitudinal distribution of the average ionization rate about the solar minimum deviates clearly from the spherically symmetric and sinusoidally (harmonically) with the latitude‐varying models used so far. The growth of the solar wind mass flux from the solar polar areas toward the equator corresponds to the earlier results concluded from Lyman alpha measurements. The method used in this work allows a higher latitudinal resolution of the ionization rates. However, there are several uncertainties both in the simulations and in the measurements. The exclusion of time‐dependent effects as well as multiple scattering requires that the results be considered only suggestive.
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Submitted on : Sunday, July 5, 2020 - 1:19:04 PM
Last modification on : Friday, November 13, 2020 - 9:00:05 AM

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T. Summanen, Rosine Lallement, Jean-Loup Bertaux, E. Kyrölä. Latitudinal distribution of solar wind as deduced from Lyman alpha measurements: An improved method. Journal of Geophysical Research Space Physics, American Geophysical Union/Wiley, 1993, 98 (A8), pp.13215-13224. ⟨10.1029/93JA00144⟩. ⟨insu-02889807⟩

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