Jul 12 – 23, 2021
Europe/Berlin timezone

Spectral parameterization of GCR observations and reconstruction of solar modulation parameters derived from the Convection-Diffusion approximation

Jul 14, 2021, 12:00 PM
1h 30m


Talk SH | Solar & Heliospheric Discussion


Moshe Godfrey Mosotho (Center for Space Research, North-West University, South Africa)


Galactic cosmic rays (GCRs) entering the heliosphere and propagating towards Earth are subject to various modulation processes including drifts, convection, adiabatic energy changes, and diffusion as a result of the turbulent solar wind. This transport can be described by the Parker equation (Parker, 1965). A widely used first-order approximation of the Parker equation is the Force-Field approximation (FFA), while a similar approximation, the Convection-Diffusion approximation (CDA) is rarely applied. Using PAMELA and AMS-02 observations, the validity of the FFA and the CDA in the energy range 1 MeV to 20 GeV was investigated. The resulting modulation parameters and the effective diffusion coefficient, derived from both approximations over a complete 11-years solar cycle, were compared. Our results show that the CDA appears to be significantly more accurate than the FFA in reproducing the measurements, while the resulting transport parameters are highly dependent on the choice of the local interstellar spectrum and the assumed diffusion coefficient parameters. Based on these findings, we therefore propose to use the CDA as a more suitable approximation than the widely used FFA for space weather applications, especially for dosimetric studies where an accurate GCR parametrization is essential.


Galactic cosmic-rays, Solar modulation

other Collaboration No answer
Subcategory Experimental Results
Collaboration other (fill field below)

Primary authors

Moshe Godfrey Mosotho (Center for Space Research, North-West University, South Africa) Prof. Du Toit Strauss (Center for Space Research, North-West University, South Africa)

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