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New Method to Calculate the Time Variation of the Force Field Parameter
Author(s) -
Santiago A.,
Lara A.,
EnríquezRivera O.,
CaballeroLopez R. A.
Publication year - 2018
Publication title -
journal of geophysical research: space physics
Language(s) - English
Resource type - Journals
eISSN - 2169-9402
pISSN - 2169-9380
DOI - 10.1002/2017ja024914
Subject(s) - heliosphere , physics , parameterized complexity , cosmic ray , solar wind , computational physics , neutron monitor , interplanetary magnetic field , modulation (music) , astrophysics , interplanetary spaceflight , polynomial , spectral line , magnetic field , statistical physics , algorithm , mathematical analysis , mathematics , quantum mechanics , acoustics
Galactic cosmic rays (CRs) entering the heliosphere are affected by interplanetary magnetic fields and solar wind disturbances resulting in the modulation of the CR total flux observed in the inner heliosphere. The so‐called force field model is often used to compute the galactic CR spectrum modulated by the solar activity due to the fact that it characterizes this process by only one parameter (the modulation potential, ϕ). In this work, we present two types of an empirical simplification (ES) method used to reconstruct the time variation of the modulation potential (Δϕ). Our ES offers a simple and fast alternative to compute the Δϕ at any desired time. The first ES type is based on the empirical fact that the dependence between Δϕ and neutron monitor (NM) count rates can be parameterized by a second‐degree polynomial. The second ES type is based on the assumption that there is a inverse relation between Δϕ and NM count rates. We report the parameters found for the two types, which may be used to compute Δϕ for some NMs in a very fast and efficient way. In order to test the validity of the proposed ES, we compare our results with Δϕ obtained from literature. Finally, we apply our method to obtain the proton and helium spectra of primary CRs near the Earth at four randomly selected times.