Geliosphere - parallel CPU and GPU based models of cosmic ray modulation in the heliosphere

Abstract

We present Geliosphere, a numerical model of the modulation of cosmic rays in the heliosphere. The current version of Geliosphere implements the stochastic differential equation method to solve Parker's equation. Sets of 1D and 2D models of Geliosphere solve Parker's equation in a backward-in-time manner for 2D models and in a backward-in-time and forward-in-time manner for 1D models. Geliosphere offers GPU-accelerated implementations of all models. Geliosphere also offers multithread CPU implementations of all available models for users who do not have access to GPUs. To verify the Geliosphere 2D model results at different heliospheric latitudes and radii, we show that the Geliosphere 2D model, with implemented heliospheric polar field modification, fits well with measurements provided by the Kiel Electron Telescope (KET), which is part of the Ulysses COsmic ray and Solar Particle INvestigation (COSPIN) experiment. Program summaryProgram title: GeliosphereCPC Library link to program files:https://doi.org/10.17632/9sb2ywg65w.1Developer's repository link:https://github.com/msolanik/GeliosphereLicensing provisions: BSD-3-ClauseProgramming language: C++Nature of problem: Calculation of the modulation of cosmic rays in the heliosphere including drift effects. Implement a heliospheric magnetic field model with polar correction used for simulation to describe nonecliptic measurements. Implementation of modulation models for CPU and GPU environments.Solution method: Stochastic differential equations are used to solve Parker's equation in forward-in-time and backward-in-time manners. The forward-in-time approach is used for the one-dimensional heliosphere model and the backward-in-time approach for one and two-dimensional heliosphere models. The two-dimensional model results are verified with measurements of the Ulysses spacecraft in non-ecliptic regions of the inner heliosphere.