Authors: Pierre-Simon Mangeard (University of Delaware), David Ruffolo (Mahidol University), John Clem (University of Delaware), Paul Evenson (University of Delaware)

Neutron monitors are ground-based instruments used to detect and measure the flux of Galactic cosmic rays (GCR) and solar energetic particles, specifically the secondary neutrons produced when primary cosmic rays interact with the Earth’s atmosphere. Before reaching Earth, the GCRs propagate through the heliosphere. Solar activity dictates the properties of the interplanetary medium that influences the flux of the GCR impinging on Earth. Using the SpaceShip Earth network of neutron monitors located around the world, we calculate a first-order anisotropy of the GCR flux at Earth. We call the direction of maximum flux “axis of symmetry”. We study the alignment between the hourly axis of symmetry and multi-hour averages of the interplanetary magnetic field observed by the spacecraft DSCOVR since 2018. We find improved alignment when comparing with a multi-hour averaged magnetic field rather than the instantaneous field. This shows that the local cosmic ray anisotropy provides some sensitivity to the magnetic field at distant locations, and we speculate on possible ways to employ this for space weather forecasting.