Modeling Long-Term Cosmic Ray Transport: The Role of Magnetic Turbulence Uncertainties in Heliospheric Field Reconstruction

Cosmogenic nuclide records can in principle allow for the estimation of the behaviour of the heliospheric magnetic field (HMF) in the distant past. This study focuses on understanding how magnetic field turbulence uncertainties impact cosmic ray (CR) transport modeling on long time scales. We present a 3D time-dependent ab initio CR modulation code that utilizes theoretically and observationally motivated temporal profiles of heliospheric parameters that influence CR transport, emphasizing both large-scale parameters (such as the tilt angle) and small-scale turbulence parameters. The model is validated against spacecraft observations of galactic CR proton differential intensities for 1977-2001, showing good agreement with observed CR intensity profiles. To investigate pre-space age cosmic ray modulation, we applied historic HMF estimates from McCracken & Beer (2015) as model inputs, revealing clear evidence of drift effects during the Dalton Minimum. The study demonstrates the critical role of magnetic turbulence characterization in understanding historic cosmic ray modulation, and the uncertainties therein