Shyam Parhi

Sensitivity of Cosmic Ray Modulation to an Outer Scale of Turbulence

We develop an ab initio modulation model, in which the diffusion tensor is specified by particle transport theory based on observed properties of the turbulence, and the spatial variation is determined by turbulence transport models that specify how turbulence properties vary throughout the heliosphere. Using a recent perpendicular diffusion treatment based upon the Taylor‐Green‐Kubo equation we study the sensitivity of solar wind modulation to an outer scale of turbulence, the “ultrascale”, which is very poorly understood. For larger values of the ultrascale (approximately hundreds of correlation lengths) we find that the radial profile of modulated cosmic ray protons compares well with the observational data from Voyager and IMP for both polarities.