3D modeling and turbulence: from the Sun to Voyager 1 Available to Purchase

We compare in‐situ observations at ACE and Ulysses with simulation results obtained from two different 3D models. Specifically, we look at results from the time dependent full 3D MHD HHMS model and also from the quick‐look tool: the 3D HAFv2 kinematic model. These comparisons provide insights into the 3D propagation of interplanetary shocks. We find excellent agreement between results from our 3D models and spacecraft data. Our results also suggest that Voyager 1 and Voyager 2 continue to observe the effects of solar‐induced shocks. The presence of planar magnetic structures is found from ACE to Voyager 1 in association with the Halloween 2003 events. These results are consistent with large‐scale compressions and may have possible consequences for cosmic ray modulation. The results of our models, along with numerous in‐situ observations, illustrate several aspects of interplanetary shock propagation that have implications for future modeling efforts. First, only continuous 3D models can accurately capture the dramatic asymmetries that often evolve over time. Second, although in‐situ observations (at Earth, L₁. etc.) are unquestionably valuable (e.g., for helping to refine or “tune” a model), because shock‐induced effects may sometimes miss a location entirely, any model (1D, 2D, or even 3D) that relies only on such observations can often make seriously erroneous predictions. Third, along the same lines, any attempt to model the propagation of solar phenomena must begin this propagation at the source — the Sun. And, finally, because such propagation is going to be heavily dependent on the state of the medium through which it is propagating, models must incorporate this pre‐event state. Thus, we emphasize the importance of using these primary solar source data as continuous inputs into models that extrapolate in three dimensions phenomena from the solar surface throughout the heliosphere and into the heliosheath.