We propose an effort aimed at bringing together recent advances in the theory and modeling of turbulent heating in the solar atmosphere with modern observational constraints. Our approach will be…

Predictive Science Inc., a for-profit research organization, was awarded a $533,918 grant from the National Aeronautics and Space Administration (NASA) to conduct research on modeling and observational analysis of turbulent heating in the solar atmosphere and solar wind. The research aims to address key science questions related to the heating and acceleration mechanisms driving the fast and slow solar wind, as well as plasma structuring and non-thermal properties observed in polar coronal holes. The grant funding will support the company's efforts to incorporate recent advances in theoretical and modeling approaches, and leverage a range of NASA solar observation data to benchmark and improve the understanding of these complex solar phenomena. This research aligns with NASA's Heliophysics program goals and the recommendations of the Heliophysics Decadal Survey.

We propose an effort aimed at bringing together recent advances in the theory and modeling of turbulent heating in the solar atmosphere with modern observational constraints. Our approach will be twofold, on one end incorporating new techniques in modeling the global solar corona and solar wind, and on the other using the latest observational constraints to benchmark, improve, and possibly rule out mechanisms and formulations. Although this is a vast area of study, we focus on two key science questions specifically selected to span a large dynamic range of scale and scientific interest from the corona to one AU, namely: 1) is the relatively steady heating and acceleration that we expect from wave turbulence sufficient to explain the relative charge-state and speed stratification of the fast and slow solar wind? 2) can the heating and acceleration from wave turbulence account for the plasma structuring and non-thermal widths measured in polar coronal holes? To address these questions, the central theme of our research plan will be conducting focused, realistic experiments using a multidimensional thermodynamic MHD model of the solar corona and solar wind. We will interpret our results in the direct context of observations and forward-modeled observables. Our heating and acceleration model will be based on a wave-turbulence-driven (WTD) formulation that captures the macroscopic propagation, reflection, and dissipation of low frequency alfvenic turbulence. Part of the research plan will focus on testing and benchmarking approximations for the heating and reflection terms in the presence of magnetic interface regions, such as coronal streamers and the fast and slow wind interface. Most importantly, our research plan emphasizes careful observational synthesis and model comparison---examining not only fullsun EUV images, but also emission lines and line-widths at various regions in the corona, and charge states in the solar wind. We can accomplish this by leveraging a new capability in our model, one that allows US to track the time-dependent, non-equilibrium ionization state of minor ions at all spatial locations in the model. This will enable US to vastly improve our calculations of synthetic observables all the way from the low corona (soho/EIT, stereo/euvi, SDO/AIA, and hinode/EIS), to the extended corona (soho/uvcs), to 1AU (ACE/wind and ulysses). This project is also timely and relevant to the goals of NASA and the heliophysics decadal survey. Our effort brings together recent advances in global coronal modeling and vets them using a wealth of information gleaned from NASA missions and instruments. Bridging the GAP between numerical models and remote sensing diagnostics has become crucial for interpreting the complexity of modern observations, and this situation will continue with the upcoming parker solar probe and solar orbiter missions. This context is specifically relevant for the science of polar coronal holes and the slow and fast properties of the solar wind, which we study here. To address these questions we have formed a team with a broad range of expertise from analytical theory, to numerical models, to observational analysis---a makeup representative of the current scope and goals of the heliophysics supporting research program.