Data Driven MHD simulations using characteristics-based boundary conditions: Tests including gravity, flux emergence, eruptions, and simulated observational noise
Data driven MHD simulations are the most promising pathway toward ascertaining the three dimensional structure of the low solar atmosphere between the photosphere and the Alfven surface. This region is characterized by subsonic to weakly super-Alfvenic flows, a mix of magnetic and pressure dominated plasma regimes, orders of magnitude variations in plasma density and temperature, and strong coupling to the solar interior. The photosphere itself is the lowest surface for which direct observations of emitted photons can be obtained. Those photons provide the most comprehensive constraints available on the plasma and electromagnetic dynamics. Given current observational capabilities, observations of this surface provide a suitable data stream from which to derive boundary conditions for 3D MHD simulations. We process that information stream through the MHD equations represented by the MHD characteristics in order to generate a self-consistent time-dependent boundary conditions for our simulations. In this talk, I present a test of our method against a ground truth simulation that includes gravity and a buoyantly rising magnetic flux tube. The tube emerges and expands into the model chromosphere, transition region, and corona, interacts with a pre-existing magnetic field, and produces an eruption of mass and magnetic field. Further, we test our method's fidelity in the presence of artificial noise introduced to the synthetic driving observations.
Dr Tarr completed his Ph.D. at Montana State University under the guidance of Dr Dana Longcope in 2013. He briefly held a visiting scientist position at the High Altitude Observatory in Boulder in 2014 before accepting a National Research Council (NRC) Research Associateship at the US Naval Research Lab in Washington D.C (2014-2017). He spent two years as a research assistant professor at George Mason University, during which time he began to explore data driven MHD simulations. In 2019 he joined the National Solar Observatory as an Assistant Astronomer in support of the Daniel K. Inouye Solar Telescope, based in Maui, where he has been ever since. His research primarily focuses on energy transfer, storage, and release in the solar atmosphere.