Author: Andrey Stejko

Aug 1, 2021

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Espresso Ristretto /ri’stred ̄o /
noun: a drink of very strong, concentrated espresso.
noun: a COFFIES Espresso Shot that highlights research from a dissertation.

My work focused on 3D global MHD and acoustic modeling of the Sun. While exploring the effect of the near-surface shear layer (NSSL) on the evolution of the global dynamo using the EULAG code (Eulerian/semi-Lagrangian fluid solver), it became apparent that the influence of near-surface shear and convection, as well as the nature of the tachocline and its overshoot region, was fundamental in shaping the period and surface expression of the global solar dynamo. The surface is often omitted in global anelastic simulations of the Sun and any effects of compression in these regions can not be simulated. It became apparent that model development must continue in order for a satisfactory reproduction of global solar processes. In order to push the envelope on this issue slightly forward, we began development of a global linearized acoustic model (GALE – Global Acoustic Linearized Euler), implementing novel pseudo-spectral techniques and optimizing for high performance parallel computing. This algorithm was developed, tested, and used for an investigation into the helioseismic techniques used to observe and measure meridional circulation on the Sun. The structure of this algorithm will serve as a foundation for a new non-linear global compressible algorithm – a project which I am to continuing to pursue as a postdoc, after the finishing of my doctoral studies this past May (2021) at the New Jersey Institute of Technology.

Stejko, A.M. (2021), ''GLOBAL MHD AND ACOUSTIC SOLAR MODELING AND HELIOSEISMIC ANALYSIS'', Ph.D. Dissertation, New Jersey Institute of Technology [LINK]

Andrey's advisor (and Dynamo Team Barista), Sasha Kosovichev, would also like to recognize Andrey's additional achievement of earning NJIT's 2021 Outstanding Graduate Student Award of the College of Science and Liberal Arts. Let us all congratulate Andrey together on his spectacular achievement!

Congrats Andrey!

Originally published in the COFFIES Press Newsletter, Volume 1, Issue 5.