Lab of Complex Systems Modeling and Control seminar: "Measuring waves and oscillations in the Sun's corona. How and why?"

The laboratory will have the next seminar online on Thursday, October 28, 16:20 via Zoom.
Speaker: Dmitrii Kolotkov, Ph.D, University of Warwick, UK
Title: "Measuring waves and oscillations in the Sun's corona. How and why?"

The outermost layer of the Sun's atmosphere, the corona, is a natural laboratory of a fully ionized plasma in which fundamental physical processes such as magnetic reconnection, acceleration of charged particles, heating and cooling, and magnetic confinement of plasma are open to direct study. In addition to the academic interest, understanding the processes in the solar corona is necessary for timely and adequate prediction of space weather conditions in the near-Earth space. One of the modern and promising approaches for studying the solar corona is the method of coronal MHD seismology - the use of direct observations of waves and oscillations in the corona for local plasma diagnostics.

Wave phenomena in the solar corona are regularly and confidently observed by many modern space-borne and ground-based telescopes. The continuously increasing amount and precision of observational data require the development and application of new methods for their processing and analysis. In this lecture, we will consider several original and state-of-the-art methods for measuring the parameters of waves and oscillations in the solar corona, which are actively used by the research community worldwide. In particular, a method for measuring the oscillation period, propagation speed, and damping law of waves using time-distance maps will be shown, based on the images of the Sun's corona in the extreme UV with high spatial and temporal resolution. We will also demonstrate the advantages and capabilities of the method of motion magnification for detection and subsequent analysis of oscillations of essentially small amplitude both in the solar corona and in other fields such as medicine and industry. We will discuss the use of Bayesian analysis with Monte Carlo Markov Chain (MCMC) sampling to fit observational data by low-dimensional multi-parametric models. The pros and cons of the traditional Fourier-based methods for the analysis of quasi-periodic processes with pronounced non-stationary properties (for example, in the lightcurves of solar flares) will be pointed out, and more recent and suitable approaches based, for example, on the method of the Empirical Mode Decomposition (EMD) and the Hilbert-Huang Transform (HHT) will be discussed.

Despite significant progress in the understanding, application, continuous development and improvement of methods for measuring the parameters of waves and oscillations in the solar corona, it is already crystal clear that the colossal amounts of data (hundreds of TB) collected over the last few decades require the integration of existing approaches with methods of big data analysis and machine learning principles, traditionally used in business intelligence. Such a mutually beneficial transfer of knowledge and application of an interdisciplinary approach in the future would allow us to consider the question of data processing from a new and more advanced point of view, and thereby significantly expand the horizons of understanding the intrinsic processes both in solar physics and in more practical problems of econometrics, medicine, and geophysics.