About

I was born in Elefsis, Greece, where I grew up with my brother, Panagiotis. As a young man, I studied physics and mathematics at Aristotelian University in Thessaloniki, where I received my BS in 1976. I then traveled to Montreal, Canada, where I studied atmospheric sciences, receiving my Ph.D in 1982 from McGill University. For the next three years I was a post-doctoral fellow at the Atmospheric Environmental Service, Cloud Physics Division, at Downsview, Ontario, an area in the north end of Toronto.


In 1985, I joined the Department of Geosciences at the University of Wisconsin -Milwaukee (UWM) as an Assistant Professor. 28 years later I am still at UWM, now as Distinguished Professor in the department of Mathematical Sciences. I currently oversee the Atmospheric Sciences program, a subdivision of the Mathematical Sciences which includes 6 other internationally recognized faculty members, and has become one of the most successful research groups at UWM.

My work has focused on the study of Atmospheric Sciences, specifically in the areas of climate dynamics and global change. I was one of the first scientists to promote the application of Chaos theory and nonlinear data analysis in Atmospheric Sciences. I and my post-doctoral fellow Jim Elsner in a series of papers in the late 1980s popularized and introduced this theory to meteorologists. Our research has led to the Tsonis criterion, a method bearing our names, and two statistical tests bearing our names. The Tsonis Criterion refers to the necessary number of points required in attractor reconstructions. The Tsonis-Elsner method is a method used to distinguish low-dimensional chaos from random fractal processes, and the Elsner-Tsonis test is a statistical test designed to assess the significance of climate oscillations. In addition, we have introduced the notion of connected subsystems in the climate system. This concept is recently gaining significance in studies of climate change. In 2004 I was the first to apply the concepts of "small-world" networks to atmospheric sciences. My research in this area has led to the discovery of a new dynamical mechanism for major climate shifts, which explains all major global temperature shifts in the 20th and 21st century. I have also done significant research in the area of global change, and have published a theory about the relationship of global temperature and the frequency of El Niño.


My interdisciplinary efforts and collaborations in nonlinear methods have resulted in over 15 papers in the subjects of Biology, Economics, Linguistics, and Psychology. With my brother Panagiotis, I have published several important papers on the mathematical properties of DNA sequences, and have developed a hypothesis regarding the mathematical framework for memories and dreams. This hypothesis has recently been verified experimentally.


I have held associate editor positions for Nonlinear Processes in Geophysics and Journal of Hydrology. I have been an invited speaker at over 30 meetings, and have authored six scientific books and a translation of an epic Greek poem. I have also organized two conferences and many sessions in AGU and EGU on nonlinear dynamics.

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Teaching


ATM SCI-100: Survey of Meteorology
Introduction to the composition, structure, energetics, and general circulation of the atmosphere. Analysis of weather systems


ATM SCI-350: Atmospheric Thermodynamics
Radiant energy, sensible heat, and atmospheric thermodynamics; the gas laws; hydrostatic and psychometric equations; dry and moist convection; clouds and their physical and energy relations


ATM SCI-750: Nonlinear Time Series Analysis
Phase space reconstruction; singular spectrum analysis; prediction; dimension estimation; application of nonlinear time series analysis techniques to selected data sets


ATM SCI-950: Seminar on Topics in Atmospheric Sciences
Selected topics in atmospheric dynamics, satellite meteorology, atmospheric & oceanic convection, air & water pollution, numerical prediction remote sensing, & others

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Books

Chaos: From Theory to Applications

While many books have been written on chaos, this unique work bridges the gap between theory and application to help both scientists and students use the theory of nonlinear dynamical systems in their own field of research. Including numerous examples, the volume will serve as a text for an upper-level undergraduate or graduate course, as well as a reference source for the researcher. Read more »

An Introduction to Atmospheric Thermodynamics 2nd edition

This is a self-contained, concise, rigorous book introducing the reader to the basics of atmospheric thermodynamics, and the author is a highly respected researcher in this field. This new edition has been brought completely up to date and reorganized to improve the quality and flow of the material. Each chapter contains worked examples and student exercises, making this an ideal text for short undergraduate courses taken as part of an atmospheric science, meteorology, physics or natural science program. Solutions available to lecturers. Read more »

RANDOMNICITY: Rules and Randomness in the Realm of the Infinite

This unique book explores the definition, sources and role of randomness. A joyful discussion with many non-mathematical and mathematical examples leads to the identification of three sources of randomness: randomness due to irreversibility which inhibits us from extracting whatever rules may underlie a process, randomness due to our inability to have infinite power (chaos), and randomness due to many interacting systems. Here, all sources are found to have something in common: infinity. The discussion then moves to the physical system (our universe).Through the quantum mechanical character of small scales, the second law of thermodynamics and chaos, randomness is shown to be an intrinsic property of nature - this is consistent with the three sources of randomness identified above. Finally, an explanation is given as to why rules and randomness cannot exist by themselves, but instead have to coexist. Many examples are presented, ranging from pure mathematical to natural and social processes, that clearly demonstrate how the combination of rules and randomness produces the world we live in. Read more »

Singular Spectrum Analysis: A New Tool in Time Series Analysis

This original new text provides an easily accessible introduction to this important new topic in time series analysis. The authors emphasize examples over theoretical explanations and the need for proper and careful statistical tests in the context of data exploration. The book's focus is on the application of the method in signal detection, filtering, and prediction. Instructors and students will appreciate the step-by-step presentation of underlying ideas. Read more »

Nonlinear Dynamics in Geosciences

Nonlinear Dynamics in Geosciences is comprised of the proceedings of "20 Years of Nonlinear Dynamics in Geosciences", held June 11-16, 2006 in Rhodes, Greece as part of the Aegean Conferences. The volume brings together the most up-to-date research from the atmospheric sciences, hydrology, geology, and other areas of geosciences, and discusses the advances made in the last two decades and the future directions of nonlinear dynamics. Topics covered include predictability, ensemble prediction, nonlinear prediction, nonlinear time series analysis, low-dimensional chaos, nonlinear modeling, fractals and multifractals, bifurcation, complex networks, self-organized criticality, extreme events, and other aspects of nonlinear science. Read more »

Weather Stricken 2011

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Research

The Atmosphere in some respects acts quite randomly. However, this "randomness" obeys certain laws. This figure shows the spatial distribution of a random walk scaling exponent for the Northern Hemisphere 500 mb height field. Contoured values greater then 50 indicate the tendency for anomalies to be persistent independent of the time scale

Total number of links (connections) at each geographic location. The uniformity observed in the tropics indicates that each node possesses the same number of connections. This is not the case in the extratropics where certain nodes possess more links than the rest. For details on how this figure was produced please read "What do networks have to do with climate?"

Summary of synchronization events, coupling between the modes during these events, and climate shifts

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