B031997 - OPTICAL TURBULENCE FOR ASTROPHYSICS

Italian

Lessons done during the course represent the text of reference that will be object of verification at the examination. Besides that, we provide a list of text of reference that we suggest to integrate the formation and allow personal supplementary investigation if wished by the student. A great part of these texts are accessible at the library of the Osservatorio Astrofisico di Arcetri (OAA):

- Tatarski 1961, Institute of Atmospheric Physics Academy of Sciences of the USSR
Wave propagation in a turbulent medium
Dover Publications INC. New York

- V. I. Tatarski 1971,
The effects of turbulence atmosphere on wave propagation
Israel Program for Scientific Translation (from ESO Library)

- H. Tennekes and J.L. Lumley
A first course in Turbulence
The MIT Press

- Francois Roddier, Progress in Optics, Vol. XIX, 1981
The effects of atmospheric turbulence in optical astronomy
Ed. Wolf

- John Hardy
Adaptive Optics for Astronomical Telescopes
Oxford Series in Optical and Imaging Science
Oxford University Press, 1998

- Pierre Lena,
Astrophysique – Methodes physiques de l’observation,
CNRS Editions, 1996

- John Wyngaard
Turbulence in the Atmosphere
Cambridge University Press, 2010

- Stull
An Introduction to Boundary Layer Meteorology
Kluwer Academic Publishers, 1988

- J.R. Holton
An Introduction to the Dynamic Meteorology
Elsevier, Academic Press, Edition 2004

- J. M. Wallace, P. V. Hobbs
Atmospheric Sciences – An Introductory Survey
Elsevier Science, 1977

- Daniel Wilks,
Statistical methods in the atmospheric science
International Geophysics Series, Vol. 100, 2011

- Python
Fabrizio Romano 2017
https://www.packtpub.com/product/learning-python-video/9781788995115

- Numerical Python: Scientific Computing and Data Science Applications with Numpy, Scipy and Matplotlib Robert Johansson, 2018

- Meso-Nh atmospheric simulation system: scientific documentation
http://mesonh.aero.obs-mip.fr/mesonh55/BooksAndGuides

- Data science with Python – Guida completa, dai big data al machine learning
Giuseppe Maggi 2020

The course aims to provide the detailed theoretical background and the required instruments for the comprehension of the nature of the turbulence in atmosphere and its effects on the propagation of electromagnetic fields (typically wavefronts in in the visible and infrared) which allow us to perform ground-based observations. The course is focused on the characteristics of the turbulence, methods to measure the turbulence, to model and forecast it. The course is applied to the astrophysics but the theoretical background is equally valid for the free space optical communication in the satellite-Earth transmission in the visible. This is a strategic field in the new generation Earth-Space communication.

Physics and astrophysics courses as requested by the curriculum of the Master diploma. For those who intend to undertake the career of applied research in the field of the high-angular resolution, we suggest to follow, beside to the course of optical turbulence for the astrophysics also the course of the adaptive optics for the astrophysics.

Frontal teaching. An important part of the course will be devoted to lesson in class supported by slides that will refer to consolidated theory joint to discussions on results recently obtained in research. During the course will be done practical exercises aiming
To provide to students the instruments required to move in the field of the research. More precisely it will be shown: (1) how to use hydrodynamical models to perform simulations applied to the optical turbulence, (2) we will provide basic elements of Python necessary for the data analysis in this field, (3) machine learning techniques.

The study of the optical turbulence plays a fundamental role for the ground-based astronomical observations, particularly those supported by adaptive optics (AO) and/or interferometry because the optical turbulence represents the fundamental limitation to the resolutions potentially achievable by top-class ground-based telescopes. Research in the optical turbulence is therefore strictly related to that of high angular resolution techniques such as adaptive optics and interferometry. The Osservatorio Astrofisico di Arcetri (OAA) has a robust tradition in the high-angular resolution techniques/disciplines, among these, the adaptive optics and the optical turbulence which concretized in many international projects. The goal is to train a new class of young researchers who will be able to be involved in the current researches/projects and to offer research perspectives in these disciplines in which the OAA has a consolidated know-how.

Oral examination. Duration ~ 45’. The goal of the examination is the verification of the comprehension of the concepts presented during the course, clarity of exposition and logical/deductive ability. The student will be asked to deal about an argument he will freely select and this will be integrated with a few other questions related to the program of the course. The final mark will take into account for a 10% of the total the fact to have followed practical lessons in class.

The course will treat the following modules:

1. Phenomenology and statistics of the optical turbulence
2. Propagation of wavefronts through the optical turbulence
3. Methods of measurement of the optical turbulence
4. Modelling and forecast of the optical turbulence
5. Hydrodynamical models at mesoscale for simulation of the optical turbulence – exercises. Basic elements of Python to perform data analysis
6. Statistical techniques: autoregression, machine learning and deep learning applied to the optical turbulence forecast and, in general, to the temporal series