55216 - Dynamic Meteorology

Learning outcomes

The attendance of this course will allow the students to acquire a knowledge of the basic dynamical and physical processes determining the properties of the atmospheric circulation and of its motions on different time scales, especially those characterizing the weather processes and their variability. Students  will gain a deeper insight of the evolution dynamics of meteorological phenomena and of the basic problems and methods of short and medium range weather forecasting. Students will learn the principal topics of dynamic meteorology, regarding the general circulation and  synoptic scale as well as meso-scale phenomena and their dynamical processes. Students will have the opportunity to study the equations of motion, their properties and particular analytical or numerical solutions, including atmospheric waves, instability processes, nonlinear effects and principles of numerical weather prediction. Students will learn theoretical aspects by analyzing properties derived from the analysis of observational meteorological data.

Course contents

Historical elements on the development of main ideas and methods in Dynamic Meteorology and numerical weather forecasting, both deterministic and probabilistic.

Overall phenomenological characteristics of the global circulation, defined on the basis of  numerical model reanalyses, and their physical interpretation.

Principal phenomena of the atmospheric circulation, structural and spectral analysis and classification on the basis of the various space-time scales of motion. Effects induced by the seasonal cycle. Comparison of quasi-periodic and chaotic phenomena of the general cicrculation.

Derivation of the equations of motions of the atmosphere in spherical geometry and related appropriate scaling.

Coordinate transformations and equations of motions in isentropic coordinates.

Derivation of the Ertel's theorem and conservation of potential vorticity.

Circulation and related theorems (Kelvin, Bierknes); circulation and vorticity.

Dynamical and diagnostic applications of potential vorticity. Principle of invertibility of potential vorticity.

Atmospheric wave dynamics and identification of basic modes in simplified cases. Sound, gravity waves, Rossby waves, free and forced by the earth orography and distribution of thermal sources).

Atmospheric flows over topography, in two and three dimensions. Properties of orographic waves and of  different flow regimes over orography.

Derivation of the quasi-geostrophic approximation and properties of the simplified set of equations. Application to the Rossby wave dynamics.

Low frequency variability: orographic instability and resonance; orographic form drag. Multiple circulation regimes and transitions between them; teleconnections.

Rossby's problem of geostrophic adjustment.

Variability of the extra-tropical atmospheric circulation. Baroclinic instability and the Eady model. Properties of the neutral and unstable baroclinic modes.

Examples and evolution of the mid-latitude baroclinic perturbations: cyclones and anticyclones,  related conceptual models and properties of their life cycle. Storm-track characteristics and asymmetries of the zonal circulation.  

Mesoscale structures of the extra-tropical cyclones: fronts, warm and cold conveyor belts, associated precipitating systems.

Baroclinic instability modified by orography. Effects of orography on the evolution of cyclones in mid latitudes. Orographic cyclogenesis and Mediterranean cyclones: phenomenology and models.

Finite amplitude effects and water cycle effects on the extra-tropical cyclones.

Surface and upper level fronts. Dynamics of frontogenesis in two and three dimensions.

Inertial instability and symmetric instability.

Condensation-evaporation processes; elements of dynamics of moist deep convection and of mesoscale convective systems.

Readings/Bibliography

J. Holton: Introduction to Dynamic Meteorology - 3rd Ed. (Academic Press);

H.B. Bluestein: Synoptic-Dynamic Meteorology in midlatitudes (2 vol., Oxford Univ. Press).

E. Kalnay: Atmospheric modeling, data assimilation and predictability (Cambridge U. Press).

Additional relevant books :

M. Satoh: Atmospheric Circulation Dynamics and General Circulation Models (Springer).

J. Pedloski: Geophysical Fluid Dynamics (Springer-Verlag);

R. A. Houze: Cloud Dynamics (Academic Press).

R.A. Pielke, 2002: Mesoscale Meteorological Modeling. 2nd Edition (Academic Press).

J. E. Martin, 2006: Mid-Latitude Atmospheric Dynamics - A First Course (Wiley).

A. H. Lynch, J. J. Cassano, 2006: Atmospheric Dynamics  (Wiley).

Y.L. Lin, 2007: Mesoscale Dynamics (Cambridge U. Press).

Teaching methods

The general topics of the course and its detaled content programme are presented and discussed during lectures, with practical demonstrations that use observational data, maps and outputs of numerical models.

Assessment methods

The verification assessment is based on the final oral exam, that will be based on a series of questions aimed at assessing the learning and understanding, by the student, of the conceptual, analytical and phenomenological elements treated in the course lectures.

Teaching tools

The slides with the content of the lectures (text in English, formulas and figures) are made available to the students in pdf format at the Internet address: http://www.isac.cnr.it/dinamica/buzzi/lezioni_meteorologia_dinamica/

Office hours

See the website of Andrea Buzzi