81755 - DYNAMIC METEOROLOGY

Academic Year 2017/2018

  • Teaching Mode: Traditional lectures
  • Campus: Bologna
  • Corso: Second cycle degree programme (LM) in Physics of the Earth System (cod. 8626)

Learning outcomes

The purpose of the course of Dynamic Meteorology is to provide a deeper learning of the basic dynamical processes underlying the general atmospheric circulation and its variability on relatively short time scales, with the approach of Physics. Such variability is associated with the evolution of meteorological phenomena and with the practical problem of short and medium range weather forecasting and its applications. The main topics of dynamic meteorology are treated, regarding the general circulation and the synoptic scale and mesoscale phenomena. The equations of motion, their properties and analytical or numerical solutions are analyzed, including waves, instability processes, linear and nonlinear effects and the fundaments of meteorological modelling. The presentation of various theoretical aspects having didactical relevance is conducted in parallel with the examination of the properties revealed by the analysis of observational data.

Course contents

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

2) Phenomenological characteristics of the global circulation, defined on the basis of numerical model re-analyses, and their physical interpretation.

3) Main 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.

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

5) Coordinate transformations and equations of motions in isentropic coordinates.

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

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

8) Dynamical and diagnostic applications of potential vorticity.

9) Principle of invertibility of potential vorticity.

10) 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). (this topic will require 3 lectures)

11) Atmospheric flows over topography, in two and three dimensions. Properties of orographic waves and of different flow regimes over orography. (this topic will require 2 lectures)

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

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

14) Rossby's problem of geostrophic adjustment.

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

16) 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.

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

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

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

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

21) Inertial instability and symmetric instability.

22) Condensation-evaporation processes; elements of dynamics of moist deep convection and of mesoscale convective systems. (this topic is usually extra)

Readings/Bibliography

Suggested textbooks:

  • 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 reading:

  • 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).
  • H. Lynch, J. J. Cassano, 2006: Atmospheric Dynamics(Wiley).
  • Y.L. Lin, 2007: Mesoscale Dynamics (Cambridge U. Press).

Teaching methods

All lectures are done in the classroom as frontal teaching

Assessment methods

The verification 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.

Exam dates are normally defined after email appointment.

Teaching tools

PC Projector and blackboard - Derivation of equations is done step by step.

Office hours

See the website of Silvana Di Sabatino