81755 - DYNAMIC METEOROLOGY

Conoscenze e abilità da conseguire

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.

Contenuti

The course is made of two modules: Module 1 is theoretical and Module 2 is based on Laboratory experiences:

The syllabus of Module 1 is:

• 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.
  
• 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.
•  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.
  

Detailed syllabus of Module 2 is described below:

This module consists of a laboratory experience divided in four experiences devoted to the use of Weather Research and Forecasting (WRF) model to simulate and analyse characteristic phenomena studied within module 1. Students will be introduced to numerical modelling and the modelling approach of WRF. Then, the model will be set up to run a didactic test case. Finally, students will be asked to run their own simulations on a case study of their choice. The laboratory experience will consist of 4 Lab experiences.

1. Lab1: Introduction to atmospheric modelling using WRF.

   Topic: Introduction to basic concepts of atmospheric numerical modelling and description of WRF. Insight into the modelling approach of WRF and verification of the correct installation of WRF.

2. Lab2: Setup of WRF simulations and Run a test case

   Topic: Practical setup of the operational domain grid and model configuration. Preparation of the static data from the GEOGRID module for an example study domain and download the initial and boundary conditions for it. Prepare the input data and configure the WRF name-list for the simulation. Run WRF.

3. Lab3: Analysis of the simulation and recognition of the theoretical aspects.

   Topic: Visualization of the simulation results. Data management and computation of the graphical results. Data analysis using the simulation results to compute quantities of physical interests. Evaluate the physical and theoretical aspects from a practical application.

4. Lab4: Build your own case study

Topic: Hints on possible atmospheric phenomena to be simulated using WRF. Setup and simulation of case studies selected by the students.

Testi/Bibliografia

- suggested textbooks:

• J. Holton: Introduction to Dynamic Meteorology - 3^rd 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 textbooks for further consultation:

• 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).

Metodi didattici

Module 1 is based on traditional teaching using slides and the blackboard.

The lectures are complemented with some forecasts from typical weather forecasting models to illustrate specifc features.

Module 2 in based on Lab experiments run at the PC. Students will use the informatic Lab for this module.

Modalità di verifica e valutazione dell'apprendimento

The verification is based on the final oral exam valid for Module 1 and Module 2. It is based on three main questions. The first question is based on the Lab experience (Module 2), the second question is a topic that the student can choose from those treated during the course. The third question is a more comprehensive question aimed at assessing the learning and understanding, by the student, of the conceptual, analytical and phenomenological elements treated in the course lectures. The final mark is made by 1/3 for the first question, 1/3 for the second and 1/3 for the third. 

Strumenti a supporto della didattica

PC and media tools. Balckboard

Orario di ricevimento

Consulta il sito web di Silvana Di Sabatino

Consulta il sito web di Francesco Barbano