99509 - CLIMATE SYSTEM MODELLING

Learning outcomes

The student will learn the conceptual basis of earth system modelling and its major components . The student will learn how the atmospheric, oceanic, cryogenic and ecosystems components can be modelled separately and how they can be coupled using examples from state-of-the-art models. The student will be exposed to strategies to design numerical experiments, verification and validation procedures using both ensemble techniques and probabilistic approaches. At the end of the course, the student will have a grasp of logic and rationale framing of earth system modelling, and will develop a capacity to design numerical experiments and a critical understanding of the verification and validation procedures.

Course contents

MODULE I

1. Introduction. The course begins with an introduction to the climate system and its mean state. Students will become familiar with the spatial and temporal scales of climate, the geographical representation of climate data, and the principal atmospheric, oceanic, and land variables used to describe the state of the climate system.

2. Simple Climate Energy Balance Models. The concept of climate energy balance is introduced through progressively more sophisticated models, from simple zero-dimensional energy balance models to representations of the greenhouse effect and major climate feedbacks, including the ice-albedo feedback.

3. Globally Resolved Energy Balance (GREB) Model. Students will explore the GREB model as an intermediate-complexity climate model, learning how radiative transfer, the hydrological cycle, atmospheric and ocean heat transport, and sea ice can be represented within a simplified modelling framework. The applications and limitations of simplified climate models for studying the mean climate and climate sensitivity are also discussed.

4. Basics of Global Climate and Climate Modelling. This section provides an overview of the Earth's climate system, including radiative forcing, the global energy budget, atmospheric and ocean circulation, land processes, and the carbon cycle. It also introduces the principles of climate modelling, including model construction, parameterization of unresolved processes, numerical methods, model hierarchy, and approaches for evaluating model performance.

5. Modelling anthropogenic Climate Change. The final part of the module examines the use of climate models to investigate anthropogenic climate change. Topics include greenhouse gas emission scenarios, historical and future climate projections, projected changes in temperature and precipitation, as well as the interpretation of climate projections in the context of natural variability and model uncertainty.

 

MODULE II

1. The Observed General Circulation. The module begins with an overview of the observed atmospheric circulation, including the time-mean, tropical, and zonally averaged circulation. Students will examine the distribution of atmospheric humidity and the roles of the mean flow, stationary eddies, and transient eddies in determining the transport of heat, moisture, and momentum.

2. Balance Requirements for the General Circulation.

• The Water Cycle. The atmospheric branch of the global water cycle is introduced through the water vapour continuity equation and tracer transport equations. Students will examine moisture transport by the mean circulation and eddies, together with its links to the continental hydrological cycle and ocean surface salinity.

• Energy in the Atmosphere. This section covers the global atmospheric energy budget, the concept of moist static energy, and the mechanisms responsible for meridional energy transport by the atmospheric circulation.

• Atmospheric Angular Momentum. The conservation of atmospheric angular momentum is presented together with its transport by the circulation and its exchange with the Earth's surface. The role of meridional and vertical momentum transports in maintaining the large-scale circulation is also discussed.

3. Stationary Rossby Waves. The final part of the module focuses on the theory and dynamics of stationary Rossby waves. Topics include wave generation, propagation, dispersion, the effects of topography, downstream development, and the contribution of Rossby waves to the transport of angular momentum and the maintenance of the planetary-scale atmospheric circulation.

 

 

Readings/Bibliography

MODULE I:

• Notes and materials distributed by the professor

• Lectures notes on Introduction to climate dynamics by Dietmar Dommenget [https://virtuale.unibo.it/mod/url/view.php?id=1207497] (https://users.monash.edu.au/~dietmard/teaching/dommenget.climate.dynamics.lecture.notes.pdf )

• Neelin JD. Climate Change and Climate Modeling. Cambridge University Press; 2010.

MODULE II:

• Wal: The atmospheric general circulation, Wallace-Battisti-Thompson-Hartman, 2023, Cambridge University Press.

• GPC: Global Physical Climatology, D. Hartmann, 2nd edition, 2016, Elsevier.

• James: Introduction to circulating atmospheres, I. James, 1994, Cambridge University Press.

• PO: Physics of the climate, J. Peixoto and A. Oort, 1992, American Institute of Physics.

• Holton: An introduction to dynamic meteorology, J. Holton and G. Hakim, 5th edition, 2013, Elsevier.

Teaching methods

• Frontal lectures with blackboard and projector
• Practical sessions with Python/Jupyter Notebook
• Homework and final project in Python/Jupyter Notebook

Assessment methods

• Students are required to develop a project assigned by the instructors. The project involves the analysis and interpretation of climate data and may also include numerical experiments and climate model simulations, depending on the assigned topic.

• During the examination, students will first present and discuss their project with the instructors. This will be followed by an oral examination covering the course material from both Module I and Module II.

• Both project discussion and the oral examination are about 20 minutes each.

Office hours

See the website of Giovanni Liguori

See the website of Salvatore Pascale