- Large-scale atmosphere and ocean dynamics
- Atmospheric convection
- Global climate modeling
- Climate dynamics Seminar
- Understanding our changing environment.
Large-scale atmosphere and ocean dynamics:
In this course, I will cover the foundations of the dynamics of the large-scale motions in the atmosphere and ocean, with emphasis on the planetary-scale motions and large-scale
ocean-atmosphere coupling processes. I will take the perspective that these large-scale motions may be explained or understood as responses to the radiative forcing exerted upon the coupled ocean-atmosphere system.
I will start with the dynamics of the Walker and Hadley circulation in the tropical atmosphere and their counterparts in the ocean--the wind-driven circulations in the tropical upper ocean. I will then proceed to the dynamics of
the El Niño and Southern Oscillation (ENSO). Recent developments in understanding the origin of ENSO and its variability on the decadal and longer time-scales will then be discussed. I will also cover the basic mechanisms for the interaction between the tropical and extratropical atmosphere with emphasis on the role of isentropic mixing of PV by baroclinic eddies in the poleward heat and moisture transport.
Depending on the interests of the class, I may also
cover classical theories for mid-latitude wind-driven circulations in the ocean
with emphasis on their role in the poleward heat transport and global heat balance. Recent developments
concerning the water exchange between the tropical and extratropical oceans may also be touched upon.
Basic dynamics of the
thermohaline circulation as well as its interaction with other components of the
climate system may also be covered.
The goal is to provide students a solid theoretical foundation for understanding and modeling global climate.
Main text book:
Andrian E. Gill, 1982: Atmospheric-ocean dynamics, Academics Press, New York, 662 pp..
Supplementary text books:
Richard Lindzen, 1990: Dynamics in atmospheric physics, Cambridge University Press, 310 pp;
Joseph Pedlosky, 1998: Ocean circulation theory, Springer-Verlag Berlin Heidelberg. 453 pp.
Atmospheric convection is introduced as a vertical heat and moisture transfer mechanism. I will
start with the Rayleigh-Benard problem as the most elementary conceptual model. I will then
cover the moist thermodynamics of the atmosphere and introduce the basic laws governing
the dynamics of moist convection. Emphasis will be given to the observed characteristics of moist convection, to the results from cumulus
ensemble models, and to how to parameterize moist convection in global climate models. The course
will also introduce the concept of radiative feedbacks of water vapor and clouds, their
critical role in global climate change, and uncertainties associated with them
in global climate models.
Global climate modeling:
Main text book:
Kerry Emanuel, 1994: Atmospheric convection. Oxford University Press. 580 pp.
The course will cover basic concepts in numerical modeling, basic computational methods
in use in general circulation models, parameterization of sub-scale processes--moist convection
in particular, and basic techniques for coupling atmosphere, ocean, and other components in the climate system. The main reference model in discussing these topics will be the NCAR Community Climate System Model (CCSM). The course will also cover basic diagnostic techniques in use for model evaluation and validation. The simpler models--the energy balance models, the radiative-convective models, and stochastic models will be introduced in this context, together with the basic feedback processes in the climate system.
Main text book:
Kevin E. Trenberth 1992: Climate System Modeling. Cambridge University Press. 788 pp.
Climate Dynamics Seminar:
A fundamental question about the climate system is why its state is always changing, and yet has so far avoided a runaway instability that could destroy all life. It is also against this background that the importance of understanding human impact on the state of the climate system better emerges. With our industrial activity changing the chemical composition of the atmosphere, are we prodding a "lamb" who poses no harm, or a "beast" who may react to devour all of us?
Understanding our changing environment:
This course attempts to shed some light on the above questions through guided reading and discussion of key papers in the area of climate dynamics, and through lectures by leading climate experts in the local climate community. The course will cover the dynamics of major modes of variability in the climate system: the Madden-Julian Oscillation, the El Nino-Southern Oscillation, the North Atlantic Oscillation, the Antarctic Oscillation, and abrupt climate changes. The course will also include lectures on climate forcing and feedbacks, the water and energy cycle, and the weather and climate connections (e.g. how global warming affects the magnitude and frequency of occurrence of extreme weather events).
The lecturers will be asked to tailor their talks to fit the level of graduate students. Background material for each lecture will be recommended to the students in advance to aid the understanding of the lecture. Each lecture will be followed by half an hour discussion. By the end of the course, the students are expected to have a basic understanding of the causes of climate change and climate variability, and an appreciation of the delicate balance and complex interaction among the various forces that maintain the stability of the climate system.
Global warming has been referred as a defining issue of the 21st century. This course is to help undergraduates to better understand the facts and logic behind the theory of global
warming. This course will introduce the energy balance of the climate system, the greenhouse effect, the climate feedbacks, the stability of the climate system, and the Gaia hypothesis. The students will essentially have a guided tour of the climate system and the science of global climate change. By the end of the course, the students will feel more informed
and ready to participate in public discussions about major issues in the area of global climate change.
Main text book: W. J. Burroughs 2001: Climate Change, Cambridge Univ. Press, 298 pp. Reference books:
IPCC Climate Change 2001: The Science of Climate Change, Cambridge Univ. Press, 881 pp; Balling R. C., 1992: The Heated Debate, Pacific Research For Public Policy, 195 pp.
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