Explores the existing theories of the El Ni'o and Southern Oscillation (ENSO) ocean-atmosphere coupled mechanisms, theory of the thermocline in a quasi-geostrophic system, and dynamics of the Atlantic Meridional Overturning Circulation (AMOC). Covers physical mechanisms, associated mathematical equations, and numerical model simulations. Discusses their direct research applications in understanding the past, present and future climate variability and change. Offered once per year. Recommended prerequisites: ATOC 5400, ATOC 5051 or ATOC 5060 and one year of calculus-based physics and math including differential equations.