Heat and mass balances of the South Atlantic Ocean calculated from a numerical model

The general circulation model of Bryan (1969), modified by the introduction of open boundary conditions at the Drake Passage and between Africa and Antarctica, has been used to study the mass and heat budgets of the South Atlantic Ocean. The model was initialized with the climatological annual mean values of temperature and salinity of Levitus (1982) and forced at its surface with the climatological wind stress data of Hellernian and Rosenstein (1983). After 3 years of integration the model reached a quasi-stationary state. A heat balance shows that the model transports 0.19 PW of heat toward the north across 30°S. While a large part of this heat is supplied by the atmosphere and involves the conversion of intermediate waters into surface waters, a comparison with climatological data of atmospheric heat fluxes suggests that an extra source of heat is necessary to maintain the northward heat flux.Copyrighted by American Geophysical Union

El Niño and the delayed action oscillator

We study the dynamics of the El Niño phenomenon using the mathematical model of delayedaction oscillator (DAO). Topics such as the influence of the annual cycle, global warming, stochastic influences due to weather conditions and even off-equatorial heat-sinks can all be discussed using only modest analytical and numerical resources. Thus the DAO allows for a pedagogical introduction to the science of El Niño and La Niña while at the same time avoiding the need for large-scale computing resources normally associated with much more sophisticated coupled atmosphere-ocean general circulation models. It is an approach which is ideally suited for student projects both at high school and undergraduate level