by Joke Lübbecke
The El Niño – Southern Oscillation (ENSO) is a climate phenomenon that entails pronounced warm or cold surface anomalies in the eastern equatorial Pacific and has impacts on the weather around the globe. In a master level class students are introduced to some fundamental theories about ENSO. One of them, the so-called recharge-discharge oscillator, is based on the idea that there is a cycle of (1) building up heat content in the equatorial Pacific, (2) the peak of a warm event, i.e. El Niño, (3) a discharge of heat to the extra-tropics, and (4) the peak of the cold phase, i.e La Niña. Instead of just learning about this concept theoretically, we had an “ENSO crafternoon” where the students came up with experiments to demonstrate the cycle.
One group used a glass casserole as their Pacific Ocean, colored water as the cold subsurface layer and oil as the warm surface layer. With a hair dryer to turn on the trade winds and a syringe to facilitate recharge and discharge from and to the extra-tropics, they nicely visualized the transitions between the phases.
Another group got even more crafty and built an IKEA-style recharge oscillator that even included the impacts – little cloud and sun symbols that pop up where atmospheric deep convection is enhanced or decreased over unusually warm or cold water.