Finding the cause of El Niño
The El Niño-Southern Oscillation (ENSO) is a cycle of warm and cold temperatures in the tropical Pacific Ocean. While climate researchers understand well the worldwide effects and impacts of the phenomenon, how it begins is less well known. The EU-funded MEMENTO (Modulating mechanisms of the onset of El Niño events) project is using oceanographic data to understand what causes ENSO, and then applying this knowledge to improve climate models. Early results show that subsurface water temperature in the western Pacific plays an important role in triggering ENSO. Researchers studied the mechanisms that explain the accumulation of these water masses, and how their subsequent movement influences atmospheric convection, evaporation, rain and trade winds in the area. Researchers then checked five different climate models to see whether they reproduced these mechanisms. Of these, two accurately reflected the build-up of warm subsurface water that precedes El Niño events. MEMENTO is currently running experimental simulations with the best of these models, using results from earlier in the project to design and implement the most suitable initial conditions for the simulations. This will help researchers to better understand the importance of the accumulation of warm waters in the ocean subsurface for the development of El Niño events and the evolution of the ENSO cycle.
Keywords
El Niño, ocean data, El Niño-Southern Oscillation, Pacific Ocean, subsurface water
