El Niño and La Niña electromagnetic signature

Hovmöller plots of sea surface temperature anomalies (a) and Br anomalies (b) averaged from 5◦ S to 5◦ N.

Oceanic magnetic field induced by tides can be used to detect changes in seawater temperature due to El Niño and La Niña, study by GFZ Potsdam shows. The anomalous warm and cold events can be made visible because the motion of electrically conducting sea water through Earth's magnetic field induces secondary electromagnetic fields. Due to its periodicity, the oceanic tidally induced magnetic field is easily distinguishable in magnetic field measurements and therefore detectable. These tidally induced signatures in the electromagnetic fields are also sensitive to changes in oceanic temperature and salinity distributions. Furthermore, subsurface processes in the onset of those anomalous events lead the surface processes by several months. This causes a lead in the oceanic tidally induced magnetic field signals over sea-surface temperature signals.

The study, lead by GFZ Potsdam scientists as part of the ESM project, has been published in the journal Ocean Sciences, an interactive open-access journal of the European Geosciences Union: doi.org/10.5194/os-14-515-2018