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Abstract:
In contrast to ocean circulation signals, ocean tides are already well detectable by electromagnetic measurements. Oceanic electric conductivities from the Coupled Model Intercomparison Project Phase 5 (CMIP5) climate simulations are combined with tidal currents of M2 and O1 to estimate electromagnetic tidal signals and their sensitivity to global warming. Ninety-four years of global warming lead to differences of ±0.3 nT in tidal magnetic amplitudes and ±0.1 mV/km in the tidal electric amplitudes at sea level. Locally, the climate induced changes can be much higher, e.g., +1 nT in the North Atlantic. In general, all studied electromagnetic tidal amplitudes show large scale climate induced anomalies that are strongest in the northern hemisphere and amount to 30% of their actual values. Consequently, changes in oceanic electromagnetic tidal amplitudes should be detectable in electromagnetic records. Electric and magnetic signals, as well as tides of different frequencies contain complementary regional information.
