Impact of oceanic warming on electromagnetic oceanic tidal signals: A CMIP5 climate model‐based sensitivity study

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 leads 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.

Estimating ocean tide model uncertainties for electromagnetic inversion studies

“…Main goal of the study is to provide errors for inversion studies that use tidal observations from satellite magnetometers 5 (Schnepf et al, 2014(Schnepf et al, , 2015Grayver et al, 2016Grayver et al, , 2017Saynisch et al, 2016Saynisch et al, , 2017.…”

Electromagnetic characteristics of ENSO

“…The influences of global climate variations, such as Greenland glacial melting and global warming, on the electromagnetic 25 oceanic tidal-induced signals have already been investigated (Saynisch et al, 2016(Saynisch et al, , 2017. For these cases, the tidal-induced radial magnetic field was found to be an appropriate measure to monitor climate variations of the global oceanic conductivity on decadal time scales.…”

“…In our study, we follow the approach of Saynisch et al (2017) and investigate whether the electromagnetic oceanic tidalinduced signals could be used as an appropriate measure for these changes in seawater conductivity and, consequently, the variating dynamics of the El Niño/Southern Oscillation.…”

“…Our study focuses on the effects of oceanic conductivity variations. B Earth is consequently assumed 25 to be constant in time. Naturally occurring secular variations in B Earth will linearly vary j M2 (eq.…”

“…Consequently, we followed the approach of Saynisch et al (2017) and assumed the tidal system to be invariable in time. Tidal amplitudes and phases of the oceanic M2 tide were taken from the TPXO8-atlas (Egbert et al, 1994;Egbert and Erofeeva, 2002).…”