Simulations of magnetic fields generated by the Antarctic Circumpolar Current at satellite altitude: Can geomagnetic measurements be used to monitor the flow?

With a volume transport of similar to134 x 10(6) m(3)/s at the Drake Passage, the Antarctic Circumpolar Current (ACC) is the strongest ocean current. In the interest of estimating the secondary magnetic fields generated by the magnetohydrodynamic interaction of this flow with Earth's main field, we compare numerical results for the magnetic fields obtained using flow from three different ocean general circulation models. These simulations all expect detectable ocean signals in the magnetic records at ground and satellite altitude ( 400 km). The variability of this contribution is highly correlated with the ACC transport, a very important variable for climate studies. Observed magnetic fields could then be used, in principle, to derive an index of variability of the ACC. However given its small amplitude compared with other magnetic contributions, extracting the ocean's signal from observations remains a challenge at this time.