Surface ocean current variations in the North Pacific related to Arctic stratospheric ozone

Abstract

Using reanalysis datasets and a coupled general circulation model, the relationship between springtime Arctic total column ozone (TCO) and surface (5 m) ocean currents in the North Pacific is investigated. We found that as March Arctic TCO decreases, a statistically significant northwestward ocean current anomaly occurs in the northern North Pacific in surface layer, but an anomalous southward ocean current appears in the central North Pacific in April, and vice versa. The decreased Arctic TCO favors an enhanced Arctic stratospheric circulation, which tends to induce the tropospheric positive Arctic Oscillation anomaly with easterly anomalies over the midlatitude eastern Asia in late March through stratosphere-troposphere dynamical coupling. The easterly anomaly over eastern Asia in late March further extends eastward and induces an easterly anomaly over the midlatitude North Pacific, which favors negative North Pacific Oscillation (–NPO)-like circulation anomaly via anomalous zonal wind shear and the interactions between synoptic scale eddies and the mean flow in early-middle April. The –NPO anomaly forces anomalous northwestward/southward surface ocean currents in the northern/central North Pacific through direct friction of wind and the Coriolis force. Our coupled numerical simulations with high- and low-ozone scenarios also support that the Arctic stratospheric ozone affects the North Pacific surface ocean currents by NPO anomalies. Moreover, the ozone-related ocean current anomalies contribute to Victoria mode-like sea surface temperature anomalies in the North Pacific by horizontal heat advection. These results imply that Arctic ozone signal could be a predictor for variations of the North Pacific surface ocean currents.