Sea surface temperature anomalies (SSTA) in portions of the extratropics are known to recur from one winter to the next without persisting through the intervening summer. Previous studies identified only a limited number of midlatitude regions where this reemergence occurs. Here we find that most of the global oceans exhibit winter-to-winter recurrence of SSTA. Indeed, recurrence of SSTA is the default process in the global ocean. Only regions strongly linked to El Nino do not show signs of SST reemergence. In midlatitudes, the temperature anomalies that recur persist below the shallow mixed layer in summer. However, SST recurrence is also found at some tropical locations and appears to be independent of subsurface ocean heat storage. Reemergence at these locations is linked to the recurrence of atmospheric drivers of SSTA, predominantly the wind-stress forcing. Our results are supported by different ocean data sets and by state-of-the-art climate model simulations. Plain Language Summary The study addresses the global distribution of the reemergence of sea surface temperature (SST) anomalies. The reemergence of SST is the phenomenon that SST anomalies from one winter to the next reemerge, while they apparently disappear in the summer. This is linked to the SST anomalies being stored in the subsurface ocean. Recent studies have shown the role of reemergence on European weather, North Atlantic Oscillations, and Pacific Decadal Oscillation. In this study we show the regions where this phenomenon is strong in the global ocean and different mechanism that cause the recurrence. Here we find that the recurrence of SST anomalies is also apparent in the tropics, which is linked to the recurrence of wind-stress forcing at the location.

http://dx.doi.org/10.1029/2018gl079137

Journal Article