| Over most of the mid-high latitudes, sea surface temperature (SST) is cold (warm) under the strong (weak) surface wind on basinwide scales. This negative correlation between SST and surface wind speed anomalies indicates that SST changes over the mid-high latitudes are mainly dominated by an atmosphere-to-ocean forcing. However, the positive SST-wind correlation is detected over the Malvinas/Brazil Confluence and Norwegian Sea in the South and the North Atlantic, respectively. The cold northward-flowing Malvinas Current encounters the warm southward-flowing Brazil Current east of Argentina. The confluence of these currents forms a sharp SST gradient all through the year, leading to a remarkable cold (warm) tongue west (east) of the SST gradient, where the annual mean surface winds are westerlies under the influence of the subtropical jet. High-resolution satellite datasets clearly depict that surface wind speeds are weak over the colder flank of the SST gradient while strong over the warmer flank all through the year. This relationship between SST and surface wind speed is indicative of an ocean-to-atmosphere forcing. In addition, we detect that such a positive SST-wind correlation is explained by the vertical mixing mechanism, using difference between SST and surface air temperature from high-resolution in-situ datasets. The same relationship between SST, surface wind speed and surface air temperature is identified in the Norwegian Sea. |
|
|