The Gulf Stream Convergence Zone

Seminar by Prof. Niklas Schneider from International Pacific Research Center and Department of Oceanography University of Hawaiʻi

03 November 2022
KST 14:00 – 15:00

The Seminar is being held in Room 1010 (Jasmin) – Integrated mechanical engineering building. Click here for the campus map.

The Gulf Stream Convergence Zone is a dipole of long-term averages of surface-wind divergence and convergence located over the Gulf Stream’s cold and warm flanks, respectively. This divergence pattern has been attributed to the storm track or to the imprint of the sea surface temperature fronts on lower atmosphere boundary layer. We reconcile these hypotheses and suggest that the Gulf surface wind divergence dipole results from the atmospheric boundary layer response to the Gulf Stream sea surface temperature front and to large-scale winds associated with synoptic atmospheric variability. We test this hypothesis with a reconstruction of the time-averaged surface wind divergence based on i) the time-mean Gulf Stream sea surface temperature front, ii) the observed, all-year, impulse response function that relates surface wind divergence to ocean mesoscale sea surface temperatures as a function of large-scale winds, and iii) the observed probability density function of large-scale winds. Supporting the hypothesis, the reconstruction captures the mean, surface wind divergence dipole with negative values on the warm, and positive values on the cold flank of the Gulf Stream. It also reproduces averages of surface wind divergence conditioned by the sign of the downwind sea surface temperature gradient and published sensitivities of the Gulf Stream Convergence Zone to the sharpness of the Gulf Stream sea surface temperature front.