Interannual Variability of Gulf Stream Dynamics from Altimetry

Within the Gulf Stream jet-extension, the onset of turbulence leads to complex, transient behavior. For example, meanders grow in amplitude downstream from Cape Hatteras and eddies are generated through a mix of barotropic and baroclinic instability. The Gulf Stream transport, mean position and meandering path exhibit year-to-year variability. Here, we explore the inter-annual variability of the statistics of dynamical properties in the Gulf Stream region using altimetry data. We analyze the different statistical moments (mean, standard deviation, skewness, and kurtosis) of jet latitude and along-jet speed. Their links to the underlying dynamics on interannual timescales and to the role of instabilities in driving the flow are analysed. Year-to-year statistics of jet latitude and along-jet speed are intimately related, specifically where the Gulf Stream destabilizes. We will show that the inter-annual variations of eddy-mean flow dynamics within the Gulf Stream can be represented by a simple stochastic model, and that this variability can have significant an impact on the transport and mixing of heat and salinity in the North Atlantic.