Long-range temporal correlations of ocean surface currents

We study the temporal correlations of sea surface currents at the Gulf of Eilat (also known as Gulf of Aqaba) and find long-range temporal correlations, from a timescale of several hours to a timescale of several months. This is done using the Fourier transform and the Detrended Fluctuation Analysis methods. We also find weak volatility correlations that indicate nonlinearity of surface currents. We use the time-dependent surface Ekman layer model to test whether the source of these correlations is the wind. It is found that the wind by itself actually leads to stronger temporal correlations than observed, as well as enhanced diurnal periodicity; other nonlinear terms as well as tides, convection, and spatial variability may weaken the temporal correlations imposed by the wind. Our results show significant spatial variability of correlation exponents even in this small region (6 ×l 10 km); in addition, stronger correlations are observed during winter.