Near-Surface Circulation in the Marmara Sea
Riccardo Gerin, Pierre-Marie Poulain, Sukru Besiktepe, Pietro Zanasca
OGS
(Abstract received 08/12/2009 for session A)
ABSTRACT
As part of the Turkish Straits System (TSS) experiment, the surface circulation of the Marmara Sea was studied using low-cost CODE Lagrangian drifters over about a year (from September 2008 to May 2009). In addition to the standard positioning and data telemetry (SST, battery) provided by the Argos Data Collection and Location System (DCLS), the drifters were equipped with GPS receivers to have a more frequent and a better determination of their positions. About 30 surface drifters were deployed in two seasonal episodes at key locations close to the Bosphorus and in the middle of the Marmara Sea (to maximize the geographical coverage), mainly in small (1 nm) clusters of three drifters. The combined raw Argos and GPS positions were edited for outliers and spikes using statistical and manual techniques and were interpolated at regular 2-hours intervals. Surface velocity were calculated by central finite differencing the interpolated positions. The Pseudo-Eulerian statistics (mean flow, variance ellipses, MKE and EKE) were calculated using a spatial averaging scale of 0.05° x 0.05° overlapping bins. The lifetime of the drifters in the Marmara Sea is very low due to the recovery by seafarers and stranding. The maximum time after deployment at sea is only about one month. The map of the mean surface flow shows two eddy located in the northern part which extend for about 30 km and reach the middle of the Sea (the western feature is anticyclonic and the eastern one is cyclonic). South of these large features, a flow of about 20 cm/s joins the Bosphorus to the Dadarnelles and another cyclonic eddy is evident in the southeastern area of the Marmara Sea.
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