Unusual upwelling event and current reversal off the Italian Adriatic coast in summer 2003

An exceptional upwelling event occurred near the Conero Promontory along the Italian Adriatic coast between 11 and 23 July 2003, as a result of dominant southeasterly sirocco winds. Contemporarily, surface currents off central and southern Italy reversed to the northwest direction. This peculiar dynamic situation happened when the Adriatic river discharge rates were extremely low due to a prolonged dry season. Satellite images of sea surface temperature and chlorophyll concentration and satellite-tracked drifters revealed that the upwelling event first appeared northwest of the promontory and then progressed to the southeast. Its offshore extension (20– 30 km) includes convoluted filament structures. Surface temperature and ocean color signatures are correlated, indicating that the cold-upwelled water is rich in nutrients. Coldest temperatures are as low as 18–19C (8C lower than the open sea). The northwestward currents reached maximum speeds larger than 40 cm/s inshore of the 20 m-isobath (<10 km from shore).