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Abstract. In this paper we document dense water formation throughout the Adriatic shelf and coastal area in January/February 2012, resulting in record-breaking densities observed during and after the event. The unprecedented dense water generation was preconditioned by a dry and warm year which resulted in a significant reduction of coastal freshwaters, superimposed on a long-term basin-wide salinity increase. The final event that triggered the dense water formation was an extended period of cold weather with strong and severe winds. Record-breaking potential density anomalies (above 30 kg m −3 ) were measured at several formation sites. Accumulated surface net heat and water losses in some coastal regions exceeded 1.5 GJ m −2 and 250 kg m −2 over 21 days, respectively. Excessiveness, importance of shelf-type dense water formation and effects on the thermohaline circulation and deep aquatic systems are discussed.

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[1] Wind forcing plays a key role in controlling the water column structure and circulation in the northern Adriatic Sea. Through shipboard observations and numerical modeling, we have documented the changing of oceanographic features before, during, and after a sequence of cold northeasterly bora wind pulses that occurred during stratified conditions in late September 2002. High-resolution meteorological, hydrodynamic, and wave model outputs were related to in situ observations of hydrologic parameters, dissolved nutrients and oxygen, suspended matter biogeochemical properties, and phytoplankton. The bora intensified the southward flowing coastal current along the Italian coast, establishing a frontal system that typically exists in winter. The bora also caused complete vertical mixing to 20-25 m in the water column, an influx of warm salty water from the south along the Croatian coast, and increased resuspension and southward transport of bottom sediments for the combined effects of currents and waves. The effects on the bottom were limited to the western coastal belt, as in the deeper central part of the basin hypoxic conditions were present during the whole observing period. During the bora, the concentration of inorganic dissolved nutrients in the bottom water increased consistently with the release of nutrients from the sediments and with the mineralization processes. Resuspension of bottom layer sediment represents an important source of nutrients for the water column in this period. The higher level of nutrients was observed together with an increase in phytoplankton biomass, suggesting a potential trigger for the autumnal phytoplankton bloom in the northern Adriatic. Finally, bora events seem to be able to generate a relevant increase of nutrient export from the northern Adriatic through the intensified Adriatic western coastal current, so they could play a relevant role in the nutrient balance of the basin.

We document dense water formation (DWF) throughout the Adriatic shelf and coastal area in January/February 2012, resulting in record-breaking densities observed during and after the event. The unprecedented dense water generation was preconditioned by a dry and warm year which resulted in a significant reduction of coastal freshwaters, superimposed on a long-term basin-wide salinity increase. The final event that triggered the DWF was an extended period of cold weather with strong and severe winds. Record-breaking potential density anomalies (above 30 kg m^−3) were measured at several DWF sites. Accumulated surface net heat and water losses in some coastal regions exceeded 1.5 GJ m^−2 and 250 kg m^−2 over 21 days, respectively. Excessiveness, importance of shelf-type DWF, effects on the thermohaline circulation and deep aquatic systems, and connection with climate change are discussed