engleski

Anomalous air-sea fluxes observed in winter/spring 2003 over the Adriatic Sea

An extensive oceanographic research was carried out in 2002/2003 in the Adriatic Sea, being accompanied with the measurements of various meteorological parameters. Air and sea surface temperatures, air pressure, wind speed and direction, humidity, precipitation and solar radiation has been measured from autumn 2002 to spring 2003 at two automatic meteo-ocean stations and at a number of regular meteorological stations, allowing for the calculation of day-to-day changes in air-sea heat, water and buoyancy fluxes over the examined area. Unfortunately, no direct measurements of cloudiness were performed at automatic stations, so it was computed by applying parameterization based on the measured solar radiation, permitting the estimation of the longwave component of surface heat flux. In addition, 2002/2003 surface fluxes were compared to the climatological averages which were previously computed on the monthly basis for the selected areas. A widespread anomaly in meteorological conditions occurred in the first half of 2003, resulting in anomalous heat and water transfer to and out of the sea. Strong and extremely persistent Bora wind (cold, dry katabatic wind) took out a lot of energy out of the sea in January-March 2003, largely cooling the waters at the northern Adriatic shelf. At the same time, in February-June period, almost no precipitation was recorded which, coupled with the high evaporation and advection of saline waters, resulted in anomalous salinity in the area. These conditions allow for the generation of dense water in winter 2003, being crucial for the replenishment of deep Adriatic waters. In addition, coastal areas, usually influenced by freshened river waters, were flooded by open-sea saline waters. Surface heat fluxes switched almost instantaneously to positive anomaly after March, transferring the energy into the sea and heating the surface layer. This transmittion was intensified in May and June, resulting in anomalous high sea surface temperature, while the bottom temperature (bellow a few tens of meters) was still lower than the average. Conclusively, both extreme positive and negative meteo-oceanographic anomalies occurred in a quite short time, emphasizing the wellknown question: are these severe regional climate anomalies a result of global climate changes, enlarging the appearance of extreme events in both directions?

air-sea fluxes; climate anomaly; Adriatic Sea

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