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Eastern Adriatic typical wind field patterns and large-scale atmospheric conditions

The famous Bora nad Scirocco winds blow along the eastern coast of the Adriatic Sea, prevailing during the colder part of the year. There are also some other less well known wind types in the region. This paper deals with the application of an objective procedure for the classification of all wind field patterns, regardless of the wind names. For this purpose, a complex principal component analysis technique has been applied. Time series of instantaneous (at 07 h, 14 h and 21 h local time) wind data have also been used, including the National Centres for Environmental Prediction - National Centre for Atmospheric Research reanalyses of the constant-pressure levels of 1000 hPa and 850 hPa, as well as the thickness of 850-1000 hPa. All refer to the period 1981-88. The results indicate 11 typical wind field patterns over the Adriatic area. Some of them have the characteristics of Bora and Scirocco, whereas the other are Etesians, sea (land) breezes or a combination of these. There is also a near-calm type. A rather high correlatin between these mesoscale wind patterns and large-scale (regional) atmospheric conditions has been established. Two controlling pressure centres, i.e. the Icelandic cyclone and the Azores anticyclone, appear as important large-scale factors which, at least indirectly, influence the creation of the eastern Adriatic wind patterns. For types representing Scirocco and Bora conditions, regional open or closed synoptic-scale circulation systems, however, have a dominant influence.

eastern Adriatic; wind field; complex principal component analysis

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