engleski

Interaction of synoptic and thermally induced flows over the Adriatic under fair weather conditions

The interplay of the synoptically forced southeastward Etesian winds with the small scale, thermally induced sea-land breezes over the Adriatic is investigated. In the study both measured and modeled surface air temperature and wind data were analyzed. Measuring sites were selected in order to cover northern, eastern and western Adriatic coast, as well as one offshore and one open-sea location. Modeled fields were obtained from operational hydrostatic mesoscale meteorological model ALADIN at horizontal resolution of 8 km. In addition, modeled wind fields were dynamically adapted to the resolution of 2 km. It is shown that model at the operational horizontal resolution of 8 km reasonably well reproduces surface airflow over the Adriatic. The finer horizontal resolution resulted in the similar wind fields, except for occasional, somewhat stronger winds that were found downstream of topographically complex regions along the eastern coast. The air temperature was not well reproduced for the open-sea site (Palagruža) and the coastal site (Brindisi), which is compared to the other coastal sites, due to its specific location, more exposed to the effects of entire Mediteranean Sea. Results also revealed salient differences in airflow above the eastern and western Adriatic, which are due to different topographical setups of the two coasts. Above the eastern and western Adriatic, the domination of the sea-land breezes and the Etesians is found, respectively. Along the eastern coast, the sea-land breezes are additionally enhanced due to additional topographical forcing and channeling effects, while along the western coast they are weaker and mainly pushed inland. Results also suggest several outstanding, region-specific airflow features that are likely to be typical for the investigated synoptic setup. During the daytime, these are: 1) the pronounced divergence above the northern Adriatic ; 2) very strong winds west of Montenegrin and Albanian coast ; and 3) enhanced winds above the central portion of the eastern coastal area. For the nighttime typical are 4) the topographically induced jets along the eastern coast, while entire day is characterized by 5) elevated wind speeds adjacent to Gargano peninsula. Both, the differences between the eastern and western Adriatic and, the occurrence of the above region-specific features can be attributed to topographical diversities and consequent effects of slope flows and airflow channeling.

etesians; sea-land breezes; topography

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