Georgiev., Christo G. (National Institute of Meteorology and Hydrology, Sofia, Bulgaria)
The evolution of Eastern Mediterranean cyclones, developing in a circulation pattern of "blocking regime" is studied on the basis of synoptic analyses, using METEOSAT imagery in the channel 6.3 åm (WV-channel).
For the period of 1980-1989, it was established that 11 cases of the cyclones over the Eastern Mediterranean are associated with "blocking regime". Nine of them could be combined into the following two types:
type I - which initiate or deepen over the central Mediterranean along the African coast, pass south of the Balkan peninsula and have a weak influence on the weather over Bulgaria; type II - which initiate or deepen over the central Mediterranean (often along its northern coasts), pass trough the Balkan peninsula and lead to severe weather events over Bulgaria.
Structural forms, that are indicators for the "blocking regime" and for the evolution of the considered cyclones were found in the brightness field of the METEOSAT WV-images. On the basis of case-studies a synoptic description of these two types Eastern Mediterranean cyclones are presented in the paper, using ECMWF global model analysis data and METEOSAT WV imagery. The weather events over Bulgaria connected with this processes is also considered. Systems of rules that formalise the conclusions of this study are presented. They could be used for adjusting of synoptic analysis and prognosis in the cases of such processes.