Atmospheric Circulation Characteristics Associated with high Static Instability Conditions Over the Athens Region

  • E. Serbis
  • C. J. Lolis
  • P. A. Kassomenos
Conference paper
Part of the Springer Atmospheric Sciences book series (SPRINGERATMO)


The main atmospheric circulation characteristics associated with high static instability conditions over the Athens region are examined for the period 1974–2004. The data used consist of daily (12UTC) values of: (1) 850, 700 and 500 hPa air temperature and dew point from radiosonde measurements at the Athens Hellinikon airport (BADC) and (2) 2.5 × 2.5 grid point 500 and 1,000 hPa geopotential height over the Mediterranean region (NCEP/NCAR), for the period 1974–2004. The stability index K (K-index) is calculated from the radiosonde measurements. Then, 5 % of the days (280 days) with the highest K values (highest instability days) are selected for the cold (16/10–15/4) and the warm (16/4–15/10) period of the year. For these days, a classification is applied to the geopotential height spatial distributions, by using Factor Analysis and K-means Cluster Analysis. The selected days are classified into nine clusters for the cold period and five clusters for the warm period. The mean 500 and 1,000 hPa geopotential height patterns are constructed for the days classified into each one of the clusters. According to the results, the clusters correspond to distinct circulation types associated with high instability conditions over the Athens region.


Geopotential Height Warm Period Cold Period Atmospheric Stability Middle Troposphere 
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Copyright information

© Springer-Verlag Berlin Heidelberg 2013

Authors and Affiliations

  1. 1.Laboratory of Meteorology, Department of PhysicsUniversity of IoanninaIoanninaGreece

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