Anatomy of the synoptic conditions occurring over southern Greece during the second half of the 20th century. Part I. Winter and summer |
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Authors: | P A Kassomenos |
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Institution: | (1) Laboratory of Meteorology, Department of Physics, University of Ioannina, Ioannina, Greece, GR |
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Abstract: | Summary ?In this study a methodology for grouping seasonal circulation types occurring over an area is introduced. This procedure
combines the surface air mass characteristics affecting the area with the synoptic conditions prevailing over it. Factor Analysis
and Cluster Analysis are used to derive the circulation types, based on surface meteorological data and surface pressure grid
data. The methods are applied to Athens, Greece, using data over the period 1954–1999 for winter (December, January, February)
and summer (June, July, August) seasons. The daily circulation types are analyzed at surface level and their temporal evolution
is examined via transition matrices. 315 grid points are used covering the area between 25° N to 60° N and 10° W to 40° E.
This analysis derives 8 circulation types for the winter and 4 for the summer.
A reduction in cyclonic activity and an increase in anticyclonic activity in the Central Mediterranean are detected in the
late 1980s and early 1990s during the winter period. During summer the etesian winds and the local flows are dominant over
Athens.
Received February 20, 2002; accepted January 9, 2003
Published online May 26, 2003 |
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Keywords: | |
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