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Study of future climatic variations of a teleconnection pattern affecting Eastern Mediterranean

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Pages :
195 - 203

Hatzaki M., Flocas H.A., Maheras P., Asimakopoulos D.N., and Giannakopoulos C.
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A teleconnection pattern has been identified between Eastern Mediterranean and Northwestern
Europe in the geopotential fields of the upper troposphere (hereafter will be referred
to as EMP) during winter and it seems to play significant role in the large-scale atmospheric
circulation over Mediterranean region with distinctive temporal and spatial characteristics.
Since teleconnections are significant components of the natural climatic variability, any future
climatic changes are expected to influence their structure and intensity and subsequently their
implications on the regional climate.
Taking into account these findings, the aim of this study is to investigate the existence of EMP
and its potential spatial variations in the future, in connection with the IPCC Emission
Scenarios of greenhouse gases. For this purpose, gridded daily data of geopotential height at
500 hPa have been used. For the present climate, the datasets derive from NCEP/NCAR
archive and cover the period 1958 to 2003 on 2.5°x 2.5° latitude by longitude grid. For the
future, the datasets derive from HadAM3P model for the period 2070-2100, on the basis of
two different IPCC scenarios. Two different approaches were employed on a seasonal basis
in order to identify the centres of action for this pattern: Rotated Principal Component Analysis
and Correlation analysis.
First, the validation of the model results (control run) against the gridded data of NCEP/NCAR
for the present period 1960-1990 demonstrated that the two datasets agree quite well. Then,
it was found that the EMP exists in the future (2070-2100) under different scenarios of
greenhouse gases emissions and subsequent global warming but not in its present form. For
the scenario that predicts global temperature increase by 2.3°C, the pattern forms with a
northeastward shift of the two poles relative to location in the present climate. If the global
temperature increase is higher (of 3.3°C), the whole EMP is shifted to the southeast by almost
10°, as compared to its present form. These results are collaborated by both approaches

teleconnection patterns, climatic changes, Eastern Mediterranean, principal component analysis, correlation analysis