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ABSTRACT: Spatially and temporally high-resolution estimates of past natural climate variability are important to assess recent significant
climate trends. The mid-latitude atmospheric circulation is the dominant factor for regional changes in temperature, rainfall,
and other climatic variables. Here we present reconstructions of gridded monthly sea level pressure (SLP) fields back to 1659
and seasonal reconstructions from 1500-1658 for the eastern North Atlantic-European region (30°W to 40°E; 30°N to 70°N). These
were developed using principal component regression analysis based on the combination of early instrumental station series
(pressure, temperature and precipitation) and documentary proxy data from Eurasian sites. The relationships were derived over
the 1901-1960 calibration period and verified over 1961-1990. Under the assumption of stationarity in the statistical relationships,
a transfer function derived over the 1901-1990 period was used to reconstruct the 500-year large-scale SLP fields. Systematic
quality testing indicated reliable winter reconstructions throughout the entire period. Lower skill was obtained for the other
seasons, although meaningful monthly reconstructions were available from around 1700 onwards, when station pressure series
became available. The quality and the reconstructed SLP fields for two exceptionally cold years (1573, 1740) are discussed
and climatologically interpreted. An EOF analysis of the 1500-1999 winter SLP revealed, firstly, a zonal flow pattern with
pronounced decadal to centenial time scale variations, secondly, a monopole pattern over northwest Europe and thirdly, a pattern
modulating the meridional flow component over Europe. These 500-year SLP reconstructions should be useful for modelling studies,
particulary for analyses of low-frequency atmospheric variability and for circulation dynamics.
Climate Dynamics 04/2012; 18(7):545-561. · 4.60 Impact Factor
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ABSTRACT: The interannual and decadal variability of summer (June to September) air temperature in the northeastern Mediterranean is analysed for the period 1950 to 1999. Extremely hot and cool summers are illustrated by means of composite analysis. The combined influence of the large-scale atmospheric circulation and thermic predictors on local temperature is assessed by means of an objective approach based on empirical orthogonal functions and canonical correlation analysis. Monthly values of sea level pressure, geopotential heights, atmospheric thickness and Mediterranean sea surface temperatures are used as predictor fields and air temperature from 24 observational sites spread over Greece and western Turkey constitute the predictand variable. Results indicate that more than 50% of the total summer temperature variability can be explained linearly by the combination of eight large-scale predictor fields on two canonical correlation modes. The first canonical mode is related to a more meridional circulation at the upper tropospheric levels, which favours local land-sea contrasts in the associated local temperature pattern. Variations of this mode are found to be responsible for the occurrence of extreme events and decadal trends in regional temperature, the latter being characterized by a cooling in the early 1960s and a warming in the early 1990s. The second canonical mode pictures variations in the intensity of the zonal circulation over the Atlantic area that drive temperature anomalies affecting mainly the Aegean Sea and the west of Greece. Our results suggest the potential of statistical downscaling for Greek summer temperature with reliable climate forecasts for planetary-scale anomalies.
Climate Dynamics 02/2003; 20(5):537-554. · 4.60 Impact Factor
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ABSTRACT: The Late Maunder Minimum (LMM, 1675–1715) denotes the climax of the `Little Ice Age' in Europe with marked climate variability. Investigations into interannual and interdecadal differences of atmospheric circulation between the LMM and the period 1961–1990 have been performedand undertaken based upon sea level pressure (SLP) difference maps, empiricalorthogonal function (EOF) analysis, and objective classification techniques. Since the SLP during the LMM winterwas significantly higher in northeastern Europe but below normal over the central and western Mediterranean, more frequent blocking situations were connected with cold air outbreaks towards central and eastern Europe. Springs were cold and characterized by a southward shift of the mid-latitude storm tracks. Summers in western, central Europe and northern Europe were wetter and slightly cooler than they are today due to a weakerAzores high and a more southerly position of the mean polar front axes. Autumns showed a significantly higher pressure over northern Europe and a lower pressure over continental Europe and the Mediterranean, an indication of an advanced change from summer to winter circulation. It is suggested that the pressure patterns during parts of the LMM might be attributed to the combination of external forcing factors (solar irradiance and volcanic activity) and internal oscillations and couplings in the North Atlantic.
Climatic Change 01/2001; 49:441-462. · 3.38 Impact Factor
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J. Luterbacher, R. Rickli,
C. Tinguely,
E. Xoplaki,
E. Schu Pbach,
D. Dietrich,
M. Ambu,
C. Pfister,
P. Beeli,
U. Dietrich, [......],
T. D. Davies,
P. D. Jones,
V. Slonosky,
P. Maheras,
M. Barriendos,
M. J. Alcoforado,
R. Glaser,
C. Beck,
A. Philipp,
U. Beyer
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ABSTRACT: The Late Maunder Minimum (LMM; 1675 -- 1715) delineates a period with marked climate variability within the Little Ice Age in Europe. Gridded monthly mean surface pressure fields were reconstructed for this period for the eastern North Atlantic -- European region (25W -- 30E and 35 -- 70N). These were based on continuous information drawn from proxy and instrumental data taken from several European data sites. The data include indexed temperature and rainfall values, sea ice conditions from northern Iceland and the Western Baltic. In addition, limited instrumental data, such as air temperature from central England (CET) and Paris, reduced mean sea level pressure (SLP) at Paris, and monthly mean wind direction in the resund (Denmark) are used. The reconstructions are based on a canonical correlation analysis (CCA), with the standardized station data as predictors and the SLP pressure fields as predictand. The CCA-based model was performed using data from the twentieth century. The perio...
10/2000;
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Jurg Luterbacher, R. Rickli,
C. Tinguely,
Elena Xoplaki,
E. Schüpbach,
Daniel Dietrich,
J. Hüsler,
Ambühl,
C. Pfister,
P. Beeli, [......],
J. Jacobeit,
C. Beck,
A. Philipp,
U. Beyer,
E. Kaas,
T. Schmith,
L. Bärring,
P. Jönsson,
L. Rácz,
Heinz Wanner
[show abstract]
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ABSTRACT: The Late Maunder Minimum (LMM; 1675-1715) delineates a period with marked climate variability within the Little Ice Age in Europe. Gridded monthly mean surface pressure fields were reconstructed for this period for the eastern North Atlantic-European region (25°W-30°E and 35-70°N). These were based on continuous information drawn from proxy and instrumental data taken from several European data sites. The data include indexed temperature and rainfall values, sea ice conditions from northern Iceland and the Western Baltic. In addition, limited instrumental data, such as air temperature from central England (CET) and Paris, reduced mean sea level pressure (SLP) at Paris, and monthly mean wind direction in the Øresund (Denmark) are used. The reconstructions are based on a canonical correlation analysis (CCA), with the standardized station data as predictors and the SLP pressure fields as predictand. The CCA-based model was performed using data from the twentieth century. The period 1901-1960 was used to calibrate the statistical model, and the remaining 30 years (1961-1990) for the validation of the reconstructed monthly pressure fields. Assuming stationarity of the statistical relationships, the calibrated CCA model was then used to predict the monthly LMM SLP fields. The verification results illustrated that the regression equations developed for the majority of grid points contain good predictive skill. Nevertheless, there are seasonal and geographical limitations for which valid spatial SLP patterns can be reconstructed. Backward elimination techniques indicated that Paris station air pressure and temperature, CET, and the wind direction in the Øresund are the most important predictors, together sharing more than 65% of the total variance. The reconstructions are compared with additional data and subjectively reconstructed monthly pressure charts for the years 1675-1704. It is shown that there are differences between the two approaches. However, for extreme years the reconstructions are in good agreement. Copyright © 2000 Royal Meteorological Society
International Journal of Climatology. 01/2000; 20:1049-1066.
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P D Jones,
T D Davies,
D H Lister,
V Slonosky,
T Jónsson,
L Bärring,
P Jönsson,
P Maheras,
F Kolyva-Machera,
M Barriendos, [......],
M J Alcoforado,
H Wanner,
C Pfister,
J Luterbacher, R Rickli,
E Schuepbach,
E Kaas,
T Schmith,
J Jacobeit,
C Beck
International Journal of Climatology 01/1999; 19(4):347-364. · 2.91 Impact Factor
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ABSTRACT: The paper discusses annual to decadal climate variability and change in the European Alps by utilizing the procedure of synoptic downscaling, i.e. it investigates the influence of global to continental scale synoptic structures and processes on the regional climate of the Alps. The European Alps lie to the southeast and under the right exit zone of the southwest-northeast oriented axis of the polar front jet over the North Atlantic ocean, in a transition zone between the Azores high and Icelandic low, between oceanic and continental and between Mediterranean and North Atlantic climates. Together with complex topographically induced phenomena like lee cyclogenesis, orographic precipitation, strong downslope winds and thermotopographical circulation systems, this transitional position makes climate studies in the Alps even more interesting. Only a minor correlation can be observed between global climate variability and Alpine climate. In contrast, the Alpine climate is strongly related to processes over the North Atlantic ocean and its sea ice system (e.g. it has a high correlation with the North Atlantic Oscillation and the dynamics and position of the Icelandic low), an area with a rather low climate prediction potential.Since the early 1970''s (or just after the Great Salinity Anomaly in the North Atlantic Ocean) the intensification of the wintertime westerly jet over the North Atlantic area led to a noticeable northwest-southeast mass transport in the exit area of the jet over Central Europe, leading to pressure and temperature rises and an increase in the amount of precipitation. There is a question over whether this phenomenon is a consequence of natural climate variability or the beginning of an anthropogenic climate change.
Theoretical and Applied Climatology 08/1997; 58(3):221-243. · 1.94 Impact Factor
