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| Titel |
Nonstationary relationship between atmospheric teleconnection patterns and Weather types in NW Iberian Peninsula |
| VerfasserIn |
A. M. Ramos, M. N. Lorenzo, L. Gimeno, J. J. Taboada |
| Konferenz |
EGU General Assembly 2009
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 11 (2009) |
| Datensatznummer |
250024391
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| Zusammenfassung |
| The teleconnection patterns play a major role in variability in our climate system in different
time and spatial scales. Although the NAO explains a substantial portion of the low-frequency
climate variability in Europe, it is also necessary to consider other teleconnection patterns
such as the Scandinavian Index (SCA), the Eastern Atlantic (EA) or the Eastern
Atlantic/Western Russia (EA-WR) indices. On the other hand, this relationship between
teleconnection patterns and the climate in Europe cannot be considered stable since there are
some studies which point out the non stationarity of this relationship, not only in surface
temperature (Gimeno et al, 2003) but also in precipitation (Vicente-Serrano and
López-Moreno, 2008).
The main objective of this work is to assess the influence of the inter-decadal variability
in the position and intensity of the teleconnection patterns pressure centers affecting Europe
on the local circulation regimes in Galicia (NW Iberian Peninsula).
An automated version of the Lamb weather type (WT) classification scheme (Jones et al
1993) using the NCEP/NCAR reanalysis data (from 1948 to 2005) was adapted
for the Galicia area (Northwestern corner of the Iberian Peninsula) by Lorenzo
et al (2008) in order to compute the daily local circulation regimes in the study
area.
In order to identify the changes over time of the regional climate modes in the European
domain (30N - 76N and 37W - 56E) we computed a moving-window Principal Component
Analysis (PCA) (30-year period) between 1948-2005 which allow us to study changes not
only in the spatial patterns over time but also in terms of position and intensity of the regional
climate modes.
Results show an increase of explained variance of the NAO pattern in the last two decades
and a displacement of the NAO centers to East. We also computed the correlation between the
four leading principal component of the PCA analysis (moving window (30 years)) and the
local WT circulation. In general, we prove that the value of these correlations varies strongly
with the time, moving from non significant to statistically significant depending on the
selected 30 year period.
Gimeno L., de la Torre, L., Nieto, R., García, R., Hernández, E. and Ribera, P. (2003)
Changes in the relationship NAO–Northern hemisphere temperature due to solar activity.
Earth and Planetary Science Letters 206, 15-20.
Vicente-Serrano, S. M., and J. I. López-Moreno (2008), Differences in the non-stationary
influence of the North Atlantic Oscillation on European precipitation under different
scenarios of greenhouse gas concentrations, Geophys. Res. Lett., 35, L18710,
doi:10.1029/2008GL034832.
Jones, P. D. , M. Hulme , K. R. Briffa. (1993) A comparison of Lamb circulation types
with an objective classification scheme. Int. J. Climatol. 13: 655- 663.
Lorenzo M.N., Taboada J.J. and Gimeno L. 2008. Links between circulation weather
types and teleconnection patterns and their influence on precipitation patterns in Galicia (NW
Spain). International Journal of Climatology 28(11),1493:1505 DOI: 10.1002/joc.1646. |
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