The East Atlantic Oscillation: Mechanism and Impact on the European Climate in Winter

N.V. Mikhailova✉, A.V. Yurovsky

Marine Hydrophysical Institute, Russian Academy of Sciences, Sevastopol, Russian Federation

✉ e-mail: mikhailova_nv@mhi-ras.ru

Abstract

The second leading mode of principal component analysis of the winter atmospheric pressure pattern in the North Atlantic-European region known as the East Atlantic Oscillation (EAO) is considered. The winter EAO pattern exhibits well-defined dipole at 500-hPa geopotential height (H500) with centers over the North Atlantic and the Central Europe. The EAO phase-to-phase shifts reflect the general atmospheric circulation changes and the zonal (meridional) circulation dominates in positive (negative) EAO phase. This induces storm tracks spatial shift, heat and moisture transport redistribution, which in turn results in anomalous winter air temperature and precipitation in the Europe. The surface air temperature and precipitation interannual variability explained by EAO index is 25 – 35 % and 15 – 25 %, respectively. Positive EAO phase is associated with the higher winter air temperatures in Europe (mean anomalies are from +0.3 to +3.5 °C), and negative EAO phase is associated with the lower winter air temperatures (mean anomalies are from –1.5 to –0.5 °C).

Basin-wide changes in the intensity and location of the North Atlantic polar jet stream are observed between the EAO opposite phases. Anomalous cyclonic (anticyclonic) circulation over the North Atlantic and southward (northward) shift of the North Atlantic jet stream is shown to be inherent in positive (negative) EAO phase.

Keywords

East Atlantic Oscillation, surface air temperature, precipitation, midtropospheric jet, atmospheric circulation, storm tracks

For citation

Mikhailova, N.V. and Yurovsky, A.V., 2016. The East Atlantic Oscillation: Mechanism and Impact on the European Climate in Winter. Physical Oceanography, (4), pp. 25-33. doi:10.22449/1573-160X-2016-4-25-33

DOI

10.22449/1573-160X-2016-4-25-33

References

  1. Wallace, J.M., Gutzler, D.S., 1981, “Teleconnections in the geopotential height field during the Northern Hemisphere winter”, Mon. Wea. Rev., no. 109, iss. 4, pp. 784-812.
  2. Barnston, A.G., Livezey, R.E., 1987, “Classification, seasonality and persistence of low-frequency atmospheric circulation patterns”, Mon. Wea. Rev., no. 115, iss. 6, pp. 1083-1126.
  3. Nesterov, E.S., 2009, “O vostochnoatlanticheskom kolebanii tsirkulyatsii atmosfery [On the East Atlantic Oscillation of the atmosphere circulation]”, Meteorologiya i gidrologiya, no. 12, pp. 32-40 (in Russian).
  4. Moore, G.W.K., Renfrew, I., 2012, “Cold European winters: Interplay between the NAO and the East Atlantic mode”, Atmos. Sci. Lett., no. 13, pp. 1-8.
  5. Comas-Bru, L., McDermott, F., 2014, “Impacts of the EA and SCA patterns on the European twentieth century NAO – winter climate relationship”, Quart. J. Roy. Meteorol. Soc., no. 140, pp. 354-363, doi: 10.1002/qj.2158.
  6. Woollings, T., Blackburn, M., 2012, “The North Atlantic jet stream under climate change, and its relation to the NAO and EA patterns”, J. Climate, no. 25, pp. 886-902.
  7. Rodriguez-Puebla, C., Encinas, A.H. & Nieto, S. [et al], 1998, “Spatial and temporal patterns of annual precipitation variability over the Iberian Peninsula”, Int. J. Clim., no. 18, pp. 299-316.
  8. Franzke, C., Feldstein, S.B., 2005, “The continuum and dynamics of Northern hemisphere teleconnection patterns”, J. Atmos. Sci., iss. 62, no. 9, pp. 3250-3267.
  9. Seierstad, I.A., Stephenson, D.B. & Kvamsto, N.G., 2007,”How useful are teleconnection patterns for explaining variability in extratropical storminess?”, Tellus A, iss. 59, no. 2, doi:10.1111/j.1600-0870.2007.00226.x.
  10. Woollings, T., Hannachi, A., Hoskins, B., 2010, “Variability of the North Atlantic eddy-driven jet stream”, Quart. J. Roy. Meteorol. Soc., no. 136, pp. 856-868.
  11. Vyazilova, N.A., 2012, “Tsiklonicheskaya aktivnost' i kolebaniya tsirkulyatsii v Severnoy Atlantike [Cyclonic activity and circulation oscillations in the Northern Atlantics]”, Meteorologiya i gidrologiya, no. 7, pp. 5-14 (in Russian).
  12. Athanasiadis, P.J., Wallace, J.M. & Wettstein, J.J., 2010, “Patterns of wintertime jet stream variability and their relation to the storm tracks”, J. Atmos. Sci., no. 67, iss. 5, pp. 1361-1381.
  13. Haylock, M.R., Hofstra, N. & Klein Tank, A.M.G. [et al], 2008 “A European daily high-resolution gridded dataset of surface temperature and precipitation”, J. Geophys. Res.: Atmospheres, no. 113, D20119, doi: 10.1029/2008JD1201.
  14. Allan, R., Ansell, T., 2006, “A new globally complete monthly historical gridded mean sea level pressure dataset (HadSLP2): 1850 – 2004”, J. Clim., no. 19, pp. 5816-5842, doi:10.1175/JCLI3937.1.
  15. Compo, G.P., Whitaker, J.S. & Sardeshmukh, P.D. [et al.], 2011, “The Twentieth Century Reanalysis Project”, Quart. J. Roy. Meteorol. Soc., no. 137, pp. 1-28.
  16. Voskresenskaya, E.N., Naumova, V.A. & Evstigneev, M.P. [et al.], 2009, “Klassifikatsiya sinopticheskikh protsessov shtormov v Azovo-Chernomorskom basseyne [Classification of the synoptic processes of the storms in the Azov and Black Sea basin]”, Naukovі pratsі Ukrains'kogo naukovo-doslіdnogo gіdrometeorologіchnogo іnstitutu, iss. 258, pp. 189-200 (in Russian).
  17. Woollings, T., Czuchnicki, C. & Franzke, C., 2014, “Twentieth century North Atlantic jet variability”, Quart. J. Roy. Meteorol. Soc., no. 140, pp. 783-791.

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