North Atlantic Oscillation

Variability

Snow cover extent fluctuations over Eurasia and NAO persistence - proposed mechanism

Snow

Data Analysis

Climate variability

• Air-sea interaction
  • Large scale
  • Upwelling
  • Sea ice
• Air-land interaction
  • Snow
• Local responses

Climate predictability

• Linear model

• Analog technique

1st cyclostationary empirical orthogonal function (CEOF) for zonal wind at 300 hPa (ERA-40) (1967-2000)

• NAO/AO interannual persistence could be due to land-atmosphere interaction over huge continental mass of Eurasia

• Land-atmosphere interaction is modulated via snow cover fluctuations, affecting soil temperature and moisture.

• Changes in snow cover, especially in early warm season, lead to changes in NAO/AO phases.

• Reduction in snow cover over Eurasia is associated with NAO/AO positive phase.

Reference

Bojariu, R., R. Garcia-Herrera, L. Gimeno, T. Zhang, and O. W. Frauenfeld. Cryosphere-Atmosphere Interaction Related to Variability and Change of Northern Hemisphere Annular Mode. In L. Gimeno, R. García-Herrera, R. M. Trigo (eds.), Trends and Directions in Climate Research: Ann. N. Y. Acad. Sci. , 1146, pp. 50-59. Wiley-Blackwell, 2008.

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Roxana Bojariu Copyright © 2002-2008

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