General Introduction					  8 

Part one: Storm tracks and blocking highs		 12 
  Introduction						 12 
  The wintertime ciculation				 13 
  High frequency transients				 15 
  Blocking highs					 17 
  Concluding remarks					 20 
  Figures						 22 
 
 Part two: Teleconnections				 37 
  Introduction and method				 37 
  Teleconnections in SST and SLH			 38 
  Seasonal teleconnections				 40 
  Conclusions						 44 
  Figures						 46 

Part three: Altimeter validation			 76 
  Introduction						 76 
  Air-sea interaction					 77 
  The North Atlantic subsurface behaviour		 79 
  Topex/Poseidon altimeter data				 80 
  Coupled model sea level height computation		 81 
  Simple comparison of model and altimeter data		 82 
  Seasonal variations of temperature and sea-level	 84 
  Interannual variations of sea level			 86 
  Concluding remarks					 87 
  Figures						 89 

Part four: Data assimilation				130 
  Introduction						130 
  Initial drift in the tropics and the North Atlantic	132 
  Global behaviour of the seasonal experiments		134 
  Concluding remarks					136 
  Figures						137 

Appendix: Ocean data assimilation review		165 

General conclusions					178 

References						181 

Appendix: model description				185