Oceano-meteorological conditions and coupling in the southeastern Bay of Biscay, for the period 2001–2005: A comparison with the past two decades

This contribution describes oceano-meteorological conditions, investigating their coupling, within the southeastern part of the Bay of Biscay. The study focuses upon: (i) simple relationships between atmospheric temperature and sea surface temperature (SST); (ii) complex relationships, such as the heat and salt content associated with the precipitation–evaporation balance and river flow; and (iii) dynamic aspects (Ekman transport, upwelling–downwelling conditions, turbulence and winter mixed layer depth), related to the wind speed and direction. Some seasons of the first five-year period of the 21st century have been defined as “extreme” (warm summer in 2003; cold and long winter in 2005; very dry spring and summer seasons in 2005; etc.). The present study confirms the presence of frequent seasonal anomalies; they appear to indicate a “deseasonalisation”, in relation to the classical seasonal cycle of the Atlantic climatic regime, at mid-latitudes. This term means that winter–summer duality prevails against the establishment (in terms of values and mean duration), of spring and autumn as transitional seasons. In contrast, oceano-meteorological time-series is characterised by its relatively scarce anomalies, in terms of annual values. In addition, a significant coupling between meteorological and oceanographic conditions is observed over the area, confirming that the meteorological forcing drives, to a great extent, oceanographic conditions at the sea surface; and water column properties, to a lesser degree.