prevail over the Azores, so that humid air masses are driven towards the north of
Europe, where winters typically become wet and mild [53–55]. Hence, drier conditions over the Seine basin are encountered during negative NAO phases. The
mechanisms driving the AMV are more controversial, since there is evidence for
both natural and anthropogenic controls on its variability. Nevertheless, the role of
Atlantic buoyancy-driven circulation on the AMV is generally recognised as predominant (see [47] and reference therein). In terms of a temporal signature, the
NAO’s periodicity mainly lies within two bands, 5–7 years and 16–19 years,
whereas the AMV is characterised by timescales varying between 60 and
100 years [21, 47, 52, 56, 57], which makes it more difficult to detect given the
relative shortness of the available records [52, 58]. These global-scale climatic
processes were proven to be largely responsible for the Seine’s observed variability
in mean annual discharge [47, 50, 59, 60].
Fig. 2 Two statistical features of the Seine discharge data recorded at the Pont d’Austerlitz (Paris,
France) gauging station since 1885. (a) Maximum annual discharge. (b) VCN30, defined as the
annual minimum of a 30-day running average of daily mean discharge. The vertical dashed lines
mark the commissioning of reservoir lakes in derivation of the Seine and its main tributaries
upstream from Paris (names of the rivers are shown along with the reservoir volumes in millions
of cubic metres, Mm
3
)
Pluri-annual Water Budget on the Seine Basin: Past, Current and Future Trends
63
Europe, where winters typically become wet and mild [53–55]. Hence, drier conditions over the Seine basin are encountered during negative NAO phases. The
mechanisms driving the AMV are more controversial, since there is evidence for
both natural and anthropogenic controls on its variability. Nevertheless, the role of
Atlantic buoyancy-driven circulation on the AMV is generally recognised as predominant (see [47] and reference therein). In terms of a temporal signature, the
NAO’s periodicity mainly lies within two bands, 5–7 years and 16–19 years,
whereas the AMV is characterised by timescales varying between 60 and
100 years [21, 47, 52, 56, 57], which makes it more difficult to detect given the
relative shortness of the available records [52, 58]. These global-scale climatic
processes were proven to be largely responsible for the Seine’s observed variability
in mean annual discharge [47, 50, 59, 60].
Fig. 2 Two statistical features of the Seine discharge data recorded at the Pont d’Austerlitz (Paris,
France) gauging station since 1885. (a) Maximum annual discharge. (b) VCN30, defined as the
annual minimum of a 30-day running average of daily mean discharge. The vertical dashed lines
mark the commissioning of reservoir lakes in derivation of the Seine and its main tributaries
upstream from Paris (names of the rivers are shown along with the reservoir volumes in millions
of cubic metres, Mm
3
)
Pluri-annual Water Budget on the Seine Basin: Past, Current and Future Trends
63