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Figure 1: Gulf of Lions, Nimbus-7 CZCS data April 13th 1979. The algorithm using y 
the ratio of the subsurface upwelling radiances Lgg (443nm) over Lgg (550nm) allow- ( 
ed us to visualize a mesoscale cyclonic eddy offshore Marseilles. o 
Outflow of the Rhône river 
  
On most of the analyzed images, the seaward outflow of the Rhône river 
is a major feature in the Gulf of Lions. However, it was almost invisible, 
through the present approach, in the month of December. A characteristic feature 
revealed by remote sensing of chlorophyll pigments is a westbound deflection of 
the plume of the river which can even lead to a U-turn type motion towards the 
shore (Fig. 1). This is presumably due to the influence of the Liguro-Provencal 
current which moves superficially in a veast Northeast-Southwest anticlockwise 
movement. Another interesting point concerning the outflow is the extension of 
the influence of the Rhône river plume on chlorophyll distribution. On June 8th 
1979 an analysis using the ratio Lgg(520nm) over Lgg (550nm) (Fig. 2) reveals an 
extension of the river plume all across the Gulf of Lions, almost reaching the 
Spanish coast. At this time of year the outflow of waters from the Rhöne is not 
at its maximum. The extent of its influence on phytoplankton distribution might 
be explained by a major spreading out of superficial warm waters. 
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