FN Archimer Export Format PT J TI Hydrographical variability on the French continental shelf in the Bay of Biscay, during the 1990s BT AF PUILLAT, Ingrid LAZURE, Pascal JEGOU, Anne-Marie LAMPERT, Luis MILLER, P AS 1:;2:;3:;4:;5:; FF 1:;2:PDG-DEL-AO;3:PDG-DEL-AO;4:PDG-DEL-DRV-RA-LERN;5:; C1 IFREMER, DEL, AO, F-29280 Plouzane, France. EPSHOM, F-29275 Brest, France. Plymouth Marine Lab, Plymouth PL1 3DH, Devon, England. C2 IFREMER, FRANCE EPSHOM, FRANCE PLYMOUTH MARINE LAB, UK SI BREST PORT-EN-BESSIN SE PDG-DEL-AO PDG-DEL-DRV-RA-LERN IN WOS Ifremer jusqu'en 2018 copubli-europe IF 1.431 TC 108 UR https://archimer.ifremer.fr/doc/2004/publication-779.pdf LA English DT Article CR AGIR94 BIOMET2 BIOMET3 DAAG 92 ERAG 93 ERAG 94 EVHOE 927 EVHOE 948 EVHOE 959 OLMAC 92 PEGASE 97 PEGASE 98 PELGAS PLAGIA 6 PLAGIA1 PLAGIA2 PLAGIA3 PLAGIA4 PLAGIA5 BO Gwen Drez Thalassa Thalia DE ;Upwelling;Cold pool;River plumes;Seasonal variability;Salinity;Hydrography AB A synthesis of 9 years of hydrographic measurements, acquired during approximately 25 cruises (1992-2000) on the French continental shelf of the Bay of Biscay, is presented. The main focus is upon salinity distribution, as it is little known in this area. The whole of the data set covers I I months of the year, with some sampling fields repeated several times a year, for multiple years. This time-series allows temperature and salinity distributions to be studied together with their seasonal, inter-annual and mesoscale variability. The seasonal trend in temperature can be described in three stages, which are in agreement with past studies. Thermal stratification occurs between May and mid-September in a layer similar to 50 m in thickness, whereas the water column remains homogenous from January to the beginning of April. The mid-September-December period corresponds to the progressive destruction of the thermocline. In contrast, the salinity distribution displays two main seasonal patterns. From March to June, the haline stratification is strong;, this is in response to high river runoff and relatively low vertical mixing. In autumn, stratification decreases because of low river discharge and wind-induced vertical mixing. Surface salinity increases by up to I psu inshore of the 100-m isobath, from spring to end of summer. The salinity gradient runs cross-shore in spring and along-shore in summer: this is due to the mean wind direction during the previous 6 months (SW from September to March. NW from March to September). Nevertheless, this seasonal signal could be biased by the high inter-annual variability. Indeed. the monthly extent of low surface salinity (S < 35) varied between years, this is driven by river runoff over the previous 3-6 months and short-term wind events (similar to 10 days), particularly when they are upwelling-favourable. Forcing at these time-scales are responsible also for mesoscale structures, such as lower salinity lenses and wind-induced coastal upwelling off Southern Brittany. In the deeper layers the inter-annual variability of a denser water structure named (the "Cold Pool") is also investigated. Consequently, the inter-annual, seasonal and mesoscale variability in salinity patterns are caused by (i) river runoff from the Loire and Gironde, that reduces surface salinity locally; and (ii) the wind that influences the location of low salinity water masses. Mesoscale structures and the observed links between inter-annual and seasonal variability, raise problems in relation to the interpretation of in situ data, making it impossible to establish the actual mean distribution. There is a pressing need within the Bay of Biscay, for sampling at higher spatial and temporal resolution. PY 2004 PD JUL SO Continental Shelf Research SN 0278-4343 PU Elsevier VL 24 IS 10 UT 000222596800005 BP 1143 EP 1163 DI 10.1016/j.csr.2004.02.008 ID 779 ER EF