Un Demi SiÃ¨cle Dâ€™Ã©valuation De Lâ€™activitÃ© De Lâ€™upwelling De La CÃ´te Atlantique Marocaine
Authors: Hilmi Karim , Bessa Ismail , Aouni, Anass El , Makaoui Ahmed , Ettahiri Omar 
Published: August 2020

Les Ã©cosystÃ¨mes d'upwelling situÃ©s en bordures Est (EBUEs) sontparmi les Ã©cosystÃ¨mes les plus productifs au monde et leur rÃ©ponse auchangement climatique d'une importance cruciale. La variabilitÃ© saisonniÃ¨reet dÃ©cennale Ã  long terme de l'activitÃ© d'upwelling de la partie nord du grandÃ©cosystÃ¨me marin du Courant des Canaries (CCLME) a Ã©tÃ© Ã©tudiÃ©e dans cetravail sur une pÃ©riode de 53 ans (1967-2019) Ã  deux stations situÃ©esrespectivement au nord (31Â°N-10,5Â°O) et au sud (24,5Â°N-15,5Â°O) de la cÃ´teatlantique marocaine, en Ã©laborant lâ€™Indice dâ€™Upwelling de Bakun (UI)mensuel. Les rÃ©sultats obtenus montrent que lâ€™upwelling prÃ©sente unevariabilitÃ© saisonniÃ¨re entre Cap Juby - Larache et une activitÃ© quasipermanente toute lâ€™annÃ©e entre Cap Juby - Cap Blanc. En relation avec lavariabilitÃ© dÃ©cennale et dans la zone nord atlantique marocaine, les plus fortesactivitÃ©s de lâ€™upwelling ont Ã©tÃ© observÃ©es en saisons dâ€™Ã©tÃ©, en particulier surla pÃ©riode 1998-2003 et son activitÃ© a lÃ©gÃ¨rement dÃ©passÃ© la moyenne sur lespÃ©riodes 1972-1977, 1980-1984, 2004-2008. Les plus faibles activitÃ©s delâ€™upwelling dans cette zone ont Ã©tÃ© observÃ©s en saisons dâ€™automne/hiver,notamment sur les pÃ©riodes 1967-1970, 1995-1998 et 2000-2005. Sâ€™agissantde la zone sud atlantique marocaine, lâ€™activitÃ© de lâ€™upwelling a prÃ©sentÃ© uneforte activitÃ© de lâ€™upwelling en Ã©tÃ© sur les pÃ©riodes 1967-1980 et 2009-2019,avec des fluctuations annuelles Ã  interannuelles variables entre ces deuxpÃ©riodes. Cette activitÃ© a Ã©tÃ© lÃ©gÃ¨rement supÃ©rieure Ã  la moyenne en Ã©tÃ© sur lapÃ©riode 1981-2007, sauf pour les annÃ©es 1982-1983, 1988-1989, 1995-1997et 2004-2007 oÃ¹ il a Ã©tÃ© observÃ© une relative tendance vers la baisse. De plus faibles activitÃ©s de lâ€™upwelling ont Ã©tÃ© observÃ©es dans cette zone sur la pÃ©riode2003-2010 en saisons dâ€™automne/hiver.
Eastern Boundary Upwelling Ecosystems (EBUEs) are among themost productive ecosystems in the world, meaning that their response toclimate change is of critical importance. In this work, we investigate the longterm seasonal and decadal variability of the upwelling activity along thenorthern part of the Canary Current Large Marine Ecosystem (CCLME) overa period of 53 years (1967-2019). Two stations were selected in this studyrepresentative of the upwelling activity in the moroccan atlantic coast, one inthe north (31Â° N-10.5Â°W) and the other in the south (24.5Â° N-15.5Â°W) usingthe monthly Bakun Upwelling Index (UI). The results shows a seasonalvariability in the northern region of morocco between Cap Juby - Larache andalmost permanent activity all year round in the southern region of moroccobetween Cap Juby - Cap Blanc. These results are consistent with previousstudies based on the seasonality of the upwelling regime in thisregion. Relatedto the decadal variability, the strongest activities of upwelling were observedduring summer seasons in the northern region, in particular over the periodv 1998-2003 and its activity slightly exceeded the average over the periods1972-1977, 1980-1984, 2004-2008. The weakest upwelling activities in thisregion were observed in the fall-winter seasons, particularly during the periods1967-1970, 1995-1998 and 2000-2005. In the southern region, the upwellingactivity showed strong upwelling activity in summer over the periods 1967-1980 and 2009-2019, with annual and interannual between these two periods.This activity was slightly above average in summer over the 1981-2007period, except for the years 1982-1983, 1988-1989, 1995-1997 and 2004-2007where a relative downward trend was observed. Lower upwelling activitieswere observed in this area over the 2003-2010 period in fall / winter seasons.