Seasonal variation in total organic carbon in the northeast Atlantic in 2000-2001

• Published in: Journal of Geophysical Research
• Main Authors: Sohrin, R, Sempere, Richard
• Other Authors: Laboratoire de MicrobiologiE de Géochimie et d'Ecologie Marines (LMGEM), Université de la Méditerranée - Aix-Marseille 2-Centre National de la Recherche Scientifique (CNRS)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2005
• Subjects: [SDU.STU.OC]Sciences of the Universe [physics]/Earth Sciences/Oceanography; Northeast Atlantic
• Online Access: https://hal.science/hal-00750977; https://hal.science/hal-00750977/document; https://hal.science/hal-00750977/file/2004JC002731.pdf; https://doi.org/10.1029/2004JC002731

International audience Total organic carbon (TOC) was measured in the midlatitudes of the northeast Atlantic in 2000-2001 during the Programme Océan Multidisciplinaire Méso Echelle (POMME). In spring, mixed layer depth (MLD) was positively correlated with the north latitude, while the surface TOC and chlorophyll-a (Chl a) were negatively correlated with it. It indicates the northward propagation of TOC accumulation along the onset of spring bloom, which was triggered by shoaling of MLD from the south. Surface TOC was highest in summer, though surface Chl a was lowest. Surface TOC was significantly correlated with surface Chl a during winter and spring but not during summer or fall, indicating the minor influence of total phytoplankton biomass on surface TOC distribution in the oligotrophic season. High surface TOC in summer and fall was related with shallow MLD, which could hold fresh TOC near the surface. Downward TOC flux from the surface to below the seasonal thermocline was estimated for the processes of winter convection (F c ), turbulent diffusion (F d ) and sinking flux (F p ). The sum of these fluxes accounts for 6-75% of annual new production. To our knowledge, this is the first estimation based on the simultaneous measurement of F c , F d , F p , and annual new production.