@article{fdi:010090317,
  title = {{O}utgassing of {CO}2 dominates in the coastal upwelling off the northwest {A}frican coast},
  author = {{L}ef{\`e}vre, {N}athalie and {V}eleda, {D}. and {H}artman, {S}. {E}.},
  editor = {},
  language = {{ENG}},
  abstract = {{T}he {E}astern {B}oundary {U}pwelling {S}ystem off northwest {A}frica is among the most productive regions of the ocean. {I}n 2019, two merchant ships equipped with an underway {CO}2 system sampled the region following exactly the same track from 10 degrees {N} to 36 degrees {N}. {W}e determine the sources and sinks of {CO}2 and the seasonal cycle along the track. {A} weak permanent upwelling ({WPU}), a permanent upwelling ({PU}) and an open ocean regions are identified. {T}he {WPU} (26 degrees {N} to 33 degrees {N}) is a source of {CO}2 in summer and autumn, and a sink of {CO}2 in winter and spring. {T}her-modynamic warming and cooling processes mainly drive the {CO}2 variations in this region. {T}he {PU} (20 degrees {N} to 26 degrees {N}) is a sink of {CO}2 in spring and a source of {CO}2 in other seasons. {T}his region is the most productive and exhibits the largest variability of the {CO}2 flux. {T}he supply of {CO}2 from subsurface waters dominate over the carbon uptake by biology, which leads to a strong outgassing, especially in winter and autumn. {A} sink of {CO}2 occurs in spring only in the {PU}. {N}ear {C}ape {B}lanc (20 degrees {N}) in {J}uly 2019, a source of {CO}2 is observed around 20 degrees {N} within +/- 1 degrees of latitude and becomes a sink of {CO}2 a few days later when the ship samples back the same area. {S}outh of 18 degrees {N}, out of the influence of the coastal upwelling, the region is a sink of {CO}2 in winter only and the region is mainly controlled by physical processes. {U}sing voyages from 2010 to 2022, seawater f{CO}2 significantly increases at a rate ranging from 1.82 mu atm yr -1 to 2.10 mu atm yr -1 close to the atmospheric increase. {T}his is associated with a p{H} decrease between 0.0016 and 0.0022 yr -1. {N}evertheless, there is no clear trend of the {CO}2 flux in any region.},
  keywords = {{A}ir -sea flux of {CO} 2 ; {F}ugacity of {CO} 2 ; {N}orthwest {A}frican upwelling ; {E}astern tropical {A}tlantic ; {V}oluntary observing ships ; {ATLANTIQUE} ; {ZONE} {TROPICALE}},
  booktitle = {},
  journal = {{D}eep-{S}ea {R}esearch {P}art {I} : {O}ceanographic {R}esearch {P}apers},
  volume = {200},
  numero = {},
  pages = {104130 [14 p.]},
  ISSN = {0967-0637},
  year = {2023},
  DOI = {10.1016/j.dsr.2023.104130},
  URL = {https://www.documentation.ird.fr/hor/fdi:010090317},
}