@article{PAR00006135,
  title = {{U}pwelling and associated heat flux in the equatorial {A}tlantic inferred from helium isotope disequilibrium},
  author = {{R}hein, {M}. and {D}engler, {M}. and {S}ultenfuss, {J}. and {H}ummels, {R}. and {H}uttl-{K}abus, {S}. and {B}ourl{\`e}s, {B}ernard},
  editor = {},
  language = {{ENG}},
  abstract = {{U}pwelling velocities w in the equatorial band are too small to be directly observed. {H}ere, we apply a recently proposed indirect method, using the observed helium isotope ({H}e-3 or {H}e-4) disequilibria in the mixed layer. {T}he helium data were sampled from three cruises in the eastern tropical {A}tlantic in {S}eptember 2005 and {J}une/{J}uly 2006. {A} one-dimensional two-box model was applied, where the helium air-sea gas exchange is balanced by upwelling from {H}e-3-rich water below the mixed layer and by vertical mixing. {T}he mixing coefficients {K}-v were estimated from microstructure measurements, and on two of the cruises, {K}-v exceeded 1 x 10(-4) m(2)/s, making the vertical mixing term of the same order of magnitude as the gas exchange and the upwelling term. {I}n total, helium disequilibrium was observed on 54 stations. {O}f the calculated upwelling velocities, 48% were smaller than 1.0 x 10(-5) m/s, 19% were between 1.0 and 2.0 x 10(-5) m/s, 22% were between 2.0 and 4.0 x 10(-5) m/s, and on 11% of upwelling velocities exceeded this limit. {T}he highest upwelling velocities were found in late {J}une 2006. {M}eridional upwelling distribution indicated an equatorial asymmetry with higher vertical velocities between the equator and 1 degrees to 2 degrees south compared to north of the equator, particularly at 10 degrees {W}. {A}ssociated heat flux into the mixed layer could be as high as 138 {W}/m(2), but this depends strongly on the chosen depths where the upwelled water comes from. {B}y combining upwelling velocities with sea surface temperature and productivity distributions, a mean monthly equatorial upwelling rate of 19 {S}v was estimated for {J}une 2006 and a biweekly mean of 24 {S}v was estimated for {S}eptember 2005.},
  keywords = {},
  booktitle = {},
  journal = {{J}ournal of {G}eophysical {R}esearch - {O}ceans},
  volume = {115},
  numero = {},
  pages = {{C}08021},
  ISSN = {0148-0227},
  year = {2010},
  DOI = {10.1029/2009jc005772},
  URL = {https://www.documentation.ird.fr/hor/{PAR}00006135},
}