@article{fdi:010060876,
  title = {{S}easonal and regional variability of upper ocean diapycnal heat flux in the {A}tlantic cold tongue},
  author = {{H}ummels, {R}. and {D}engler, {M}. and {B}ourl{\`e}s, {B}ernard},
  editor = {},
  language = {{ENG}},
  abstract = {{SST} variability within the {A}tlantic cold tongue ({ACT}) region is of climatic relevance for the surrounding continents. {A} multi cruise data set of microstructure observations is used to infer regional as well as seasonal variability of upper ocean mixing and diapycnal heat flux within the {ACT} region. {T}he variability in mixing intensity is related to the variability in large scale background conditions, which were additionally observed during the cruises. {T}he observations indicate fundamental differences in background conditions in terms of shear and stratification below the mixed layer ({ML}) for the western and eastern equatorial {ACT} region causing critical {F}roude numbers ({F}r) to be more frequently observed in the western equatorial {ACT}. {T}he distribution of critical {F}r occurrence below the {ML} reflects the regional and seasonal variability of mixing intensity. {T}urbulent dissipation rates (epsilon) at the equator (2 degrees {N}-2 degrees {S}) are strongly increased in the upper thermocline compared to off-equatorial locations. {I}n addition, epsilon is elevated in the western equatorial {ACT} compared to the east from {M}ay to {N}ovember, whereas boreal summer appears as the season of highest mixing intensities throughout the equatorial {ACT} region, coinciding with {ACT} development. {D}iapycnal heat fluxes at the base of the {ML} in the western equatorial {ACT} region inferred from epsilon and stratification range from a maximum of 90 {W} m(-2) in boreal summer to 55 {W} m-(2) in {S}eptember and 40 {W} m(-2) in {N}ovember. {I}n the eastern equatorial {ACT} region maximum values of about 25 {W} m(-2) were estimated during boreal summer reducing to about 5 {W} m(-2) towards the end of the year. {O}utside the equatorial region, inferred diapycnal heat fluxes are comparably low and rarely exceeding 10 degrees {W} m(-2). {I}ntegrating the obtained heat flux estimates in the {ML} heat budget at 10 {W} on the equator accentuates the diapycnal heat flux as the largest {ML} cooling term during boreal summer and early autumn. {I}n the western equatorial {ACT} elevated meridional velocity shear in the upper thermocline contributes to the enhanced diapycnal heat flux within this region during boreal summer and autumn. {T}he elevated meridional velocity shear appears to be associated with intra-seasonal wave activity.},
  keywords = {{OCEAN} {ATLANTIQUE}},
  booktitle = {},
  journal = {{P}rogress in {O}ceanography},
  volume = {111},
  numero = {},
  pages = {52--74},
  ISSN = {0079-6611},
  year = {2013},
  DOI = {10.1016/j.pocean.2012.11.001},
  URL = {https://www.documentation.ird.fr/hor/fdi:010060876},
}