@article{fdi:010086663,
  title = {{I}nternal tides off the {A}mazon shelf during two contrasted seasons : interactions with background circulation and {SSH} imprints},
  author = {{T}chilibou, {M}. and {K}och {L}arrouy, {A}riane and {B}arbot, {S}. and {L}yard, {F}. and {M}orel, {Y}. and {J}ouanno, {J}ulien and {M}orrow, {R}.},
  editor = {},
  language = {{ENG}},
  abstract = {{T}he {A}mazon shelf break is a key region for internal tide ({IT}) generation. {I}t also shows a large seasonal variation in circulation and associated stratification. {T}his study, based on a high-resolution model ( explicitly (1/36 degr{\'e}) forced by tide, aims to better characterize how the {IT}s vary between two contrasted seasons. {D}uring the season from {M}arch to {J}uly ({MAMJJ}) the currents and mesoscale eddies are weak while the pycnocline is shallower and stronger. {F}rom {A}ugust to {D}ecember ({ASOND}) mean currents and mesoscale eddies are strong, and the pycnocline is deeper and weaker than in {MAMJJ}. {F}or both seasons, semi-diurnal {M}2 {IT}s are generated on the shelf break mainly between the 100 and 1000 m isobath in the model. {S}outh of 2 degr{\'e} {N}, the conversion from barotropic to baroclinic tide is more efficient in {MAMJJ} than in {ASOND}. {L}ocal dissipation of the coherent {M}2 at the generation sites is higher in {MAMJJ} (30 %) than in {ASOND} (22 %), because higher modes are favourably generated (modes 2 and 3), making the internal wave packet more dispersive. {T}he remaining fraction (70 %-80 %) propagates away from the generation sites and mainly dissipates locally every ~ 100 km, which corresponds to the mode 1 reflection beams. {A}bout 13 %, 30 %, and 40 % of the {M}2 coherent {IT} dissipates at the first, second, and third beams. {M}2 coherent baroclinic flux propagates more northward during {MAMJJ} while it seems to be blocked at 6 degr{\'e} {N} during {ASOND}. {T}here is no intensified dissipation of the coherent {M}2 that could explain the disappearance of the coherent flux. {I}n fact, the flux at this location becomes more incoherent because of strong interaction with the currents. {T}his has been shown in the paper using 25 h mean snapshots of the baroclinic flux that shows branching and stronger eastward deviation of the {IT} when interacting with mesoscale eddies and stratification during {ASOND}. {F}inally, we evaluated sea surface height ({SSH}) frequency and wavenumber spectra for subtidal (f < 1/28 h-1), tidal (1/28 h-1 < f < 1/11 h-1), and supertidal (f > 1/11 h-1) frequencies. {T}idal frequencies explain most of the {SSH} variability for wavelengths between 250 and 70 km. {B}elow 70 km, the {SSH} is mainly incoherent and supertidal. {T}he length scale at which the {SSH} becomes dominated by unbalanced (non-geostrophic) {IT} was estimated to be around 250 km. {O}ur results highlight the complexity of correctly predicting {IT} {SSH} in order to better observe mesoscale and sub-mesoscale eddies from existing and upcoming altimetric missions, notably the {S}urface {W}ater {O}cean {T}opography ({SWOT}) mission.},
  keywords = {{ATLANTIQUE} ; {BRESIL} ; {ZONE} {TROPICALE} ; {AMAZONE}},
  booktitle = {},
  journal = {{O}cean {S}cience},
  volume = {18},
  numero = {6},
  pages = {1591--1618},
  ISSN = {1812-0784},
  year = {2022},
  DOI = {10.5194/os-18-1591-2022},
  URL = {https://www.documentation.ird.fr/hor/fdi:010086663},
}