@article{fdi:010037741,
  title = {{S}easonal variability of the surface chlorophyll in the western tropical {P}acific from {S}ea{W}i{FS} data},
  author = {{M}essi{\'e}, {M}onique and {R}adenac, {M}arie-{H}{\'e}l{\`e}ne},
  editor = {},
  language = {{ENG}},
  abstract = {{W}e used {S}ea-viewing {W}ide {F}ield-of-view {S}ensor ({S}ea{W}i{FS}) to document the seasonal cycle of surface chlorophyll in the western tropical {P}acific. {S}urface waters in this region can be divided into two ecosystems. {T}he western end of the cold, salty waters of the cold tongue with high nutrient low chlorophyll ({HNLC}) characteristics occupies most of the eastern part {O}f the region, while warm, fresh, and oligotrophic waters of the warm pool stand in the western part. {N}evertheless, disruption of the oligotrophy may show up at different locations. {W}e reconstructed the seasonal cycle of chlorophyll, sea surface temperature ({SST}), winds, and surface currents from satellite data and satellite-derived products by extracting the annual and semi-annual harmonics of the time series at each grid point. {T}he calculation was done for the 1999-2004 years in order to exclude the consequences of the major 1997-1998 {E}l {N}ino {S}outhern {O}scillation event. {T}he variance explained by the seasonal cycle for this period highlights three regions with high seasonality: (1) {T}he oligotrophy/{HNLC} transition zone undergoes meridional seasonal displacements. {T}he cold tongue is at its northernmost (southernmost) position during boreal spring (fall). {T}hese displacements can be explained in terms of meridional advection of chlorophyll-rich waters and are consistent with the seasonal cycle of the north and south equatorial countercurrents that transport phytoplankton-poor waters. (2) {O}cean-color images show seasonal enrichments in the far western north equatorial countercurrent ({NECC}) area, especially during boreal spring. {T}he chlorophyll maximum coincides with the maximum {NECC} velocity, follows a {SST} minimum, and occurs during the upwelling-favorable phase of the wind stress curl. {W}e attribute these enrichments to local upwelling associated with current meandering, horizontal advection from further west, and transport of nutrient-rich waters by the {N}ew {G}uinea coastal undercurrent. (3) {N}ear the {S}olomon {A}rchipelago, we observe enhancements of chlorophyll concentration southwest of the islands in austral winter, when both the southwestward surface currents and the southeasterly wind stress are strongest. {T}his may be a combination of an island-mass effect and wind-driven upwelling. {H}orizontal advection from the {S}olomon area leads to an almost concurrent seasonal chlorophyll enrichment in the northern {C}oral {S}ea. {I}n the {G}ulf of {P}apua, high chlorophyll concentrations at the same time can be explained by the presence of a strong cyclonic circulation. {T}his study highlights the richness of the response of surface chlorophyll to physical processes at the seasonal time scale in a region usually acknowledged as oligotrophic.},
  keywords = {seasonal variations ; surface chlorophyll ; surface currents ; biological physical interactions ; remote sensing ; {E}uphotic zone},
  booktitle = {},
  journal = {{D}eep {S}ea {R}esearch {P}art {I} {O}ceanographic {R}esearch {P}apers},
  volume = {53},
  numero = {10},
  pages = {1581--1600},
  ISSN = {0967-0637},
  year = {2006},
  DOI = {10.1016/j.dsr.2006.06.007},
  URL = {https://www.documentation.ird.fr/hor/fdi:010037741},
}