Publications des scientifiques de l'IRD

Radenac Marie-Hélène, Plimpton P. E., Lebourges Dhaussy Anne, Commien L., McPhaden M. J. (2010). Impact of environmental forcing on the acoustic backscattering strength in the equatorial Pacific : diurnal, lunar, intraseasonal, and interannual variability. Deep-Sea Research Part I. Oceanographic Research Papers, 57 (10), p. 1314-1328. ISSN 0967-0637.

Titre du document
Impact of environmental forcing on the acoustic backscattering strength in the equatorial Pacific : diurnal, lunar, intraseasonal, and interannual variability
Année de publication
2010
Type de document
Article référencé dans le Web of Science WOS:000283206600014
Auteurs
Radenac Marie-Hélène, Plimpton P. E., Lebourges Dhaussy Anne, Commien L., McPhaden M. J.
Source
Deep-Sea Research Part I. Oceanographic Research Papers, 2010, 57 (10), p. 1314-1328 ISSN 0967-0637
We analyzed several records of mean volume backscattering strength (S-v) derived from 150 kHz acoustic doppler current profilers (ADCPs) moored along the equator in upwelling mesotrophic conditions and in the warm pool oligotrophic ecosystem of the Pacific Ocean. The ADCPs allow for gathering long time-series of non-intrusive information about zooplankton and micronekton at the same spatial and temporal scales as physical observations. High S-v are found from the surface to the middle of the thermocline between dusk and dawn in the mesotrophic regime. Biological and physical influences modified this classical diel cycle. In oligotrophic conditions observed at 170 degrees W and 140 degrees W during El Nino years, a subsurface S-v maximum characterized nighttime S-v profiles. Variations of the thermocline depth correlated with variations of the base of the high S-v layer and the subsurface maximum closely tracked the thermocline depth from intraseasonal to interannual time-scales. A recurring deepening (20-60 m) of the high S-v layer was observed at a frequency close to the lunar cycle frequency. At 165 degrees E, high day-to-day variations prevailed and our results suggest the influence of moderately mesotrophic waters that would be advected from the western warm pool during westerly wind events. A review of the literature suggests that S-v variations may result from changes in biomass and species assemblages among which myctophids and euphausiids would be the most likely scatterers.
Plan de classement
Limnologie physique / Océanographie physique [032]
Localisation
Fonds IRD [F B010052887]
Identifiant IRD
fdi:010052887
Contact