Publication Date:
2019
Description:
Abstract
Two Bio‐Argo floats measured the concentration of chlorophyll‐a, the backscattering coefficient, the fluorescence of humic‐like dissolved organic matter, dissolved oxygen, and temperature and salinity in the northern and central basins of the South China Sea for over 2 years. Temporal evolutions of bio‐optical properties were analyzed at surface, subsurface, and in the whole water column, respectively. It was found that (1) The seasonal variability of the surface chlorophyll‐a was highly controlled by photoacclimation, especially in the central basin; (2) backscattering in the upper 150 m was nearly constant, exhibiting no distinct seasonality; (3) with vertical mixing, particles from the deep chlorophyll maxima were entrained into the mixed layer resulting in enhanced surface chlorophyll during the early winter. This phenomenon may mislead a study based on satellite data which is likely to interpret it as blooming rather than a redistribution of phytoplankton within the water column; (4) analysis of a winter bloom and an anticyclonic eddy reveal that physical entrainment and biological photoacclimation modulated the vertical distributions of chlorophyll‐a and particles and potentially also changes of phytoplankton community composition; and (5) fluorescent dissolved organic matter was found to be highly coupled to phytoplankton dynamics in both basins, with a maximum (after removing the contribution of physical convective mixing) located at the depth of chlorophyll‐a subsurface maximum.
Print ISSN:
2169-9275
Electronic ISSN:
2169-9291
Topics:
Geosciences
,
Physics
