2007 Annual Report - jamstec japan agency for marine-earth ...

tion by the large vertical diffusivity suggested by the previous
research (Fig.10). It is generally very difficult to estimate vertical
diffusivity in the open ocean, which is important in various
physical, biological and chemical processes in the ocean.
However, results obtained here indicate observation by floats
with sensors to measure biological and chemical parameters is
also effective in consistent estimation of diffusivity.
e. Development of next generation float
Argo Group is developing a next-generation float with a
buoyancy control system combining an oil pump and a plunger.
Fig. 10 Schematic diagram to show relation of vertical density
structure with nutrients, concentration of chlorophyll and dissolved
oxygen based on float data and shipboard water sampling data.
Nutrients (nitrate) in the STMW layer (layer in green color) is transported
upwards by strong vertical diffusion to feed to the seasonal
pycnocline (layer in white color), which maintains primary production
represented by the layer of maximizing chlorophyll (Chl. A) concentration
and dissolved oxygen.
Fig. 9
Time series of a layer with high concentration of chlorophyll
(layer with concentration higher than 0.1g/l), depth with maximum
concentration of chlorophyll, an upper end of STMW and
mixed layer depth measured with floats with chlorophyll and oxygen
sensors.
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