Optical Characteristics of Seawater – Viewing Phytoplankton from a Satellite–
- As of May 2021, he is working at the National Institute of Polar Research.
It is extremely important to estimate the primary production of phytoplankton when considering the carbon cycle in the ocean. The increase of seawater temperature associated with global warming in recent years is thought to affect the primary productivity of the ocean. However, the conventional primary productivity estimation method uses sea surface temperature as an input variable, and it is difficult to correctly discuss the change in primary production due to global warming. Therefore, we designed a method of estimating primary production using the light absorption coefficient of phytoplankton, which is a parameter independent of seawater temperatures.
Figure. (a) Basic production estimated by the method
based on the light absorption coefficient, (b) basic production estimated by the
conventional method, and (c) difference between a and b.
In marine ecosystems, the size structure of phytoplankton is one of the factors that determine the energy transfer efficiency in the food web. Therefore, spatiotemporal monitoring of the wide-range phytoplankton-size structure is important for evaluating changes in the marine ecosystem. Based on previous studies, the light absorption spectrum is known to differ depending on the size and group of phytoplankton. Therefore, we designed a method to estimate the phytoplankton-size structure based on the light absorption spectrum.
Figure. Distributions of (a) CSD slope, which is an indicator of phytoplankton-size structure, and (b) chlorophyll a (Chl. a).
Black contour line shows Chl. a = 0.10 mg m-3.