The Northwest Pacific region, which includes parts of northeast China, Japan, Korea and southeast Russia, is one of the most densely populated areas of the world. Eutrophication is an emerging environmental problem in this region, where a significant number of red tides and hypoxic conditions have been reported in coastal waters - possibly due to anthropogenic influences such as extensive chemical fertilizer use and sewage effluent. To assess this problem, NOWPAP CEARAC, the Special Monitoring and Coastal Environment Assessment Regional Activity Centre of the Action Plan for the Protection, Management and Development of the Marine and Coastal Environment of the Northwest Pacific Region of the United Nations Environmental Programme, has developed "Procedures for assessment of eutrophication status including the evaluation of land-based sources of nutrients for the NOWPAP region" (NOWPAP Common Procedures). The NOWPAP Common Procedures include the screening procedure to detect symptoms of eutrophication with selected parameters. One of the selected parameters is remotely sensed chlorophyll-a concentration (satellite Chl-a). To prepare a long-term consistent satellite Chl-a from 1998 to 2016, regression analysis was conducted by pixel to pixel using the daily composites of SeaWiFS and MODIS Remote Sensing Reflectance for overlapping period (July 2002 to December 2004). Two different empirical in-water algorithms, a NASA standard and a regionally developed one for turbid water, were applied to estimate Chl-a in the eastern and western parts of the Northwest Pacific region, respectively. The assessment of eutrophication was then conducted by the level and trend of satellite Chl-a.
Total suspended matter concentration (TSM) algorithms for ocean color sensors use empirical relationship between
satellite-retrieved remote sensing reflectances and TSM. However the estimated-TSM has no enough accuracy because
the reflectance at visible bands has error after atmospheric correction in high turbid area. The purpose of this study is to
estimate simultaneously total suspended matter concentration, aerosol optical thickness and Angstrom exponent using
three bands at near infrared from MODIS/Aqua and SeaWiFS data. We applied this scheme to MODIS/Aqua and
SeaWiFS data, and satellite-derived TSM were compared with ship-observed TSM dataset in Yellow Sea and East China
Sea. RMSE of TSM was 0.338 in log-log coordinates and correlation coefficient was 0.850. The scheme was better than
Clark’s or Tassan’s TSM algorithm.
Global Imager (GLI) is the visible to infrared imager aboard ADEOS-II satellite with 30 and 6 channels for 1 km and 250m resolutions, respectively. The sensor was successfully captured the first image on January 25, 2003. Sea surface temperature (SST) will be retrieved in combination with simultaneous SST observation by low-resolution microwave sensor, AMSR-E. Distribution of chlorophyll and other constituents will be obtained from ocean color channels. Frequent observations with 250 m visible channels will be also available, and combination with 1 km ocean color and SST will be useful for coastal applications. Early scientific results of GLI ocean group will be presented in this presentation.
KEYWORDS: Meteorology, Algorithm development, Remote sensing, Satellites, Data analysis, Atmospheric corrections, Data archive systems, Data centers, Data processing, Reflectivity
High resolution SeaWiFS data was used to detect a red tide event occurred in the Ariake Sound, Japan, in winter of 2000 to 2001. The area is small embayment surrounding by tidal flat, and it is known as one of the most productive areas in coast of Japan. The red tide event damaged to seaweed (Nori) culture, and the relation to the reclamation at the Isahaya Bay in the Sound has been discussed. SeaWiFS chlorophyll data showed the red tide started early December 2000, from the Isahaya Bay, although direct relationship to the reclamation was not clear. The red tide persisted to the end of February. Monthly average of SeaWiFS data from May 1998 to December 2001 indicated that the chlorophyll increased twice a year, early summer and fall after the rain. The red tide event was part of the fall bloom which started later and continued longer than other years. Ocean color is useful to detect the red tide; however, it is required to improve the algorithms to accurately estimate chlorophyll in high turbid water and to discriminate toxic flagellates.
We developed an algorithm to estimate primary production from ocean color satellite data, and estimated the global distribution of primary production with OCTS and SeaWiFS data. The VGPM is one of the simplest and most usable models for primary production estimation from satellite chlorophyll. We propose two-phytoplankton community model of primary production to improve the VGPM. In general, chlorophyll concentration tends to be proportional to phytoplankton cell size and phytoplankton productivity tends to be inversely proportional to cell size. Based on these facts, we improved PBopt(maximum carbon fixation rate within a water column), which is one of the most important parameters of the VGPM. We assume that the phytoplankton community is composed of large and small cell size phytoplankton and that there are limits to the biomass of small phytoplankton. Based on this hypothesis, we matched PBopt to the functions of sea surface temperature and sea surface chlorophyll concentration. The results indicate that small phytoplankton has higher productivity with higher temperature dependency. We estimated the global distribution of primary production using this modified VGPM. The global distribution of primary production is basically similar to that of chlorophyll concentration. The modified VGPM estimates lower productivity than original VGPM in high chlorophyll concentration areas, and conversely estimates higher productivity in low chlorophyll concentration areas. With total global primary production, the modified VGPM results are 12% lower than the original VGPM.
The downward spectral irradiance and upward spectral radiance, and chlorophyll a concentration of surface water were determined in the North Pacific Ocean: Bering Sea, Gulf of Alaska, Central and Equatorial Pacific, Kuroshio region, Yellow Sea, Japan Sea, Tokyo Bay, and Ise Bay. These areas included Case I and Case II water. The optical characteristics in the study area were based on measurements of underwater spectral irradiance. The strong correlation between the attenuation coefficient at 490 nm, K490, and other at wavelengths were observed. The relation between chlorophyll concentration and K490 showed a good correlation at eh coastal and bay areas except a the stations near river mouths. These relations suggested that suspended and dissolved matter were largely of biogenous origin such as fragmented and decomposed phytoplankton. In the clear ocean, at low chlorophyll concentrations, the data points were widely scattered, implying that K490 is sensitive to changes in suspended particles.
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