Although remote sensing data have been used to estimate total suspended matter （TSM） in coastal waters, it has limitations when applied to estuary waters in low spatial resolution situations. The spatial resolution ...Although remote sensing data have been used to estimate total suspended matter （TSM） in coastal waters, it has limitations when applied to estuary waters in low spatial resolution situations. The spatial resolution of ocean color satellites such as SeaWiFS and MODIS is usually -1 km, and therefore is not adequate for small, local-scale areas such as the Zhujiang （Pearl） River estuary. In contrast, 30 m-resolution EO-1 Hyperion imagery has potential for studying TSM in localized areas. We measured the surface spectral radiance reflectance of the river estuary water in the visible and near infra-red spectral range. Sensitivity analysis indicated that the ratio of remote sensing reflectance at 813 nm （Rrs（813）） to reflectance at 559 nm （Rrs（559）） could be used to estimate TSM concentration, and a linear relationship was established between the ratio and in-situ TSM concentration. We applied the linear relationship to Hyperion imagery to map TSM concentration in the estuary. The Hyperion imagery provided sufficient spatial resolution to detect spatiotemporal changes in TSM concentrations in the estuary small estuary area. This study demonstrated the usefulness of Hyperion imagery for mapping the distribution of TSM in estuary waters. Keyword： Hyperion; total suspended matter （TSM）; Zhujiang （Pearl） River estuary展开更多
Seven-year(2005-2011)Synthetic Aperture Radar(SAR)images are applied to study oceanic eddies in the East China Sea.It is found that most of these eddies detected from the SAR images are less than 10 km,which are subme...Seven-year(2005-2011)Synthetic Aperture Radar(SAR)images are applied to study oceanic eddies in the East China Sea.It is found that most of these eddies detected from the SAR images are less than 10 km,which are submesoscale eddies.Seasonal differences are evident in the distribution of eddies,with the highest and the lowest number of eddies noted in summer and winter,respectively.Since slick streaks in SAR images look dark,an eddy identified due to the slicks is referred to as“black eddy”.As a result of wave-current interactions in the zones of current shear,it can be seen that an eddy exhibits a bright curve,the eddy is called“white eddy”.During the seven years,95 black eddies and 50 white eddies are identified in the study area.Black eddies are found in the whole study area while white eddies are mainly distributed in the vicinity of the Kuroshio Current.This study suggests that the distribution of the white eddy is denser around the Kuroshio because of the strong shear in the Kuroshio region.In terms of the eddy sizes,white eddies are generally smaller than black eddies.展开更多
基金Supported by the National Natural Science Foundation of China(No. 40976106)the Science Foundation Program of Guangdong Ocean University (No. 1012339)the Open Fund of State Key Laboratory of Satellite Ocean Environment Dynamics of Second Institute of Oceanography, SOA (No. SODE1203)
文摘Although remote sensing data have been used to estimate total suspended matter （TSM） in coastal waters, it has limitations when applied to estuary waters in low spatial resolution situations. The spatial resolution of ocean color satellites such as SeaWiFS and MODIS is usually -1 km, and therefore is not adequate for small, local-scale areas such as the Zhujiang （Pearl） River estuary. In contrast, 30 m-resolution EO-1 Hyperion imagery has potential for studying TSM in localized areas. We measured the surface spectral radiance reflectance of the river estuary water in the visible and near infra-red spectral range. Sensitivity analysis indicated that the ratio of remote sensing reflectance at 813 nm （Rrs（813）） to reflectance at 559 nm （Rrs（559）） could be used to estimate TSM concentration, and a linear relationship was established between the ratio and in-situ TSM concentration. We applied the linear relationship to Hyperion imagery to map TSM concentration in the estuary. The Hyperion imagery provided sufficient spatial resolution to detect spatiotemporal changes in TSM concentrations in the estuary small estuary area. This study demonstrated the usefulness of Hyperion imagery for mapping the distribution of TSM in estuary waters. Keyword： Hyperion; total suspended matter （TSM）; Zhujiang （Pearl） River estuary
基金The National Key Research and Development Program of China under contract Nos 2016YFA0601803 and 2017YFA0604100the National Natural Science Foundation of China under contract Nos 41476022,41490643 and 41706008the China Ocean Mineral Resources R&D Association under contract Nos DY135-E2-2-02 and DY135-E2-3-01.
文摘Seven-year(2005-2011)Synthetic Aperture Radar(SAR)images are applied to study oceanic eddies in the East China Sea.It is found that most of these eddies detected from the SAR images are less than 10 km,which are submesoscale eddies.Seasonal differences are evident in the distribution of eddies,with the highest and the lowest number of eddies noted in summer and winter,respectively.Since slick streaks in SAR images look dark,an eddy identified due to the slicks is referred to as“black eddy”.As a result of wave-current interactions in the zones of current shear,it can be seen that an eddy exhibits a bright curve,the eddy is called“white eddy”.During the seven years,95 black eddies and 50 white eddies are identified in the study area.Black eddies are found in the whole study area while white eddies are mainly distributed in the vicinity of the Kuroshio Current.This study suggests that the distribution of the white eddy is denser around the Kuroshio because of the strong shear in the Kuroshio region.In terms of the eddy sizes,white eddies are generally smaller than black eddies.
