During 2012 and 2014, China has two Haiyang(which means ocean in Chinese, referred to as HY) satellites operating normally in space which are HY-1B and HY-2A. HY-1B is an ocean color environment satellite which was la...During 2012 and 2014, China has two Haiyang(which means ocean in Chinese, referred to as HY) satellites operating normally in space which are HY-1B and HY-2A. HY-1B is an ocean color environment satellite which was launched in April 2007 to observe global ocean color and sea surface temperature, and HY-2A is an ocean dynamic environment satellite which was launched in August 2011 to obtain global marine dynamic environment parameters including sea surface height,significant wave height, ocean wind vectors, etc. Ocean observation data provided by HY-1B and HY-2A have been widely used by both domestic and international users in extensive areas such as ocean environment protection, ocean disaster prevention and reduction, marine environment forecast,ocean resource development and management, ocean investigations and scientific researches, etc.展开更多
The Chinese Ocean Color and Temperature Scanner(COCTS)on-board the Chinese second ocean color satellite,HY-1B,obtained approximately 6 years of data between 2007 and 2013 in China coastal seas and the adjacent waters....The Chinese Ocean Color and Temperature Scanner(COCTS)on-board the Chinese second ocean color satellite,HY-1B,obtained approximately 6 years of data between 2007 and 2013 in China coastal seas and the adjacent waters.However,its radiometric performance has hardly been analyzed,which confuses its applicability in ocean remote sensing.This study tracked the long-term radiometric responsivity trend of HY-1B COCTS based on a stable marine target.Firstly,we identified a temporally stable maritime site of 12°~15°N and 116°~119°E according to the water and atmospheric optical properties using Aqua MODIS products.Then,the time-series of top-of-atmosphere(TOA)reflectance was obtained for each band of HY-1B COCTS and Aqua MODIS over this site according to the criteria of sun-target-view geometry.Finally,exponential or linear degradation models were built and used to adjust the radiometric levels of HY-1B COCTS.Results indicate that the radiometric performance exhibited continuous degradation for all bands at varying levels between 0.4%and 8.1%yr^(−1).The worst degradation occurred at 412 nm,with an annual average rate of 8.1%.The degradation at 443 nm reached 5.5%yr^(−1)following 412 nm.The radiometric performance at 490 nm,520 nm,and 565 nm was relatively stable with a drift of~3%yr^(−1).The 670 nm,750 nm,and 865 nm bands remain most stable with the degradation of~1%yr^(−1).Taking Terra MODIS as a reference,the temporal consistency of HY-1B COCTS was significantly improved for each band after radiometric adjustment.Cloud-free imageries between 2007 and 2013 showed relatively high spatial consistency.The bias of TOA reflectance was~5%in visible bands and~10%in near-infrared bands after degradation correction.These improvements confirm the application potentials of HY-1B COCTS in ocean remote sensing.展开更多
HY-1B/COCTS是我国自主研发的第2颗海洋卫星HY-1B星搭载的水色水温扫描仪(Chinese ocean color and temperature scanner,COCTS)。由于COCTS的不同探测器对地物光谱响应有差异,其图像的行间存在明暗的条带噪声。针对COCTS图像在水色遥...HY-1B/COCTS是我国自主研发的第2颗海洋卫星HY-1B星搭载的水色水温扫描仪(Chinese ocean color and temperature scanner,COCTS)。由于COCTS的不同探测器对地物光谱响应有差异,其图像的行间存在明暗的条带噪声。针对COCTS图像在水色遥感中的应用特点,在分析可见光-近红外波段地物光谱特征的基础上,使用其第4和第8波段数据构建的归一化差分水体指数(normalized difference water index,NDWI)提取图像的水体信息;采用矩匹配法对COCTS图像水体区域的条带噪声进行去除,并以均值、标准差、信噪比、偏度、峰度、信息熵和平均梯度7个指标对条带噪声去除后的COCTS图像进行质量评价。结果表明,该方法能有效消除图像的条带噪声,使图像质量得到改善。展开更多
Mr. Jiang Xingwei, Director of National Marine Environment Forecast Center intro-duced some problems occurred on HY-1A during its two years' operation after it was launched in May, 2002. The observation instrument...Mr. Jiang Xingwei, Director of National Marine Environment Forecast Center intro-duced some problems occurred on HY-1A during its two years' operation after it was launched in May, 2002. The observation instrument suddenly faced the sun instead of the earth. However, the scientists adjusted the attitude of HY-1A by means of sending the command through a sun protection telecontrol system.展开更多
文摘During 2012 and 2014, China has two Haiyang(which means ocean in Chinese, referred to as HY) satellites operating normally in space which are HY-1B and HY-2A. HY-1B is an ocean color environment satellite which was launched in April 2007 to observe global ocean color and sea surface temperature, and HY-2A is an ocean dynamic environment satellite which was launched in August 2011 to obtain global marine dynamic environment parameters including sea surface height,significant wave height, ocean wind vectors, etc. Ocean observation data provided by HY-1B and HY-2A have been widely used by both domestic and international users in extensive areas such as ocean environment protection, ocean disaster prevention and reduction, marine environment forecast,ocean resource development and management, ocean investigations and scientific researches, etc.
基金supported by the National Key R&D Program of China[grant numbers 2018YFB0504900 and 2018YFB0504904]the National Natural Science Foundation of China[grant numbers.42071325 and 42176183]LIESMARS Special Research Funding,the“985 Project”of Wuhan University,and Special funds of State Key Laboratory for equipment.
文摘The Chinese Ocean Color and Temperature Scanner(COCTS)on-board the Chinese second ocean color satellite,HY-1B,obtained approximately 6 years of data between 2007 and 2013 in China coastal seas and the adjacent waters.However,its radiometric performance has hardly been analyzed,which confuses its applicability in ocean remote sensing.This study tracked the long-term radiometric responsivity trend of HY-1B COCTS based on a stable marine target.Firstly,we identified a temporally stable maritime site of 12°~15°N and 116°~119°E according to the water and atmospheric optical properties using Aqua MODIS products.Then,the time-series of top-of-atmosphere(TOA)reflectance was obtained for each band of HY-1B COCTS and Aqua MODIS over this site according to the criteria of sun-target-view geometry.Finally,exponential or linear degradation models were built and used to adjust the radiometric levels of HY-1B COCTS.Results indicate that the radiometric performance exhibited continuous degradation for all bands at varying levels between 0.4%and 8.1%yr^(−1).The worst degradation occurred at 412 nm,with an annual average rate of 8.1%.The degradation at 443 nm reached 5.5%yr^(−1)following 412 nm.The radiometric performance at 490 nm,520 nm,and 565 nm was relatively stable with a drift of~3%yr^(−1).The 670 nm,750 nm,and 865 nm bands remain most stable with the degradation of~1%yr^(−1).Taking Terra MODIS as a reference,the temporal consistency of HY-1B COCTS was significantly improved for each band after radiometric adjustment.Cloud-free imageries between 2007 and 2013 showed relatively high spatial consistency.The bias of TOA reflectance was~5%in visible bands and~10%in near-infrared bands after degradation correction.These improvements confirm the application potentials of HY-1B COCTS in ocean remote sensing.
文摘HY-1B/COCTS是我国自主研发的第2颗海洋卫星HY-1B星搭载的水色水温扫描仪(Chinese ocean color and temperature scanner,COCTS)。由于COCTS的不同探测器对地物光谱响应有差异,其图像的行间存在明暗的条带噪声。针对COCTS图像在水色遥感中的应用特点,在分析可见光-近红外波段地物光谱特征的基础上,使用其第4和第8波段数据构建的归一化差分水体指数(normalized difference water index,NDWI)提取图像的水体信息;采用矩匹配法对COCTS图像水体区域的条带噪声进行去除,并以均值、标准差、信噪比、偏度、峰度、信息熵和平均梯度7个指标对条带噪声去除后的COCTS图像进行质量评价。结果表明,该方法能有效消除图像的条带噪声,使图像质量得到改善。
文摘Mr. Jiang Xingwei, Director of National Marine Environment Forecast Center intro-duced some problems occurred on HY-1A during its two years' operation after it was launched in May, 2002. The observation instrument suddenly faced the sun instead of the earth. However, the scientists adjusted the attitude of HY-1A by means of sending the command through a sun protection telecontrol system.
