海洋一号C(HY-1C)卫星是中国首颗海洋水色业务卫星,其搭载的海岸带成像仪(Coastal Zone Imager, CZI)具有大幅宽、短重访周期的优势,可实现海洋和海岸带的大面积观测。作为光学传感器,CZI受云影响严重,准确识别云是CZI数据处理的关键,但...海洋一号C(HY-1C)卫星是中国首颗海洋水色业务卫星,其搭载的海岸带成像仪(Coastal Zone Imager, CZI)具有大幅宽、短重访周期的优势,可实现海洋和海岸带的大面积观测。作为光学传感器,CZI受云影响严重,准确识别云是CZI数据处理的关键,但是CZI缺少红外和短波红外等对云敏感的波段,云检测难度大。针对该问题,本文提出一种融合多尺度卷积和侧窗滤波的轻量化云检测方法,该方法通过多尺度卷积获取云的不同尺度特征,通过侧窗滤波突出边缘特征,减少椒盐噪声的影响,提升云边缘检测的精度。实验结果表明,本文所提出的方法可有效进行云检测,在云边缘提取方面表现较好,F1-score达92.77%,Kappa系数达0.89,与现有云检测方法相比优势明显,且模型训练速度快、参数量少,可为HY-1C CZI遥感影像处理提供有力支撑。展开更多
China has successfully launched four Haiyang-2(HY-2)series altimetry satellites.HY-2A has attracted significant attention in gravity field recovery,but the performance of other HY-2 series satellites,including HY-2B/C...China has successfully launched four Haiyang-2(HY-2)series altimetry satellites.HY-2A has attracted significant attention in gravity field recovery,but the performance of other HY-2 series satellites,including HY-2B/C/D,is seldom discussed.This study evaluated the performance of all the HY-2 series satellites in recovering marine gravity field.First,the crossover discrepancies in sea surface height of the four satellites,HY-2A,HY-2B,HY-2C,and HY-2D,were analyzed to assess their altimetry stability.It was found that HY-2B had the best altimetry quality,followed by HY-2D.Subsequently,different combina-tions of altimetry data were used to calculate vertical deflections and gravity anomalies in the South China Sea(112°E-119°E,12°N-20°N).The results showed that combining data from HY-2B,HY-2C,and HY-2D improved the inversion accuracy of gravity anomalies by 0.3 mGal compared to using HY-2A data alone.HY-2C and HY-2D contributed to enhancing the accuracy of the east component of vertical deflections.展开更多
Estimated ocean subsurface fields derived from satellite observations provide potential data sources for operational marine environmental monitoring and prediction systems.This study employs a statistic regression rec...Estimated ocean subsurface fields derived from satellite observations provide potential data sources for operational marine environmental monitoring and prediction systems.This study employs a statistic regression reconstruction method,in combination with domestic autonomous sea surface height and sea surface temperature observations from the Haiyang-2(HY-2)satellite fusion data,to establish an operational quasi-realtime three-dimensional(3D)temperature and salinity products over the Maritime Silk Road.These products feature a daily temporal resolution and a spatial resolution of 0.25°×0.25°and exhibit stability and continuity.We have demonstrated the accuracy of the reconstructed thermohaline fields in capturing the 3D thermohaline variations through comprehensive statistical evaluations,after comparing them against Argo observations and ocean analysis data from 2022.The results illustrate that the reconstructed fields effectively represent seasonal variations in oceanic subsurface structures,along with structural changes resulting from mesoscale processes,and the upper ocean’s responses to tropical cyclones.Furthermore,the incorporation of HY-2 satellite observations notably enhances the accuracy of temperature and salinity reconstructions in the Northwest Pacific Ocean and marginally improves salinity reconstruction accuracy in the North Indian Ocean when compared to the World Ocean Atlas 2018 monthly climatology thermohaline fields.As a result,the reconstructed product holds promise for providing quasi-real-time 3D temperature and salinity field information to facilitate fast decisionmaking during emergencies,and also offers foundational thermohaline fields for operational ocean reanalysis and forecasting systems.These contributions enhance the safety and stability of ocean subsurface activities and navigation.展开更多
Antarctic sea ice is an important part of the Earth’s atmospheric system,and satellite remote sensing is an important technology for observing Antarctic sea ice.Whether Chinese Haiyang-2B(HY-2B)satellite altimeter da...Antarctic sea ice is an important part of the Earth’s atmospheric system,and satellite remote sensing is an important technology for observing Antarctic sea ice.Whether Chinese Haiyang-2B(HY-2B)satellite altimeter data could be used to estimate sea ice freeboard and provide alternative Antarctic sea ice thickness information with a high precision and long time series,as other radar altimetry satellites can,needs further investigation.This paper proposed an algorithm to discriminate leads and then retrieve sea ice freeboard and thickness from HY-2B radar altimeter data.We first collected the Moderate-resolution Imaging Spectroradiometer ice surface temperature(IST)product from the National Aeronautics and Space Administration to extract leads from the Antarctic waters and verified their accuracy through Sentinel-1 Synthetic Aperture Radar images.Second,a surface classification decision tree was generated for HY-2B satellite altimeter measurements of the Antarctic waters to extract leads and calculate local sea surface heights.We then estimated the Antarctic sea ice freeboard and thickness based on local sea surface heights and the static equilibrium equation.Finally,the retrieved HY-2B Antarctic sea ice thickness was compared with the CryoSat-2 sea ice thickness and the Antarctic Sea Ice Processes and Climate(ASPeCt)ship-based observed sea ice thickness.The results indicate that our classification decision tree constructed for HY-2B satellite altimeter measurements was reasonable,and the root mean square error of the obtained sea ice thickness compared to the ship measurements was 0.62 m.The proposed sea ice thickness algorithm for the HY-2B radar satellite fills a gap in this application domain for the HY-series satellites and can be a complement to existing Antarctic sea ice thickness products;this algorithm could provide long-time-series and large-scale sea ice thickness data that contribute to research on global climate change.展开更多
文摘海洋一号C(HY-1C)卫星是中国首颗海洋水色业务卫星,其搭载的海岸带成像仪(Coastal Zone Imager, CZI)具有大幅宽、短重访周期的优势,可实现海洋和海岸带的大面积观测。作为光学传感器,CZI受云影响严重,准确识别云是CZI数据处理的关键,但是CZI缺少红外和短波红外等对云敏感的波段,云检测难度大。针对该问题,本文提出一种融合多尺度卷积和侧窗滤波的轻量化云检测方法,该方法通过多尺度卷积获取云的不同尺度特征,通过侧窗滤波突出边缘特征,减少椒盐噪声的影响,提升云边缘检测的精度。实验结果表明,本文所提出的方法可有效进行云检测,在云边缘提取方面表现较好,F1-score达92.77%,Kappa系数达0.89,与现有云检测方法相比优势明显,且模型训练速度快、参数量少,可为HY-1C CZI遥感影像处理提供有力支撑。
基金funded by the National Natural Science Foundation of China(No.42074017).
文摘China has successfully launched four Haiyang-2(HY-2)series altimetry satellites.HY-2A has attracted significant attention in gravity field recovery,but the performance of other HY-2 series satellites,including HY-2B/C/D,is seldom discussed.This study evaluated the performance of all the HY-2 series satellites in recovering marine gravity field.First,the crossover discrepancies in sea surface height of the four satellites,HY-2A,HY-2B,HY-2C,and HY-2D,were analyzed to assess their altimetry stability.It was found that HY-2B had the best altimetry quality,followed by HY-2D.Subsequently,different combina-tions of altimetry data were used to calculate vertical deflections and gravity anomalies in the South China Sea(112°E-119°E,12°N-20°N).The results showed that combining data from HY-2B,HY-2C,and HY-2D improved the inversion accuracy of gravity anomalies by 0.3 mGal compared to using HY-2A data alone.HY-2C and HY-2D contributed to enhancing the accuracy of the east component of vertical deflections.
基金The China-ASEAN Marine Cooperation Foundationthe Fundamental Research Funds for the Central Universities under contract No.B210203041+1 种基金the Postgraduate Research&Practice Innovation Program of Jiangsu Province under contract No.KYCX23_0657the opening project of the Key Laboratory of Marine Environmental Information Technology of Ministry of Natural Resources under contract No.521037412.
文摘Estimated ocean subsurface fields derived from satellite observations provide potential data sources for operational marine environmental monitoring and prediction systems.This study employs a statistic regression reconstruction method,in combination with domestic autonomous sea surface height and sea surface temperature observations from the Haiyang-2(HY-2)satellite fusion data,to establish an operational quasi-realtime three-dimensional(3D)temperature and salinity products over the Maritime Silk Road.These products feature a daily temporal resolution and a spatial resolution of 0.25°×0.25°and exhibit stability and continuity.We have demonstrated the accuracy of the reconstructed thermohaline fields in capturing the 3D thermohaline variations through comprehensive statistical evaluations,after comparing them against Argo observations and ocean analysis data from 2022.The results illustrate that the reconstructed fields effectively represent seasonal variations in oceanic subsurface structures,along with structural changes resulting from mesoscale processes,and the upper ocean’s responses to tropical cyclones.Furthermore,the incorporation of HY-2 satellite observations notably enhances the accuracy of temperature and salinity reconstructions in the Northwest Pacific Ocean and marginally improves salinity reconstruction accuracy in the North Indian Ocean when compared to the World Ocean Atlas 2018 monthly climatology thermohaline fields.As a result,the reconstructed product holds promise for providing quasi-real-time 3D temperature and salinity field information to facilitate fast decisionmaking during emergencies,and also offers foundational thermohaline fields for operational ocean reanalysis and forecasting systems.These contributions enhance the safety and stability of ocean subsurface activities and navigation.
基金The National Natural Science Foundation of China under contract No.42076235.
文摘Antarctic sea ice is an important part of the Earth’s atmospheric system,and satellite remote sensing is an important technology for observing Antarctic sea ice.Whether Chinese Haiyang-2B(HY-2B)satellite altimeter data could be used to estimate sea ice freeboard and provide alternative Antarctic sea ice thickness information with a high precision and long time series,as other radar altimetry satellites can,needs further investigation.This paper proposed an algorithm to discriminate leads and then retrieve sea ice freeboard and thickness from HY-2B radar altimeter data.We first collected the Moderate-resolution Imaging Spectroradiometer ice surface temperature(IST)product from the National Aeronautics and Space Administration to extract leads from the Antarctic waters and verified their accuracy through Sentinel-1 Synthetic Aperture Radar images.Second,a surface classification decision tree was generated for HY-2B satellite altimeter measurements of the Antarctic waters to extract leads and calculate local sea surface heights.We then estimated the Antarctic sea ice freeboard and thickness based on local sea surface heights and the static equilibrium equation.Finally,the retrieved HY-2B Antarctic sea ice thickness was compared with the CryoSat-2 sea ice thickness and the Antarctic Sea Ice Processes and Climate(ASPeCt)ship-based observed sea ice thickness.The results indicate that our classification decision tree constructed for HY-2B satellite altimeter measurements was reasonable,and the root mean square error of the obtained sea ice thickness compared to the ship measurements was 0.62 m.The proposed sea ice thickness algorithm for the HY-2B radar satellite fills a gap in this application domain for the HY-series satellites and can be a complement to existing Antarctic sea ice thickness products;this algorithm could provide long-time-series and large-scale sea ice thickness data that contribute to research on global climate change.
