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A general purpose exact Rayleigh scattering look-up table for ocean color remote sensing

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Acta Oceanologica Sinica 2006年第1期25卷 48-56页

作者： he xianqiang PAN Delu BAI Yan GONG Fang Key Laboratory of Ocean Dynamic Processes and Satellite Oceanography of State Oceanic Administration Hangzhou 310012 China Second Institute of Oceanography State Oceanic Administration Hangzhou 310012 China Shanghai Institute of Technical Physics Chinese Academy of Sciences Shanghai 200083 China

The current exact Rayleigh scattering calculation of ocean color remote sensing uses the look-up table （LUT）, which is usually created for a special remote sensor and cannot be applied to other sensors. For practical application, a general purpose Rayleigh scattering LUT which can be applied to all ocean color remote sensors is generated. An adding-doubling method to solve the vector radiative transfer equation in the plane-parallel atmosphere is deduced in detail. Compared with the exact Rayleigh scattering radiance derived from the MODIS exact Rayleigh scattering LUT, it is proved that the relative error of Rayleigh scattering calculation with the adding-doubling method is less than 0.25%, which meets the required accuracy of the atmospheric correction of ocean color remote sensing. Therefore, the adding-doubling method can be used to generate the exact Rayleigh scattering LUT for the ocean color remote sensors. Finally, the general purpose exact Rayleigh scattering LUT is generated using the adding-doubling method. On the basis of the general purpose LUT, the calculated Rayleigh scattering radiance is tested by comparing with the LUTs ofMODIS, SeaWiFS and the other ocean color sensors, showing that the relative errors are all less than 0.5%, and this general purpose LUT can be applied to all ocean color remote sensors.

关键词： ocean color Rayleigh scattering look-up table radiative transfer adding-doubling method

Upper ocean responses to category 5 typhoon Megi in the western north Pacific

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Acta Oceanologica Sinica 2012年第1期31卷 51-58页

作者： CheN Xiaoyan PAN Delu he xianqiang BAI Yan WANG Difeng Department of Earth Sciences Zhejiang UniversityHangzhou 310027China State Key Laboratory of Satellite Ocean Environment Dynamics Second Institute of OceanographyState Oceanic AdministrationHangzhou 310012China

Category 5 typhoon Megi was the most intense typhoon in 2010 of the world. It lingered in the South China Sea （SCS） for 5 d and caused a significant phytoplankton bloom detected by the satellite image. In this study, the authors investigated the ocean biological and physical responses to typhoon Megi by using chlorophyll-a （chl-a） concentration, sea surface temperature （SST）, sea surface height anomaly （SSHA）, sea surface wind measurements derived from different satellites and in situ data. The chl-a concentration （〉3 mg/m3） increased thirty times in the SCS after the typhoon passage in comparison with the mean level of October averaged from 2002 to 2009. With the relationship of wind stress curl and upwelling, the authors found that the speed of upwelling was over ten times during typhoon than pre-typhoon period. Moreover, the mixed layer deepened about 20 m. These reveal that the enhancement of chl-a concentration was triggered by strong vertical mixing and upwelling. Along the track of typhoon, the maximum sea surface cooling （6-8~C） took place in the SCS where the moving speed of typhoon was only 1.4-2.8 m/s and the mixed layer depth was about 20 m in pre-typhoon period. However, the SST drop at the east of the Philippines is only 1-2~C where the translation speed of typhoon was 5.5-6.9 m/s and the mixed layer depth was about 40 m in pre-typhoon period. So the extent of the SST drop was probably due to the moving speed of typhoon and the depth of the mixed layer. In addition, the region with the largest decline of the sea surface height anomaly can indicate the location where the maximum cooling occurs.

关键词： sea surface temperature chlorophyll-a concentration sea surface height anomaly upwelling typhoon Megi ocean remote sensing

Remote sensing of sea surface nutrient in the frontal zone of Changjiang diluted water and the Taiwan Warm Current

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Acta Oceanologica Sinica 2007年第3期26卷 22-32页

作者： ZHANG Xiaoyu LIN Yi＇ an he xianqiang WANG Difeng GONG Fang ZHANG Wei Department of Earth Sciences Zhejiang University Hangzhou 310027 China State Key Laboratory of Satellite Ocean Environment Dynamics Second Institute of Oceanography State Oceanic Administration Hangzhou 310012 China

Field investigation was carried out during 4 to 15 April 2001 around the Changjiang River Estuary. The similar distribution of sea surface nutrients and suspended sediment （SS） concentration is attributed to the physical mixing of Changjiang diluted water （CDW） with the Taiwan Warm Current （TWC）. On the basis of the observed positive relationship between total phosphorus （TP） and SS concentration, the sea surface TP is inversed from satellite SS data. SS is believed to be an ideal eutrophic state assessing index substitution for TP, the eutrophication classification critical value of SS adopted in this research was based on the linear model： CTP =0. 000 6Css_ ＋0. 016 3, r^2 =0.564 5, n =32. Although lack of in-situ chromophoric dissolved organic matter （CDOM） measurement, a good relationship was observed between the in-situ DIN （dissolved inorganic nitrogen） concentration with near real time SeaWiFS absorption coefficient of CDOM （ACD） data： cDIN= 1. 406 5AACB_ - 0. 035 9, r^2 = 0. 741 5, n = 16. This empirical regression algorithm was also utilized for inversing the DIN concentration from SeaWiFS ACD data, and for establishing the eutrophication classification critical value of satellite ACD data. The established remote eutrophication classification sys- tem was later used for seawater eutrophic state assessment. The evaluation suggested that the Zhoushan Fishing Ground especially the western border is affected seriously with the nutrient input. The nutrient is mainly from the terrestrial source transported by the Changjiang River runoff. The seawater quality classification precision was assessed by in-situ data, which suggested the seawater quality distribution is similar to the two classification systems, and the remote classification error is below 25%.

关键词： Changjiang River Estuary remote sensing nutrient inversion eutrophic evaluation

The dynamic observation of dissolved organic matter in the Zhujiang(Pearl River)Estuary in China from space

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Acta Oceanologica Sinica 2018年第7期37卷 105-117页

作者： LIU Dong BAI Yan he xianqiang PAN Delu WANG Difeng WEI Ji'an ZHANG Lin State Key Laboratory of Satellite Ocean Environment Dynamics Second Institute of OceanographyState Oceanic AdministrationHangzhou 310012China Key Laboratory of Watershed Geographic Sciences Nanjing Institute of Geography and LimnologyChinese Academy of SciencesNanjing 210008China

The distributions of estuarine colored dissolved organic matter（CDOM）are the combined results of physicalbiogeochemical processes.Remote sensing is needed to monitor highly dynamically estuarine CDOM.Using in situ data from four seasonal cruises,an algorithm is developed to estimate CDOM absorption coefficient at 400nm（aCDOM（400））in the Zhujiang（Pearl River）Estuary（ZJE）.The algorithm uses band ratios of Rrs（667）/Rrs（443）and Rrs（748）/Rrs（412）.By applying it to moderate resolution imaging spectroradiometer onboard Aqua satellite（MODIS/Aqua）data from 2002 to 2014,seasonal climatology aCDOM（400）in the ZJE is calculated.CDOM distributions are majorly influenced by water discharge from the Zhujiang River and underwater topography.Along the section vertical to a water depth gradient,the seasonal aCDOM（400）exponentially decreased（y=aebx,b〈0）,but with great differences among seasons.Riverine fresh water is the primary source of CDOM in the ZJE.Fulvic acid fraction decreases with increasing salinity.Using developed algorithms,conservative CDOM mixing equation,and river discharge,effective riverine end-member concentration and flux of dissolved organic carbon（DOC）in summer and winter from 2002 to 2014 are first estimated from the MODIS/Aqua data.Both effective riverine end-member DOC concentration and flux are positively related to the river discharge,significantly in summer with R-2 of 0.698 for concentration and 0.965 7 for flux.

关键词： colored dissolved organic matter dissolved organic carbon Zhujiang（Pearl River）Estuary effective riverine end-member flux remote sensing

Areas of the global major river plumes

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Acta Oceanologica Sinica 2013年第1期32卷 79-88页

作者： KANG Yan PAN Delu BAI Yan he xianqiang CheN Xiaoyan CheN Chen-Tung Arthur WANG Difeng Department of Earth Sciences Zhejiang University State Key Laboratory of Satellite Ocean Environment Dynamics Second Institute of OceanographyState Oceanic Administration Institute of Marine Geology and Chemistry National Sun Yat-sen University Kaohsiung

River plumes are the regions where the most intense river-sea-land interaction occurs, and they are char- acterized by complex material transport and biogeochemical processes. However, due to their highly dy- namic nature, global river plume areas have not yet been determined for use in synthetic studies of global oceanography. Based on global climatological monthly averaged salinity data from the NOAA World Ocean Atlas 2009 （WOA09）, and monthly averaged salinity contour maps of the East and South China Seas from the Chinese Marine Atlas, we extract the monthly plume areas of major global rivers using a geographic information system （GIS） technique. Only areas with salinities that are three salinity units lower than the average salinity in each ocean are counted. This conservative estimate shows that the minimum and max- imum monthly values of the total plume area of the world＇s 19 largest rivers are 1.72× 106 kin2 in May and 5.38× 106 klTl2 inAugust. The annual mean area of these river plumes （3.72× 106 knl2） takes up approximately 14.2% of the total continental shelves area worldwide （26.15 × 106 km2）. This paper also presents river plume areas for different oceans and latitude zones, and analyzes seasonal variations of the plume areas and their relationships with river discharge. These statistics describing the major global river plume areas can now provide the basic data for the various flux calculations in the marginal seas, and therefore will be of useful for many oceanographic studies.

关键词： river plume World Ocean Atlas geography information system Changjiang River marginal sea

Satellite remote sensing of ultraviolet irradiance on the ocean surface

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Acta Oceanologica Sinica 2015年第6期34卷 101-112页

作者： LI Teng PAN Delu BAI Yan LI Gang he xianqiang CheN Chen-Tung Arthur GAO Kunshan LIU Dong LEI Hui State Key Laboratory of Satellite Ocean Environment Dynamics Second Institute of Oceanography State Oceanic Administration Institute of Remote Sensing and Earth Science Hangzhou Normal University Key Laboratory of Tropical Marine Bio-resources and Ecology South China Sea Institute of Oceanology Chinese Academy of Sciences Institute of Marine Geology and Chemistry College of Marine Sciences National Sun Yat-Sen University State Key Laboratory of Marine Environmental Science Xiamen University

Ultraviolet （UV） radiation has a significant influence on marine biological processes and primary productivity; however, the existing ocean color satellite sensors seldom contain UV bands. A look-up table of wavelength- integrated UV irradiance （280-400 nm） on the sea surface is established using the coupled ocean atmosphere radiative transfer （COART） model. On the basis of the look-up table, the distributions of the UV irradiance at middle and low latitudes are inversed by using the satellite-derived atmospheric products from the Aqua satellite, including aerosol optical thickness at 550 nm, ozone content, liquid water path, and the total precipitable water. The validation results show that the mean relative difference of the 10 d rolling averaged UV irradiance between the satellite retrieval and field observations is 8.20% at the time of satellite passing and 13.95% for the daily dose of UV. The monthly-averaged UV irradiance and daily dose of UV retrieved by satellite data show a good correlation with the in situ data, with mean relative differences of 6.87% and 8.43%, respectively. The sensitivity analysis of satellite inputs is conducted. The liquid water path representing the condition of cloud has the highest effect on the retrieval of the UV irradiance, while ozone and aerosol have relatively lesser effect. The influence of the total precipitable water is not significant. On the basis of the satellite-derived UV irradiance on the sea surface, a preliminary simple estimation of ultraviolet radiation＇s effects on the global marine primary productivity is presented, and the results reveal that ultraviolet radiation has a non-negligible effect on the estimation of the marine primary productivity.

关键词： ultraviolet radiation remote sensing radiative transfer marine primary productivity

The black water around the Changjiang (Yangtze) Estuary in the spring of 2003

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Acta Oceanologica Sinica 2009年第4期28卷 23-31页

作者： BAI Yan he xianqiang PAN Delu ZHU Qiankun GONG Fang State Key Laboratory of Satellite Ocean Environment Dynamics State Oceanic Administration Hangzhou 310012 China Second Institute of Oceanography State Oceanic Administration Hangzhou 310012 China

The Changjiang （Yangtze） Estuary is located in the East China Sea shelf with shallow water. Affected by the tide mixing and the runoff of the Changjiang River and the Qiantang River the turbidity is very high. Generally, the water-leaving radiance is high in the turbid water because of the large particle scattering. Based on the in-situ data and ocean color remote sensing data of SeaWiFS, it was found that there was a black water region with the normalized water-leaving radiances less than 0.5 mW/（cm2-μm2-sr）. The optical principle of the occurrence of this black water was analyzed by the inherent optical properties and the ocean color components. The results show that black water is caused by the relative low values of the suspended particle matter concentration and the back scattering ratio. In the black water region, the percentage of the phytoplankton absorption was relatively high, and the large size of the phytoplankton caused the low value of the particle backscattering ratio.

关键词： Black water Changjiang Estuary Inherent optical properties Ocean color remote sensing

Vector radiative transfer numerical model of coupled ocean-atmosphere system using matrix-operator method

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Science China Earth Sciences 2007年第3期50卷 442-452页

作者： he xianqiang PAN DeLu BAI Yan ZHU QianKun GONG Fang State Key Laboratory of Satellite Ocean Environment Dynamics Second Institute of OceanographyState Oceanic AdministrationHangzhou 310012China Shanghai Institute of Technical Physics Chinese Academy of SciencesShanghai 200083China Graduate University of Chinese Academy of Sciences Beijing 100039China

A vector radiative transfer numerical model of the coupled ocean-atmosphere system is developed based on the matrix-operator method, which is named PCOART. Using the Fourier analysis, the vector radiative transfer equation (VRTE) is separated into a set of equations depending only on the observa-tion zenith angle. Using the Gaussian-Quadrature method, VRTE is finally transferred into the matrix equation solved by the adding-doubling method. According to the reflective and refractive properties of the ocean-atmosphere interface, the vector radiative transfer numerical model of the ocean and at-mosphere is coupled in PCOART. Compared with the exact Rayleigh scattering look-up tables of MODIS (Moderate-resolution Imaging Spectroradiometer), it is shown that PCOART is an exactly numerical model, and the processing methods of the multi-scattering and polarization are correct. Also, validated with the standard problems of the radiative transfer in water, it is shown that PCOART can be used to calculate the underwater radiative transfer problems. Therefore, PCOART is a useful tool for exactly calculating the vector radiative transfer of the coupled ocean-atmosphere system, which can be used to study the polarization properties of the radiance in the whole ocean-atmosphere system and the remote sensing of the atmosphere and ocean.

关键词： vector radiative transfer numerical model coupled ocean-atmosphere system matrix-operator method adding-doubling method polarization remote sensing

Palladium Complexes with N,O-Bidentate Ligands Based on N-Oxide Units from Cyclic Secondary Amines:Synthesis and Catalytic Application in Mizoroki-heck Reaction

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Chinese Journal of Chemistry 2024年第3期42卷 294-300页

作者： Xuefeng Jia Yanyan Wen Changhui he xianqiang Huang Key Laboratory of Magnetic Molecules and Magnetic Information Materials of Ministry of Education School of Chemistry and Materials ScienceShanxi Normal UniversityTaiyuanShanxi030032 China Shandong Provincial Key Laboratory of Chemical Energy Storage and Novel Cell Technology School of Chemistry & Chemical EngineeringLiaocheng UniversityLiaochengShandong252059 China

Palladium-catalyzed Mizoroki-heck reaction is a powerful and efficient method for construction of Csp2–Csp2 bonds.herein,four palladium complexes(I—IV)with N,O-bidentate ligands(L1—L4)based on N-oxide units from cyclic secondary amines were easily synthesized and successfully applied in Mizoroki-heck reaction of aryl bromides with electron-deficient olefins.X-ray diffraction analyses indicated the palladium(II)atom of II took the distorted square planar geometry and was four-coordinated by nitrogen and oxygen atoms from two ligands(L2).Two free chloride ions were presented as counter anions in complex II.But the palladium(II)center of IV was coordinated by nitrogen and oxygen atoms from one ligand(L4)as well as two chlorine atoms,which exhibited the nearly square-planar geometry.The study on catalytic properties of palladium complexes revealed that complex II exhibited high activity superior to the other complexes.The coupling reactions of a series of aryl bromides and olefin derivatives proceeded in the presence of 2—5 mol%palladium complex II,giving the desired products in good to excellent yields.The advantages of this method such as good compatibility of functional groups,high yields,and short reaction times made it more attractive for constructing Csp2–Csp2 bonds in the synthesis of functional molecules and materials.

关键词： Palladium complexes N,O-Bidentate ligands N-Oxide units Mizoroki-heck reaction Aryl bromide Electron-deficient olefins C—C coupling Homogeneous catalysis Substituent effects