基于神经网络的黄东海春季二类水体三要素浓度反演方法

介绍了一种基于人工神经网络的二类水体海域的三要素浓度反演方法。根据2003年春季黄东海试验中获得的高质量现场数据,建立了由现场测量遥感反射率分别反演三要素浓度的神经网络模型。反演的平均相对误差分别叶绿素32．5％,黄色物质8．9％,总悬浮物24．2％。同时分析了神经网络模型在水色反演模式应用中的稳定性。     

南海叶绿素a浓度垂直分布的统计估算

分析整理了1993—2006年近10 a南海北部海域、南沙海域和南海其他海域的叶绿素a浓度历史航次调查资料,基于前人提出的全球叶绿素浓度垂直分布的统计分析模式,根据南海表层叶绿素a浓度大小的不同分级,对南海叶绿素a浓度进行了参数化处理,拟合估算了南海各水层剖面的叶绿素a浓度分布值,并结合不同海区的环境特征,分析了南海叶绿素a浓度垂直分布与其海水物理环境的关系。初步分析结果表明,叶绿素a浓度随深度垂直变化的拟合曲线呈一定倾斜的正态分布特征,当表层叶绿素a浓度较低时,作为南海深水海盆区的代表,拟合值更接近实测平均值的分布,叶绿素a浓度高值集中在次表层剖面上;当表层叶绿素a浓度较高时,作为近岸区和河口区的代表,高值多集中在表层海水,拟合误差偏大。该统计估算模式对于揭示南海叶绿素a浓度垂直分布结构进行了有益的尝试,为发展适合不同海区特点的模式以及校正参数奠定了基础。利用该模式与海洋水色卫星遥感数据有效结合,将对南海叶绿素a浓度时空分布格局的研究具有重要的意义。     

2016年夏季黄、渤海颗粒有机碳的分布特征及影响因素

本文根据2016年6-7月黄、渤海航次获得的调查数据,分析了黄、渤海海域颗粒有机碳（POC）的浓度变化、空间分布特征并结合盐度、叶绿素a、POC/PON、POC/Chl a平面分布特征和相关性分析,探讨了黄、渤海海域POC的来源和影响因素。结果表明:2016年夏季渤海海域POC平均浓度（500.2±226.5）μg/L,北黄海POC平均浓度（358.2±101.5）μg/L,南黄海POC平均浓度（321.0±158.1）μg/L,渤海海域POC浓度高于黄海,整个海域POC浓度表层高于底层。POC的平面分布特征为近岸高,外海低。调查海域表层POC/PON均值为8.89,POC/Chl a均值为182.52;中层POC/PON均值为8.87,POC/Chl a均值为179.56;底层POC/PON均值为9.41,POC/Chl a均值为178.80。黄海海域浒苔衰败对POC/PON与POC/Chl a影响较大。相关性分析结果表明渤海海域盐度、总悬浮物和叶绿素a与POC存在显著的相关性,是影响POC分布的主要控制因素。南黄海除表层POC浓度与盐度、总悬浮物和叶绿素a浓度有很好的相关性外,中层和底层POC浓度与盐度、总悬浮物和叶绿素a浓度不存在显著的相关性。渤海海域POC主要受陆源和浮游植物共同影响,浮游植物是POC的主要贡献者,而黄海海域POC受长江冲淡水、黄海暖流、苏北沿岸流、生物活动和底层沉积物等多种因素影响,其中苏北近岸和青岛外海,有机碎屑为POC的主要贡献者。     

南黄海秋季叶绿素a的分布特征与浮游植物的固碳强度

依据2005年10月中下旬对南黄海的调查结果,系统阐述了2005年秋季南黄海叶绿素a的分布特征,并估算了南黄海和东中国近海初级生产力水平及浮游植物固碳强度,分析了控制其变化的生物地球化学机制.结果表明,南黄海表层叶绿素a含量的变化范围为0.11~2.38 mg/m3,平均浓度为0.66 mg/m3,明显高于50 m层的含量.南黄海表层和次表层叶绿素a分布趋势基本一致,均显现出西北高、东南低的趋势,在近岸海域出现显著的高值带,这主要是由于受到陆源输入和沿岸流带来的高营养盐的影响;中部海域的低值区则主要受控于来自东海低营养盐海流的“冲淡”作用.在垂直分布上,叶绿素a最高值基本出现在次表层,与以往发现的该海域次表层溶解氧最大值一致,这显然与南黄海浮游植物及区域水团特性有关.2005年秋季南黄海初级生产力(C)变化在95~1 634 mg/(m2·d),平均为586 mg/(m2·d),其分布趋势显示了海洋初级生产力与海水磷浓度以及水团、海流的关系.应用初级生产力估算的浮游植物固碳强度的结果表明,我国东部近海浮游植物年总固碳量约为222Mt,约占全球近海浮游植物的年固碳量的2.0%,为我国东部近海通过海-气界面总表观碳汇强度每年1 369万t的16.2倍,在不同的海域,浮游植物固碳量是其通过海-气界面总表观碳汇强度的倍数不同(渤海为3.0倍,黄海为6.7倍,东海为81.6倍).     

Distributions of chlorophyll a and carbon fixed strength of phyto-plankton in autumn of the southern Huanghai Sea waters

1IntroductionRecently,the increasing carbon dioxide(CO2)in the atmosphere is viewed by many as perhaps themost serious global environment problemfacing man-kind.Numerous studies and surveys aiming at theglobal CO2flux therefore,have been made to esti-mate…     

Bio-Optical Relationship of Case I Waters: The Difference between the Low- and Mid-Latitude Waters and the Southern Ocean

Both historic and currently operational chlorophyll algorithms of the satellite-borne ocean color sensors, such as SeaWiFS, were evaluated for in situ spectral radiation and chlorophyll data in some Case I waters, including the waters in the Indian Ocean sector of the Southern Ocean. Chlorophyll a concentration of the data set (n = 73) ranged from 0.04 to 1.01 mg m^–3. The algorithms had higher accuracy for the low- and mid-latitude waters (RMSE: 0.163–0.253), specifically the most recently developed algorithms of OCTS and Sea WiFS showed 0.163 and 0.170 of Root Mean Square Errors, respectively. However, these algorithms had large errors (0.422–0.621) for the Southern Ocean data set and underestimated the surface chlorophyll by more than a factor of 2.6. The absorption coefficients in the blue spectral region retrieved from remote sensing reflectance varied in a nonlinear manner with chlorophyll a concentration, and the value in the Southern Ocean was significantly lower than that in the low- and mid-latitude waters for each chlorophyll a concentration. The underestimation of chlorophyll a concentration in the Southern Ocean with these algorithms was caused by the lower specific absorption coefficient in the region compared with the low- and mid-latitude waters under the same chlorophyll a concentration.     

HY-1 CCD宽波段水色要素反演算法

利用2003年春季黄海、东海区现场实测数据,建立了HY1卫星4波段CCD成像仪水色要素反演算法.由于HY1CCD的宽波段特性阻碍了黄色物质的反演,因此反演的水色要素仅包括水体表层的总悬浮物、悬浮泥沙(SS)以及叶绿素a的浓度.现场遥感反射率光谱由ASD地物波谱仪测量,对于叶绿素a的浓度利用现场萃取荧光法测量,总悬浮物、悬浮泥沙由实验室滤膜称重法获得.反演算法的拟合相关系数均大于0.88,平均相对误差在40%以下.对反演算法进行了误差灵敏度分析,结果表明对于总悬浮物、悬浮泥沙和低浊度水体中的叶绿素a的浓度反演算法能够满足日常的业务运行要求,但是对于高浊度水体中叶绿素a的浓度反演算法对某个波段组合比较敏感,仍需要进一步探讨.     

Satellite observations of the partial pressure of carbon dioxide in the surface water of the Huanghai Sea and the Bohai Sea

Based on 5 831 continuous in situ measurements of the partial pressure of carbon dioxide on the sea surface p(CO2),related parameters of the sea surface temperature(SST) and chlorophyll-a(Chl a) concentration in 2010 winter,spring and summer of the Huanghai Sea and the Bohai Sea,the inherent relations among them are investigated preliminarily.This study reveals that the seasonal variability of SST and Chl a concentration has a significant influence on p(CO2).The authors have proposed a new algorithm to estimate p(CO2) from SST and Chl a concentration measurements.Compared with the vessel data,the root mean square error(RMSE) of p(CO2) retrieved by using the new model is 13.45 μatm(1atm=101.325 kPa) and the relative error is less than 4%.Then,SST and Chl a concentration data observed by satellite are used to retrieve p(CO2) in the Huanghai Sea and the Bohai Sea;and a better accuracy can be obtained if the quality control for sea surface chlorophyll-a concentration observed by satellite is used.The RMSE of retrieved p(CO2) data with quality control and that without quality control are 15.82 μatm and 31.74 μatm,respectively.     

近20年渤海叶绿素a浓度时空变化

浮游植物作为食物链的基础,对海洋生态系统具有重要作用。渤海作为我国最大的内海和重要渔业生物的产卵场、育幼场和索饵场,该区浮游植物研究具有重要意义。叶绿素a浓度是反映浮游植物生物量的重要指标。利用Google Earth Engine平台,对1997–2010年的宽视场海洋观测传感器(SeaWiFS)叶绿素a浓度数据和2002–2018年的水色卫星中分辨率成像光谱仪传感器(MODIS Aqua)叶绿素a浓度数据进行合并,并研究其时空变化特征。研究表明,近20年来,渤海全年叶绿素a浓度增加了14.1%,且增加显著。叶绿素a浓度在所有季节都呈现增加趋势;除11月外,其他各月都呈现稳定或增加趋势。从滦河入河口沿岸至渤海海峡的渤海中部,叶绿素a浓度增加较明显。同时也分析了海洋表面温度、风速和降水量数据。夏季渤海周边区域降水量和风速增加以及秋季海表温度的降低都有助于同季叶绿素a浓度的升高。渤海浮游植物可能受陆源营养物质输入影响较大。     

Size-fractionated phytoplankton standing stock and primary production in the Bohai Sea during late spring

During June 1997 cruise by R/V Science No.l, observations on temporal and spatialvariations of the size-fractionated phytoplankton standing stock and primary production were carried out in the Bohai Sea. The size-fractionated chlorophyll a (Chl a) and primary production, photosynthet-ically available radiation (PAR), as well as the related physico-oceanographic and zooplanktonic parameters were measured at five time-series observation stations representing sub-areas of the sea. Results obtained show that there were the marked features of spatial zonation of Chl a and primary production in the Bohai Sea. The values in the Laizhou Bay, the Liaodong Gulf and the Bohai Gulf were high and showed close relation with tidal fluctuations, i.e. high Chl a concentration occurred during high tide in the Laizhou Bay, and during low tide in the Liaodong Gulf and the Bohai Gulf. In the strait and the central region of the Bohai Sea, the values were relatively low and no relationship with tidal fluctuation could be foun     

2012年春季渤海中部及邻近海域叶绿素a与环境因子的分布特征

分析了2012年春季渤海中部及其邻近海域32个站点叶绿素a和环境因子的空间分布特征及其相互关系。结果发现:渤海中部靠近黄河口邻近水域相对于其他水域,呈现出相对较高的水温和较低的盐度,这与黄河淡水输入以及近岸水深相对较浅有密切关系。营养盐浓度在空间分布上表现为黄河口附近海域较高,在垂直分布上表现为中、底层高于表层,显示出黄河水输入与沉积物营养盐再释放的影响;此外,营养盐浓度与结构显示,渤海海域存在明显的磷和硅限制,磷限制尤其严重。叶绿素a浓度的空间分布显示,表层叶绿素a浓度的高值区出现在渤海湾湾口处,而中层与底层的叶绿素a浓度高值区出现在渤海中部。主成分分析结果表明,磷酸盐和温度是影响表层叶绿素a浓度的重要因素,而中、底层叶绿素a浓度主要受磷酸盐的影响。     

中国海域潮汐非调和常数的计算与分析

联合利用中国沿岸长期验潮站实测资料和全球海潮模型NAO.99b在中国海域的结果,进行潮汐非调和常数的计算.分别对渤海、黄海、东海和南海进行分析,结果表明,中国海域潮汐类型复杂,渤海、黄海、东海以半日潮性质为主,南海以日潮性质为主;渤海、南海平均大潮差多分布在0.42～2.09 m,平均小潮差分布在0.27～1.33 m,东海、黄海平均大潮差多分布在1.12～4.44 m,平均小潮差多分布在0.41～2.41 m;渤海、黄海平均大潮高潮位分布在0.48～1.77 m,东海在0.42～2.41 m,南海在0.21～1.35 m;渤海、东海以及南海北部浅海海域潮高日不等现象显著.     

Optical water type discrimination and tuning remote sensing band-ratio algorithms: Application to retrieval of chlorophyll and Kd(490) in the Irish and Celtic Seas

This paper assesses the feasibility of applying remote sensing algorithms based on blue/green reflectance ratios to Case 2 waters. Two algorithms from the SeaDAS (NASA) image processing package, OC4v4 for surface chlorophyll concentration, Chl, and K(490) for the attenuation coefficient for downward irradiance at 490 nm, K_d(490), were investigated using an extensive set of observations from the Irish and Celtic Seas. In situ data from a profiling radiometer were used as inputs for the algorithms to avoid uncertainties in atmospheric correction procedures, and direct measurements of Chl and K_d490 and were used for validation purposes. The standard versions of the algorithms performed poorly: OC4v4 generally overestimated Chl (with a very low coefficient of determination), and K(490) progressively underestimated K_d490 for values greater than 0.3 m⁻¹. A two-step procedure for level 2 product generation was therefore devised in which the numerical coefficients of OC4v4 and K(490) were tuned for the two optical water types known to occur most frequently in this region (McKee, D., Cunningham, A., 2006. Identification and characterisation of two optical water types in the Irish Sea from in situ inherent optical properties and seawater constituents. Estuarine, Coastal and Shelf Science 68, 305–316) by statistical regression on a data set of 102 stations from the Irish and Celtic Seas. The water types were distinguished by the magnitude of their normalised water leaving radiance signals at 665 nm, nL_w(665), and appropriate versions of the tuned algorithms applied to each water type. When this procedure was tested on an independent data set of 19 stations from the Bristol Channel, Chl values were recovered with an RMS error of 0.36 mg m⁻³ and K_d(490) values with an RMS error of 0.095 m⁻¹. The identification of water types from water-leaving radiance signals, and the application of band-ratio algorithms tuned for specific water types, may therefore provide a simple means of improving the quality of remote sensing products in optically complex shelf seas.     

Spatio-temporal variability of chlorophyll a and its responses to sea surface temperature, winds and height anomaly in the western South China Sea

To understand the response of marine ecosystem to environmental factors, the oceanographic (physical and biochemical) data are analyzed to examine the spatio-temporal distributions of chlorophyll a (Chl a) associated with surface temperature, winds and height anomaly for long periods (1997-2008) in the western South China Sea (SCS). The results indicate that seasonal and spatial distributions of Chl a are primarily influenced by monsoon winds and hydrography. A preliminary Empirical Orthogonal Function (EOF) analysis of remotely sensed data is used to assess basic characteristics of the response process of Chl a to physical changes, which reveals interannual variability of anomalous low Chl a values corresponding to strong El Ni o (1997-1998), high values corresponding to strong La Ni a (1999-2000), low Chl a corresponding to moderate El Ni o (2001-2003), upward Chl a after warm event in 2005 off the east coast of Vietnam. The variability of Chl a in nearshore and the Mekong River Estuary (MER) waters also suggests its response to these warm or cold processes. Considering the evidence for covariabilities between Chl a and sea surface temperature, winds, height anomaly (upwelling or downwelling), cold waters input and strong winds mixing may play important roles in the spatial and temporal variability of high Chl a. Such research activities could be very important to gain a mechanistic understanding of ecosystem responses to the climate change in the SCS.     

Comparisons of surface Chl a and primary productivity along three transects of the southern South China Sea,northern Java Sea and eastern Indian Ocean in April 2011

Results are presented about the changes in chlorophyll a density, carbon fixation and nutrient levels in the surface waters of three transects of the southern South China Sea (SCS), northern Java Sea (...     

南海东北部叶绿素a浓度对台风“风泵”和黑潮共同作用的响应

南海东北部是寡营养海域,夏季浮游植物叶绿素浓度较低,热带气旋“风泵”效应带来的上层海洋扰动可能引起表层浮游植物的显著增长。以往的研究通常关注热带气旋风应力和海洋中尺度涡对上层海洋浮游植物的影响,本文利用航次CTD、实测叶绿素a浓度、Argo温盐剖面和遥感数据,探讨了台风“风泵”和黑潮共同作用下真光层内浮游植物的变化特征及其成因。结果表明,2015年台风“莲花”过境1周后产生向吕宋海峡西北侧南海海域(A区)入侵的黑潮流套,该入侵的黑潮流套使台风前原有的气旋涡消失,抑制了台风产生的上升流对表层(0～40 m)营养盐供给,使次表层(60～90 m)营养盐富集,进而抑制了表层的叶绿素a增长,促进了次表层叶绿素a的增长;吕宋海峡西侧南海海域(B区)表层的浮游植物叶绿素a浓度增加不仅是源于叶绿素最大层浮游植物的向上输运,更是由于浮游植物的繁殖增长;A区台风引起的流套式的黑潮入侵,促进了B区台风后气旋式流场的形成,产生的持续增强的气旋涡为B区表层叶绿素持续增长提供了充足的营养盐供给。     

中国东部海域浮游植物类群遥感反演研究

浮游植物类群遥感反演能够为全面认识浮游植物在海洋生态系统中的作用提供重要的数据资料.但由于复杂的水体光学特性,近海浮游植物类群遥感反演存在着巨大挑战.本研究以复杂光学二类水体—中国东部海域为研究区,通过使用3种建模方法,即波段组合法、基于奇异值分解的多元线性回归法、基于奇异值分解的XGBoost回归法,利用遥感反射率数...     

近岸水域CZCS资料分析

Ｎｉｍｂｕｓ－７卫星上的多通道扫描辐射计─━海岸带水色扫描仪（ＣＺＣＳ），被设计用来提供海洋近表层浮游植物色素浓度和其他与水色有关现象（如悬浮沉积物、有机污染等）的资料。由于自然和人为的排放以及由潮流引起的再悬浮沉积物的影响，对近岸水域ＣＺＣＳ遥感资料的分析存在一定的困难，对于近岸水域应作出慎重的研究，因为此类水域的生物－海洋学状况具有较大变化性。计算时必须对每一种情况作出试验，以便找出卫星辐射率测量与浮游植物色素分布，近岸上升流锋，有机污染以及悬浮沉积物之间的关系．本文阐述和讨论了ＣＺＣＳ资料的处理以及估算近岸水域色素和县浮沉积物浓度的算法．     

Long-term variations of temperature and salinity of the Bohai Sea and their influence on its ecosystem

Long-term variations of the sea surface salinity (SSS), air temperature (AT) and sea surface temperature (SST) of the Bohai Sea during 1960–1997 were analyzed. They all showed positive trends. The trends of the annual mean SSS, AT and SST of the Bohai Sea were, respectively, 0.074 y⁻¹, 0.024°C y⁻¹ and 0.011°C y⁻¹. The increases of AT and SST were consistent with, the recent warming in northern China, in the Huanghai Sea (Yellow Sea) and in the East China Sea. The rise of SSS can be attributed to the rapid reduction of the total river discharge into the Bohai Sea, as well as to the increase inflow of high salinity water from the Huanghai Sea. It may also be attributed to increasing human use of river water and increases in evaporation from the sea surface. These changes in the marine environment seemed to have important influence on the Bohai Sea ecosystem.     

渤海海温与叶绿素季节空间变化特征分析

以2003年MODIS数据为数据源，在图像处理、空间插值的基础上作海温与叶绿素浓度的空间相关分析。结果表明，整个海域的叶绿素浓度和海温的分布具有明显的区域和季节变化特征。基本规律是叶绿素浓度从近岸向渤海中央递减；温度则随季节发生变化，随着温度升高，近海叶绿素浓度增高，而渤海中央区域叶绿素浓度降低。渤海叶绿素浓度的分布与河口径流、季节等因素有关。从空间关系看，海温与叶绿素浓度不存在很明显的空间分布相关性，但不同季节有不同的相关性。上述研究可用于估算海洋初级生产力。