大连长兴岛海域疏浚区GF-1 WFV影像悬浮物遥感反演研究

利用2017年8-9月期间大连长兴岛海域实测遥感反射率、悬浮物浓度及GF-1 WFV数据,研究了该区域悬浮物浓度的遥感反演算法,发现遥感反射率与悬浮物浓度的散点图存在两种不同的变化趋势,将2008-2015年期间辽东湾内其它海域的数据与长兴岛海域数据进行叠加后,可初步推断产生两种变化趋势的主要原因在于疏浚区与非疏浚区悬浮物的粒径大小不同,导致其光学特性和反演算法也存在差异。将两种算法分别应用于2017年9月20日辽东湾及长兴岛近岸海域的GF-1 WFV4影像,发现采用非疏浚区算法反演长兴岛海域悬浮物浓度时,出现明显的低估现象,而疏浚区算法则能较好地反映出疏浚施工过程中悬浮物的分布规律,具有较好的工程应用价值。     

江苏近岸海域悬沙浓度的时空分布特征

2006—2007年间的四个季节在江苏近岸海域69个站位采集水样,获取悬沙浓度。通过对TM遥感数据反演,获取该海域四季大面悬沙浓度,并与调查的实测悬沙浓度进行对比。结果显示,大面调查的非同步数据基本可正确反映大区域悬沙浓度的季节与空间分布趋势。悬沙浓度等值线由高至低、由陆向海分布,底层浓度约为表层的2—3倍;废黄河口和长江口外海域为悬沙浓度高值区,而海州湾为低值分布区,东南部陆架区受台湾暖流影响出现低值中心。冬季整个海域悬沙浓度均较高,其次为春季,夏季最低;废黄河口海域的高值中心在不同季节分布位置有所移动。海底沉积物的再悬浮是苏北近岸悬沙最主要的来源,河流输沙量的季节变化是影响长江口海域悬沙浓度变化的关键因子。相关分析结果表明,潮流为影响悬沙浓度分布的主要控制因子;季风、风暴潮和风浪虽对悬沙的分布具有一定的影响,但冬季的低温环境是形成该季节整个海域悬沙浓度显著偏高的重要因素。     

盐城近岸海域水质分布特征及富营养化研究

文章于2018年春、夏、秋季对盐城近岸海域海水营养盐和化学需氧量等环境因子进行调查采样,并分析其时空分布特征;应用有机污染指数法和富营养化指数法2种评价方法,对该海域的海水富营养化水平进行评价。结果显示,研究海域环境因子季节变化显著,有机污染指数和富营养化指数的时空分布特征基本一致,指数由高到低的季节依次为春季、秋季、夏季,空间上呈各河入海口向远岸海域逐渐降低的趋势;聚类分析将江苏近岸海域分为废黄河三角洲区域和辐射沙洲区域2个大类;盐城入海河流输入对污染物的分布有强烈影响,同时水动力情况影响环境因子分布;陆源污染和淡水输入是引起海水环境因子变化的关键因素。     

基于HJ-1卫星数据的荣成湾叶绿素a浓度时空变化特征分析

本研究利用4个航次的叶绿素a浓度实测值以及HJ-1卫星数据,对三种适用于黄海Ⅱ类水体的叶绿素a浓度反演算法(MODIS OC3M算法、NSOAS黄东海算法和进化建模法)的精度进行了验证,并利用其中的最优算法对荣成湾海域2009~2016年叶绿素a浓度的时空变化特征进行分析,以期为该海域的生态修复提供科学参考。结果表明:OC3M算法为最优算法,利用其反演得到的叶绿素a浓度季节变化特征为:秋季最高,夏季和春季次之,冬季最低;年际变化上,天鹅湖及近岸区叶绿素a浓度整体呈下降趋势,养殖区的叶绿素a浓度保持稳定;叶绿素a浓度的空间分布呈现近岸高、外海低的变化趋势。     

基于SDGSAT-1影像的总悬浮物浓度反演方法研究

总悬浮物浓度是海洋的重要水质参数之一,其对水体透明度、水下光场及初级生产力有显著影响,同时对河流入海口与海岸带冲淤变化过程有重要作用。本文基于我国自主研制的SDGSAT-1卫星遥感影像,使用准分析算法（Quasi-Analytical Algorithm,QAA）获取水体固有光学量,并结合2022年4月黄河口区域总悬浮物浓度实测数据,建立水体固有光学量与总悬浮物浓度实测数据的单波段、波段加减、波段比值,以及多波段组合等模型并开展遥感反演,最后将反演结果同实测数据及基于Sentinel-2B影像的总悬浮物浓度反演结果进行对比。研究结果表明：基于SDGSAT-1影像的总悬浮物浓度反演结果在黄河口高浓度区域的决定系数为0.622,均方根误差为7.94 mg/L;基于Sentinel-2B影像的总悬浮物浓度反演结果在黄河口高浓度区域的决定系数为0.589,均方根误差为8.27 mg/L。故在我国近岸海域总悬浮物浓度反演方面,SDGSAT-1影像反演精度与Sentinel-2B影像反演精度相媲美。     

基于GF-1号的舟山近岸悬浮泥沙浓度反演研究

文章利用舟山近岸实测光谱数据和国产卫星GF-1号宽视场成像仪(WFV)遥感数据,反演该海域悬浮泥沙浓度。结果表明:(1)线性模型和二次模型相比,二次模型的精确度略高于线性模型,但对于悬沙低浓度区,反演误差过大,故线性模型更适用于舟山近岸水体悬浮泥沙浓度反演;(2)GF-1号B2和B3是悬沙浓度变化的敏感波段,B3/B2波段组合的线性模型反演效果较好;(3)GF-1号遥感数据能够较理想地实现定量反演近岸水体的悬浮物。     

基于空间插值的长江口邻近海域春季悬浮物和叶绿素a空间分布分析

针对目前利用实测数据对长江口邻近海域水质状况进行分析研究相对偏少的情况,基于“淞航”号2018年春季航次对该海域的综合观测,利用实验室水样分析数据对船载温盐深仪（CTD）的测量数据进行校正,并对该区域2018年春季时节悬浮物（TSM）和叶绿素a(Chl-a)浓度的空间插值结果进行分析。研究结果表明：CTD观测数据与水样分析数据呈较强线性相关关系。反距离权重插值对TSM和Chl-a浓度空间分布具有整体最优的效果。TSM浓度在近岸和近海底较高,在观测区域内出现两个高值中心;Chl-a浓度在近岸海域较高,有较明显的片状高值结构,垂向上表层较高。TSM与Chl-a浓度分布在长江口南北表现出不同的特征,且两者具有一定的负相关性。长江径流、外海洋流、潮汐混合等水动力过程是影响该区域TSM和Chl-a浓度分布的主要因素。     

山东半岛沿岸海域悬浮体时空分布及形成机制分析

依据2015年GOCI(geostationary ocean color imager)卫星影像反演的悬浮体浓度数据,分析了山东半岛沿岸海域表层悬浮体质量浓度和锋面月变化特征,揭示该海域悬浮体的分布特征和扩散格局,并结合风速、波高以及海表温度数据,对其控制因素进行初步探讨。结果显示:研究区内悬浮体质量浓度整体表现为冬季最高,春秋次之,夏季最低的分布特征;悬浮体扩散过程可以划分为4个阶段,冬季稳定外输,春季向岸退缩,夏季近岸贮存,秋季向外扩散。此外,山东半岛近岸存在一条悬浮体质量浓度高于10 mg/L的浑浊带,该浑浊带同样表现出季节变化,它在秋季开始形成,其悬浮体含量、幅宽及延伸范围在冬季达到最大,春季减弱,夏季消失。研究认为山东半岛沿岸海域的表层悬浮体来源主要是海底沉积物的再悬浮。风场、海浪以及沿岸流的强弱变化对悬浮体分布和输运的季节变化有重要的控制作用:风场和海浪影响海水混合搅拌强度,改变海底沉积物再悬浮作用的临界深度,进而影响表层海水悬浮体浓度,致使悬浮体浓度与风浪的月际变化趋势基本一致;沿岸流携带高浓度悬浮体沿山东半岛输运形成沿岸浑浊带,沿岸流的强度变化直接控制浑浊带的季节变化。     

南海叶绿素浓度季节变化及空间分布特征研究

以南海海域1997年10月至2002年9月SeaWiFS卫星遥感叶绿素浓度的资料为基础,分析了多年平均的南海叶绿素浓度的时空分布,初步分析结果表明,冬季南海大部分海域叶绿素浓度普遍较高,春季大部分海域较低;南海各个海区的叶绿素月平均最低浓度基本出现在春季的4月或5月,而最高浓度出现的月份却有不同的特征,在中央海盆区出现在12月,在广东沿岸海区出现在7月,在越南东南部近岸海域在8月和12月有两个最高值;在吕宋海峡的西部区域,尽管叶绿素浓度的最高值也出现在12月,但是叶绿素浓度的最低值却出现在夏季的7月.在空间上近岸区域的叶绿素浓度明显高于中央海盆区,西部海域普遍高于东部海域.南海叶绿素浓度的这一时空分布特征与流场(如上升流等)、海面温度场和风场等的变化有关,也与陆源物质的输入等关系密切.     

基于GOCI的渤海悬浮物分布及日变化遥感初探

悬浮物作为污染物示踪剂,对研究海区陆源污染扩散、分布极为重要。利用2008-2017年渤海多个航次的现场实测光谱和悬浮物浓度数据,研究了渤海表层悬浮物浓度遥感反演算法,发现秦皇岛海域悬浮物算法不同于其他渤海区域。将反演算法应用于GOCI静止卫星影像,得到2015年9月13日8个时相的渤海悬浮物浓度空间分布形态,并探讨了8 h短周期内的变异幅度。研究结果表明:渤海大部分悬浮物浓度较低(0~10 mg/L),短周期内变异幅度很小;悬浮物高值主要分布在以黄河三角洲为中心的渤海湾、莱州湾沿岸一带(最高可达300 mg/L),短周期内变异幅度大(60 mg/L以上,可达200 mg/L);辽东湾辽河口区域、复州湾、金州湾附近海域悬浮物浓度相对较高,金州湾部分区域短周期内变异幅度较高,或与该区域围填海等人为活动有关。     

Horizontal distribution of particulate matter and its characterization using phosphorus as an indicator in surface coastal water,Harima-Nada,the Seto Inland Sea,Japan

To study the horizontal distribution and characterization of suspended particulate matter (SPM) in the coastal environment, the distribution and seasonal variation of particulate phosphorus (PP), divided as organic (POP) and inorganic (PIP) fractions with POC, PON, and Chl.a, in 4 seasons throughout Harima-Nada of the Seto Inland Sea, Japan, were investigated. A high concentration of PIP was observed not only in the northern coastal area, which received much freshwater discharge, but also in the channel parts. In winter, when Δσt was low, the difference between surface and bottom σt, resuspension of sinking particles or/and surface sediment which has a high PIP/PP ratio seems to have occurred, and then a high concentration of PIP in surface water was observed. In spring and summer, PIP/PP ratios (0.24) of surface waters were close to those of phytoplankton (0.1–0.2). On the other hand, PIP/PP ratios in autumn and winter, when Δσt was low, were similar to those of surface sediment in Harima-Nada (0.32–0.39). SPM in Harima-Nada showed higher PP contents than other coastal environments, and its mean value of 9.10 mg P/g was close to the phytoplankton P content of 9.75 mg P/g. This suggests that SPM in Harima-Nada was strongly affected by phytoplankton. The C/N ratio in Harima-Nada in spring was high (11), although high Chl.a and low PIP/PP were observed, possibly resulting from preferential decomposition of nitrogen in comparison with carbon. We consider that the PIP/PP ratio is a good indicator to characterize SPM and to predict its origin as well as the C/N.     

渤海悬浮物分布的遥感研究

利用渤海湾和莱州湾现场实测的悬浮物含量和光谱数据,建立了基于555和670nm波段遥感反射率的悬浮物含量遥感反演模型。经检验,模型平均相对误差优于20%,对输入端误差不敏感。基于该模型,利用ENVISAT MERIS遥感数据,从空间分布格局、大风过程的短期扰动以及季节性差异等方面分析了渤海悬浮物的时空分布特征。(1)渤海悬浮物含量的高值区集中分布在莱州湾(尤其是黄河口和莱州湾湾底)和渤海湾沿岸,此外在辽东湾沿岸海域悬浮物含量也相对较高,而在渤海大部水体悬浮物含量较低。(2)大风过程可在短期内(约1~3d)显著改变全渤海的悬浮物空间分布格局,其中渤海湾和莱州湾响应最为强烈,辽东湾响应相对较弱,这与其各自的水深条件、底质类型和悬浮物粒径等因素有关。(3)渤海悬浮物含量总体上呈春夏低、秋冬高的分布特征;季节性差异最显著的区域是渤海湾、莱州湾和辽东湾,差异性最小的是秦皇岛近岸海域;风力等气候因素是悬浮物分布呈现季节性差异的主要原因,入海径流是另一重要因素。     

南海北部海域叶绿素a浓度时空特征遥感分析

利用2007-2010年MODIS的L2级叶绿素a浓度产品作为数据基础, 对叶绿素a浓度年平均和月平均数据进行分级分区处理, 研究南海北部海域叶绿素a浓度时空分布特征及其与海洋环境因素的关系。初步研究结果表明:2007-2010年在南海北部海域叶绿素a浓度的高值区(>5.0 mg/m3)主要分布在广东省沿岸河流的入海口, 分布范围在夏季最大, 在春秋次之, 在冬季最小;叶绿素a浓度的次高值区(1.0～5.0 mg/m3)主要分布在海岸线到50 m等深线之间的海域, 分布范围夏冬较大, 能扩展到50 m等深线附近, 而春秋较小, 会退缩到50 m等深线以内;叶绿素a浓度的中值区(0.3～1.0 mg/m3)主要分布在50 m到100 m等深线之间的海域, 时空变化复杂;叶绿素a浓度的低值区(<0.3 mg/m3)主要分布在100 m等深线以外的海域, 其区域平均值夏季最低, 春秋次之, 冬季最高, 同时该区域叶绿素a浓度在春夏秋三季空间分布较均匀, 而冬季受季风和黑潮入侵影响空间分布较为复杂。南海北部海域海表叶绿素a浓度的时空变化特征与季风、沿岸河流、海流、海表温度等海洋环境因素的变化有关。     

福建东山湾浮游动物的种类组成和分布特点

1981年7月至1982年6月(每月1次)的周年调查结果表明:福建东山湾浮游动物的种类组成较丰富,已鉴定有176种,其中,暖水种占大多数;以暖水种和暖温带种为优势,分别在夏季和冬季形成总生物量高峰;阶段性浮游幼虫,特别是短尾类溞状幼虫等在夏季总生物量高峰中占有重要地位,以及多样性指数和均匀度的季节变化较显著等,显示了亚热带河口-港湾区浮游动物生态的基本特点。此外,东山湾浮游动物总生物量、种类数及多样性指数等的平面分布规律都较明显。     

北部湾海域叶绿素a质量浓度时空分布研究

叶绿素a质量浓度是水体富营养化的重要指标,及时和有效地对水体叶绿素a质量浓度进行监测和评价,对环境保护十分必要。本文基于2011年至2016年的卫星遥感数据,分析了北部湾海表叶绿素a质量浓度的时空分布特征。研究结果表明:北部湾叶绿素a质量浓度有明显的月变化和季节性变化,北部湾叶绿素a月平均质量浓度在8月和1月分别达到峰值,北部湾冬季与夏季的叶绿素a季平均质量浓度高于春季和秋季,夏季北部湾海域表层的叶绿素a质量浓度开始迅速升高,秋季北部湾中南部叶绿素a质量浓度呈下降的趋势。在空间分布上,北部湾近岸海域叶绿素a质量浓度平均水平较高,叶绿素a质量浓度高值区集中在湾北部雷州半岛西部沿岸的浅水区海域,而低值区在湾中部以及湾南部的深水区海域。     

Observed vs. predicted variability in non-algal suspended particulate matter concentration in the English Channel in relation to tides and waves

The study of water clarity is essential to understand variability in biological production, particularly in coastal seas. The spatial and temporal variability of non-algal suspended particulate matter (SPM) in surface waters of the English Channel was investigated and related to local forcing by means of a large satellite dataset covering the study area with a spatial resolution of 1.2 km and a daily temporal resolution. This analysed dataset is a time series of non-algal SPM images derived from MODIS and MERIS remote-sensing reflectance by application of an IFREMER semi-analytical algorithm over the period 2003–2009. In a first step, the variability of time series of MODIS images was analysed through temporal autocorrelation functions. Then, non-algal SPM concentrations were assessed in terms of site-specific explanatory variables such as tides, wind-generated surface-gravity wave amplitudes and chlorophyll-a (Chl-a), based on three statistical models with fitting parameters calibrated on a dataset of merged MERIS/MODIS images gathered from 2007 to 2009 over the whole English Channel. Correlogram analysis and the first model highlight the local patterns of the influence of the tide, especially the neap–spring cycle, on non-algal surface SPM. Its effect is particularly strong in the central and eastern English Channel and in the western coastal areas. The second model shows that waves prevail as driver at the entrance of the English Channel. The most sophisticated of the three statistical models, although involving only three explanatory variables—the tide, waves and Chl-a—is able to estimate non-algal surface SPM with a coefficient of determination reaching 70% at many locations.     

Dynamics of the turbidity maximum zone in a macrotidal estuary (the Gironde,France): Observations from field and MODIS satellite data

Over a 1-year period, field and satellite measurements of surface water turbidity were combined in order to study the dynamics of the turbidity maximum zone (TM) in a macrotidal estuary (the Gironde, France). Four fixed platforms equipped with turbidity sensors calibrated to give the suspended particulate matter (SPM) concentration provided continuous information in the upper estuary. Full resolution data recorded by the moderate resolution imaging spectroradiometer (MODIS) sensors onboard the Terra and Aqua satellite platforms provided information in the central and lower estuary twice a day (depending on cloud cover). Field data were used to validate a recently developed SPM quantification algorithm applied to the MODIS ‘surface reflectance’ product. The algorithm is based on a relationship between the SPM concentration and a reflectance ratio of MODIS bands 2 (near-infrared) and 1 (red). Based on 62 and 75 match-ups identified in 2005 with MODIS Terra and Aqua data, the relative uncertainty of the algorithm applied to these sensors was found to be 22 and 18%, respectively.Field measurements showed the tidal variations of turbidity in the upper estuary, while monthly-averaged MODIS satellite data complemented by field data allowed observing the monthly movements of the TM in the whole estuary. The trapping of fine sediments occurred in the upper estuary during the period of low river flow. This resulted in the formation of a highly concentrated TM during a 4-month period. With increasing river flow, the TM moved rapidly to the central estuary. A part of the TM detached, moved progressively in the lower estuary and was finally either massively exported to the ocean during peak floods or temporary trapped (settled) on intertidal mudflats. The massive export to the ocean was apparently the result of combined favorable environmental conditions: presence of fluid mud near the mouth, high river flow, high tides and limited wind speeds. The mean SPM concentration within surface waters of the whole estuary showed strong seasonal variations but remained almost unchanged on a 1-year-basis. These observations suggest that the masses of suspended sediments exported toward the ocean and supplied by the rivers were almost equivalent during the year investigated (2005). Results show the usefulness of information extracted from combined field and current ocean color satellite data in order to monitor the transport of suspended particles in coastal and estuarine waters.     

Resolving physically and biologically driven suspended particulate matter dynamics in a tidal basin with a distribution-based model

Understanding suspended particulate matter (SPM) dynamics in coastal waters is crucial to assess changes in coastal sediment budgets and biogeochemical fluxes. SPM dynamics are subject to various physical and biological factors and processes such as, e.g. tidal currents and aggregation which can be enhanced by extracellular polymeric substances (EPS) that are produced by algae and bacteria. It is still unclear how the different factors and processes interact and together determine SPM dynamics. To unravel the interacting processes and factors, we propose a new distribution-based modeling approach. Based on the derivation of explicit equations for size distribution characteristics of SPM such as the average radius, we derived a model of reduced complexity characterized by low initialization and parameterization effort as well as low computational cost. The proposed 0D model includes the processes of aggregation and fragmentation due to shear, aggregation due to differential settling, deposition, resuspension and tidal exchange, and describes the evolution of the SPM concentration in the water column linked by the settling velocity to the change of the mass average radius of the aggregate distribution. A systematic parameter variation for critical bottom shear stress of erosion, the size of resuspended aggregates, the fractal dimension, the collision efficiency, and the aggregate strength has been performed and compared to observations in the back-barrier basin of Spiekeroog Island in the German Wadden Sea. This analysis confirms the hypothesis that in winter biological influences on SPM dynamics are smaller compared to summer. This is mainly reflected by a significant shift in the various parameters. We hence conclude that biological control mechanisms have a much more quantitative relevance for SPM dynamics than currently represented by state-of-the-art SPM transport models.     

厦门海域分粒级叶绿素a含量的分布特征

据2002年12月至2004年2月间厦门海域6个航次分粒级叶绿素a含量的调 查资料,研究了该海域分粒级浮游植物叶绿素a含量的分布特征及其控制因子．结果 表明:厦门海域叶绿素a含量平均值为5．36mg／m3,各调查月份中,8月份的含量最 高(13．6mg／m3),5月的次之(5．33mg／m3),12、2月的含量较低．叶绿素a含量的水 平分布在冬季时较为均匀;春、夏季在宝珠屿海域出现最高值(33．28mg／m3),九龙江 口外出现次高值(13．84mg／m3)．厦门海域全年以微型浮游植物占优势,小型浮游植 物在夏季高生物量时占比较高(41．O％),微微型浮游植物所占比例较小(年平均值 为9．7％)．冬季低温是浮游植物生长的主要限制因子,春、夏季随着温度升高,营养 盐的缺乏限制了浮游植物的生长．