On Light Absorption Properties off Southeastern China— from Estuarine to Shelf Water

本论文研究中国东南近海几种不同特征水体的光吸收特性及其控制机制，包括河口水体—珠江口、沿岸水体—台湾海峡南部、陆架水体—南海东北部，并探讨浮游植物吸收对浮游植物群落结构的指示作用；另外，追踪厦门西海域两次水华过程水体光吸收特征的变动。就440nm水体吸收而言，珠江口春、冬季最主要成分是非色素颗粒吸收，南海东北部则是浮游植物吸收；夏季台湾海峡南部也以浮游植物吸收为主，但非色素颗粒与CDOM二者的贡献与之相当。三个海域吸收组成分别体现河口水体、陆架水体和近岸水体的特征。南海东北部、台湾海峡南部的非色素颗粒吸收光谱斜率Sd（350-700nm）接近，平均分别为0.0099、0.00912nm-1，和...Absorption properties off southeastern China were investigated, including several kinds of regimes such as the Pearl River Estuary (PRE), the southern Taiwan Strait (TWS) and the northeastern South China Sea (NSCS) — a continental shelf water. In addition, a time series of absorption properties as well as algal pigments were measured in the western Xiamen Bay in order to assess temporal variations...学位：工学博士院系专业：海洋与环境学院环境科学研究中心_环境科学学号：B20023400

Variation in absorption coefficients in the western South China Sea and its implication for remote sensing

受沿岸上升流、气旋式冷涡及其夹带的冲淡水的影响，夏季（2007年）南海西部水体吸收特征与冬季（2006年）迥异。冬季水体吸收分布较稳定：浮游植物吸收aph(443)表层值在0.01-0.02m-1间；次表层最大~0.04m-1，深度在50-75m间；CDOM吸收ag(443)表层值均小于0.005m-1，在底层或浮游植物吸收最大层出现最高值，可超过0.03m-1。夏季水体吸收分布则要复杂许多。观测期间发现三处高盐低温中心（～110E/13.5N、111E/12.5N、112E/14.5N），由气旋式冷涡或沿岸上升流所致；13N以南表层大面积覆盖低盐水，可能是冷涡（112E/14.5N）夹带的湄...Based on two cruises survey during summer 2007 and winter 2006, absorption properties in the western South China Sea were investigated. For the sampling stations in the winter, both absorption coefficients of phytoplankton and CDOM had a unique distribution pattern. Phytoplankton absorption coefficients at 443 nm (aph(443)) were ranged from 0.01 to 0.02 m-1 on the surface, with a subsurface maximu...学位：博士后院系专业：海洋与环境学院海洋学系_海洋科学学号：BH1700020

Advances inthe studies onlight absorption properties of phyto-plankton

国家自然科学基金资助项目(40376031);; 国家863计划资助项目(2002AA639540);; 国家自然科学重点基金资助项目(40331004

An evaluation of two semi-analytical ocean color algorithms for waters of the South China Sea

基于42组不同年份不同季节获得的遥感反射率、水体各组分吸收系数的实测数据,对QAA(QuASI-AnAlyTICAl AlgOrITHM)和gSM(gArVEr-SIEgEl-MArITOrEnA)算法在寡营养的南海和富营养的福建沿岸两种不同类型水体的吸收系数反演进行了检验。以水样测量值为参考,两种算法在本研究水体中的反演成效与他人在其它水域的研究结果相当。QAA算法在南海的反演成效高于福建沿岸水体。对于443nM的总吸收系数A(443),南海的对数均方根误差rMSE为0.044,平均相对误差ε为7.9%,对数平均偏差δ为0;福建沿岸水体rMSE=0.190,ε=30.6%,δ=-0.167。gSM算法在两类水体的反演成效类似,A(443)之rMSE和ε,南海分别为0.156和27.7%,福建沿岸分别为0.146和32.1%;但从A(443)的δ值看,其在南海反演值低于实测值(δ=-0.142),在福建沿岸则略呈高于实测值(δ=0.016)。两种算法中的部分经验参数与实测值之间的差异是产生反演误差的主要原因,为了提高反演精度,对算法中经验参数的更进一步区域化调整可能是必要的。With 42 in situ measurements of remote sensing reflectance and component absorption coefficients taken in the South China Sea and coastal waters off Fujian, China during different seasons, the authors evaluate the performance of the Quasi-Analytical Algorithm (QAA) and the Garver-Siegel-Maritorena (GSM) algorithm for water absorption coefficients.It is found that the retrieval performances of the two algorithms are similar to those of the algorithms by other researchers conducted in other regions.In this study , QAA performs better in the South China Sea than in the waters off coastal Fujian.For the total absorption coefficient at 443 nm a(443), the rootmean-square error (RMSE) is 0.046 in the South China Sea, with an averaged percentage error (ε) of 7.9% , and averaged error in log scale (δ) close to 0.For the waters off coastal Fujian, RMSE, ε and δ are 0.194, 30.6%, and -0.167, respectively.The performance of the GSM is similar for the two waters.For a(443), RMSE and ε are 0.161 and 27.7% in the South China Sea and 0.149 and 32.1% in the waters off coastal Fujian , respectively; their δ values, however, are negative (-0.142; indicating underestimation) in the South China Sea and positive (0.016; indicating slight overestimation)in the waters off coastal Fujian.Further analysis indicates that the differences between the empirical parameters employed in the algorithms and actual values of the studied waters are the main reasons causing the errors in remote sensing retrievals, therefore, it is necessary to regionally refine those parameters in order to improve the algorithm performance.863计划项目(2006AA09A302;2008AA09Z108);国家自然科学基金项目(40521003

Short-term dynamics of nutrients influenced by upwelling in a small oligotrophic coastal ecosystem, Gan Bay, in the northwest Philippines

We present a time-series analysis of nutrient and pCO(2) (partial pressure of CO2) levels in an oligotrophic coastal ecosystem (Gan Bay), which was likely to be influenced by upwelled subsurface water. Gan Bay is off Currimao Harbor, in the northwest Philippines and is located at the boundary of the South China Sea (SCS). This 42-h time-series observation was conducted in December 2006. In addition to continuous observations of dissolved oxygen (DO) and pCO(2), discrete samples were collected at a depth of 5 m every 3 h for measurements of nutrients, including soluble reactive phosphorus (SRP) and inorganic nitrogen (NO3- + NO2-) in order to examine their dynamics and possible physical and biological controls. We observed remarkably large short-term variations in the surface water, spanning a 10-fold change for SRP (32-330 nM) and from <0.3 mu M to 4.3 mu M for (NO3- + NO2-. DO also varied substantially from a lower end of 171 to 205 mu M O-2. Surface water pCO(2) changed from an equilibrium stage with the atmosphere (similar to 386 mu atm) to a stage where it was a significant source for the atmospheric CO2 (seawater pCO(2) similar to 469 mu atm). We found that the variation of nutrients was driven neither by tidal mixing nor by biological activities, as was suggested by the variations in the total bacterial abundance and chlorophyll a. Instead, our inverse T-S relationship suggested a two end-member mixing process during the observation period. The N:P ratio throughout the observation period was similar to 13.2, which is characteristic of SCS subsurface and deep waters. Moreover, pCO(2) was correlated inversely with the sea surface temperature. It is likely, therefore, that an upwelled subsurface cold water with high nutrients, low-temperature and high-pCO(2) existed. It should be noted that this upwelled cold water did not appear to impact the entire observation period (approximately 35 h of 42 h), which might suggest an extremely dynamic nature for this upwelled cold water mass. (C) 2009 National Natural Science Foundation of China and Chinese Academy of Sciences. Published by Elsevier Limited and Science in China Press. All rights reserved

A preliminary study of the variation of phytoplankton absorption coefficients in the northern South China Sea

The temporal and spatial variabilities of phytoplankton absorption coefficients (a(ph)(lambda)) and their relationships with physical processes in the northern South China Sea were examined., based on in situ data collected from two cruise surveys during May 14 to 25 2001. and November 2 to 21, 2002. Significant changes in the surface water in a,h values and B/R ratios (a(ph)(440)/a(ph)(675)) were observed in May, which were caused by a phytoplankton bloom on the inner shelf stimulated by a large river plume due to heavy precipitation. This is consistent with the observed one order of magnitude elevation of chlorophyll a and a shift from a pico/nano dominated phytoplankton community to one dominated by micro-algae. Enhanced vertical mixing due to strengthened northeast monsoon in November has been observed to result in higher surface a(ph)(675) (0.002-0.006 m(-1) higher) and less pronounced subsurface maximum on the outer shelf/slope in November as compared with that in May. Measurements of a(ph) and B/R ratios from three transects in November revealed a highest surface a(ph)(675) immediately outside the mouth of the Zhujiang (Pearl) River Estuary, whereas lower a(ph)(675) and higher B/R ratios were featured in the outer shelf/slope waters, demonstrating the respective influence of the Zhujiang River plume and the oligotrophic water of the South China Sea. The difference in spectral shapes of phytoplankton absorption (measured by B/R ratios and bathochromic shifts) on these three transects infers that picoprocaryotes are the major component of the phytoplankton community on the outer shelf/slope rather than on the inner shelf. A regional tuning of the phytoplankton absorption spectral model (Carder et al., 1999) was attempted, demonstrating a greater spatial variation than temporal variation in the lead parameter a(0)(lambda). It was thus implicated that region-based parameterization of ocean color remote sensing algorithms in the northern South China Sea was mandatory.National Basic Research Program of China [2009CB421200, 2009CB421201]; National Natural Science Foundation of China [40821063]; High-Tech R&D Program of China [2006AA09A302, 2008AA09Z108

Changes of temperature and bio-optical properties in the South China Sea in response to Typhoon Lingling, 2001

A large patch of enhanced chlorophyll a concentration (Chla), lower sea surface temperature (SST), and lower sea surface height (SSH) was revealed in the central South China Sea (SCS) in November 2001 after the passage of typhoon Lingling. Maximum SST reduction of 11 degrees C occurred one day after Lingling's passage on 11/11. Subsequently, against a background level of 0.08 mg/m(3), average Chla within the area of 12.60-16.49 degrees N, 112.17-117.05 degrees E increased to 0.14 mg/m(3) on 11/12 and then to 0.37 mg/m(3) on 11/14. Dissolved organic matter and detritus were differentiated from Chla using a recent bio-optical algorithm. They contributed 64% to the increase of total absorption immediately after Lingling, while most of the changes later (74%) were due to phytoplankton. The area under Lingling's impact covered ca. 3 degrees latitude and 4 degrees longitude, which is much greater than the two summer cases previously observed in the northern SCS. This event lasted for ca. 15 days, and resulted in carbon fixation in the order of 0.4 Mt. Such a drastic response was attributed to the coupling of typhoon-induced nutrient pumping with the pre-established cyclonic gyre in the central SCS driven by the prevailing northeast monsoon

Characteristics of Chromophoric Dissolved Organic Matter Absorption in the Southern Taiwan Strait During Summer 2005

2005年7月对台湾海峡南部有色溶解有机物质(CDOM)吸收特性的调查结果表明,CDOM在355 nm波段的吸收值(ag(355),紫外可见分光光度法)变化范围在0.02~0.27 m-1之间,平均0.13 m-1,与大洋水体相近;光谱斜率Sg(拟合光谱范围300~500 nm)为0.017~0.043 nm-1,平均0.022 nm-1.ag(355)的空间分布特征及其与盐度、叶绿素a的相关关系提示在本次观测期间,该海域有色溶解有机物质主要来源于现场生产,但东山以南近岸表层水中陆源影响为显著.与浮游生物活动有关的紫外区波段(300~350 nm)强吸收信号的出现,进一步说明了该海域有色溶解有机物质现场生产机制的重要性.An investigation of Chromophoric Dissolved Organic Matter(CDOM) in the southern Taiwan Strait(TWS) was carried up during summer 2005.It was found that CDOM absorption coefficients at 355 nm(ag(355)),determined by UV-visible spectrophotometer,ranged from 0.02～0.27 m-1,similar to those observed in the open ocean.The spectral slope(Sg)(300～500 nm) varied from 0.017 to 0.043 nm-1.ag(355) showed a linear,inverse relationship with salinity in the surface water near Dongshan Island.However,for most of the samples with salinity higher than 32(53 samples),ag(355) was highly correlated with chlorophyll a with a correlation coefficient(r2) of 0.53.Several samples showed obvious absorption peaks in UV-B bands(300～350 nm),which was probably associated with MAAs released by planktons.It was thus demonstrated that during the period under investigation,CDOM was mainly originated from local production rather than terrestrial input.国家自然科学基金重点项目(40331004);; 国家自然科学基金面上项目(40376031);; 厦门大学新世纪人才计划资

浮游植物类群遥感算法PHYSAT在台湾海峡的适用性研究

浮游植物类群遥感是海色遥感的热点问题,关乎全球变化生态响应研究及有害藻华的辨识.针对目前广泛应用的浮游植物类群遥感全球算法PHYSAT,应用台湾海峡夏季表层浮游植物光合色素与SeaWiFS同步卫星遥感数据,探讨其区域适用性.结果显示两种主要类群(硅藻(Diatom)和聚球藻(Synechococcus))的遥感光谱异常(Ra)分布交错,且同一类群的Ra在不同航次、不同站位之间也存在差异,用PHYSAT算法阈值标准均不能得到有效识别.在建立归一化离水辐射率nLwref(λ,Chla)台湾海峡区域查找表的基础上,重新生成硅藻和聚球藻的Ra,不同类群的Ra依旧混杂.这可能与建立PHYSAT算法的标准海域和台湾海峡水体光学组分差异及台湾海峡的水体光学组分时空差异,尤其是颗粒后向散射系数bbp的变动有关.采用K-means和FCM(Fuzzy c-means)方法对443nm归一化的Ra进行聚类,准确率超过70%.该结果说明在类似台湾海峡的区域水体,浮游植物类群的遥感分辨可能需要更多考虑光谱谱形上的差异,而非如PHYSAT算法进行量值范围区分.国家重点研发技术海洋环境安全保障专项(2017YFC1404804);;国家自然科学基金(41776146);;厦门大学校长基金(20720180106

Comparison of remote sensing chlorophyll a(Chla)derived from three empirical algorithms in the northeastern South China Sea water

比较了2000年夏季邻近珠江口的南海东北部海区海洋水色传感器SeaWiFS遥感与走航叶绿素a(Chla)的分布 ,着重对比在运用Ruddick的浑浊水体大气校正方法的条件下OC2,OC4和OCTSC的3种标准经验算法反演的SeaWiFS遥感Chla与实测Chla偏离的相对程度。结果表明 ,3种产品都能够反映Chla从近岸向远岸降低的空间分布特征 ,但从近岸到远岸划分3个子区域分别对遥感与走航Chla求均值比较的结果表明 ,OC4产品偏离实测Chla分布的程度明显小于其他2种产品。此外3种产品的Chla频率分布差异显著。这一结果可以为选择适用于该海域海洋环境变动研究的SeaWiFSChla标准产品提供参考This study compared SeaWiFS Chla derived from three standard empirical algorithms with ship measured Chla in the northeastern South China Sea in summer,2000.OC4,OC2and OCTSC were applied respectively to retrieve remote sensing Chla products after Ruddick atmospheric correction was done.By comparing the bias of average remote sensing Chla relative to average real Chla at three portions distributing from inshore to offshore regions,it was found that OC4product demonstrated the best among three products,with relative errors10%～32%lower than those produced by OC2and OCTSC for the coastal water adjacent to the estuarine water where Chla concentration was high and the other inˉterference matter such as color dissolved organic matter and suspended sediment were rich.OCTSC product appeared the worst in this region.It was thus suggested that SeaWiFS Chla retrieved by adopting Ruddick atmospheric correction and OC4standard empirical algorithm might be applicable to the investigation of marine environmental variability in the northeast South China Sea.国家863青年基金“近岸纳污海域高光谱现场探测系统”(2002AA639540) ;; 国家杰出青年基金“珠江三角洲及其邻近的南海北部海域中碳的生物地球化学循环研究”项目(49825111