【作者】 檀赛春；

【导师】 石广玉；

【作者基本信息】 中国科学院研究生院（大气物理研究所） ， 大气物理学与大气环境， 2007， 博士

【摘要】 海洋初级生产力(OPP)在全球碳循环中起着重要作用,在相当程度上控制着海–气界面CO2的交换,是全球变化研究中的重要内容。本文的研究目标是通过卫星遥感反演整个中国近海、长时间序列的OPP,并利用真光层中的辐射传输模式研究不同水体光学特性的变化对叶绿素a浓度和OPP遥感的影响,同时分析中国近海OPP的时空演化及其可能原因,特别是亚洲频繁发生的沙尘暴对海洋生态系统的可能影响。本文的研究可以弥补现场调查的时空局限性,对于理解海洋生物地球化学过程及其可能的气候环境效应十分关键。另外,研究亚洲沙尘对海洋叶绿素a浓度和OPP的可能影响为目前尚未得到充分重视的沙尘的间接气候和环境效应问题的研究提供了一个参考,也为该问题今后的进一步深化研究提供了一个很好的基础。本文的主要研究内容包括4方面:水色和OPP遥感原理及方法介绍,建立中国近海OPP的遥感反演模式及精度分析;利用辐射传输模式进行各种水体对OPP遥感影响的敏感性实验研究;中国近海OPP的时空演化及其可能原因分析;初探亚洲沙尘对中国近海生态系统的可能影响。第一部分内容是后面3部分研究得以进行的基础。第一部分首先介绍水色和OPP遥感的原理,并综述了OPP的反演方法,在此基础上选定当前应用广泛且最有效的OPP算法的修正算法(修正的VGPM)建立了中国近海OPP的反演模式,并讨论了影响OPP反演精度的因子,同时将有关参数的卫星遥感结果同现场观测资料进行对比分析。结果表明叶绿素a浓度、真光层深度及最大光合作用速率都是影响中国近海OPP遥感精度的主要因子,而卫星遥感的OPP能够反映中国近海OPP的变化趋势。第二部分利用真光层中的辐射传输模式进行了一系列敏感性试验,以研究不同水体光学特性的变化对叶绿素a浓度和OPP遥感的影响,主要结果是:对于含有不同成分浓度的水体,输入的遥感反射率误差越大,所引起的叶绿素a浓度和OPP的反演误差也越大。叶绿素a浓度在0.2-1 mgm -3时,各种叶绿素反演算法的适用性最好,而对于较高和较低叶绿素a浓度的水体,反演误差都较大。此外,OPP的反演误差随总悬浮物质浓度的减小而减小。忽略叶绿素a浓度峰值分布时造成OPP的反演误差,在南海最大可达71%,而在黄海最大为29%。第三部分利用修正的VGPM模式反演了1998-2005年中国近海的OPP,同时分析了其时空演化跟其他物理化学环境因子之间的关系。研究结果表明:渤海、北黄海、南黄海、东海北部、东海南部和南海的初级生产力有明显的季节变化,它们在一年内都表现出很好的双峰分布(渤海分别在夏初和秋季,黄海和东海分别在春季和秋季,南海则在冬季和夏季),且第1个峰值高于第2个峰值。东海南部和南海夏季最低,而其他几个海域则是冬季最低。在渤海、黄海和东海,温度、透入海中的光(跟海表辐射强度和透明度有关)是影响其时空演化的主要因素,而在南海营养盐则是最主要的因子。第四部分利用卫星遥感的叶绿素a浓度、海表温度、气溶胶指数资料以及我们反演得到的OPP资料,讨论分析了亚洲频繁发生的沙尘暴输送到黄海和南海以后,对浮游植物生长以及OPP的可能影响。得出的主要结论如下:亚洲沙尘对贫营养的大洋水域的作用尤为突出,而对近岸水的促进作用相对较小,这可能是因为近岸水本身就是富营养的;亚洲沙尘有可能促进了黄海的春季藻华;1998、2001、2002和2006年的几次典型的长距离沙尘过程表明,亚洲沙尘促进了黄海和南海的叶绿素a浓度和OPP的增加,并且大多都是滞后一周至两周的时间开始起作用,少数几次沙尘事件最长可滞后约1个月。本文创新之处主要有以下几点:○1利用目前应用广泛且最有效的OPP反演算法的修正算法,建立中国近海的OPP反演模式,并且分析了中国近海各海域OPP的空间和长时间变化趋势,这弥补了现场测量的时空局限性。○2应用真光层中的辐射传输模式分析不同水体光学特性的变化对OPP反演精度的影响,这对于分析OPP产品的不确定性可能更加有效。○3探讨了近10年来,亚洲沙尘对中国近海叶绿素和OPP的可能影响,采用强和特强沙尘暴个例的实际详细记录同卫星遥感的气溶胶指数资料相结合的方法,来分析亚洲沙尘暴入海的日期、天数和强度,这样可能更准确地抓住了入海的沙尘,从而为分析沙尘暴对海洋的影响提供了更可靠的基础。本文试图通过遥感揭示中国近海OPP的时空变化规律,同时希望揭示不同水体对OPP遥感不确定性的可能影响,并试图找出影响它的主要因子。另外,希望揭示亚洲沙尘经过长距离输送沉降到海洋之后,可能为黄海和南海“施肥”从而影响其生态系统的规律,这部分工作需要今后更进一步的研究和证实。更多还原

【Abstract】 Ocean primary productivity (OPP) controls the exchange of carbon dioxide at the air–sea interface and plays an important role in the global carbon cycle and climate change. The objective of this dissertation is to study long-time OPP in the whole China seas by satellite remote sensing and the impacts of variation in optical properties of various waters on chlorophyll a (Chl a in short) concentration and OPP through radiative transfer model in the euphotic layer. At the same time, we analyzed the spatiotemporal variability of OPP in the China seas and tried to give the answer to explain the variability. In addition, the probable effects of Asian dust year after year on ocean ecosystem were studied preliminarily. The study in this dissertation can complement the spatiotemporal limitation of in situ investigation, and it’s also very important to understand the biogeochemical processes and the probable climate and environment effects. Moreover, the study on probable impacts of Asian dust on Chl a concentration and OPP will be an implication to the study on the indirect climate and environment effects of dust which was still not concerned so much, and can be took as the basis of further study on this problem.There are 4 parts in this dissertation: to establish the retrieval model for OPP in the China seas and its accuracy analysis after introduction of the principle and methods of remote sensing of ocean color and OPP; to study the impacts of various ocean waters on remote sensing of OPP using sensitivity experiments and radiative transfer model; to analyze the spatiotemporal variability of OPP in the China seas and its possible reasons; to study the effects of Asian dust on ocean ecosystem in the China seas preliminary. The first part is the basis of the latter three parts.In the first part, the principle of remote sensing of ocean color and OPP was introduced first and the retrieval methods of OPP was summarized, then the modified Vertically-Generalized Productivity Model (VGPM) which is the very popular model and the most usable for primary production estimation was selected to establish OPP retrieval model in the China seas. We discussed the factors influencing the accuracy of OPP in detail and summarized the result based on the analysis of the difference between data from remotely sensed and in situ measurements. The results show that Chl a concentration, euphotic layer depth and the maximum photosynthetic rate are the most important factors that influence the accuracy of remote sensing of OPP in the China seas and the trends of OPP in the China seas still can be reflected by OPP estimated through the modified VGPM.In the second part, sensitivity experiments was done by using radiative transfer model in the euphotic layer to study the impacts of variation in optical properties of various waters on remote sensing of Chl a concentration and OPP. The results indicate: for the water with different constituents, the potential error of Chl a concentration and OPP will increase along with the increasing of error of remote sensing reflectance. When the Chl a concentration was in the range of 0.2-1 mg m -3, we can get the best results no matter what algorithms were selected; if not, none of these methods can be expected to get the compatible accuracy. Moreover, the error of OPP decreases along with the decreasing of total suspended substance concentration. The difference of OPP caused by uniform and non-uniform Chl a profile can be 71% in the South China Sea (SCS) and 29% in the Yellow Sea (YS), respectively.In the third part, the OPP in the China seas from 1998 to 2005 was estimated by the modified VGPM, and then its spatiotemporal variability together with the relationship between OPP and some physiochemical environmental factors were analyzed. The results show: the OPP in the Bohai Sea, northern YS, southern YS, northern East China Sea (ECS), southern ECS, and SCS has obvious seasonal variation, and two peaks distribution of primary production with the larger of the first peak was also clear (it appeared in early summer and fall in the Bohai Sea, spring and fall in the YS and ECS, winter and summer in the SCS, respectively). The lowest OPP was occurred in summer in the southern ECS and SCS, while in winter in the other sea areas. Temperature and light penetrating into the water (it relates to radiance on the sea surface and transparency) are the most important factors which influence the spatiotemporal variability of OPP in the Bohai Sea, YS and ECS, while in the SCS nutrients are the most important factor.In the fourth part, the probable effects of Asian dust deposition to the YS and SCS on phytoplankton growth and OPP were discussed by using the data of Chl a concentration, SST and aerosol index from remotely sensed and OPP retrieved by us. The main results show: the promotion impacts of Asian dust on phytoplankton growth and OPP in the oligotrophic open ocean are very notable, while that in the coastal waters are relatively small maybe due to its eutrophic environment; Asian dust may initiated the early spring bloom in the YS; the increasing of Chl a concentration and OPP after a delay of about one to two weeks as Asian dust deposition to the YS and SCS is clearly seen from several typical long-range distance dust events in the year of 1998, 2001, 2002 and 2006; and it’ll delay about one month just during a few dust storm events.The innovation of this dissertation is as follows:○1 The retrieval model for OPP in the China seas was established by using the modified VGPM which is the very popular model and the most usable for primary production estimation, and then the spatial and long-time temporal variability of OPP was analyzed, which can complement the spatiotemporal limitation of in situ measurement.○2 The influence of variation in optical properties of various waters on the accuracy of OPP retrieval was studied through radiative transfer model in the euphotic layer, which may be more sufficient to determine the level of uncertainty of OPP product.○3 The probable effects of Asian dust on chlorophyll and OPP in the China seas during recent ten years were discussed in this dissertation, and the date, days and intensity of Asian dust storm deposition to ocean were analyzed using the satellite remote sensing aerosol index data compared with the detail records of strong and very strong dust storm, which maybe catch the dust storm deposition to ocean more accurately, and consequently become more reliable basis for studying the effects of dust on ocean.We try to find out the rule of the spatiotemporal variability of OPP in the China seas by satellite remote sensing, expect to uncover the probable effects of various waters on the uncertainty of remote sensing of OPP, and attempt to find out the primary factor. In addition, we expect to uncover the rule of“fertilization”effects of Asian dust on ecosystem in the YS and SCS after deposition to the ocean through long-distance transportation, which need to be studied and confirmed further in future.更多还原