全球海洋观测系统展望

一、引言 海洋在全球变化中起着关键性的作用。为了弄清海洋的作用我们必须进行长期的全球资料收集,并由此进行全球性的海洋观测,这需要熟悉海洋以及海洋与大气、陆地耦合的基本知识,以及必须的技术与人力、物力来发展和负担长期的海洋观测活动。 全球海洋观测系统的主要任务是长期、系统地收集物理、化学及生物学的观测资料,从而提供全球海洋现时状况,这些资料也能提供全球气候耦合模式的初始条件。在1990年8月的一份报告中,Henry Stommel曾指出:希望在2000年能得到完善的海洋“动态”模型,以此用来预测海洋涡流事件、厄尔尼诺事件、深水和中间层水构造的异常现象以及污染物扩散等问题,同时也可提供气候模式边界条件。     

我国极地海底观测系统的发展与展望

极地海洋特殊环境对观测技术提出了更高的要求.随着海底观测技术的日趋成熟,极地海底观测系统也得到了一定的发展,但后勤保障的高要求制约了系统的发展,目前广泛使用的仍是潜标系统.受国家高技术研究发展计划、国家海洋公益性行业科研专项经费项目和南北极环境综合考察与评估专项等支持,我国发展了极地在线近岸海洋环境监测系统、极地潜标和极地大型海—气耦合浮标等海床基观测系统,对我国的极地海洋学观测与研究做出了积极贡献.但总体而言,我国的极地海底观测仍未形成真正意义上的网络体系.未来有望在北冰洋太平洋扇区和南大洋普里兹湾率先建立海床基观测体系,系统观测并揭示该海域的环境变化特性.     

西北太平洋黑潮延伸体观测回顾和展望

西北太平洋黑潮延伸体是全球海洋动力过程最复杂、对全球气候变化最敏感和全球海洋渔业产量最大的区域之一,然而,目前对该海区物理、生态及生地化循环等过程的认识仍受限于长期连续海洋观测资料的缺乏。本文回顾了国际上针对黑潮延伸体海区的相关观测情况和取得的主要进展,介绍了近年来我国在该区域观测系统的构建工作及取得的初步成果,包括构建了全球首个西北太平洋黑潮延伸体定点观测系统;发现黑潮延伸体海区海洋涡旋的平流效应对该海区模态水的总潜沉率贡献超过一半,所携带当地的模态水只需要一年半的时间就可到达海盆的西边界;基于潜标首次展示了黑潮延伸体区域3种不同类型次温跃层涡旋流速的直接观测结果,为开展其生成消亡机制及其全球次表层物质能量输运提供了重要的现场观测基础。最后,本文展望了今后观测系统的发展方向,即在跨圈层和多学科交叉方面发展成为我国在西北太平洋重要的深远海综合观测网络。这将为揭示多尺度物理-生物过程耦合、深海能量串级及其气候效应与深海碳循环等领域实现突破提供重要的观测支撑。     

自适应海洋观测

“自适应海洋观测”指固定或移动的海洋观测平台能够根据海洋环境和信号的变化,自主调节测量和运行参数,获取最关键的海洋信息.自主水下航行器运用自适应检测和采样技术,在研究上升流锋面等实验中显示出前所未有的观测准确度和效率.一个海洋观测系统的综合效能,取决于固定平台和移动平台的功能互补以及自适应观测能力的增强.     

美国的两大海洋观测系统:OOI与IOOS

介绍美国两大海洋观测系统:基金委员会支持的”大洋观测计划”即OOI计划,和大气海洋署组织的”整合海洋观测系统”即IOOS计划,两者相关但不相同,十分值得我国在建设海洋观测系统中学习参考.     

新一代对地观测系统的发展

对地观测系统(EOS，Earth Observation System)是获取空间对地信息、促进地球系统科学和空间信息科学等学科发展的支柱。长期以来，人们就期望着对自己居住的地球有一个全面深刻的了解，研究这种从几十年到几百年时间尺度的全球变化，依赖于观测系统和观测技术的发展。因此有必要建立一个对地球整体的观测系统，利用空间优势，获取有关地球体系及其各个组成部分的详细数据或信息。 近50年来，世界对地观测技术得到了迅猛的发展。NASA针对全球变化研究对建立长期的数据采集系统的实际需求，于20世纪80年代初开始规划地球观测系统（EOS）计划，并于90年代初实施。它包括一系列卫星、自然科学知识组成和一个数据系统，支持一系列极地轨道和低倾角卫星对地球的陆地表面、生物圈、大气和海洋进行长期观测。地球观测卫星系列是EOS计划的最基本和最重要的环节。EOS卫星系列计划在今后的10年内陆续发射一系列的太阳轨道环境遥感卫星，构成连续15年的数据采集系统，其规模在地球观测卫星发展史上是空前的。在EOS计划的基础上NASA规划了ESE战略计划，将继续发展国际新一代对地观测系统。迄今为止，Terra、Aqua和Arua卫星已经发射成功，引起地球遥感科学界的瞩目，为地球科学研究提供重要的数据资源。     

基于成本分析的高密度勘探观测系统优化设计与评价

观测系统设计是地震资料采集的基础,其优劣将直接影响到后续的地震资料处理解释工作.高密度观测系统在多个实际工区的应用表明,经高密度观测系统采集的资料较老成果在信噪比和分辨率上有明显提高.本次研究基于高密度观测系统的主要采集参数与观测系统总成本、综合质量因子的关系,建立优化模型,并利用该模型对多套观测系统参数进行最优性价比...     

从海洋内部研究海洋

几百年来,人类总是从海洋外面——在船上或者岸上研究海洋。随着技术的最新发展,人类现在可以从海洋内部来研究海洋。简要讨论了海底观测系统和活动观测平台为各领域的海洋研究提供的空前机遇,并指出中国发展海洋科学必须对这一新趋势给予密切注意。     

海洋浮游生物原位观测技术研究进展

原位观测技术在生物海洋学过程研究中的应用,从海洋生物多样性、海洋生物的生理生态响应和宏观的生态过程及其变动机制等方向的研究中得到迅速的发展,极大提高了对海洋生物学、生态学以及不同时空尺度生物地球化学过程的认识.包括原位光学检测技术、水下显微摄像与自动化鉴定技术、水下流式细胞技术、分子生物传感器等新型原位观测技术,拓宽了各类型观测平台的研究对象范围.重点阐述生物海洋学原位观测技术的发展现状、应用实例及其在立体海洋观测系统中的应用前景.     

全球观测系统实地观测的内容和要求

全球性观测系统在检测，监测和预测地球系统的变化中发挥着越工重要的作用。地球系统的复杂性，多尺度性，非线性性，突变性，非平衡性等要求各种全球性观测系统之间必须加强联系与协调。评述了全球性观测系统联系与协调的发展趋势，并依据《全球性观测系统实地观测的内容和体系纲要》、介绍了全球性观测系统实地观测的内容和规范要求。     

2002年国外物理海洋学研究主要进展

在技术进步和多学科交叉的推动下,当今的物理海洋学研究已经大大突破传统的研究范畴。与气候变化相联系的缓慢变化海洋物理过程成为现阶段物理海洋学的核心研究内容之一。世界大洋环流研究计划（WOCE）在经过20年实施后于2002年结束,国际上物理海洋学研究又面临一个新的起点。2002年国外物理海洋学的研究涵盖了与大尺度问题相关的许多领域,主要成果体现在：热盐过程和热盐环流变率、海洋混合、年代际与长期海洋变率、印度洋气候变化、海洋盐度与气候变化、古海洋学、海洋模型等方面。     

Species diversity variations in Neogene deep-sea benthic foraminifera at ODP Hole 730A,western Arabian Sea

Deep-sea benthic foraminifera are an important and widely used marine proxy to understand paleoceanographic and paleoclimatic changes on regional and global scales, owing to their sensitivity to oceanic and climatic turnovers. Some species of benthic foraminifera are sensitive to changes in water mass properties whereas others are sensitive to organic fluxes and deep-sea oxygenation. Benthic faunal diversity has been found closely linked to food web, bottom water oxygen levels, and substrate and water mass stability. The present study is aimed at analyzing species diversity trends in benthic foraminifera and their linkages with Indian monsoon variability during the Neogene. Species diversity of benthic foraminifera is examined in terms of number of species (S), information function (H), equitability (E) and Sanders’ rarefied values, which were combined with relative abundances of high and low productivity benthic foraminifera at Ocean Drilling Program Hole 730A, Oman margin, western Arabian Sea. The Oman margin offers the best opportunity to understand monsoon-driven changes in benthic diversity since summer monsoon winds have greater impact on the study area. The species diversity was higher during the early Miocene Climatic Optimum (～17.2–16.4 Ma) followed by a decrease during 16.4–13 Ma coinciding with a major increase in Antarctic ice volume and increased formation of Antarctic Bottom Water. All the diversity parameters show an increase during 13–11.6 Ma, a gradual decrease during 11.6–9 Ma and then an increase with a maximum at 7 Ma. Thereafter the values show little change until 1.2 Ma when all the parameters abruptly decrease. The benthic foraminiferal populations and diversity at Hole 730A were mainly driven by the Indian monsoon, and polar waters might have played a minor or no role since early Neogene period as the Arabian Sea is an enclosed basin.     

Sea surface heights obtained from Modular Ocean Model simulation and comparison with Topex/Poseidon data for the Indian Ocean

The Modular Ocean Model (MOM) is perhaps the most versatile ocean model available today for the simulation of the large scale circulation of the ocean. The Topex/Poseidon altimeter which has been operating since September 1992 has been providing sea surface heights (SSH) of the accuracy of 5–10 cms with a repeat cycle of 10 days. We examine in this paper, the SSH in the Indian Ocean obtained from a global simulation of MOM with a resolution of 1° in the longitude, 1/3° in the latitude between 30°S and 30°N and 20 levels in the vertical with climatological windforcing and restoring conditions on temperature and salinity. They are compared with the SSH from the Topex/Poseidon altimeter after suitable filtering in the time domain to remove smaller time and length scales. In addition, unfiltered data from both sources are analysed by estimating the cross-spectral density to find the coherence and crossphase at different frequencies. The agreement between the two, over most of the Northern Indian Ocean, especially the Arabian Sea and the Bay of Bengal is quite good.     

Chlorophyll modulation of mixed layer thermodynamics in a mixed-layer isopycnal General Circulation Model — An example from Arabian Sea and equatorial Pacific

Western tropical Indian Ocean, Arabian Sea, and the equatorial Pacific are known as regions of intense bio-chemical-physical interactions: the Arabian Sea has the largest phytoplankton bloom with seasonal signal, while the equatorial Pacific bloom is perennial with quasi-permanent upwelling. Here, we studied three dimensional ocean thermodynamics comparing recent ocean observation with ocean general circulation model (OPYC) experiment combined with remotely sensed chlorophyll pigment concentrations from the Coastal Zone Color Scanner (CZCS). Using solar radiation parameterization representing observations that a higher abundance of chlorophyll increases absorption of solar irradiance and heating rate in the upper ocean, we showed that the mixed layer thickness decreases more than they would be under clear water conditions. These changes in the model mixed layer were consistent with Joint Global Ocean Flux Study (JGOFS) observations during the 1994-1995 Arabian Sea experiment and epi-fluorescence microscopy (EFM) on samples collected during Equatorial Pacific Ocean Climate Study (EPOCS) in November, 1988. In the Arabian Sea, as the chlorophyll concentrations peak in October (3 mg/m³) after the summer plankton bloom induced by coastal upwelling, the chlorophyll induced biological heating enhanced the sea surface temperature (SST) by as much as 0.6‡C and sub-layer temperature decreases and sub-layer thickness increases. In the equatorial Pacific, modest concentrations of chlorophyll less than 0.3 mg/m³ is enough to introduce a meridional differential heating, which results in reducing the equatorial mixed layer thickness to more than 20 m. The anomalous meridional tilting of the mixed layer bottom enhances off equatorial westward geostrophic currents. Consequently, the equatorial undercurrent transports more water from west to east. We proposed that these numerical model experiments with use of satellite andin situ ocean observations are consistent under three dimensional ocean circulation theory combined with solar radiation transfer process.     

Evolution of salinity field in the upper layers of the east central Arabian Sea and northern Bay of Bengal during summer monsoon experiments

The intra-seasonal variability observed in the salinity field of the upper layers at a few locations in the east central Arabian Sea and the northern Bay of Bengal during the summer monsoon seasons of 1977 and 1979 is documented with the aid of short time series (1–2 weeks) of salinity measurements made from USSR and Indian ships deployed during MONSOON-77 (1977) and MONEX-79 (1979) field experiments. In the Arabian Sea a typical subsurface maxima observed beneath the mixed layer base either disappeared or considerably weakened due to strong vertical mixing caused by the monsoonal forcing. In the northern Bay of Bengal the salinity variability in the top 30 m water column was rapid and appeared to be influenced by large amounts of fresh water from rain and probably from the major adjoining rivers. Some simple diagnostic calculations are presented to assess the relative importance of various processes which control the observed salinity variability.     

A model of the subsidence history of the West Coast of India

The occurrence of earthquakes all along the West Coast of India and in the Arabian Sea is explained systematically in terms of the interaction between the underthrusting Indian ocean floor and the Indian subcontinent. This north ward compression due to the repeated underthrusting of the oceanic floor has caused the formation of trenches, grabens and normal faults on the continental margin.     

Development and propagation of a pollution gradient in the marine boundary layer during INDOEX (1999)

The development and propagation of a pollution gradient in the marine boundary layer over the Arabian Sea during the Intensive Field Phase of the Indian Ocean Experiment (1999) is investigated. A hypothesis for the generation of the pollution gradient is presented. Infrared satellite images show the formation of the pollution gradient as the leading edge of a polluted air mass in the marine boundary layer and also its propagation over the Arabian Sea and the northern Indian Ocean. Aerosol data measured from two research vessels over the Arabian Sea show a variation in the concentrations caused by the passage of this pollution gradient. Depth of the pollution gradient was found to be about 800 m. A numerical model was used to simulate the development of this gradient and its propagation over the ocean. Results show that its formation and structure are significantly influenced by the diurnal cycle of coastal sea-land breeze circulations along India’s west coast. Transport of aerosols and gases over the Arabian Sea in the lower troposphere from land sources appears to be through this mechanism with the other being the elevated land plume.     

Sea-Surface Temperatures and the History of Monsoon Upwelling in the Northwest Arabian Sea during the Last 500,000 Years

Arabian Sea sediments record changes in the upwelling system off Arabia, which is driven by the monsoon circulation system over the NW Indian Ocean. In accordance with climate models, and differing from other large upwelling areas of the tropical ocean, a 500,000-yr record of productivity at ODP Site 723 shows consistently stronger upwelling during interglaciations than during glaciations. Sea-surface temperatures (SSTs) reconstructed from the alkenone unsaturation index (U^K′₃₇) are high (up to 27°C) during interglaciations and low (22-24°C) during glaciations, indicating a glacial-interglacial temperature change of >3°C in spite of the dampening effect of enhanced or weakened upwelling. The increased productivity is attributed to stronger monsoon winds during interglacial times relative to glacial times, whereas the difference in SSTs must be unrelated to upwelling and to the summer monsoon intensity. The winter (NE) monsoon was more effective in cooling the Arabian Sea during glaciations then it is now.     

中国的全球构造位置和地球动力系统

现今之中国位于亚洲大陆东南部,西太平洋活动带中段;在全球板块构造图上,中国位于欧亚板块的东南部,南为印度板块,东为太平洋板块和菲律宾海板块。地质历史上,以中朝、扬子、塔里木等小克拉通为标志的中国主体属于冈瓦纳和西伯利亚两个大陆之间的转换(互换)构造域:古生代时期,位于古亚洲洋之南,属冈瓦纳结构复杂的大陆边缘;中生代阶段,位于特提斯之北,属劳亚大陆的一部分。显生宙中国大地构造演化依次受古亚洲洋、特提斯-古太平洋、太平洋-印度洋三大动力体系之控制,形成古亚洲洋、特提斯和太平洋三大构造域。不论古亚洲洋,还是特提斯,都不是结构简单的大洋盆地,而是由一系列海底裂谷带(小洋盆带)和众多微陆块组合而成的结构复杂的洋盆体系。加之中、新生代的太平洋构造域和特提斯构造域叠加在古生代的古亚洲洋构造域之上,使中国地质构造图像在二维平面上呈现镶嵌构造,在三维空间上呈现立交桥式结构,使中国不仅是亚洲,也是全球构造最复杂的一个区域。不同阶段的地球动力体系在中国的叠加、复合,使多旋回构造-岩浆和成矿作用成为中国地质最突出的特征。因而中国的造山带大多是多旋回复合造山带,成矿(区)带大多是多旋回复合成矿(区)带,大型含油气盆地大多是多旋回叠合盆地。     

Integrated Campaign for Aerosols,gases and Radiation Budget (ICARB): An overview

During March–May 2006, an extensive, multi-institution, multi-instrument, and multi-platform integrated field experiment ‘Integrated Campaign for Aerosols, gases and Radiation Budget’ (ICARB) was carried out under the Geosphere Biosphere Programme of the Indian Space Research Organization (ISRO-GBP). The objective of this largest and most exhaustive field campaign, ever conducted in the Indian region, was to characterize the physico-chemical properties and radiative effects of atmospheric aerosols and trace gases over the Indian landmass and the adjoining oceanic regions of the Arabian Sea, northern Indian Ocean, and Bay of Bengal through intensive, simultaneous observations. A network of ground-based observatories (over the mainland and islands), a dedicated ship cruise over the oceanic regions using a fully equipped research vessel, the Sagar Kanya, and altitude profiling over selected regions using an instrumented aircraft and balloonsondes formed the three segments of this integrated experiment, which were carried out in tandem. This paper presents an overview of the ICARB field experiment, the database generated, and some of its interesting outcomes though these are preliminary in nature.

The ICARB has revealed significant spatio-temporal heterogeneity in most of the aerosol characteristics both over land and ocean. Observed aerosol loading and optical depths were comparable to or in certain regions, a little lower than those reported in some of the earlier campaigns for these regions. The preliminary results indicate:

• low (< 0.2) aerosol optical depths (AOD) over most part of the Arabian Sea, except two pockets; one off Mangalore and the other, less intense, in the central Arabian Sea at ～18°N latitude
• High Ångström exponent in the southern Arabian Sea signifying steep AOD spectra and higher abundance of accumulation mode particles in the southern Arabian Sea and off Mangalore
• Remarkably low Ångström exponents signifying increased concentration of coarse mode aerosols and high columnar abundance in the northern Arabian Sea
• Altitude profiles from aircraft showed a steady BC level up to 3 km altitude with structures which were associated with inversions in the atmospheric boundary layer (ABL)
• A surprisingly large increase in the BC mass fraction with altitude
• Presence of a convectively mixed layer extending up to about 1 km over the Arabian Sea and Bay of Bengal
• A spatial off shore extent of <100 km for the anthropogenic impact at the coast; and
• Advection of aerosols, through airmass trajectories, from west Asia and NW arid regions of India leading to formation of elevated aerosol layers extending as far as 400 km off the east coast.