Seasonal and annual variations of marine sinking particulate flux during 1993~1996 in the central South China Sea

A total of 67 samples from the upper and lower sediment traps in the central South China Sea were analyzed, which were collected during 1993~1996. It is indicated that the distribution of stable isotope values, surface primary productivity, fluxes of total particulate matter, carbonate, biogenic opal, organic carbon, planktonic foraminiferal species and their total amount exhibit obviously seasonal and annual fluctuations. High values of the fluxes occurred in the prevailing periods of the northeastern and southwestern monsoons, and the low values occurred during the periods between the two monsoons. The fluxes of some planktonic foraminiferal species (Globigerinoides sacculifer, G. ruber, Globigerinita glutinata, Neogloboquadrina dutertrei) and their percentages also exhibit two prominent peaks during the prevailing periods of the northeastern and southwestern monsoons respectively, while those of Globigerina bulloides, Globorotalia menardii and Pulleniatina obliquiloculata only exhibit one peak in the prevailing periods of the northeastern monsoon. In addition, fluxes and percentages of Globigerinoides sacculifer and Globorotalia menardii as well as the fluxes of carbonate and total amount of planktonic foraminifera decrease gradually from 1993 to 1996, and those of Globigerina bulloides, Globigerinita glutinata and biogenic opal increase gradually from 1993 to 1996. The fluxes of carbonate and organic carbon in the upper trap are higher than those in the lower one. The study indicates that the seasonal and annual variations of the sediment fluxes and planktonic foraminiferal species are mainly controlled by the changes of surface primary productivity and hydrological conditions related to the East Asian monsoon. The lower carbonate and organic carbon fluxes in the lower trap are related to the dissolution.     

北太平洋副热带模态水形成区潜沉率的年际变化及其机制

根据Huang和Qiu 1995年的潜沉率计算公式,采用同化的海洋模式资料和海洋-大气界面的通量观测资料,计算了北太平洋副热带海域3个模态水形成区逐年的潜沉率,研究了潜沉率产生年际变化的机制.研究结果表明:西部、中部和东部3个模态水形成区潜沉率的年际变化主要周期分别为6,2~5和2 a;北太平洋副热带模态水的3个形成区的潜沉率都发现年代际的变化特征:在1985年以前,西部模态水形成区的潜沉率年际变化最为显著,但1985后年际变化振幅明显减小;在中部模态水形成区,1975~1992年间潜沉率随时间的变化的振幅较大,潜沉率在这段时间内的平均值也达到33.99 m/a,而在1970~1975年间和1993~1998年间潜沉率都小于20 m/a;西部副热带模态水形成区的潜沉率的年际变化与这里海面的净热通量的年际变化有很好的相关性,中部副热带模态水形成区潜沉率的年际变化则取决于局地Ekman流的年际变化,而在东部模态水形成区局地风应力旋度的变化直接影响潜沉率的大小.     

Towards models of strategic spatial choice behaviour: theory and application issues

Models of spatial choice behaviour have been around in geography urban planning for decades to assess the feasibility of planning actions or to predict external (competition) effects on existing destinations. Although these models differ in terms of complexity and key concepts, they all have in common that spatial choice behaviour is predicted as a function of the attributes of the choice alternatives and distance or travel time separation only. None of these models do take into account that the attributes of choice alternatives and travel time may be highly non-stationary and that often the utility that people derive from visiting a particular location also depends on the choice behaviour of other individuals. Under these circumstances, individuals may exhibit strategic choice behaviour. That is, they will choose particular choice options taking into account their expected behaviour of others such as to maximize their own utility. The purpose of the proposed paper is to discuss possible models of strategic choice behaviour for these urban planning problems. Theory will be outlined and some critical issues in the application of such models to problems of spatial choice will be discussed.     

莱州湾南岸潍河下游地区咸水入侵灾害成因及特征

通过对莱州湾南岸咸水入侵较严重地潍河下游地区晚更新世以来沉积特征及现代自然环境条件变化的分析，探讨了沉积相对咸水入侵产生及空间范围特征的环境机理。晚更新世以来的三次海平面升降变化造成了潍河下游地区海陆沉积环境交替，形成了巨厚的海陆交互相沉积层。海进时期，大面积的滨海平原被淹没，在近海平原洼地滞留的海水经过蒸发、浓缩变为卤水，成为咸水入侵的物源；海退后陆源碎屑在滨海地区沉积形成了巨厚的古河道砂层。20世纪70年代末期以来，随着对地下淡水的过度开采，淡咸水水头压力差减小．卤水通过古河道砂层快速南侵。通过对潍河下游地区100余个地质钻孔水化学连续监测资料分析，阐明了咸水入侵的特征，有针对性地提出了咸水入侵的防治措施。     

多比例尺空间数据库的层次对象模型

多比例尺空间数据库是社会和技术发展到一定阶段后对地理信息系统提出的必然要求。本文分析了产生该问题的原因,多比例尺空间数据库的定义及相关性,回顾了多比例尺空间数据库建立的3种模型以及其组织结构、管理方式和优缺点。本文设计了层次对象模型作为多比例尺数据库实现的概念模型,将多比例尺表达分解为目标集合层次树和目标细节树的设计,详细论述了模型解决多比例尺数据管理的方法,最后讨论了多比例尺数据库的应用前景。     

Anomalous change of the Antarctic sea ice and global sea level change

ＡｎｏｍａｌｏｕｓｃｈａｎｇｅｏｆｔｈｅＡｎｔａｒｃｔｉｃｓｅａｉｃｅａｎｄｇｌｏｂａｌｓｅａｌｅｖｅｌｃｈａｎｇｅ￥ＸｉｅＳｉｍｅｉ;ＺｏｕＢｉｎｇ;ＷａｎｇＹｉａｎｄＢａｏＣｈｅｎｇｌａｎ（１．ＮａｔｉｏｎａｌＭａｒｉｎｅＥｎｖｉｒｏｎｍｅｎｔＦ...     

迁徙中的承袭、交融与分异——广东客家建筑与聚落形态时空发展解析

客家是一支在一定时期内处于流迁状态的民系。在其迁徙过程中,宗族组织化的群体自身的文化惯性对撞地理环境与社会环境的差异,使客家民系对于生存空间关系的处理呈现多样的态度。为厘清广东主要客居地内不同传统客家村居形态之间的关联性及其发展脉络,本研究从类型学角度,分别在微观建筑形态与中观聚落格局两个层面,依据关键空间属性来划分空间形制的基本类型,并整理比较建筑类型与聚落类型的地理分布。而后,从历史地理学角度挖掘客家民系在广东省内的流迁历程,并顺沿多条流迁动线分别探讨不同建筑类型、不同聚落类型之间的承袭、交融与分异关系,进而得出以下结论：① 在“建筑”与“聚落”两个尺度层面上的空间营造活动中,建筑形制决策倾向于依附民系内生文化,聚落模式决策倾向于呼应局域地区的社会经济与自然环境;② 在沿迁徙路径的时空推移过程中,主要建筑类型沿主干河流由上游向中下游传播承袭,韩江水系和东江水系之间的支线水陆途径促进了建筑类型在规模、围合防卫程度、聚合组织形式等方面的渐变过渡;③ 相对于客家文化核心区,“广府-客家”“福姥-客家”文化锋面上客家建筑“中轴”对空间组织的主导力发生急剧弱化,意味着宗族组织出现扁平化的变化态势,主要表现为该地带宗族“房系”发达度下降,以及宗祠的经济文化凝聚力衰退;④ 从空间概念的历时性承袭与发展视角来看,空间形态控制性基因应为明确的“属性”化因子,而非具象化要素,聚居空间的基因分析,应当分别基于“人”“地”的不同线索,探索不同尺度人居空间形态的控制因子。     

http://www.sciencedirect.com/science/article/pii/S167498711300162X

Seismic observations have shown structural variation near the base of the mantle transition zone(MTZ)where subducted cold slabs,as visualized with high seismic speed anomalies(HSSAs),flatten to form stagnant slabs or sink further into the lower mantle.The different slab behaviors were also accompanied by variation of the "660 km" discontinuity depths and low viscosity layers(LVLs) beneath the MTZ that are suggested by geoid inversion studies.We address that deep water transport by subducted slabs and dehydration from hydrous slabs could affect the physical properties of mantle minerals and govern slab dynamics.A systematic series of three-dimensional numerical simulation has been conducted to examine the effects of viscosity reduction or contrast between slab materials on slab behaviors near the base of the MTZ.We found that the viscosity reduction of subducted crustal material leads to a separation of crustal material from the slab main body and its transient stagnation in the MTZ.The once trapped crustal materials in the MTZ eventually sink into the lower mantle within 20-30 My from the start of the plate subduction.The results suggest crustal material recycle in the whole mantle that is consistent with evidence from mantle geochemistry as opposed to a two-layer mantle convection model.Because of the smaller capacity of water content in lower mantle minerals than in MTZ minerals,dehydration should occur at the phase transformation depth,~660 km.The variation of the discontinuity depths and highly localized low seismic speed anomaly(LSSA) zones observed from seismic P waveforms in a relatively high frequency band(~1 Hz) support the hypothesis of dehydration from hydrous slabs at the phase boundary.The LSSAs which correspond to dehydration induced fluids are likely to be very local,given very small hydrogen(H~+) diffusivity associated with subducted slabs.The image of such local LSSA zones embedded in HSSAs may not be necessarily captured in tomography studies.The high electrical conductivity in the MTZ beneath the northwestern Pacific subduction zone does not necessarily require a broad range of high water content homogeneously.     

近年来我国地面反射率的若干重要特征

本文利用１９８６－１９９０年我国１４个具有地理、气候代表性的日射观测的实测资料，分析了我国地面反射率的若干最新特征，为认识和研究我国地理和气候变化提供了某些依据。     

Summertime atmospheric teleconnection pattern associated with a warming over the eastern Tibetan Plateau

By using a surface air temperature index (SATI) averaged over the eastern Tibetan Plateau (TP), investigation is conducted on the short-term climate variation associated with the interannual air warming (or cooling) over the TP in each summer month. Evidence suggests that the SATI is associated with a consistent teleconnection pattern extending from the TP to central-western Asia and southeastern Europe. Associated rainfall changes include, for a warming case, a drought in northern India in May and June, and a stronger mei-yu front in June. The latter is due to an intensified upper-level northeasterly in eastern China and a wetter and warmer condition over the eastern TP. In the East Asian regions, the time-space distributions of the correlation patterns between SATI and rainfall are more complex and exhibit large differences from month to month. Some studies have revealed a close relationship between the anomalous heating over the TP and the rainfall anomaly along the Yangtze River valley appearing in the summer on a seasonal mean time-scale, whereas in the present study, this relationship only appears in June and the signal's significance becomes weaker after the long-term trend in the data was excluded. Close correlations between SATI and the convection activity and SST also occur in the western Pacific in July and August: A zonally-elongated warm tone in the SST in the northwestern Pacific seems to be a passive response of the associated circulation related to a warm SATI. The SATI-associated teleconnection pattern provides a scenario consistently linking the broad summer rainfall anomalies in Europe, central-western Asia, India, and East Asia.