A further investigation of the decadal variation of ENSO characteristics with instability analysis

Based on instability theory and some former studies, the Simple Ocean Data Assimilation （SODA） data are analyzed to further study the difference between the propagation of the ENSO-related oceanic anomaly in the off-equatorial North Pacific Ocean before and after 1976. The investigation shows that after 1976 in the off-equatorial North Pacific Ocean, there is a larger area where the necessary conditions for baroclinic and/or barotropic instability are satisfied, which may help oceanic anomaly signals propagating in the form of Rossby waves to absorb energy from the mean currents so that they can grow and intensify. The baroclinic energy conversion rate in the North Pacific after 1976 is much higher than before 1976, which indicates that the baroclinic instability has intensified since 1976. Prom another perspective, the instability analysis gives an explanation of the phenomena that the ENSO-related oceanic anomaly signal in the North Pacific has intensified since 1976.     

Quantifying the non-conservative production of potential temperature over the past 22000 years

The energy budgets of the ocean play a crucial role in the analysis of climate change. Potential temperature is traditionally used as a conservative quantity to express variations associated with “heat” in oceanography, such as the heat content and heat transport. However, potential temperature is usually not conserved during turbulent mixing, so the use of conservative temperature is more accurate. Based on climatological simulations under the modern and Last Glacial Maximum (LGM;~21 ka;ka=thousand years ago), as well as a transient climate simulation of the past 22 000 years, we quantify the errors induced by the neglect of the non-conservation of potential temperature in paleo-climate research for the first time. The temperature error reaches 0.9℃ near the coasts aff ected by river discharges but is much smaller in the open oceans, typically 0.03°C above the main thermocline and less than 0.01℃ elsewhere. The error of the ocean heat content (OHC) is roughly 3×10^22 J and is relatively steady over the past 22 000 years. However, the OHC increases to six times the original value during the last glacial termination from 20 ka to 7 ka. As a result, the relative OHC error decreases from 1.2% in the LGM climate to 0.14% in the modern climate. The error of the ocean meridional heat transport (OMHT) is generally smaller than 0.005 PW (1 PW=10 15 W), with very small temporal variations (typically 0.000 4 PW), and induces a relative OMHT error of typically 0.3% over the past 22 000 years. Therefore, the neglect of the non-conservation of potential temperature induces a relative error of generally less than 1% in the analyses of basin-scale climate variations.     

Variability of surface velocity in the Kuroshio Current and adjacent waters derived from Argos drifter buoys and satellite altimeter data

By combining Argos drifter buoys and TOPEX/POSEIDON altimeter data, the time series of sea-surface velocity fields in the Kuroshio Current (KC) and adjacent regions are established. And the variability of the KC from the Luzon Strait to the Tokara Strait is studied based on the velocity fields. The results show that the dominant variability period varies in different segments of the KC: The primary period near the Luzon Strait and to the east of Taiwan Island is the intra-seasonal time scale; the KC on the continental shelf of the ECS is the steadiest segment without obvious periodicity, while the Tokara Strait shows the period of seasonal variability. The diverse periods are caused by the Rossby waves propagating from the interior ocean, with adjustments in topography of island chain and local wind stress. Supported by the National Basic Research Program of China (973 Program, Nos. 2007CB411804, 2005CB422303), the NSFC (No. 40706006), the Key Project of International Science and Technology Cooperation Program of China (No. 2006DFB21250) and the “111 Project” (B07036), the Program for New Century Excellent Talents in University (NECT-07-0781)     

Relationship Between Producer Services Developing Level and Urban Hierarchy —— A Case Study of Zhujiang River Delta

As the Central Place Theory indicates, the centricity of a central city can influence the extension of its service. Since the service industry in the theory is mostly consumer services, it is worth studying the relationship between the producer services and the centricity of the city in the service society with producer services becoming a more important part of the service industry. The paper takes the case of the Zhujiang （Pearl） River Delta （PRD）, a developed region in China, to study the relationship between the developing level of producer services and the urban hierarchy. Based on the analysis about the spatial difference of the producer services in the nine cities of the PRD, and the division of the nine cities according to some economic indices, it is shown that there is a correlation between the developing level of producer services and the urban hierarchy. Furthermore, two deductions about the future status of the producer services in the city and the location of the producer services in a large region can be made from this correlation between the developing level of producer services and the urban hierarchy.     

20世纪90年代中国城市发展空间差异变动分析

城市化速度加快,城市区域化和区域城市化以及城镇体系开放性增强等是20世纪90年代中国城市发展的总体特征。以省级行政区为基本空间单元,选取25项城市发展指标, 利用SPSS统计分析软件对1990年和2000年中国城市发展进行主成份分析和聚类分析,得出20世纪90年代中国城市发展空间差异的变动特征是：① 城市发展水平的东西空间差异增大,东部沿海地区城市发展重心南移;② 城市发展速度东部沿海地区快于中西部地区,东部地区的南部大于北部,基础较好的城市集群发展速度较快;③ 东部沿海地区的北京和上海集聚性、外向性和创新性特点都很显著,中西部地区城市发展特征结构仍处于低水平均衡状态。国家目标、战略和政策的作用及其效果累积,城市发展动力机制和地理区位条件的差异是这一时期中国城市发展空间差异变动的主要原因。     

高密度开发城市的交通与土地利用互动关系——以广州为例

在评述国内外城市交通系统与土地利用互动关系研究的基础上,以广州为案例,利用有关政府部门资料、统计资料和实地调查资料,引入定量分析和GIS、RS空间分析技术,系统全面地研究了我国高密度开发城市交通系统与土地利用互动关系。结果表明：城市交通系统与土地利用之间相互影响、相互作用。交通系统的发展引起城市空间形态、土地利用开发、土地利用价格和用地布局特征的变化;反之,土地利用特征的改变也带来了交通线网格局、交通密度特征及交通模式的改变。     

山东五莲七宝山多金属矿红石岗矿段Cd，Ga等分散元素的富集规律研究

本文对红石岗矿段的Ⅰ-1,Ⅰ-2号银铅锌共生矿体利用详查、补充详查工作部分坑道、钻探工程样品的副样进行了微量元素分析。结果表明其中的Ga和Cd元素超过了伴生组分要求,其分布与主组分分布基本一致,利用spss软件对各元素之间的相关性进行分析,Ga元素和Ge元素,Cd元素和Zn元素极强相关;Tl元素和Ga元素,In元素和Fe元素,Cd元素和Pb元素强相关。Zn/Cd比值显示该矿床为中低温矿床,这与前人的研究结论是一致的。In主要赋存在黄铁矿中,Cd主要赋存在闪锌矿中、方铅矿次之,Tl和Ga具有较强的共生关系。闪锌矿中Cd可能主要以类质同象形式存在。     

Study on the migrant labour force of China in recent years

This paper, taking Nanhai City of Guangdong Province as an example, focuses on five interrelated aspects of the migrant labour force of China in recent years. Attention is initially paid to the background of the labour migration from inland towards coastal area. Then, the demographic characteristics of the migrant labour force are analysed before turning to the analysis on the reasons for the migration. Fourthly, the impacts of the migrant workers on the socio-economic development of Nanhai City and the problems are examined. Finally, the prospects and some suggestions for the labour migration are put forward. Migrant labour force is sometimes called floating population by both Chinese and western scholars.     

Bearing capacity of strip footings on <Emphasis Type="Italic">c</Emphasis>–<Emphasis Type="Italic">φ</Emphasis> soils with square voids

The presence of underground voids has an adverse influence on the performance of shallow foundations. In this study, the bearing capacity and failure mechanism of footings placed on cohesive-frictional soils with voids are evaluated using discontinuity layout optimization. By introducing a reduction coefficient, a set of design charts that can be directly applied to the classical bearing capacity formulation is presented. The results indicate that the undrained bearing capacity with voids is sensitive to soil weight and cohesion, as both the bearing capacity and stability issues exist in the problem. The failure mechanism is directly related to a variety of soil properties, the locations of single voids, and the horizontal distance between two voids. The presence of voids has a more dominant effect on c–φ soils compared to that on undrained soil. An interpretation of the critical and adverse locations for single-void and dual-void cases with various soil strengths is presented.