Perspective of urban land use in Beijing

This paper illustrates the features of urban land use in Beijing and approaches the factors particularly influencing the urban internal structure model. The brief review of the development process proves that the historical background and human decisions determined the basic framework of the structure. The spatial structure of land use shows that Beijing still keeps the characteristics of an industrialized city due to the importance of industry. Another particular feature was the absence of a central business district in Beijing, although in socialist system urban spatial structure also displays zonal, sectoral and star forms. The particular form in Beijing is the separated integrated district as the basic subdistrict. Finally the urban problems are discussed and suggestions made.     

Numerical investigation on propulsion of the counter-wind current in the northern South China Sea in winter

The propulsion of the winter counter-wind current in the northern South China Sea (SCS) is investigated with a regional, three-dimensional, primitive equation model. This current is usually called the SCS Warm Current (SCSWC). Model results well reproduced the banded structure of the Guangdong coastal current, the SCSWC and the slope current from the coast to the slope in the northern SCS in the climatological data. The across-shelf flow is active in the shelf break area. Both onshore and offshore flows exist; the net across-shelf transport is shoreward throughout the year, and is larger in winter than in other seasons. The joint effect of baroclinicity and relief (JEBAR) is the dominant forcing of the across-shelf transport in the shelf break area. The major mass source of the SCSWC is the onshore-veered slope current. It is the JEBAR effect that supplies the necessary negative vorticity to maintain the slope current flowing across the isobaths and veering to the right hand to feed the SCSWC. Analyses of the momentum fields indicate that the onshore pressure gradient in the outer shelf balances the Coriolis force induced by the northeastward SCSWC in the frame of geostrophy. In winter, such an onshore pressure gradient is mainly provided by the strong density contrast between waters of the shelf and of the upper slope, which results from the Kuroshio intrusion via the Luzon Strait. The notable intrusion of the Kuroshio in winter is crucial for maintaining the density structure in the shelf break area and facilitates the set-up of the onshore pressure gradient over the outer shelf.     

基于坡耕地与聚落空间耦合的三峡库区腹地奉节县人地关系研究

以三峡库区腹地奉节县的27个乡镇为例,应用网格分析技术,以1km×1km网格为单元,揭示了聚落与坡耕地资源之间的配置关系以及不同岩性区聚落-坡耕地耦合模式差异,并对研究区人地关系做了类型划分。结果表明：①奉节县27个乡镇聚落和坡耕地的空间分布表现出较强的空间趋同性,二者用地比、斑块等级大小高值都主要位于北部梅溪河河谷和中部长江河谷地区,低值主要分布于南部石灰岩地区;②坡耕地偏多型主要分布于砂岩区,坡耕地偏少型主要分布于石灰岩区,而坡耕地-聚落均衡型则表现出随机分布格局;③研究区坡耕地大量存在的原因主要归结于坡耕地基数大和坡耕地退耕难度大。受坡耕地分布的影响,坡耕地偏多型的土壤侵蚀较其他耦合类型严重;④27个乡镇人地关系划分为人地矛盾突出型、人地矛盾较突出型、人地矛盾较缓和型和人地矛盾缓和型四种类型,而人地矛盾较突出类型所占比重最大,面临着退耕压力和耕地压力突出的双重问题。     

Observational Studies of the X-Ray Quasi-Periodic Oscillations of a Solar Flare

We study an M2.6 flare observed with RHESSI on 22 August 2005. The light curves of the hard X-rays (counts and photon fluxes), the derived number fluxes, as well as the energy fluxes of energetic electrons all presented a damped quasi-periodic oscillation. The modulation depth of the hard X-rays increased with the energies. For the energy fluxes of energetic electrons, the modulation depth can be as high as 90%. During the oscillations, however, the plasma temperature had no apparent change. No correspondence was found between the motions of the flare loops and the quasi-periodic oscillations. We conclude that an oscillation with a high modulation depth for a period of about four minutes cannot be easily explained with the existing mechanisms.     

青藏高原东北缘4个强震重点监视区库仑破裂应力的近百年变化和危险性分析

针对青藏高原东北缘地区前人基于多学科研究资料圈定的4个未来强震重点监视区,构建了顾及到中下地壳黏弹性弛豫效应的区域岩石圈模型;考虑1920-2010年期间发生在本区域及其周边的18次Ｍ_s≥７级强震在这一区域的黏弹性静态库仑破裂应力变化,和长期构造背景加载下的应力积累情况,定量分析了每个重点监视区近百年来的库仑破裂应力变化,并在此基础上初步分析了各重点监视区的未来发震危险性程度。结果表明：西秦岭断裂带监视区和六盘山断裂带监视区均处于长期构造背景场和历史地震影响共同加载应力的状况;而海原断裂带监视区和东昆仑断裂带监视区,如果不考虑长期构造背景的应力加载,则处于地震影响的卸载状况。考虑到这4个重点监视区的大震平均复发周期及上次大震事件的离逝时间,认为西秦岭断裂带监视区的未来强震危险性程度最高,海原断裂带次之,然后是东昆仑断裂带和六盘山断裂带。     

����ʱƵ����������GNSS/INS��ϵ��������˲�ģ��

??????????????????Kalman??????????????????????????Kalman?????????????????????????????????????????????????????????????GNSS/INS?????????????????????????????????????????????????????????????????????????????????????????Kalman??????????????     

Investigation of dynamic processes in the period of formation and development of the blocking anticyclone over European Russia in summer 2010

The blocking anticyclone (BA) observed in the summer of 2010 over the European part of Russia led to enormous economical damage, substantially increased the mortality of the population, and had serious negative consequences for human health. Dynamic processes in the troposphere, i.e., wave trains, which could contribute to anticyclone formation and sustenance, are investigated. In order to study these wave trains, three-dimensional Plumb vectors have been calculated and analyzed. It is shown that, in June 2010, three wave trains propagated eastward in the troposphere over the Atlantics. The first two wave trains, having reached Europe, continued to propagate in eastern and southeastern directions. Only the third wave train, upon reaching Europe, continued to propagate toward the northeast and, on June 17–19, entered northwestern Russia. The anticyclone, which started to form on June 18 precisely in this region, subsequently developed into a stable BA observed over European Russia up to mid-August. The propagation direction of the wave trains could change due to the formation of a double structure of the zonal flow in the troposphere. The wave trains are revealed in the middle of June in regions with increased cloudiness over the northwestern part of the Atlantic Ocean and over the northwestern and northern parts of the central United States. Eastwardpropagating wave trains, which could contribute to the intensification of the corresponding BAs that brought anomalously high temperatures to European Russia, were also revealed in July and August of 2010 and 1972. The calculated 10-day backward trajectories are analyzed to determine the character of motions of air particles that penetrated into the anticyclone over the region of Moscow during the 2010 summer in the period of its development.     

The spatial and temporal distribution of heavy metals in sediments of Victoria Harbour, Hong Kong

Victoria Harbour has received substantial loadings of pollutants from industrial and municipal wastewater discharged since the 1950s. Inputs of contaminants have declined dramatically during the last two decades as a result of better controls at the source and improved wastewater treatment facilities. To assess the spatial and temporal changes of metal contaminants in sediments in Victoria Harbour, core and grab sediments were collected. The central harbour areas were generally contaminated with heavy metals. The spatial distribution of trace metals can probably be attributed to the proximity of major urban and industrial discharge points, and to the effect of tidal flushing in the harbour. In the sediment cores, the highest concentrations of trace metals were observed to have accumulated during the 1950s-1980s, corresponding with the period of rapid urban and industrial development in Hong Kong. From the late 1980s, there has been a major decline in the concentrations of trace metals, due to a reduction in industrial activities and to the enactment of wastewater pollution controls in the territory. The Pb isotopic compositions of the sediments revealed the anthropogenic inputs of Pb to the harbour. The (206)Pb/(207)Pb ratios varied from 1.154 to 1.190, which were lower than those of background geological materials in Hong Kong ((206)Pb/(207)Pb: 1.201-1.279). The data also indicated that the Pb in the harbour sediments most likely originated from mixed sources, including the leaded gasoline used in the past and other anthropogenic sources.     

水体溶解态黑碳的分子标志物苯多羧酸的气相色谱-质谱分析

苯多羧酸分子标志物法是定量水体中溶解态黑碳的常用方法,然而由于部分苯多羧酸,尤其是硝基苯多羧酸商业化标准品的缺失,采用该方法定量溶解态黑碳仍需进一步完善和优化。本文通过已有的苯多羧酸商业化标准品,建立了气相色谱-质谱联用仪(GC-MS)分离和定量 9 种缺少商业化标准品苯多羧酸的分析方法。并首次将菲-D10 作为溶解态黑碳的替代物,指示苯多羧酸法定量溶解态黑碳过程中的损失率。结果表明,该方法具有良好的重现性(RSD=10.34%),方法检出限为 0.67~5.38 ng/L。本文采用该方法分析了大亚湾表层水体溶解态黑碳的分布特征,其浓度范围为 30.38~46.19 μg/L,平均值为(38.93±6.17)μg/L,空间分布表现为从湾内到外海递减的趋势。     

Precipitation variability and its relationship to hydrologic variability in Alberta

By applying wavelet‐based empirical orthogonal function (WEOF) analysis to gridded precipitation (P) and empirical orthogonal function (EOF) analysis to gridded air temperature (T), potential evapotranspiration (PET), net precipitation (P‐PET) and runoff (Q), this paper examines the spatial, temporal and frequency patterns of Alberta's climate variability. It was found that only WEOF‐based precipitation patterns, possibly modulated by El Nino Southern Oscillation (ENSO) and Pacific Decadal Oscillation(PDO), delineated Alberta into four major regions which geographically represent northern Alberta Boreal forests, southern Alberta grasslands and Aspen Parklands and the Rocky Mountains and Foothills. The leading mode of wavelet‐based precipitation variability WPC1 showed that between 1900 and 2000, a wet climate dominated northern Alberta with significant 4–8, 11 and 25‐year periodic cycles, while the second mode WPC2 showed that between 1960 and 2000, southern Alberta grasslands were characterized by decreasing precipitation, dominated by 11‐year cycles, and the last two modes WPC3 and WPC4 were characterized by 4–7 and 25‐year cycles and both delineated regions where moisture from the Pacific Ocean penetrated the Rocky Mountains, accounted for much of the sub‐alpine climate. These results show that WEOF is superior to EOF in delineating Alberta precipitation variability to sub‐regions that more closely agree with its eco‐climate regions. Further, it was found that while WPC2 could not explain runoff variations in southern Alberta, WPC1, WPC3 and WPC4 accounted for runoff variability in their respective sub‐regions. Copyright © 2009 John Wiley & Sons, Ltd.