Cold Air Activities in July 2004 and Its Impact on Intense Rainfalls over Southwest China

The severe rainfall events in the mid-summer of July 2004 and the roles of cold air in the forma- tion of heavy precipitation are investigated by using daily observational precipitation data of China and NCEP/NCAR reanalysis.The results show that the severe rainfalls in Southwest China are closely related to the cold air activities from the mid-high latitudes,and the events take place under the cooperative effects of mid-high latitude circulation and low latitude synoptic regimes.It is the merging of a cold vortex over mid-latitudes with the northward landing typhoon and eastward Southwest China Vortex,as well as the abrupt transformation from a transversal trough into an upright one that causes three large alterations of mid-high atmospheric circulation respectively in the early and middle ten days of this month.Then,the amplitude of long waves soon magnifies,leading to the unusual intrusion of cold air to low-latitude areas in the mid-summer.Meanwhile,the warm and humid southwest summer monsoon is quite active.The strong interactions of cold air and summer monsoon over Southwest China result in the large-scale convective rain- falls on the southern side of cold air. With regard to the activities of cold air,it can influence rainfalls in three prominent ways.Firstly,the incursion of upper-level cold air is often accompanied by partial southerly upper-level jet.The ascending branch of the corresponding secondary circulation,which is on the left front side of the jet center,provides the favorite dynamic upward motion for the rainfalls.Secondly,the southward movement of cold air contributes to the establishment of atmospheric baroclinic structure,which would lead to baroclinic disturbances.The atmospheric disturbances associated with the intrusion of cold air can destroy the potential instability strat- ification,release the convective available potential energy(CAPE)and finally cause convective activities.In addition,the advection processes of dry and cold air at the upper level along with the advection of humid and warm air at the lower level are rather significant for the reestablishment of potential instability in the precipitation area,which is one of the crucial factors contributing to persistent rainfalls.     

Main Controlling Factors on Hydrocarbon Accumulation and Distribution in Marine Sedimentary Sequences in South China

Multiple source rock assemblages were deposited in the sedimentary provinces in South China in geologic history,and some of them were destructed by and some survived against multiple tectonic movements.Therefore,multiple sources,mixed sources,and uneven distribution of sources occurred in the marine sedimentary basins in South China during the late stage of hydrocarbon pooling.Epidiagenesis of the marine carbonate reservoirs and its modification to reservoir poroperm characteristics determined the formation and the scale of natural gas pools.The exploration practices show that the large to medium gas fields mainly occur in areas with high-quality reservoirs.Detailed study of the paleo-oil accumulations and typical oil and gas reservoirs reveals that the basins experienced multiphase superimposition and modification,leading to the distribution of the Paleozoic paleo-oil accumulations and bitumen in the peripheral areas.The phenomenon that oil and gas production concentrates in the Sichuan basin indicates that the overall sealing conditions of a basin determine the oil/gas potentials and the scale of oil and gas production.This is a critical factor controlling the accumulation and distribution of gas in the marine sequences in South China.The early oil and gas pools in the Yangtze platform left billions of bitumen in the peripheral areas due to the destruction of seals.Since the Himalayan,"late-generation and late-accumulation" gas pools represented by the gas pools in the Sichuan (四川) basin were formed in the marine sedimentary sequences in South China as a result of the change of the sealing conditions.Current gas discoveries appear to be "paleo-generation and paleo-accumulation" gas pools but actually are "late-generation and late-accumulation" gas pools.These patterns of hydrocarbon pooling clearly depict themselves in western Sichuan basin and Weiyuan (威远)gas field.It is revealed that the gas pools in the Sichuan basin were mainly formed as a result of hydrocarbon phase change (thermal cracking of oil to gas),miscible migration,and dynamic equilibration since the Himalayan.A large number of gas pools were formed in the Himalayan and the gas pools in the marine sequences are characterized by late pooling; this kind of gas fields/pools are controlled by:(1) effectiveness of modification and superimposition of the marine basins,(2) effectiveness of the source rocks,(3) effectiveness of the overall preservation conditions,and (4) effectiveness of plays.     

天津市地热资源开发利用特征及存在问题分析

天津地区的地热地质条件良好,蕴藏着丰富的地热资源。在地热资源的开发利用过程中,每年可产生可观的经济、社会和环境效益,但由于开发方式的不尽合理,带来诸多问题。文章阐述了天津开发利用地热资源的特征,分析了存在的问题。认为不同热储层间水力联系的存在和地热井间距的过小,造成开采层间相互影响较大;地热井布局不合理、开采层位相对集中、回灌程度不高导致局部热储层压力大幅度下降,持续的大幅度压力下降将引发吊泵和地面沉降;超标准排放地热尾水会造成资源浪费和热污染;采、灌井间距的过小和相对位置的不合理,存在冷突破风险。针对不同问题,给出了针对性解决问题的建议。     

Relationship between cloud characteristics and radar reflectivity based on aircraft and cloud radar co-observations

Cloud properties were investigated based on aircraft and cloud radar co-observation conducted at Yitong, Jilin, Northeast China. The aircraft provided in situ measurements of cloud droplet size distribution, while the millimeter-wavelength cloud radar vertically scanned the same cloud that the aircraft penetrated. The reflectivity factor calculated from aircraft measurements was compared in detail with simultaneous radar observations. The results showed that the two reflectivities were comparable in warm clouds, but in ice cloud there were more differences, which were probably associated with the occurrence of liquid water. The acceptable agreement between reflectivities obtained in water cloud confirmed that it is feasible to derive cloud properties by using aircraft data, and hence for cloud radar to remotely sense cloud properties. Based on the dataset collected in warm clouds, the threshold of reflectivity to diagnose drizzle and cloud particles was studied by analyses of the probability distribution function of reflectivity from cloud particles and drizzle drops. The relationship between reflectivity factor (Z) and cloud liquid water content (LWC) was also derived from data on both cloud particles and drizzle. In comparison with cloud droplets, the relationship for drizzle was blurred by many scatter points and thus was less evident. However, these scatters could be partly removed by filtering out the drop size distribution with a large ratio of reflectivity and large extinction coefficient but small effective radius. Empirical relationships of Z-LWC for both cloud particles and drizzle could then be derived.     

基于车载激光点云的高精地图矢量化成图

针对车载激光点云中对各特征物提取结果后矢量化成图时的自动化问题,本文基于双方向积分法实现了边缘检测及矢量化成图,旨在保证特征物基本特征的同时,也保证点云的绝对精度。将输入的特征点云进行离群点过滤,以保证外包框算法特征点云的准确度;将三维点云按照外包框算法投影至最优平面,为后续沿各方向积分提供输入;利用八邻域KD-tree算法求出样本特征点云的均值邻域半径,依据邻域半径对各方向积分提供积分域中的微分元;根据提供的微分元沿各方向进行积分,在该积分元内找到距平面最值的最优解;按照积分结果构建点云索引,并根据点云特征构建模型,最终得到高精地图的矢量化点云。试验证明了该方法在处理实际问题时的可行性。     

宁夏农业综合开发战略转型区划研究

农业综合开发战略转型区划研究,是科学适应新形势下国家对农业综合开发提出的“坚持可持续、提升竞争力”要求的前提和基础。针对已有农业区划的单一目标和单一类型划分问题,以宁夏为例,基于农业相关的耕地、气候、水、地形、地貌、项目布局、生态规划等空间数据,采用地理学综合区划的方法,提出了动态与静态结合、定性与定量结合、农业与生态结合的13项多维指标体系,提出了合理且可操作的技术流程,科学划分了包含过渡类型的一级区划（7大类型：重点开发区、“重点+限制”开发区、保护性开发区、“保护+限制”开发区、“限制+重点”开发区、“限制+保护”开发区和限制性开发区）和二级区划（24个亚类）,实现了农业可持续和生态环境保护的双重目标。本文是国家财政部明确提出农业综合开发要科学划分重点开发区、保护性开发区和限制性开发区之后,首次实现在省（区）级以乡（镇）为单位的科学划分,可为今后农业综合开发战略转型项目的科学布局和精准投入提供重要依据,为宁夏农业综合开发战略转型工作的具体落地实施提供科学保障,同时也可为其他省份或地区的农业综合开发战略转型区划工作提供有益参考。     

富火山物质烃源岩评价方法——以北疆石炭系为例

正新疆北部石炭系发育一套巨厚的混杂有火山物质的烃源岩。有机质丰度以及类型等指标显示具有作为烃源岩的潜力。笔者综合运用薄片等分析资料将其划分为凝灰岩、沉凝灰岩、凝灰质泥岩、含碳质泥岩,并分类研究了其地球化学特征。针对富火山物质烃源岩成熟度高、有机质丰度低的特点,首次运用生烃模拟实验结合数值模拟开展其有机碳含量恢复,建立了不同火山物质含量烃源岩有机     

加载速率对岩石单轴压缩试验影响的数值模拟研究

在单轴压缩数值模拟试验中,加载速率由每次边界条件变化幅度和边界条件变化后的平衡计算时间这两个因素共同控 制。同样的加载速率,两个因素的不同组合也会对加载效果有很大的影响。因此,探究以上两因素对岩石单轴压缩数值模拟 试验的影响机制,可对高效进行高精度的各加载速率下的数值模拟试验起到积极作用。本文使用MatDEM软件,基于软件自 动设定的加载区间以及标准平衡迭代,设置不同的应力施加步数Nd与平衡迭代比率Rb,进行不同加载速率下的数值模拟试 验。模拟结果表明：（1）单步加载后平衡迭代次数越多（Rb越大）,该步中应力波传播与动能衰减越充分。在最优阻尼条件下, 当单步加载后平衡迭代次数等于40次（Rb等于0.8）时,每步加载中动能充分平衡,可以最低计算量取得准静态模拟结果; （2）单步加载应力增量越小（Nd越大）,数值模拟试验精度越高;（3）当加载速率一定即计算量相同时,为保证更高的模拟试验 精度,应采用低单步应力增量与低单步加载后平衡迭代次数（Nd大、Rb小）的加载方案。本文为定量研究岩石加载速率问题和 相关数值模拟提供了参考。     

城市功能分区的空间聚类方法研究及其应用——以济南市为例

作为空间数据挖掘的一种重要手段,空间聚类目前已在许多领域得到了应用.它是城市功能分区中的关键性步骤.根据空间-属性一体化的概念模型,把影响城市功能分区的空间坐标、空间关系和属性特征纳入到统一的空间计算模型,分别运用K-平均算法、神经网络方法,对城市功能分区进行空间聚类计算,充分挖掘空间坐标和空间关系数据中隐含的空间聚集信息.实例分析表明,基于神经网络的空间聚类结果可以为城市功能分区提供准确、可靠的依据.     

江苏冬夏季人体舒适度指数异常的背景场研究

利用江苏地区37个气象观测站1980—2009年逐日资料,及同时段美国NCEP/NCAR再分析资料以及北太平洋海温资料,通过合成和遥相关法,研究了当江苏冬、夏季人体舒适度指数（CIHB）出现异常偏高和偏低时,大气环流与北太平洋海温场的基本特征。结果表明：（1）CIHB偏高年较偏低年,冬季,东亚大槽偏浅,冬季风明显偏弱,尤其是北风分量偏弱最为明显,江苏上空下沉气流偏弱,均不利于冷空气东移南压以及向下入侵;夏季,副热带高压偏西、偏强,南亚高压偏东、偏北、偏强,夏季风明显偏强,尤其是南风分量偏强显著,导致往北的暖湿气流强盛,垂直运动总体偏弱,不利于夏季对流活动的发生。（2）冬季,CIHB偏高年中西太平洋的海温高于偏低年,尤其是在我国东部近海的黑潮区,偏暖幅度最为明显,无论是超前相关还是同期相关,西太平洋海温与冬季CIHB都是以正相关为主,其中暖池区的正相关最为显著。