The role of dynamic transport in the formation of the inverted charge structure in a simulated hailstorm

The inverted charge structure formation of a hailstorm was investigated using the Advanced Weather Research and Forecasting(WRF-ARW) model coupled with electrification and discharge schemes. Different processes may be responsible for inverted charge structure in different storms and regions. A dynamical-derived mechanism of inverted charge structure formation was confirmed by the numerical model: the inverted structure was formed by strong updraft and downdraft under normal-polarity charging conditions such that the graupel charged negatively in the main charging region in the middle-upper level of the cloud. The simulation results showed the storm presented a normal charge structure before and after hail-fall; while during the hail-fall stage, it showed an inverted charge structure—negative charge region in the upper level of the cloud and a positive charge region in the middle level of the cloud—appearing at the front edge near the strong updraft in the hailstorm. The charging processes between the two particles mainly occurred at the top of the cloud, where the graupel charged negatively and ice crystals positively due to the strong updraft. When the updraft air reached the top of the storm, it would spread to the rear and front. The light ice crystals were transported backward and forward more easily. Meanwhile, the positively charged ice crystals were transported downward by the frontal subsidence, and then a positive charge region formed between the ?10 and ?25°C levels. Subsequently, a negative charge region materialized in the upper level of the cloud, and the inverted charge structure formed.     

南极洲低层两种位势高度再分析资料的比较

比较NCEP/NCAR和ECMWF两种再分析资料南半球低层等压面(700 hPa及以下)的平均位势高度场,结果表明:两者在南极洲差异显著,除12月、1月(南半球夏季)外,NCEP/NCAR资料存在一个虚假的很强的极地高压,而ECMWF资料正常。分析表明该两种再分析资料的上述差异来源于南极洲地面以下虚拟气压场的产生过程;NCEP/NCAR资料较ECMWF少了一个对南极洲过低地面温度的修正。由此得到的NCEP/NCAR资料若用于南半球低层大气环流整体结构的分析,会导致严重的错误。     

“水-能源-粮食”视角下粤港澳大湾区生态安全格局的构建及优化

从“水－能源－粮食”3个维度对粤港澳大湾区的生态系统服务进行评价,利用珞珈一号夜光数据修正生态阻力面,运用最小累积阻力模型构建并优化湾区的生态安全格局。结果表明：1）粤港澳大湾区生态源地总面积为9 626.1 km²,主要分布在研究区东部和西部的山地、丘陵地区,对应位于江门市、惠州市中部和肇庆市;2）生态廊道共计38条,总长度为2 023.09 km,其中最短为11.76 km,最长为304.99 km,集中于植被覆盖较好的山地丘陵地区,中部无廊道分布;3）生态源地辐射区面积为28 929.5 km²,达到湾区总面积的51.88%,若要实现60%的覆盖率,则需要至少新增生态源地辐射面积4 524.856 km²;4）为了更好地优化粤港澳大湾区生态安全格局,提出在惠州市北部和南部新增两处生态源地辐射区,并构建以“一带、一轴、四组团”为核心的生态安全格局优化模式。     

直井段偏移对后期定向钻井作业的影响分析

在定向井、水平井钻井过程中,直井段井身质量的控制对后期定向造斜与轨迹控制的影响往往被忽视,国内对定向井、水平井直井段井身质量要求基本是以常规直井的标准为依据,没有重视到直井段位移、井斜和方位对定向施工的影响。对于定向井、水平井来说,直井段偏移不仅对后期轨迹控制、定向施工和完井作业带来危害,同时给油田后续开发中井位的部署带来不利影响,对于平台丛式井直井段偏移可能造成井眼相碰,因此,定向井、水平井直井段控制的好与坏,将会给定向井、水平井的钻（完）井带来很大影响。本文统计分析近年完成的定向井、水平井直井段偏移情况和影响,简述直井段偏移的形成原因,对直井段不同类型偏移造成的影响进行了分析并提出了应对方案。     

Oil source analysis of Upper Tertiary Shawan Formation in Chepaizi area,in the northwest margin of Junggar basin

Well che89, located in the Chepaizi area in the northwest margin of Junggar basin, acquires high production industrial oil flow, which is an important breakthrough in the exploration of the south foreland slope area of Junggar basin. The Chepaizi area is near two hydrocarbon generation depressions of Sikeshu and Shawan, which have sets of hydrocarbon source rock of Carboniferous to Jurassic as well as Upper Tertiary. Geological and geochemical parameters are proper for the accumulation of mixed source crude oil. Carbon isotope, group composition and biomarkers of crude oil in Upper Tertiary of well Che89 show that the features of crude oil in Upper Tertiary Shawan Formation are between that of Permian and Jurassic, some of them are similar to these two, and some are of difference, they should be the mixed source of Permian and Jurassic. Geochemical analysis and geological study show that sand extract of Lower Tertiary Wulunguhe Formation has the same source as the crude oil and sand extract of Upper Tertiary Shawan Formation, but they are not charged in the same period. Oil/gas of Wulunguhe Formation is charged before Upper Tertiary sedimentation, and suffered serious biodegradation and oxidation and rinsing, which provide a proof in another aspect that the crude oil of Upper Tertiary Shawan Formation of well Che89 is not from hydrocarbon source rock of Lower Tertiary.

     

北京和广州地区云闪初始击穿电场变化特征

对比分析了北京和广州地区各100例云闪初始阶段前30 ms快电场变化波形上初始击穿脉冲的特征。依据脉冲的结构特征,两地区的云闪初始击穿脉冲可分为单极性单峰型、单极性多峰型、双极性单峰型和双极性多峰型脉冲,两地区均以单极性和单峰型脉冲为主。对脉冲参量特征的统计发现,脉冲的10%-90%上升时间、半峰值宽度地区差异性小于脉冲类型差异性;双极性单峰型脉冲的半峰值宽是单极性单峰型的1.2倍。不同类型脉冲过零时间的中值、平均值在10μs左右量级,且广州地区较北京地区的大;云闪初始击穿脉冲宽度平均值显著小于相同地区正地闪的,而脉冲间隔显著大于正地闪的。初始击穿脉冲最为集中的出现在云闪最初的1~2 ms,其比例随时间以显著的负指数分布下降。研究发现,双极性脉冲的过零时间与脉冲宽度之间、起始半周期峰值幅度与过冲幅度之间均存在较好的线性关系。     

Effect of compressive strength on the performance of the NEMO-LIM model in Arctic Sea ice simulation

Satellite records show that the extent and thickness of sea ice in the Arctic Ocean have significantly decreased since the early 1970s. The prediction of sea ice is highly important, but accurate simulation of sea ice variations remains highly challenging. For improving model performance, sensitivity experiments were conducted using the coupled ocean and sea ice model (NEMO-LIM), and the simulation results were compared against satellite observations. Moreover, the contribution ratios of dynamic and thermodynamic processes to sea ice variations were analyzed. The results show that the performance of the model in reconstructing the spatial distribution of Arctic sea ice is highly sensitive to ice strength decay constant (C^rhg). By reducing the C^rhg constant, the sea ice compressive strength increases, leading to improved simulated sea ice states. The contribution of thermodynamic processes to sea ice melting was reduced due to less deformation and fracture of sea ice with increased compressive strength. Meanwhile, dynamic processes constrained more sea ice to the central Arctic Ocean and contributed to the increases in ice concentration, reducing the simulation bias in the central Arctic Ocean in summer. The root mean square error (RMSE) between modeled and the CryoSat-2/SMOS satellite observed ice thickness was reduced in the compressive strength-enhanced model solution. The ice thickness, especially of multiyear thick ice, was also reduced and matched with the satellite observation better in the freezing season. These provide an essential foundation on exploring the response of the marine ecosystem and biogeochemical cycling to sea ice changes.

     

Cretaceous deformation history of the middle Tan-Lu fault zone in Shandong Province, eastern China

Based on field analysis of fault-slip data from different rock units of the Cretaceous basins along the middle part of the Tan-Lu fault zone (Shandong Province, eastern China), we document polyphase tectonic stress fields and address the changes in sense of motion of the Tan-Lu fault zone during the Cretaceous. The Cretaceous deformation history of the Tan-Lu fault zone can be divided into four main stages. The first stage, during the earliest Cretaceous, was dominated by N-S extension responsible for the formation of the Jiaolai basin. We interpret this extension to be related to dextral strike-slip pull-apart opening guided by the Tan-Lu fault zone. The second stage, during the middle Early Cretaceous, was overwhelmingly rift-dominated and characterized by widespread silicic to intermediate volcanism, normal faulting and basin subsidence. It was at this stage that the Tan-Lu-parallel Yi-Shu Rift was initiated by E-W to WNW-ESE extension. The tectonic regime then changed during the late Early Cretaceous to NW-SE-oriented transpression, causing inversion of the Early Cretaceous rift basin and sinistral slip along the Tan-Lu fault zone. During the Late Cretaceous, dextral activation of the Tan-Lu fault zone resulted in pull-apart opening of the Zhucheng basin, which was subsequently deformed by NE-SW compression. This deformation chronology of the Tan-Lu fault zone and the associated Cretaceous basins allow us to constrain the regional kinematic models as related to subduction along the eastern margin of Asia, or related to collision in the Tibet region.     

基于GIS与ANN耦合技术的地裂缝灾情非线性模拟预测系统——以山西榆次地裂缝灾害为例

现代地裂缝在世界许多国家普遍存在 ,已成为当今世界范围内的主要地质灾害之一。本文在详尽分析了山西榆次地裂缝的各个致灾因子的基础上 ,利用GIS技术建立了地质学意义上的专题层 ;然后采用人工神经网络技术构建出了地裂缝灾害活动性的评价模型 ,并建立了地裂缝活动性的评价系统 ,对榆次地裂缝进行了灾害活动性评价 ,为榆次市城建和国土规划等部门的正确决策提供了重要的科学依据     

区域地震信息网站简易备份策略和实现

本文在综合分析地震行业区域中心门户网站基础架构的基础上,根据地震信息发布的安全需求,对网站数据备份与恢复的技术和策略进行了分忻,提出了一种简单易行的网站数据备份与恢复的流程和机制,并在实际应用中得到运用。该方法简单实用和易行,为网站技术系统的运行维护提供了一种借鉴模式。