基于局地增长模培育法的对流可分辨尺度WRF模式对河南“21·7”特大暴雨的预报评估          下载免费PDF全文

刘侃  陈超辉  何宏让  姜勇强  陈祥国  王伟亮 《大气科学学报》2023,46(5):725-737

基于WRF(Weather Research and Forecasting)模式,选取河南“21·7”特大暴雨事件,采用局地增长模培育法(Local Breeding Growth Mode,LBGM)生成对流尺度集合预报系统,在此基础上对24 h累积降水量进行SAL(Structure,Amplitude and Location)检验,结合预报成功指数(Threat Score,TS)、公平成功指数(Equitable Threat Score,ETS)评分等评分结果进行对比分析,综合评估集合预报成员的预报效果,表明:1)基于局地增长模培育法生成初始扰动的集合预报系统成员对于强降水预报有一定优势,在降水强度和位置的预报上与实况较接近;2)经检验,成员e003的TS和ETS评分在20日00时—21日00时(北京时,下同)和21日08时—22日08时两个强降水时段内表现最佳,并在SAL检验中对应较好的降雨强度A和雨区位置L,而成员e008暴雨TS、ETS评分最低,对应SAL检验中具有一定的位置偏差,即TS、ETS评分和SAL检验之间存在相关性,将二者有机结合,可以为业务工作中定量评估模式降水预报效果提供参考;3)通过对比整体评分表现较好的成员e003和较差的成员e008,两者预报的位势高度场与ERA5(ECMWF reanalysis v5,ERA5)再分析资料之间的差值,可以验证降水预报误差主要源于对低涡系统的预报偏差,同时预报评分较好的成员其位势高度偏差较小,综合评估效果更佳。  相似文献   

中条山-吕梁山前寒武纪变质杂岩的独居石电子探针定年研究   总被引：14，自引：0，他引：14  

刘树文  张臣  刘超辉  李秋根  吕勇军  余盛强  田伟  凤永刚 《地学前缘》2007,14(1):64-74

中条山和吕梁山前寒武纪变质杂岩是华北克拉通中部带南段的重要组成部分,它们的变质作用及其相关的花岗质岩浆作用是我们全面认识华北克拉通中部带的性质与演化的关键,具有重要的科学意义。中条山前寒武纪变质杂岩两个样品的独居石电子探针Th-U-Pb化学法定年表明,永济和横岭关岩体变质二长花岗质岩石记录了两个主要峰年龄范围,分别为1884.7~1849.9Ma和1743.5~1738.8Ma;前者为变质年龄,后者为流体活化的年龄。吕梁山五个样品的独居石电子探针Th-U-Pb化学法定年表明,石榴石二云母片岩和花岗质片麻岩的记录了>1902Ma、1883.3~1865.6Ma和1731.3Ma。>1902Ma年龄代表早期岩浆和深熔事件,1883.3~1865.6Ma代表峰期变质事件,1731.3Ma代表晚期流体活动事件。石榴石花岗岩记录了1882.8~1850.9Ma深熔岩浆事件。未变质花岗岩脉记录的1742.6Ma和石榴石二云母片岩记录的1731.1Ma为晚期岩浆-流体活动事件。综合上述独居石电子探针定年的结果,不难看出中条山—吕梁山前寒武纪变质杂岩主期变质作用发生在1885~1849Ma,并伴生有同期的S-型花岗质岩浆活动,与恒山—五台山—阜平杂岩的变质变形作用同时发生,进一步证明华北克拉通中部带的拼合作用发生在古元古代晚期。  相似文献   

中国山地开发、保护与山区社会经济发展的出路   总被引：4，自引：1，他引：3  

陈朝辉  方国祥 《热带地理》1999,19(1):50-54

我国山区地域广阔,自然资源丰富,并且,山区特殊的自然环境成为平原区的生态屏障。但是,山区生态系统脆弱,植被一经破坏便不易恢复,土地生产潜力也较低,社会经济发展的基础差。为保证山区自然资源的可持续利用和社会经济的可持续发展,山区应在切实保护环境和资源的条件下,进行合理、适度的开发。广大山区脱贫和实现小康应寄望于全国现代化和城市化的实现。为此,应积极采取措施,促进这一目标的早日实现  相似文献   

基于数值预报产品的面雨量分析与检验     

张玉琴  吴朝野  何国平  毛家勋  姜波  尹雪梅  何朝辉 《四川气象》2011,(3):60-64

通过分析检验2007～2009年5～10月T213、德国、日本数值模式在雅砻江流域1～4区的面平均雨量——即面雨量预报发现,3个模式面雨量有无TS评分的差异较小,随着面雨量量级的加大各模式的差异变大。多模式集成预报总体上优于单模式,小雨级、中雨级优势更明显。二滩电站入库流量与面雨量集成预报值的相关系数在全流域明显低于与实测值的相关系数,但预报值与实测值的波动趋势几乎是一致的,仍对预报有较好的参考价值。  相似文献   

南亚和东亚热带夏季风分界域变化   总被引：1，自引：1，他引：0       下载免费PDF全文

郭品文  宋超辉 《应用气象学报》2014,25(5):527-537

利用1948—2012年NCEP/NCAR逐日再分析风场资料,对亚洲两个热带夏季风子系统 (南亚夏季风和东亚热带夏季风) 边界进行划分。根据所得出的边界提出了亚洲两大热带夏季风子系统分界域的观点,定义偏向指数来确定两大热带夏季风子系统边界的偏向;通过对比,确定出边界在纬向上的变动较大的区域,并以确定的变动较大的纬度区域来研究亚洲两大热带夏季风分界域的变化规律;最后通过边界指标刻画出季风强度的变化情况,分析其关键环流特征。选取涡度作为边界的确定指标,边界的变动可以分为东部型、中部型、西部型。根据边界的振幅情况选取10°~17.5°N作为主要研究区域,由边界指标定义的夏季风指数得出,亚洲两大热带夏季风子系统强度的一致性变化占主导地位,其次为反相变化。  相似文献   

汶川M_s8.0地震强震动基线改正及其在位错反演中的初步应用          下载免费PDF全文

邵志刚  周朝晖  徐晶  张永久 《地球科学》2014,39(12):1903-1914

通过研究近场强震动记录, 发现汶川M_s8.0地震近场峰值加速度在空间上存在较明显的上盘效应和方向性效应, 与汶川引起的地质灾害空间分布具有较好的一致性.但在所有强震仪所记录的汶川M_s8.0地震同震加速度记录积分所得地壳同震速度中, 有的台站数据存在典型的线性偏移, 有的台站数据除线性偏移外还存在明显的非线性偏移.采用非线性基线改正方法处理汶川M_s8.0强震同震记录, 改正后所得同震位移明显要比线性基线改正更合乎实际情况.以强震动、GPS和InSAR同震位移处理结果做约束, 反演了汶川M_s8.0地震同震位错分布, 对于汶川M_s8.0地震主要同震破裂断裂(北川-映秀断裂), 强震动反演结果不仅较好地刻画了汶川M_s8.0地震同震主断裂上地表破裂空间分布详细变化特征, 同时也较好地反映北端破裂衰减情况, 该结果表明: 强震动资料可以为强震后的救援和灾害评估等工作提供具有参考价值的研究结果; 另一方面, 受数据数量的制约, 用强震动改正后位移反演所得位错分布中仅汉旺断裂南段存在较为明显位错, 强震仪布设时应更多地考虑是否相对均匀地分布在具有发震潜势的断裂周缘, 以期更好地在震后应急救灾中发挥更好的作用.   相似文献   

Sulfur isotopic composition of the Bainiuchang super-large Ag polymetallic deposit, Yunnan Province, China： Implications for the source of sulfur in ore-forming fluids   总被引：1，自引：1，他引：0  

Hongjing Xie  Chaohui Zhu  Qian Zhang  Dapeng Wang  Liangwu Fan 《中国地球化学学报》2009,28(3):284-292

The Bainiuchang deposit in Yunnan Province, China, is located geographically between the Gejiu ore field and the Dulong ore field. In addition to >7000 t Ag reserves, the deposit possesses large-scale Pb, Zn, Sn reserves and a mass of dispersed elements (i.e., In, Cd, Ge, Ga, etc.). Based on systematic studies of sulfur isotopic composition, the authors conclude: The Bainiuchang deposit experienced two epochs of metallogenesis, i.e., the Middle-Cambrian sea-floor exhalative sedimentary metallogenic epoch and the Yanshanian magmatic hydrothermal superimposition metallogenic epoch. In the two metallogenic epochs, the δ³⁴S values of sulfides were all near 0, showing a tendency of being enriched slightly in heavy sulfur. The δ³⁴S values of sulfides in the early metallogenic epoch are within the range of 2‰–5‰ with a peak value range of 2‰–3‰ and an average of 3.0‰, and those of sulfides in the late metallogenic epoch are within the range of 2‰–6‰ with a peak value of 3‰–4‰ and an average of 3.9‰. For the single metallogenic epoch, sulfur in the ore-forming fluids in the early epoch already reached isotopic equilibrium and was derived mainly from underneath the magma chamber or basement metamorphic igneous rocks. Sulfur in the sulfides in the late epoch was derived mainly from magmatic hydrothermal fluids formed in the process of remelting of the basement metamorphic igneous rocks.  相似文献   

Lead Isotopic Composition and Lead Source of the Huogeqi Cu-Pb-Zn Deposit, Inner Mongolia, China   总被引：1，自引：0，他引：1  

ZHU Xiaoqing ZHANG Qian HE Yuliang ZHU Chaohui 《《地质学报》英文版》2006,80(4):528-539

The Huogeqi orefield located on the northern side of Mt. Langshan, Inner Mongolia occurs in the Middle Proterozoic Langshan Group metamorphic rocks, and the orebodies arc stratiform. In the past twenty years, many Chinese geologists have conducted researches on the Huogeqi Cu-Pb-Zn deposit, but there has been still a controversy on its origin. Some advocate that the deposit is of sedimentary-metamorphic rcworking origin, some hold that it is of sea-floor SEDEX origin, and others have a preference for magmatic superimposition origin. The crux of the controversy is that there is no common understanding about the source of ore-forming materials. In this paper, the Pb isotopic compositions of regional Achaean-Early Proterozoic basement rocks, various types of sedimentary- metamorphic rocks and volcanic rocks in the mining district, Late Proterozoic and Hercynian magmatic rocks arc introduced and compared with the orc-lead composition, so as to constrain the source of the ore lead. The result indicates that （1） sulfides in the ores have homogeneous Pb isotopic compositions, showing a narrow variation range. Their ^206pb/^204pb ratios arc within a range of 17.027- 17.317; ^207Pb/^204pb ratios, 15.451-15.786 and ^208Pb/^204pb ratios, 36.747-37.669; （2） the Pb isotopic compositions of the regional Achaean-Early Proterozoic basement rocks arc characteristic of the old Pb isotopic composition at the early-stage evolution of the Earth, which varies over a wider range, reflecting significant differences in Pb isotopic compositions of the ores. All this indicates that the source of ore lead has no bearing on the basement rocks; （3） the sedimentary-metamorphic rocks in the mining district arc characterized by highly variable and more radiogenic Pb isotopic compositions and their Pb isotopic ratios arc obviously higher than those of ores, demonstrating that ore lead did not result from metamorphic rcworking of these rocks; （4） Pb isotopic compositions of Late Proterozoic diorite-gabbro and Hercynian granite are higher than those of ores. Meanwhile, the Pb isotopic compositions of sulfides in the small-sized strata-penetrating mineralized veinlets formed at later stages arc completely consistent with that of sulfides in stratiform-banded ores, suggesting that these veiniets arc the product of autochthonous rcworking of the stratiform-banded ores during the period of metamorphism and the late magmatic superimposition-mineralization can be excluded; （5） amphibolite, whose protolith is basic volcanic rocks, has the same Pb isotopic compositions as ores, implying that ore lead was derived probably from basic volcanism. So, the source of ore-forming materials for the Huogeqi deposit is like that of the volcanic massive sulfide （VMS） deposits. However, the orebodies do not occur directly within the volcanic rocks, and instead they overlie the volcanic rocks, showing some differences from those typical VMS-type deposits.  相似文献   

A simulating experiment on the geochemical variation trend at the initial period of meteoric waters converting to underground waters and ore fluids     

ZHU Xiaoqing 《中国地球化学学报》2005,24(4):306-315

Experimental studies were undertaken on leaching of sedimentary rocks （ dolomite and sandstone） and Hg, Sb ores by distilled water under the condition of a completely open system （room temperature and room pressure）. The aim is to find whether the halogen elements or metal elements first enter the solution at the early stage of meteoric waters converting to groundwaters and ore fluids, and, at the same time, to understand how and when they enter distilled water solutions from the rocks. The experimental resuhs have shown that F and Cl began to enter the fluids in the initial period of thirty days. With increasing leaching duration, the amounts of the elements that entered the fluids increased steadily. During the period from 120 days to 150 days the amounts increased more drastically, followed a slow increase. It is found that the capability of Cl entering the solutions is much greater than that of F. Hg and Sb were found not to have entered the solutions till 120 days later. During this period of time the pH value of the solutions began to drop. As for Hg and Sb ores, Hg and Sb began to enter the solutions on the 60th or 90th day, greatly ahead of schedule, but the two metallic elements in the rock samples began to enter the solutions 150 days later. Relatively speaking, Hg is more easily leached out than Sb from the rocks. In some rock samples, Sb could be detected in the solutions at the end of the experiment. However, Cu, Pb and Zn had not been detected in the leaching solutions from the beginning to the end of the experiment. In the whole leaching process the pH value of the solutions tend to decrease slowly from 7.1 at the beginning to 6.5 at the end. That is to say, in the interaction between pure water and rock the halogen elements in the rocks were preferentially leached out and then entered the fluids. With increasing water/rock reaction duration and amount of halogen-group elements in the solution and with decreasing pH value of the solution, some active metallic elements began to release in small amounts. This experimental result can explain the source and mechanism of volatile components and trace metals in underground waters. Meanwhile, as for those ore deposits produced by ore fluids derived from meteoric waters, the experimental result is also helpful to the understanding of the geochemical variation trend at the initial stage of conversion of meteoric waters to ore fluids.  相似文献   

专业技术职务评审工作的实践与探讨     

郑松华  陈发荣等 《华南地震》1991,11(2):90-95

本文总结介绍作者所在单位专业技术职务评审的原则、方法和经验，对评审项目的划分和选取。计分标准，评委会职责等总理 进行了讨论。该方法在作者单位实践，取得较好效果。  相似文献