榕江双偏振雷达与三穗雷达在黔东南一次大暴雨过程中的应用对比分析          下载免费PDF全文

董文韬  毛倩  李舒颖  蔡垚  张超 《中低纬山地气象》2023,47(6):30-36,58

为进一步提升黔东南三穗CINRAD-CD雷达及榕江双偏振雷达产品在山区强降雨过程中的应用能力,提升短临预报预警服务水平,对2部雷达在2022年7月18日大暴雨过程中观测和定量降水估测的差异进行对比分析。结果表明：榕江雷达总体探测能力强于三穗雷达,在黔东南州西部地区,由于雷公山地形阻挡作用,榕江雷达对低层探测能力减弱,在黔东南州中部及以东地区榕江雷达探测能力明显强于三穗雷达;2部雷达探测得到的组合反射率因子峰值与地面分钟降雨量峰值对应关系较好,当降雨减弱时,三穗雷达衰减更明显;三穗单偏振雷达对降水的起止时段及累积降水量的估测能力明显不足,而榕江双偏振雷达QPE产品对降水起止时间及降雨定量估测结果基本接近实况,在业务应用中具有较高的参考价值。  相似文献   

1991—2020年江苏省连阴雨特征与区域指数构建          下载免费PDF全文

姚阮  艾文文  罗晓春  王博妮 《气象与减灾研究》2023,46(2):103-110

利用江苏省70个县级气象基本站1991—2020年逐日降水、日照时数资料,筛选出不同等级的连阴雨事件,建立连阴雨事件库。分析了江苏省连阴雨事件的时空分布特征和典型连阴雨过程,构建了区域连阴雨指数。结果表明：1） 江苏省以强连阴雨事件为主,事件年均发生次数、日数和降水总量从北到南依次增多。2） 苏北、苏中、苏南地区连阴雨事件的年发生次数、日数和降水总量表现出较明显的年代际差异,年际波动从北到南逐渐增强。苏北地区的连阴雨事件集中于盛夏发生,苏中地区多发于初春和盛夏,苏南地区于春夏大部分时间均较为频繁,秋冬亦较常见。3） 综合考虑连阴雨事件发生日数、降水量以及事件分布面积,构建区域连阴雨指数,以反映某一区域的连阴雨强弱情况。该指数较好地反映了2020年苏北、苏中、苏南三地区的区域连阴雨过程和强度变化。  相似文献   

气候变化对江西省主要室外空气计算参数的影响          下载免费PDF全文

陈琦  章毅之  姚琳 《气象与减灾研究》2023,46(2):131-140

利用江西83个地面气象站1963—2022年逐日平均气温和14时气温数据,计算每10 a滑动平均采暖室外计算温度、夏季空气调节室外计算日平均温度、冬季通风室外计算温度和夏季通风室外计算温度,分析江西省气候变化及其对室外空气计算参数的影响。结果表明：江西省年平均气温呈明显上升趋势,其中赣北地区上升幅度大于赣南、赣中南部,冬季平均气温增加趋势（0.31℃/（10 a））大于夏季（0.14 ℃/（10 a））,冬季平均气温在1997年发生显著突变,之后冬季平均气温较多年平均值高0.6℃。气候变化背景下,室外空气计算参数变化明显,采暖室外计算温度、夏季空气调节计算温度和冬季通风室外计算温度呈升高趋势,夏季通风室外计算温度的变化趋势不明显。其中,冬季室外计算温度的上升幅度高于夏季,赣北地区的东部和中南部升高趋势较大。采暖室外计算温度升高,建筑的传热负荷设计值减小;夏季空气调节室外计算温度的升高使新风负荷增加,增加室内空气冷却能耗;冬季通风室外计算温度的升高有利于减小冬季通风负荷。  相似文献   

Dynamic Study on Fracture Problems in Viscoelastic Sedimentary Rocks Using the Numerical Manifold Method     

Zhijun Wu  Louis Ngai Yuen Wong  Lifeng Fan 《Rock Mechanics and Rock Engineering》2013,46(6):1415-1427

The viscoelastic deformation behavior of a sedimentary rock under different loading rates is numerically modeled and investigated by the numerical manifold method (NMM). By incorporating a modified 3-element viscoelastic constitutive mode in the NMM, crack initiation and propagation criteria, and crack identification and evolution techniques, the effects of the loading rates on the cracking behavior of a sedimentary rock, such as crack open displacement, crack sliding displacement, crack initiation, crack propagation and final failure mode, are successfully modeled. The numerical results reveal that under a high loading rate (>1,000 MPa/s), due to the viscoelastic property of the sedimentary rock, not only the structural behavior deviates from that of elastic model, but also different cracking processes and final failure modes are obtained.  相似文献   

Distinct variations of crustal shear wave velocity structure and radial anisotropy beneath the North China Craton and tectonic implications     

Cheng Cheng  Ling Chen  Huajian Yao  Mingming Jiang  Bingyu Wang 《Gondwana Research》2013,23(1):25-38

This study presents the crustal shear wave velocity structure and radial anisotropy along two linear seismic arrays across the North China Craton (NCC) from ambient noise tomography. About a half to one year long ambient noise data from 87 stations were used for obtaining the inter-station surface wave empirical Green's functions (EGFs) from cross-correlation. Rayleigh and Love dispersion curves within the period band 5–30 s were measured from the EGFs of the vertical and transverse components, respectively. These dispersion data were then used to determine the crustal shear wave velocity structure (V_SV and V_SH) and radial anisotropy (2(V_SH ? V_SV) / (V_SH + V_SV)) from point-wise linear inversion with constraints from receiver function analysis. Our results reveal substantial structural variations among different parts of the NCC. The Bohai Bay Basin in the eastern NCC is underlain by a thin crust (~ 30 km) with relatively low velocities (particularly V_SV) and large positive radial anisotropy in the middle to lower crust. Such a crustal structure is no longer of a cratonic type and may have resulted from the widespread tectonic extension and intensive magmatism in this region since late Mesozoic. Beneath the Ordos Basin in the western NCC, the crust is relatively thicker (≥ 40 km) and well stratified, and presents a large-scale low velocity zone in the middle to lower crust and overall weak radial anisotropy except for a localized lower crust anomaly. The overall structural features of this region resemble those of typical Precambrian shields, in agreement with the long-term stability of the region. The crustal structure under the Trans North China Orogen (TNCO, central NCC) is more complicated and characterized by smaller scale velocity variations, strong positive radial anisotropy in the middle crust and rapid change to weak-to-negative anisotropy in the lower crust. These features may reflect complex deformations and crust–mantle interactions, probably associated with tectonic extension and magmatic underplating during the Mesozoic to Cenozoic evolution of the region. Our structural images in combination with previous seismic, geological and geochemical observations suggest that the Phanerozoic lithospheric reactivation and destruction processes may have affected the crust (especially the middle and lower crust) of the eastern NCC, and the effect probably extended to the TNCO, but may have minor influence on the crust of the western part of the craton.  相似文献   

鄂尔多斯盆地南梁西区长6油层组砂岩低孔 超低渗储层特征及主控因素     

马瑶  李文厚  欧阳征健  张东阳  孟鹄 《地质通报》2013,32(9):1471-1476

南梁西区位于鄂尔多斯盆地陕北斜坡的西南部.长6油层组作为其主要的勘探目标层位,在研究区东北部发育三角洲前缘亚相、南部发育深湖浊流亚相.砂岩储层主要由长石砂岩及岩屑长石砂岩组成.研究区砂岩中胶结物类型有方解石、伊利石、绿泥石和硅质胶结物,使得砂岩孔隙物性降低.通过对储层孔渗参数的研究,得出长6油层组主要为低孔超低渗储层.根据毛细管压力曲线的形态认为,研究区目的层的孔喉结构为Ⅱ类,孔喉分选中等偏差,并提出成岩作用是影响其储集性能的主要因素.  相似文献   

辽宁西丰大岩体的解体及其地质意义     

王忠江  翟富荣  王岐  谢少强  何振清  仲米山  于恩波  李琢  陈垚 《地质与资源》2013,22(2):86-93

西丰大岩体在辽宁省地质上占有十分显赫的位置,一方面它出露面积巨大,另一方面与其相关的矿产比较丰富.西丰大岩体未解体之前是辽宁省最大的岩体之一,位于辽宁省的东北角,南起清河,向北延至吉林省,在辽宁省境内出露面积逾2500km2.与其相关的矿产有铁矿、铜矿、铅锌金银钼多金属矿及萤石矿.根据构造-岩浆演化期次原则,按岩石学、岩石地球化学、同位素年代学、岩体间的接触关系及岩体与地层的接触关系等,将西丰大岩体(辽宁省部分)进行了详细解体,重新归并成早二叠世、早三叠世、中侏罗世和晚白垩世4个侵入期次.其中早二叠世有3个侵入序次、早三叠世1个侵入序次、中侏罗世3个侵入序次、晚白垩世4个侵入序次,共划分为11个侵入序次.在此基础上对岩性的成矿专属性、矿床成因类型和成矿时限进行了专门研究.  相似文献   

北太行山安妥岭早白垩世碱性玄武岩的发现及地质意义     

梁涛  罗照华  卢仁  杨宗锋  樊秉鸿 《华北地质》2013,36(1):10-22

以岩墙状产出的安妥岭玄武岩形成于早白垩世(K-Ar表观年龄为122.31±1.34 Ma),其内发现橄榄岩包体、碳酸盐矿物集合体以及歪长石、刚玉、金云母巨晶.安妥岭玄武岩中可见橄榄石的碳酸盐化、绿泥石化和蛇纹石化以及单斜辉石的绿泥石化和碳酸盐化.安妥岭玄武岩样品的Si02含量介于46.50％～50.20％,Zr/TiO2-Nb/Y图解投点均落于碱性玄武岩区,微量元素蛛网图解中显示出明显的Nb、Ta和Ti的负异常,具有右倾平滑的稀土配分模式,(La/Yb)PM=33.4～40.1.两件安妥岭玄武岩样品的87Sr/86Sr比值分别为0.71 1300和0.706233,相应的143Nd/144Nd比值和εNd(122 Ma)分别为0.511848及0.511897和-13.73及-12.76.部分熔融源区组成和部分熔融作用控制着安妥岭玄武岩的成分变异,安妥岭玄武岩岩浆在上升过程中没有发生明显的结晶分异和地壳混染作用.运用地幔熔融柱模型,反演获得了安妥岭熔融柱就位于82.5～75.3 km深度范围内,即122.31 Ma时安妥岭岩石圈的厚度为75.3km,并认为安妥岭玄武岩是安妥岭岩石圈拆沉作用的产物.结合邻区南大岭和南口熔融柱深度位置,认为安妥岭-南大岭-南口岩石圈厚度经历小规模减薄(J2)-增厚(J2-K1)-拆沉(K1)-稳定(K1-今)的演化过程,安妥岭岩石圈拆沉作用为安妥岭斑岩钼矿形成的深部控制因素.  相似文献   

鄂尔多斯盆地子洲气田北部山₂段沉积体系研究     

杨博  魏颖  马瑶  赵敏 《地下水》2013,(1):161-163

通过野外观察、岩心描述与室内研究相结合的方法,对鄂尔多斯盆地子洲气田北部山西组山2段研究,分析研究区山西组山2段的沉积相特征及沉积相带空间展布规律,确定研究区山2段主要为三角洲沉积体系。进行沉积微相的划分,掌握研究区储层砂体叠置形态规律。  相似文献   

The Impact of the Numbers of Monitoring Stations on the National and Regional Air Quality Assessment in China During 2013–18     

Hongyan LUO  Xiao TANG  Huangjian WU  Lei KONG  Qian WU  Kai CAO  Yating SONG  Xuechun LUO  Yao WANG  Jiang ZHU  Zifa WANG 《大气科学进展》2022,39(10):1709-1720

China national air quality monitoring network has become the core data source for air quality assessment and management in China. However, during network construction, the significant change in numbers of monitoring sites with time is easily ignored, which brings uncertainty to air quality assessments. This study aims to analyze the impact of change in numbers of stations on national and regional air quality assessments in China during 2013–18. The results indicate that the change in numbers of stations has different impacts on fine particulate matter (PM_2.5) and ozone concentration assessments. The increasing number of sites makes the estimated national and regional PM_2.5 concentration slightly lower by 0.6?2.2 μg m^?3 and 1.4?6.0 μg m^?3 respectively from 2013 to 2018. The main reason is that over time, the monitoring network expands from the urban centers to the suburban areas with low population densities and pollutant emissions. For ozone, the increasing number of stations affects the long-term trends of the estimated concentration, especially the national trends, which changed from a slight upward trend to a downward trend in 2014?15. Besides, the impact of the increasing number of sites on ozone assessment exhibits a seasonal difference at the 0.05 significance level in that the added sites make the estimated concentration higher in winter and lower in summer. These results suggest that the change in numbers of monitoring sites is an important uncertainty factor in national and regional air quality assessments, that needs to be considered in long-term concentration assessment, trend analysis, and trend driving force analysis.  相似文献