一次华北暴雨过程中边界层东风活动及作用   总被引：7，自引：0，他引：7       下载免费PDF全文

吴庆梅  刘卓  王国荣  翟亮  丁青兰 《应用气象学报》2015,26(2):160-172

利用常规气象观测资料、NCEP 1°×1°逐6 h分析资料、微波辐射计资料及FY-2E气象卫星及雷达探测资料,针对2013年6月4日发生在北京及周边地区的一次暴雨过程中边界层东风活动及作用进行了天气学诊断分析,结果表明:对流性暴雨过程伴随有源自东北平原的边界层东风活动,东风活动具有尺度小、降温明显和湿度大等特点。暴雨过程是边界层东风和中低空暖式切变线、偏南风急流和500 hPa短波槽共同作用的结果;东风湿冷空气的锋面抬升和地形抬升作用共同加强了中低层暖湿气流的辐合上升运动,同时东风冷垫和地形抬升作用触发了雷暴的再次发生,相应雷暴具有高架对流特点。东风气流起到了边界层水汽输送作用,中低层偏南暖湿气流为暴雨的产生提供了充足的水汽和不稳定层结条件。  相似文献   

低温雨雪过程的粒子群-神经网络预报模型   总被引：3，自引：0，他引：3       下载免费PDF全文

陆虹  翟盘茂  覃卫坚  金龙  谢敏  钱晰  赵华生 《应用气象学报》2015,26(5):513-524

利用逐日气温和降水量数据、NCEP/NCAR再分析资料以及预报场资料,通过分析提取我国南方区域持续性低温雨雪过程及其预报因子,使用粒子群-神经网络方法建立非线性的统计集合预报模型 (PSONN-EPM),对我国南方区域持续性低温雨雪过程进行预报试验。结果表明:以过程的冷湿程度及影响范围为标准,将低温雨雪过程分为一般过程和严重过程,并建立不同的预报模型效果较好。通过10 d独立样本预报试验看,基于粒子群-神经网络方法建立的集合预报模型比基于逐步回归方法建立的预报模型的预报平均相对误差小,对严重过程预报能力高于对一般过程预报,且这种非线性统计集合建模方法在建模过程中不需要调整神经网络参数,在实际预报业务中值得尝试。  相似文献   

“75·8”持续性强降水事件及其大尺度水汽输送特征     

胡娅敏  翟盘茂  陈阳 《气象与环境科学》2015,38(3):13-18

首先研究了河南"75·8"强降水事件的极端异常特征,然后从水汽通量的角度定性分析这次事件的水汽输送特征,最后采用了Hysplit模型定量分析了不同源地的水汽来源对河南"75·8"强降水的贡献率。研究表明,1975年8月5-8日在河南省发生的是一次大范围持续性极端降水过程,事件发生期间区域平均降水程度超过其气候平均值3倍标准差。强降水事件是在中高纬度环流异常和台风共同作用下发生的,贝加尔湖以东阻塞高压和副热带高压合并阻挡了7503号台风北上。定量计算结果进一步表明,河南"75·8"强降水的水汽来源与7503号台风具有十分密切的联系。  相似文献   

海南岛附近四季风场的中尺度环流   总被引：10，自引：0，他引：10  

翟武全  李国杰  孙斌  党人庆 《热带气象学报》1997,13(4):315-322

利用一层σ坐标原始方程数值诊断模式研究海南岛，雷州半岛及其四周海域的地面风场特征，在春夏秋冬四季典型盛行气流下试验，均明显呈现绕流，爬坡，辐合线、海陆风和山谷风效应，看出在不同季节下的中尺度环流存在一定的差异。试验表明，区域内的复杂地形和海陆分布是形成各种中尺度环流的重要原因，同时，揭示出本地气候分布的特征与中尺度环流间存在的密切的关系。  相似文献   

Lookback time as a test for f(R) gravity in the Palatini approach     

Zhong-Xu Zhai  Wen-Biao Liu 《中国天文和天体物理学报》2011,(11)

We use the recently released data of lookback time (LT)-redshift relation, the cosmic microwave background shift parameter and the baryon acoustic oscillation measurements to constrain cosmological parameters of f (R) gravity in the Palatini formalism by considering the f (R) form of type (a) f (R) = R β/Rn and (b) f (R) = R + α ln R β. Under the assumption of a Friedmann-Robertson-Walker universe, we achieved the best fitting results of the free parameters (Ωm0, n) for (a) and (Ωm0, α) for (b). We find tha...  相似文献   

中尺度模式和新一代天气雷达产品识别云降水方法     

胡雯  黄勇  翟菁 《气象科技》2007,35(4):470-473

介绍一种结合中尺度模式产品和新一代天气雷达产品的云降水识别方法。首先利用中尺度模式(MM5)产品计算得到降水潜力区识别因子,分析降水潜力区。进一步结合新一代天气雷达产品,分析潜力区内云团的降水参数,确定有利于降水的云团。分析结果表明,潜力综合指标对未来可能出现的具有大量水资源的对流性系统具有指示意义,可以用于分析对流性系统的降水潜力;另一方面雷达降水等级是对实际对流云团水资源等级的划分。综合这两者进行降水潜力的分析判别,可以增强降水云的识别能力。  相似文献   

Observations of the dynamical response of a coastal embayment to wind, tide and buoyancy forcing     

Li Zhai  Jinyu Sheng  Richard J. Greatbatch 《Continental Shelf Research》2007,27(20):2534-2555

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Cracking mechanisms during galena mineralization in a sandstone-hosted lead–zinc ore deposit: case study of the Jinding giant sulfide deposit, Yunnan, SW China     

Junlai Liu  Anjian Wang  Haoran Xia  Yunfeng Zhai  Lan Gao  Qunye Xiu  Zhaochong Zhang  Zhidan Zhao  Dianhua Cao 《Mineralium Deposita》2010,45(6):567-582

There are two types of lead–zinc ore bodies, i.e., sandstone-hosted ores (SHO) and limestone-hosted ores (LHO), in the Jinding giant sulfide deposit, Yunnan, SW China. Structural analysis suggests that thrust faults and dome structures are the major structural elements controlling lead–zinc mineralization. The two types of ore bodies are preserved in two thrust sheets in a three-layered structural profile in the framework of the Jinding dome structure. The SHO forms the cap of the dome and LHO bodies are concentrated beneath the SHO cap in the central part of the dome. Quartz, feldspar and calcite, and sphalerite, pyrite, and galena are the dominant mineral components in the sandstone-hosted lead–zinc ores. Quartz and feldspar occur as detrital clasts and are cemented by diagenetic calcite and epigenetic sulfides. The sulfide paragenetic sequence during SHO mineralization is from early pyrite to galena and late sphalerite. Galena occurs mostly in two types of cracks, i.e., crescent-style grain boundary cracks along quartz–pyrite, or rarely along pyrite–pyrite boundaries, and intragranular radial cracks in early pyrite grains surrounding quartz clasts. The radial cracks are more or less perpendicular to the quartz–pyrite grain boundaries and do not show any overall (whole rock) orientation pattern. Their distribution, morphological characteristics, and geometrical relationships with quartz and pyrite grains suggest the predominant role of grain-scale cracking. Thermal expansion cracking is one of the most important mechanisms for the generation of open spaces during galena mineralization. Cracking due to heating or cooling by infiltrating fluids resulted from upwelling fluid phases through fluid passes connecting the SHO and LHO bodies, provided significant spaces for crystallization of galena. The differences in coefficients of thermal expansion between pyrite and quartz led to a difference in volume changes between quartz grains and pyrite grains surrounding them and contributed to cracking of the pyrite grains when temperature changed. Combined thermal expansion and elastic mismatch due to heating and subsequent cooling resulted in the radial and crescent cracking in the pyrite grains and along the quartz–pyrite grain boundaries.  相似文献   

塔里木盆地寒武系层序地层格架   总被引：16，自引：0，他引：16  

赵宗举  张运波  潘懋  吴兴宁  潘文庆 《地质论评》2010,56(5):609-620

通过露头、钻测井及地震层序地层特征综合分析,建立了塔里木盆地寒武系三级层序地层格架,将寒武系划分出6个可全盆地追踪与对比的三级层序。结合反映全球海平面相对变化的全岩碳同位素旋回与反映沉积古水深相对变化的沉积旋回的对比分析,可将塔里木盆地寒武系三级层序分为主要受全球海平面变化控制形成的全球海平面层序(层序CSQ2、CSQ4、CSQ5、CSQ6)及主要受地区性构造沉降作用控制形成的构造层序(层序CSQ1、CSQ3)2类。塔北轮南地区寒武系台地边缘总体呈现由早寒武世的缓坡向中—晚寒武世的镶边台地的演变以及由西向东的进积叠置型式,推测主要与寒武纪全球海平面总体微弱下降及塔里木盆地基底沉降速率总体稳定且较小有关。  相似文献   

Unveiling controls of the latitudinal gradient of surface pCO₂ in the Kuroshio Extension and its recirculation regions（northwestern North Pacific） in late spring     

Chenglong Li  Weidong Zhai  Di Qi 《海洋学报(英文版)》2022,41(5):110-123

In the northwestern North Pacific, annual net air-sea CO₂ flux is greatest in the Kuroshio Extension（KE） zone,owing to its low annual mean partial pressure of CO₂（pCO₂）, and it decreases southward across the basin. To quantify the influences of factors controlling the latitudinal gradient in CO₂ uptake, sea surface pCO₂ and related parameters were investigated in late spring of 2018 in a study spanning the KE, Kuroshio Recirculation（KR）, and...  相似文献