时变涡动输送和阻高形成──1980年夏中国的持续异常天气   总被引：17，自引：3，他引：17  

吴国雄  刘辉  陈飞  赵宇澄  卢莹 《气象学报》1994,52(3):308-320

１９８０年６至８月发生在中国的持续时间长、强度大的南方低温洪涝及北方高温干旱天气与中高纬地区阻塞高压在东北亚持续发展维持有关。本文研究了时变天气系统的输送过程在强迫阻高形成中的作用。结果表明，源于欧洲强斜压带上的天气尺度扰动在东传过程中出现动能转化。这种转化满足双向法则：在向小尺度系统转化的同时，还向时间平均西风急流及大尺度的阻塞系统输送能量。位涡分析也表明，天气尺度系统维持着急流轴南侧的反气旋式平均位涡和北侧的气旋式平均位涡，并在急流分流区下游激发出高纬强烈的反气旋性涡度增长和相应的正变高。研究表明，这种波流相互作用激发阻高增长的过程比著名的１９７６年夏西欧阻高的发展还强烈得多。因此，在研究中国北方的持续异常天气形势时，除了注意热带、副热带系统的动态外，还必须注意欧洲及西亚地区强斜压带的发展及其上天气尺度系统的传播和输送特征。  相似文献   

背景西风对由局地天气尺度波所形成阻塞的影响     

罗德海  徐辉 《中国海洋大学学报(自然科学版)》2002,32(4):501-510

本文从理论上研究了在不同的背景西风条件下阻塞胚胎与局地天气尺度波之间的相互作用。结果发现合适的弱西风对阻塞的形成是至关重要的 ,较强的背景西风不利于阻塞的形成。同时局地天气尺度波的位置也起着重要作用。  相似文献   

基于气候统计特征的雷达回波质控方法     

王国荣  平凡  仰美霖  庞琦烨 《气象科技》2019,47(1):19-28

利用北京南郊S波段雷达2011—2016年的观测资料,从雷达气候统计的角度,利用不同强度回波发生频率的统计特征及其空间分布特征,对雷达地物杂波和波束遮挡的识别与订正方法进行研究。结果表明:①利用雷达回波出现频率特征,可以很好地识别雷达近中心地物杂波和受地形高度影响的地物杂波特征;同时还可以直观地识别出雷达波束遮挡区域以及遮挡程度。北京南郊雷达地物杂波主要分布在近雷达中心和北京西部、西北部的山前地区,地物杂波主要集中在0.5°仰角和1.5°仰角层上。雷达波束遮挡主要集中在由高大建筑引起遮挡的东南方位向和由于地形引起波束遮挡的西西北方位向,波束遮挡主要集中在0.5°仰角层。②采用局部可变区域平均垂直廓线方法利用高仰角回波订正低仰角回波,能有效订正地物杂波,并保留回波的局部特征。对于波束遮挡区域的回波填补,也能够较好地保持上下层仰角回波之间的连续性,同时兼顾了回波不均性分布等特性。③基于雷达气候特征进行地物杂波识别和波束遮挡识别,无需依照先验知识,相比于传统方法能更好地反映本地雷达回波真实情况,且具有方法简单、可快速复用、本地适用性强等优点。  相似文献   

黏性泥石流拦挡工程数值模拟     

马宗源  张骏  廖红建 《岩土力学》2007,28(Z1):389-392

运用计算流体动力学技术对泥石流中的Bingham黏性泥石流流体对拦挡坝的冲击进行了数值模拟,所用软件为通用CFD软件CFX,使用CAD软件AutoCAD和Unigraphics（简称UG）建立了泥石流沟谷三维地形及拦挡坝模型,计算出泥石流的速度场及泥石流流体对拦挡坝的冲击力的大小与分布。  相似文献   

Paleozoic amphibolite–granulite facies magmatic complexes in the hinterland of the Uralide Orogen     

M. Friberg  A. Larionov  G. A. Petrov  D. G. Gee 《International Journal of Earth Sciences》2000,89(1):21-39

Received: 7 May 1999 / Accepted: 2 November 1999  相似文献   

上海洋山深水港区12年来海床冲淤变化分析   总被引：2，自引：0，他引：2  

邵荣顺  吴明阳  左书华 《海洋工程》2012,30(1):106-111

洋山深水港区海域是由大、小洋山两条岛链围成的喇叭口型的海域,是以落潮流为主、高含沙量、强潮流的潮汐水道,泥沙运动主要以悬沙为主。通道内潮流基本为东南-西北向往复流,潮流平均流速为1.0～1.5 m/s,最大流速可达2.0～2.5 m/s,平均含沙量在1.4 kg/m3。对上海洋山深水港区的水文地貌特性、海床冲淤演变以及冲淤变化原因等作了分析。结果认为,伴随着工程建设的进程,陆域边界不断地改变,海床的冲淤演变也随着不断地调整,逐步形成了目前"南淤北冲"的海床冲淤格局。洋山港竣工后三年又步入了稳定的调整期,冲淤变化幅度趋于逐年减小。  相似文献   

Relationship between zonal position of the North Atlantic Oscillation and Euro-Atlantic blocking events and its possible effect on the weather over Europe     

Yao Yao  DeHai Luo 《中国科学:地球科学(英文版)》2014,57(11):2628-2636

The North Atlantic Oscillation(NAO) exhibited a marked eastward shift in the mid-1970 s. Observations show that the extreme weather events in Europe have emerged frequently in the past decades. In this paper, based upon the daily NAO index, we have calculated the frequency of in-situ NAO events in winter during 1950-2011 by defining the Eastern-type NAO(ENAO) and Western-type NAO(WNAO) events according to its position at the east(west) of 10°W. Then, the composites of the blocking frequency, temperature and precipitation anomalies for different types of NAO events are performed. Results show that the frequency of Euro-Atlantic blocking events is distributed along the northwest-southeast(southwest-northeast) direction for the negative(positive) phase. Two blocking action centers in Greenland and European continent are observed during the negative phase while one blocking action center over south Europe is seen for the positive phase. The action center of blocking events tends to shift eastward as the NAO is shifted toward the European continent. Moreover, the eastern-type negative phase(ENAO) events are followed by a sharp decline of surface air temperature over Europe(especially in central, east, and south Europe), which have a wider and stronger impact on the weather over European continent than the western-type negative phase(WNAO) events do. A double- branched structure of positive precipitation anomalies is seen for the negative phase event, besides strong positive precipitation anomalies over south Europe for ENAO event. The eastern-type and western-type positive phase(ENAO+ and WNAO+) can lead to warming over Europe. A single-branched positive precipitation anomaly dominant in central and north Europe is seen for positive phase events.  相似文献   

Variations of the atlantic and pacific blocking anticyclones and their correlation in the Northern Hemisphere     

Huang?FeiEmail author  Zhou?Faxiu  Olson?P.?J. 《中国海洋大学学报(英文版)》2002,1(1):38-44

Blocking is a large-sclae, mid-latitude atmospheric anticyclone that splits the westerly into two jets and has a profound effect on local and regional climates. This study examined the seasonal, interannual, and decadal variability of the Atlantic and Pacific blocking anticyclones in the Northern Hemisphere based on the National Centers for Environmental Prediction (NCEP)/National Center for Atmospheric Research (NCAR) reanalysis data between 1958 and 1999. The preferred blocking region during these forty-two years was located over the Atlantic. Most blocking anticyclones over the Atlantic occurred in spring, while most of those over the Pacific occurred in winter. Similar two-to four-year and eleven-year oscillations were found for both the Atlantic and Pacific blocks by using wavelet analysis. The dominant mode for the Pacific blocks is decadal variation, while for the Atlantic blocks the predominant one is interannual variation with a period of about three years. The frequencies of the Pacific and Atlantic blocks varied almost in phase on interannual time scales except during the period of 1965–1977, and frequencies were out of phase on decadal time scale throughout the forty-two years.  相似文献   

Flow duration of a dike constrained by palaeomagnetic data     

Brigitte Smith  Alain Bonneville  Rachid Hamzaoui 《Geophysical Journal International》1991,106(3):621-634

  相似文献   

克立金储量计算方法在平果铝土矿中的应用     

黎乾汉 《南方国土资源》2001,14(1):71-75

岩溶堆积型铝土矿是我国铝土矿床的新类型 ,文章利用探采资料以及不同勘探网度、不同储量方法计算结果 ,运用对比方法探讨克立金法在该类矿床储量计算方面的应用条件和效果。  相似文献