Observational Zonal Mean Flow Anomalies: Vacillation or Poleward Propagation?          下载免费PDF全文

SONG Jie 《大气和海洋科学快报》2013,6(1):1-7

North-south displacements and meridional vacillations of the eddy-driven jet are widely accepted as the dominant cause of variability of the observational zonal-mean zonal wind anomalies(denoted [u]’).In this study,a new idea regarding the primary variability of the observational [u]’ in the middle latitude troposphere is presented.It is hypothesized that there are two different classes of primary variability of the observational [u]’:the poleward propagation of the [u]’(abbreviated as PP) and meridional vacillations.To validate this hypothesis,one-point correlation maps of [u]’ at 200-hPa during the boreal cold season(November-April) of every year from 1957-2002 are used as a criterion.Twelve PP years,in which the PP events are dominant in the variability of [u]’,and 15 no_PP years,in which the PP events are recessive and the meridional vacillations are dominant in the variability of [u]’,are examined.The results show that the variabilities of [u]’ are different in the chosen PP and no_PP years.In the PP years,the PP events dominate the variability of [u]’;however,the meridional vacillations are prevalent in the no_PP years.  相似文献   

黄河中游夏季降水异常的先兆特征和预测方法     

宋文玲  顾薇  柳艳菊  刘长征 《气象》2013,39(9):1204-1209

本文利用黄河中游61站降水资料,分析了其变化规律和同期及前期环境场特征,并建立了夏季降水预测模型。研究发现：黄河中游夏季降水具有显著的年际变化特征,显著周期在3年左右;黄河中游夏季降水主要受到同期东亚高空急流、西太平洋副热带高压(以下简称副高)以及贝加尔湖附近低槽的影响,当急流和副高偏强（弱）偏北（南）、贝加尔湖附近高度场偏低（高）时,黄河中游降水偏多（少）。另外,前期秋季南方涛动指数、北非副热带高压（20°W~60°E）、南海副热带高压（100°~120°E）、北半球副高强度及北半球极涡强度发生异常时,对夏季环流产生影响,从而影响黄河中游夏季降水,据此,建立预测模型。评估发现该模型具有较强的预测能力,可用于黄河中游夏季降水的定量预测。  相似文献   

力觉临场感遥操作机器人(1):技术发展与现状     

宋爱国 《南京气象学院学报》2013,5(1):1-19

人机交互式机器人作为最具实用价值的特种机器人已成为当前机器人学研究的前沿和热点.临场感(Telepresence)技术是人机交互的核心.首先,回顾了力觉临场感遥操作机器人技术的产生、发展和现状,介绍了力觉临场感遥操作机器人在核领域、空间探测领域与远程医疗领域的应用情况;其次,对力觉临场感遥操作机器人的4大关键技术:传感技术、力反馈与触觉再现技术、大时延控制技术和虚拟预测环境建模技术等进行了综述;还介绍了东南大学仪器科学与工程学院机器人传感与控制研究所近20年来开展临场感遥操作机器人技术研究,以及在核探测、康复医疗领域应用的情况.通过回顾与分析,指出了力觉临场感遥操作机器人技术今后需要研究的几个重点问题.  相似文献   

SWAN雷达产品在甘肃河东地区冰雹短临预报中的应用     

傅朝  闫晗  刘维成  宋琳琳 《干旱气象》2013,(1):199-205

选取2011年7月发生在甘肃省河东地区的7次冰雹个例,综合分析SWAN系统输出的雷达产品资料的主要特征,提取冰雹天气的雷达产品资料的指标,根据这些指标利用SWAN系统外推算法资料生成冰雹临近预报产品。通过2012年甘肃河东地区的2次冰雹天气过程对与其同时的临近预报产品检验结果表明,预报效果良好,具有较高的业务应用价值。  相似文献   

我国华南3月份降水异常的可能影响因子分析   总被引：4，自引：3，他引：1  

李宏毅  林朝晖  宋燕  陈红  许建玉 《大气科学》2013,37(3):719-730

利用1951～2005年华南地区3月份的降水资料、NOAA海温资料、Ni?o3.4指数和NCEP再分析资料,分析了华南3月份降水异常与同期环流场、全球海温场的关系,从环流和海温的角度揭示了华南3月份降水异常的可能原因。结果表明,当华南3月份降水偏多(少)时,在对流层中低层,北太平洋海区存在气旋(反气旋)性环流异常,西太平洋及南海海面上存在反气旋(气旋)性环流异常,这样的环流异常有利(不利)于东南暖湿气流与北方东部异常冷空气在华南地区形成水汽辐合,导致降水显著增多(减少)。进一步的分析表明,ENSO和北印度洋及南海附近海温是影响华南3月份降水异常的重要外强迫因子,ENSO对华南3月降水异常的影响是通过影响春季西太平洋副热带高压和低层风场异常实现的,而北印度洋及南海附近海温对华南3月降水异常的影响则是通过垂直环流场异常和低层风场以及西太平洋副热带高压异常来实现的。  相似文献   

Evaluating the Tree Population Density and Its Impacts in CLM-DGVM     

SONG Xiang  ZENG Xiaodong  ZHU Jiawen 《大气科学进展》2013,30(1):116-124

Vegetation population dynamics play an essential role in shaping the structure and function of terrestrial ecosystems.However,large uncertainties remain in the parameterizations of population dynamics in current Dynamic Global Vegetation Models(DGVMs).In this study,the global distribution and probability density functions of tree population densities in the revised Community Land Model-Dynamic Global Vegetation Model(CLM-DGVM) were evaluated,and the impacts of population densities on ecosystem characteristics were investigated.The results showed that the model predicted unrealistically high population density with small individual size of tree PFTs(Plant Functional Types) in boreal forests,as well as peripheral areas of tropical and temperate forests.Such biases then led to the underestimation of forest carbon storage and incorrect carbon allocation among plant leaves,stems and root pools,and hence predicted shorter time scales for the building/recovering of mature forests.These results imply that further improvements in the parameterizations of population dynamics in the model are needed in order for the model to correctly represent the response of ecosystems to climate change.  相似文献   

Two modes of the silk road pattern and their interannual variability simulated by LASG/IAP AGCM SAMIL2.0     

宋丰飞  周天军  王璐 《大气科学进展》2013,30(3):908-921

In this study, two modes of the Silk Road pattern were investigated using NCEP2 reanalysis data and the simulation produced by Spectral Atmospheric Circulation Model of IAP LASG, Version 2 (SAMIL2.0) that was forced by SST observation data. The horizontal distribution of both modes were reasonably reproduced by the simulation, with a pattern correlation coefficient of 0.63 for the first mode and 0.62 for the second mode. The wave train was maintained by barotropic energy conversion (denoted as CK) and baroclinic energy conversion (denoted as CP) from the mean flow. The distribution of CK was dominated by its meridional component (CK _y ) in both modes. When integrated spatially, CK _y was more efficient than its zonal component (CK _x ) in the first mode but less in the second mode. The distribution and efficiency of CK were not captured well by SAMIL2.0. However, the model performed reasonably well at reproducing the distribution and efficiency of CP in both modes. Because CP is more efficient than CK, the spatial patterns of the Silk Road pattern were well reproduced. Interestingly, the temporal phase of the second mode was well captured by a single-member simulation. However, further analysis of other ensemble runs demonstrated that the successful reproduction of the temporal phase was a result of internal variability rather than a signal of SST forcing. The analysis shows that the observed temporal variations of both CP and CK were poorly reproduced, leading to the low accuracy of the temporal phase of the Silk Road pattern in the simulation.  相似文献   

双天基平台光学测量GEO目标的轨道确定     

王蕾  宋叶志  叶钊  曾春平  邵瑞 《测绘科学》2022,47(1):9-14

针对地基测控系统对GEO卫星监测在时间与空间上存在较多盲区、不能实时获取GEO目标的空间态势感知信息、无法有效对非合作性质的GEO目标进行空间监测的问题,提出了天基光学相机的双GEO平台对GEO目标进行轨道确定的技术方案.根据光学可视条件筛选数据,利用生成的模拟数据对GEO目标进行轨道确定,将所得轨道与参考轨道进行比对...  相似文献   

40m天线面板调试与精度分析     

金旺  汪敏  张巨勇  赵辉  张萍  宋俊峰  许春 《天文研究与技术》2006,3(4):401-407

总结了40m天线面板安装调试及检测的过程，分析了反映望远镜面板指标的吨性能检测结果。结果表明天线面板精度优于原设计要求。  相似文献   

中尺度磁绳结构的行星际观测     

宋其武  吴德金 《天文学报》2004,45(4):381-388

由磁绳结构主导、平均尺度约二、三十个小时的行星际磁云是日冕物质抛射在行星际膨胀、传播的体现。最近，Moldwin等人报道在太阳风中还观测到一些尺度在几十分钟的小尺度磁绳结构，并认为太阳风中的磁绳结构在尺度分布上可能具有双峰特征，在全面检视了WIND卫星(1995年-2000年)和ACE卫星(1998年-2000年)的观测资料后，发现了在行星际太阳风中一些尺度为几个小时的中尺度磁绳结构，利用初步整理的其中28个中尺度磁绳结构事件，认为太阳风中的磁绳结构在尺度分布上可能是连续的，这对行星际太阳风中磁绳结构物理起源的研究可能提出重要的物理限制。  相似文献