Linear Magnetoconvection in Rotating Fluid Spheres Permeated by a Uniform Axial Magnetic Field     

Ataru Sakuraba 《地球物理与天体物理流体动力学》2013,107(4):291-318

A linear analysis of thermally driven magnetoconvection is carried out with emphasis on its application to convection in the Earth's core. We consider a rotating and self-gravitating fluid sphere (or spherical shell) permeated by a uniform magnetic field parallel to the spin axis. In rapidly rotating cases, we find that five different convective modes appear as the uniform field is increased; namely, geostrophic, polar convective, magneto-geostrophic, fast magnetostrophic and slow magnetostrophic modes. The polar convective (P) and magneto-geostrophic (E) modes seem to be of geophysical interest. The P mode is characterized by such an axisymmetric meridional circulation that the fluid penetrates the equatorial plane, suggesting that generation of quadrapole from dipole fields could be explained by a linear process. The E mode is characterized by a few axially aligned columnar rolls which are almost two-dimensional due to a modified Proudman-Taylor theorem.  相似文献   

探地雷达在河道探测中的应用     

郭成超  王复明  谢晓莉  尚向阳 《物探与化探》2012,(5):887-892

基于有限差分法,建立了探地雷达电磁波在河道传播的正演模型,并模拟了水下不同构造的典型工况,得到了相应的二维反射图像。和实际探测的河道图谱进行了比较,通过对模拟图像的分析和实际雷达探测图谱的解释,研究了探地雷达方法在河道探测中的可行性。  相似文献   

基于拉格朗日法的水汽输送气候特征分析——江淮梅雨和淮北雨季的对比   总被引：1，自引：0，他引：1  

杨浩  江志红  刘征宇  张强 《大气科学》2014,38(5):965-973

利用基于拉格朗日方法的轨迹模式（HYSPLIT_4.9）,结合海量气块追踪分析法,对比了江淮梅雨和淮北雨季平均水汽输送特征,从水汽来源及源地贡献方面探讨二者的相对独立性,对比两雨季降水异常年水汽输送特征。结果表明,气候态上,江淮梅雨的水汽输送主要来自印度洋、太平洋、孟湾—南海,其中来自印度洋的水汽输送贡献最大,超过50%;淮北雨季来自印度洋、欧亚大陆、孟湾—南海、太平洋的水汽贡献差异不大,但与江淮梅雨的水汽源地对比,淮北雨季来自印度洋的水汽输送贡献少20%,而欧亚大陆偏多19%。对比降水异常年发现,来自印度洋、孟湾—南海以及欧亚大陆水汽贡献的变化对江淮梅雨和淮北雨季降水异常有重要影响。江淮梅雨偏多年,印度洋的水汽输送贡献比梅雨偏少年减少17%,孟湾—南海则增加了11%。在淮北雨季偏多年,印度洋的水汽输送贡献比偏少年多19%,孟湾—南海和欧亚大陆的水汽输送则分别减少6%和17%。  相似文献   

Mid-latitude atmospheric responses to heat and vorticity forcing using a linear baroclinic model   总被引：1，自引：0，他引：1  

QIU Shuang  FANG Jiabei  YANG Xiuqun 《气象科学》2014,34(2):149-161

Based on diagnostic analysis of reanalysis data for 58-year, the distribution characteristics of decadal variability in diabatic heating, transient eddy heating and transient eddy vorticity forcing related to the sea surface temperature (SST) anomalies over the North Pacific, as well as their relationship with anomalous atmospheric circulation have been investigated in this paper. A linear baroclinic model(LBM) was used to investigate atmospheric responses to idealized and realistic heat and vorticity forcing anomalies, and then to compare relative roles of different kinds of forcing in terms of geopotential height responses. The results illustrate that the responses of atmospheric height fields to the mid-latitude heating can be either baroclinic or barotropic. The response structure is sensitive to the relative horizontal location of heating with respect to the background jet flow, as well as to the vertical profile of heating. The response to the idealized deep heating over the eastern North Pacific, mimicking the observed heating anomaly, is baroclinic. The atmospheric response to the mid-latitude vorticity forcing is always barotropic, resulting in a geopotential low that is in phase with the forcing. The atmospheric responses to the realistic heat and vorticity forcing show the similar results, suggesting that diabatic heating, transient eddy heating and transient eddy vorticity forcing can all cause atmospheric anomalies and that the vorticity forcing plays a relatively more important role in maintaining the equivalent-barotropic structure of geopotential height anomalies.  相似文献   

改进的SCIT算法在人工防雹作业中的应用分析     

段艺萍  徐亚娟  支树林 《气象与减灾研究》2014,(4):42-49

基于新一代天气雷达三维组网产品,利用改进后的对流风暴跟踪(SCIT)算法,对2013年3月22日发生在江西省北部地区的一次降雹天气过程进行冰雹回波识别和跟踪分析。选用能反映冰雹云特征的6个基于雷达反射率三维拼图的人工防雹作业指标,借助经验阈值形成人工防雹作业条件的模糊逻辑判断方法。以地面降雹实况记录为检验标准,对改进后的SCIT算法的识别结果进行检验。结果表明,改进后的SCIT算法共识别出可实施人工作业的冰雹云对流单体4个,不仅多于观测到的地面降雹站点数(3个),也多于未改进的SCIT算法识别出的冰雹云回波单体数,且识别出的位置与实况完全一致,表明应用改进后的SCIT算法有助于增强人工防雹作业的准确率。  相似文献   

On the use of IMU (inertial measurement unit) sensors in geomorphology     

Georgios Maniatis 《地球表面变化过程与地形》2021,46(11):2136-2140

Inertial measurement units (IMUs) are mobile sensors assemblies constructed using a combination of MEMS (micro electrical mechanical systems) accelerometers, gyroscopes and magnetometers. Both the technology and its applications to geomorphic problems are developing rapidly, since they demonstrate the prospect of monitoring individual sediment grains, of various sizes, during transport and at high frequency. This prospect has numerous implications which range from hazard identification and warning to complex theoretical derivations for sediment transport modelling. At the same time, the deployment of IMUs needs to be underpinned by a number of technical considerations regarding the limitations of the technology and the physics of the inertial measurements. IMU measurements should be reported in a manner that allows for clear understanding of the scope of the study, with sufficient detail for repeatability and clear error characterization. At a secondary level, IMU measurements should be linked clearly with the physics of sediment motion. Here the author highlights five technical issues which can lead to the misinterpretation of IMU measurements. His scope is to begin a dialogue towards a collective agreement on a presentation/reporting protocol for IMU measurements in geomorphic studies that will allow for the coherent contextualization of the technology and accelerate its scientific impact within geosciences.  相似文献   

双线铁路CRTSⅢ型板式无砟轨道布板设计系统研制     

王博 《测绘与空间地理信息》2021,44(4):198-201

深入研究了CRTSⅢ型板式(简称Ⅲ型)无砟轨道布板设计关键技术,设计并研制了基于C/S(客户端/服务器)结构模式的Ⅲ型无砟轨道布板设计系统,可以实现双线铁路并行等高段的布板计算并获得轨道板各承轨台轨顶中心(简称承轨台定位点)的线路空间三维坐标信息。文中阐述了双线铁路Ⅲ型无砟轨道布板设计关键技术和系统设计实现流程,对我国Ⅲ型无砟轨道技术体系向智能化发展具有一定借鉴和参考意义。  相似文献   

流域面雨量的计算方法   总被引：3，自引：0，他引：3  

李飞  田万顺 《河南气象》2003,(3):20-21

经对面雨量的几种计算方法对比分析，确定了以等雨量线法为计算流域面雨量的方法，同时对于计算方法进行了部分优化，并应用于业务中。  相似文献   

全三维地震解释   总被引：12，自引：10，他引：12  

杨勤勇 《地球物理学进展》1999,14(3):128-137

三维地震为油气工业的增储上产作出了重大贡献，随着采集处理成本的不断降低，周期的不断缩短，全三维处理和叠前深度偏移等技术的推广应用，以及计算机技术的迅速发展，全三维地震解释已成为国内外致力发展的技术。  相似文献   

Effect of vertical overturning circulation scale and moist static energy tendency on MJO phase speed          下载免费PDF全文

Feng Hu  Tim Li 《大气和海洋科学快报》2022,15(1):68-75

本文通过对1979-2019年ERA-I再分析资料进行诊断分析,研究了MJO垂直环流(VOC)纬向尺度和湿静力能(MSE)趋势纬向不对称性对MJO传播速度的综合影响.研究结果表明,MJO传播速度与VOC的纬向尺度和MSE趋势纬向梯度之间存在显著的正相关关系.基于上述两个参数,本文建立了线性回归模型,该模型可以较好的估计...  相似文献