台风“潭美”(2013)偏心不对称结构特征分析及数值模拟     

黄昌兴  ;周芳  ;薛谌彬 《气象与减灾研究》2014,(2):11-18

利用NCEP再分析资料、FY-2E卫星资料和常规观测资料等,采用天气学分析、物理量诊断等方法,对1312号台风"潭美"空心结构特征及成因以及其造成的暴雨天气过程进行了初步分析。结果表明,台风"潭美"深对流云系一块位于台风中心北侧,一块位于南侧,且后期北侧减弱,几乎完全偏向台风的南侧,台风中心周围仅有浅薄稀疏的低云云线。"潭美"动力、热力结构均存在明显空心和不对称性特征,其与中高层气旋性环流偏离、高层辐散不对称、水汽输送不对称等有关;强降水分布与台风不对称性结构及地形等有关。WRF中尺度模式能较好地模拟出不对称性结构以及降水强度和分布。  相似文献   

甘肃东部一次暴雪过程的诊断分析和数值模拟   总被引：3，自引：0，他引：3  

冀兰芝  全志伟  宋琳琳  孔祥伟  张静 《干旱气象》2014,(5):845-850

应用NCEP1°×1°的6 h再分析资料和常规气象观测资料以及RUC模式高分辨资料,对2013年2月17日甘肃河东暴雪天气从天气实况、环流特征、水汽条件、动力条件及西北区域RUC模式输出的模拟结论进行了诊断分析。结果表明：高空冷槽、700 hPa低涡、地面冷锋是这次暴雪的主要影响系统;降雪前期,低层正涡度增强,低层辐合、高层辐散是暴雪发生的动力机制;降雪前期,由于低涡辐合作用,700 hPa高度以下,湿度猛增,为降雪提供了充沛的水汽条件;降雪中心和政上空有θse密集强能量锋区;西北区域RUC模式模拟的24 h内降水量范围、落区、量级与实况一致,模拟的地面风速偏大。  相似文献   

有限深两层流体内孤立波非线性数值模拟入口边界条件研究          下载免费PDF全文

王旭  尤云祥  黄文昊 《海洋工程》2014,32(2):1-12

基于有限深两层流体KdV(Korteweg-de Vries)、eKdV(extended KdV)和MCC(Miyata-Choi-Camassa)理论,以内孤立波诱导上下层深度平均水平速度为入口边界条件,采用理想流体完全非线性欧拉方程,建立了两层流体中内孤立波生成的CFD(Computational Fluid Dynamics)数值模拟方法。以系列数值模拟结果为依据,结合内孤立波非线性和色散参数的组合条件,给出了选择合适内孤立波理论解作为CFD数值模拟入口边界条件的方法,从而实现了振幅与波形可控的内孤立波完全非线性数值模拟。  相似文献   

浅基础地基荷载-变形特性的分析研究     

罗强  贾虎  栾茂田 《海洋工程》2014,32(4):72-81

在土体主应力方向的旋转过程中,主应力方向与塑性主应变增量方向之间存在着非共轴现象,非共轴现象对应力-应变关系具有显著的影响。通过有限元二次开发,将角点结构非共轴理论应用到有限元程序ABAQUS中;对密砂单剪试验进行数值模拟,研究了非共轴现象及其对应力-应变关系的影响;采用离心模型试验方法,对圆形浅基础作用下饱和密砂地基荷载-变形特性进行试验研究;对离心模型试验进行数值模拟,将试验结果与数值计算结果进行对比,对非共轴模型的计算结果的合理性进行验证。研究结果表明:非共轴现象对浅基础地基荷载-变形特性具有显著的影响;当选取合理的非共轴塑性模量时,非共轴模型的计算结果与离心模型试验结果比较接近。  相似文献   

港池泊稳的能量平衡方程数值模拟     

李雪  董胜  陈更 《中国海洋大学学报(自然科学版)》2014,44(7):100-106

对基于能量平衡方程的多向随机波浪传播数学模型进行改进,通过模拟不同防波堤绕射引起的港池泊稳,验证模型的合理性和有效性。利用非线性弥散关系提高模型计算浅水变形的精度;采用二次逆风差分格式离散控制方程,避免了加入绕射项引起的数值耗散;并将文氏谱加入模型中,使其更加适合中国海域的工程应用。应用改进后模型绘制的双突堤和岛式防波堤绕射系数图与我国《海港水文规范》图进行了对比。对比结果十分接近,可以较好地描述港池的泊稳状况,为综合计算波浪在近岸的浅水变形、折射、绕射、反射和能量耗散等作用奠定了基础。  相似文献   

广西典型海湾物质输运滞留时间研究     

李谊纯  董德信  许铭本  牙韩争 《广东海洋大学学报》2014,(6):65-70

为研究广西典型海湾物质输运的时间尺度,建立了钦州湾和铁山港湾水动力与物质输运数学模型,计算了钦州湾和铁山港湾物质输运的滞留时间和半交换周期,探讨了滞留时间随入海径流量的变化以及与半交换周期的关系.结果显示,钦州湾的滞留时间为413 - 595 h,半交换周期为148 - 178 h,铁山港湾的滞留时间为215 - 598h,半交换周期约为50 h,钦州湾和铁山港湾的滞留时间均随径流量增大而减小.铁山港的滞留时间在小流量情况下随径流量的变化显著,在大流量下随径流量变化较小,而钦州湾的滞留时间随径流量大致呈线性变化.钦州湾和铁山港的滞留时间和半交换周期之间尚无明确的函数关系,这反映了不同海域的水深、地形及径流与潮汐相互作用的差异性和复杂性.  相似文献   

Characterizing landscape spatial heterogeneity in multisensor images with variogram models     

Bingwen Qiu  Canying Zeng  Chongcheng Cheng  Zhenghong Tang  Jianyang Gao  Yinpo Sui 《中国地理科学(英文版)》2014,24(3):317-327

Most evaluation of the consistency of multisensor images have focused on Normalized Difference Vegetation Index （NDVI） products for natural landscapes, often neglecting less vegetated urban landscapes. This gap has been filled through quantifying and evaluating spatial heterogeneity of urban and natural landscapes from QuickBird, Satellite pour l＇observation de la Terre （SPOT）, Ad- vanced Spacebome Thermal Emission and Reflection Radiometer （ASTER） and Landsat Thematic Mapper （TM） images with variogram analysis. Instead of a logarithmic relationship with pixel size observed in the corresponding aggregated images, the spatial variability decayed and the spatial structures decomposed more slowly and complexly with spatial resolution for real multisensor im- ages. As the spatial resolution increased, the proportion of spatial variability of the smaller spatial structure decreased quickly and only a larger spatial structure was observed at very coarse scales. Compared with visible band, greater spatial variability was observed in near infrared band for both densely and less densely vegetated landscapes. The influence of image size on spatial heterogeneity was highly dependent on whether the empirical sernivariogram reached its sill within the original image size. When the empirical semivariogram did not reach its sill at the original observation scale, spatial variability and mean characteristic length scale would increase with image size; otherwise they might decrease. This study could provide new insights into the knowledge of spatial heterogeneity in real multisen- sor images with consideration of their nominal spatial resolution, image size and spectral bands.  相似文献   

基于模型流的资源环境模型复合语言与应用     

王晨亮  岳天祥  范泽孟 《地球信息科学学报》2014,(1):31-38

资源环境领域的研究对象常被抽象为若干子模型复合而成的复杂模型,如何有效地集成这些子模型成为资源环境模型集成的主要内容。随着各种地学相关问题的日益复杂和多样化,传统的建模语言与友好易用的图形建模等集成建模方式已无法满足大规模高复杂的模型构建需求。本文在已有的相关理论基础上,针对复合模型构建的灵活性和复杂性之间的矛盾,将模型复合模式的本质抽象化,提出资源环境"模型流"的形式化语言描述,实现了模型流建模环境。应用实例表明,基于模型流的模型构建方式采用简洁的符号表示,避免了繁琐的图形构建环节,可快速灵活地构建高复杂度模型。模型流的提出为模型复合的调度性能优化和智能自动化集成等进一步的研究奠定了基础。  相似文献   

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孟庆筱  王太松  吕健  董彦知  郭宝震 《大地测量与地球动力学》2014,34(1):38-42

????????????????????????????棬??????????????????????????????????????????GPS???????????????????????????M≥5.0????????????????????????????????????????????????Ч???????XY?????????????????????????????????????????????????????????????????????????ο???????????  相似文献   

Modeling seasonal variations of subsurface chlorophyll maximum in South China Sea   总被引：1，自引：0，他引：1  

Xiang Gong  Jie Shi  Huiwang Gao 《中国海洋大学学报(英文版)》2014,13(4):561-571

In the South China Sea(SCS), the subsurface chlorophyll maximum(SCM) is frequently observed while the mechanisms of SCM occurrence have not been well understood. In this study, a 1-D physical-biochemical coupled model was used to study the seasonal variations of vertical profiles of chlorophyll-a(Chl-a) in the SCS. Three parameters(i.e., SCM layer(SCML) depth, thickness, and intensity) were defined to characterize the vertical distribution of Chl-a in SCML and were obtained by fitting the vertical profile of Chl-a in the subsurface layer using a Gaussian function. The seasonal variations of SCMs are reproduced reasonably well compared to the observations. The annual averages of SCML depth, thickness, and intensity are 75 ± 10 m, 31 ± 6.7 m, and 0.37 ± 0.11 mg m-3, respectively. A thick, close to surface SCML together with a higher intensity occurs during the northeastern monsoon. Both the SCML thickness and intensity are sensitive to the changes of surface wind speed in winter and summer, but the surface wind speed exerts a minor influence on the SCML depth; for example, double strengthening of the southwestern monsoon in summer can lead to the thickening of SCML by 46%, the intensity decreasing by 30%, and the shoaling by 6%. This is because part of nutrients are pumped from the upper nutricline to the surface mixed layer by strong vertical mixing. Increasing initial nutrient concentrations by two times will increase the intensity of SCML by over 80% in winter and spring. The sensitivity analysis indicates that light attenuation is critical to the three parameters of SCM. Decreasing background light attenuation by 20% extends the euphotic zone, makes SCML deeper(~20%) and thicker(12% – 41%), and increases the intensity by over 16%. Overall, the depth of SCML is mainly controlled by light attenuation, and the SCML thickness and intensity are closely associated with wind and initial nitrate concentration in the SCS.  相似文献