排序方式： 共有14条查询结果，搜索用时 15 毫秒
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基于Rayleigh-Gans散射原理构造一个S波段双线偏振雷达模拟器。模拟器考虑了云冰、雪、雨和雹4种水凝物,以水凝物的混合比和数浓度以及水凝物粒子的轴比、相对介电常数、下落倾角为输入量,计算得到水平/垂直偏振反射率因子、差分反射率、比差分相位等偏振量。通过二维理想飑线模拟的试验结果表明,模拟器合理地再现了二维理想飑线系统成熟期的主要偏振特征:雹的反射率较高,差分反射率较低(又称Zdr洞);对流云区的Zdr柱;层云区的反射率和比差分相位的0℃层亮带特征;雨滴反射率与差分反射率因子的“雨线”统计特征。利用该模拟器建立了模式变量和偏振雷达观测的联系,有助于未来将偏振雷达观测资料应用于模式预报效果评估及对流尺度资料同化等方面的研究和应用。 相似文献
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采用1977年1月至2006年12月高分辨率全球大洋环流模型OFES输出结果对琉球群岛附近海域的中尺度涡进行了研究分析。结果表明:(1)尺度较大的涡旋的分布密集区主要有台湾以东海域、琉球海沟上层海域和四国以南海域。(2)琉球海流流经海域的反气旋涡旋占优势,有利于琉球海流的发展。(3)琉球海流受中尺度涡的影响十分显著,纬度越低,其受中尺度涡的影响越明显,而黑潮相对比较稳定,受中尺度涡的影响并不显著。(4)四国以南海域暖涡从黑潮脱落之后向西南移动,该涡旋的移动对琉球海流和黑潮产生特别显著的影响。文章的最后还讨论了中尺度涡与黑潮弯曲以及琉球海流可能存在的联系。 相似文献
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Debris flow often causes enormous loss to life and property,especially on alluvial fans.Engineering structures such as retention check dams are essential to reduce the damage.In hazard mitigation evaluation and planning it is of significance to determine the location,size and type of dam and the effects of damage mitigation.We present a numerical simulation method using Kanako simulator for hazard mitigation planning of debris flow disaster in Tanjutani Gully,Kyoto City,Japan.The simulations were carried out for three situations:1) the simulations of erosion,deposition,hydrograph changing and inundation when there were no mitigation measures;2) the simulations of check dams in four locations(470 m,810 m,1,210 m and 1,610 m from the upstream end) to identify the best location;3) the simulations of check dams of three types(closed,slit and grid) to analyze their effects on sediment trapping and discharge reduction.Based on the simulations,it was concluded that two closed check dams(located at 470 m and 1,610 m from the upstream end) in the channel and a drainage channel on the alluvial fan can reduce the risk on the alluvial fan to an acceptable level. 相似文献
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使用中尺度数值模式WRF中的双参数云微物理方案WDM6针对2008年台风“凤凰”登陆过程中造成的强降水进行数值模拟,通过卫星模拟器利用MTSAT-1R和TRMM卫星观测的红外云顶黑体亮温TBB、PR雷达反射率资料使用统计方法验证模拟结果。通过修改云水向雨水自动转化过程、冰晶核化过程、雪和霰的下落末速度、雪和霰的截距进行敏感性试验,减小模拟结果和卫星观测结果的差异。研究结果表明:WDM6方案模拟的台风“凤凰”登陆后的降水,强对流云系及对流柱状雷达回波基本符合实况,但模拟结果局部偏强。WDM6方案模拟产生了较多的浅对流云,低估了对流云系的出现频率。不同云类型模拟的雷达回波均偏强,对流云系雷达回波垂直分布接近观测。敏感性试验结果说明修改WDM6方案中云水向雨水自动转化率有效地改善了模拟效果。同时发现云滴初始数浓度影响云水向雨水自动转化率并最终影响云系结构和雷达反射率的模拟结果,过高的云滴初始数浓度会使模拟结果变差。 相似文献
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使用POM(Princeton Ocean Model)海洋环流模式模拟西北太平洋海域的温盐场,之后运行中国科学院大气物理研究所同化系统(Ocean Variational Analysis System,OVALS),使用Argo观测网格化产品进行2006年整个计算域三维变分同化。无论从平面分布还是断面分布来看,除海表面温度(SST)外,温度同化的效果都比较好,尤其是800 m水深以浅,均方差值甚至能减小1.0℃以上。而且随着同化积分时间的增加,同化后误差减小越来越显著,3、4月份的同化效果明显高于1、2月份。与OFES(OGCM for the Earth Simulator)海洋模式结果相比,同化在一定程度上改进了模拟结果。在POM(Princeton Ocean Model)数值模拟基础上,利用3个西太平洋代表性浮标的观测资料,运用松弛逼近法同化2006年6月断面数据。当松弛系数取0.5时,模拟时间大约半天,模拟值就能快速逼近或完全等于观测值。虽然只对观测剖面进行了数据同化,但该同化可以产生更大范围的效果,而且这种效果可以持续更长时间。 相似文献
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地球模拟器是由日本宇宙开发事业团、日本原子能研究所以及海洋科学技术中心共
同开发的矢量型超级计算机，用于预测及解析整个地球的大气环流预测、全球变暖预测、地
壳变动等。具体介绍了地球模拟器的性能、地球模拟器中心设立的大气与海洋模拟研究小组
(AOSG)，固体地球模拟研究小组，复杂性模拟研究小组，高度计算表现方法研究工作、2005
年地球模拟器中心批准的各个领域的研究项目以及利用地球模拟器开展的国际合作项目。另
外，还介绍了2002年7月至2005年3月地球模拟器的利用状况及实际操作性能。 相似文献
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《Chemie der Erde / Geochemistry》2021,81(2):125734
The origin of ferroan A-type granites in anorogenic tectonic settings remains a long-standing petrological puzzle. The proposed models range from extreme fractional crystallization of mantle-derived magmas to partial melting of crustal rocks, or involve combination of both. In this study, we apply whole-rock chemical and Sm-Nd isotopic compositions and thermodynamically constrained modeling (Magma Chamber Simulator, MCS) to decipher the genesis of a suite of A1-type peralkaline to peraluminous granites and associated intermediate rocks (monzodiorite-monzonite, syenite) from the southwestern margin of the Archean Karelia craton, central Finland, Fennoscandian Shield. These plutonic rocks were emplaced at ca. 2.05 Ga during an early stage of the break-up of the Karelia craton along its western margin and show trace element affinities to ocean island basalt-type magmas. The intermediate rocks show positive εNd(2050 Ma) values (+1.3 to +2.6), which are only slightly lower than the estimated contemporaneous depleted mantle value (+3.4), but much higher than average εNd(2050 Ma) of Archean TTGs (–10) in the surrounding bedrock, indicating that these rocks were essentially derived from a mantle source. The εNd(2050 Ma) values of the peralkaline and peraluminous granite samples overlap (–0.9 to +0.6 and –3.2 to +0.9, respectively) and are somewhat lower than those in the intermediate rocks, suggesting that the mafic magmas parental to granite must have assimilated some amount of older Archean continental crust during their fractionation, which is consistent with the continental crust-like trace element signatures of the granite members. The MCS modeling indicates that fractional crystallization of mantle-derived magmas can explain the major element characteristics of the intermediate rocks. The generation of the granites requires further fractional crystallization of these magmas coupled with assimilation of Archean crust. These processes took place in the middle to upper crust (∼2–4 kbar, ∼7–15 km) and involved crystallization of large amounts of clinopyroxene, plagioclase and olivine. Our results highlight the importance of coupled FC-AFC processes in the petrogenesis of A-type magmas and support the general perception that magmas of A-type ferroan granites become more peraluminous by assimilation of crust. They further suggest that variable fractionation paths of the magmas upon the onset of assimilation may explain the broad variety of A-type felsic and intermediate igneous rocks that is often observed emplaced closely in time and space within the same igneous complex. 相似文献