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浅析翡翠的岩石类型对其比重、折射率的影响 总被引：1，自引：0，他引：1
翡翠的矿物组成、岩石类型不同，将会对翡翠的比重、折射率产生直接的影响。从翡翠的岩石学、矿物学角度出发，讨论了翡翠的岩石类型，依据组成翡翠的主要矿物的比重和折射率值，建立了翡翠矿物组成成分及含量与其比重、折射率关系图解，确定了各种翡翠的比重、折射率变化范围分别为：2．93～3．60和1．593～1．750；优质翡翠的比重、折射率分别为：3．178-3．240和1．644～1．657．为翡翠的质量评估提供了客观依据。 相似文献
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WANG Xiaoying WANG Xianliang DAI Ziqiang KE Fuyang CAO Yunchang WANG Feifei and SONG Lianchun 《大气科学进展》2014,31(2):355-362
This paper presents a novel approach for assessing the precision of the wet refractivity field using BDS （BeiDou navigation satellite system） simulations only,GPS,and BDS＋GPS for the Shenzhen and Hongkong GNSS network.The simulations are carried out by adding artificial noise to a real observation dataset.Instead of using the δ and σ parameters computed from slant wet delay,as in previous studies,we employ the Bias and RMS parameters,computed from the tomography results of total voxels,in order to obtain a more direct and comprehensive evaluation of the precision of the refractivity field determination.The results show that：（1） the precision of tropospheric wet refractivity estimated using BDS alone （only 9 satellites used） is basically comparable to that of GPS; （2） BDS＋GPS （as of current operation） may not be able to significantly improve the data＇s spatial density for the application of refractivity tomography; and （3） any slight increase in the precision of refractivity tomography,particularly in the lower atmosphere,bears great significance for any applications dependent on the Chinese operational meteorological service. 相似文献
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一次雷暴前后大气折射率的多普勒天气雷达测量试验及结果 总被引：3，自引：1，他引：2
由温度、气压和水汽压决定的大气折射率会影响天气雷达电磁波的传播路径和目标回波的相位。因此,通过测量目标回波相位的变化能够算出大气折射率的变化,进而得到水汽信息,为研究局地对流天气和水汽平流提供资料。本文阐述了多普勒天气雷达反演大气折射率的原理和方法,并利用江苏省气象台的S波段多普勒天气雷达反演了一次雷暴过程前后的大气折射率,表明了雷达探测大气折射率的可靠性。这项工作有望为研究水汽变化和天气过程提供高分辨率的遥感资料,也可以为数值模式提供水汽场辅助数据,有良好的应用前景。 相似文献
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In this study, the variation of radio refractivity with respect to temperature and moisture is analyzed. Also, the effects of vertical gradients in temperature and moisture on the propagation paths of electromagnetic waves of weather radar are examined for several sites across the United States using several years of sounding data from the National Weather Service. The ray path is important for identifying storm characteristics and for properly using the radar data in initializing numerical weather prediction models. It is found that during the warm season the radio refractivity gradient is more sensitive to moisture gradients than to temperature gradients. Ray paths from the commonly accepted vertical ray path model are compared to a ray path computed from a stepwise ray tracing algorithm using data from actual soundings. For the sample of about 16 000 soundings examined, we find that only a small fraction of the ray paths diverge significantly from those calculated using a ray path model based on the US Standard Atmosphere. While the problem of ray dueting in the presence of a temperature inversion is fairly well known, we identify the presence of a strong vertical moisture gradient as the culprit in the majority of the cases where significant deviations occurred. 相似文献
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S. B. S. S. Sarma 《Journal of Earth System Science》1991,100(2):145-154
We discuss high resolution measurements on radio refractive index, in the boundary layer and above the atmosphere in the Indian
sub-continent spread over a period of more than a solar cycle by making use of airborne microwave refractometers, operating
around 9 GHz. Some atmospheric turbulence parameters comparable with earlier results have also been derived. The results demonstrate
sharp gradients of radio refractive index, layer structures and the variability of the boundary layer in time and space.
An erratum to this article is available at . 相似文献
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分别在湖北省药姑山和九宫山的山头上开展GPS掩星观测实验,成功获取山基掩星观测数据,对掩星事件进行了分析和统计.给出利用山基掩星观测数据反演大气折射指数剖面和电波弯曲角的原理和算法.利用山基GPS掩星观测模拟数据,对反演方法进行试算和检验,结果表明反演方法准确可行.将该反演方法应用于观测数据的反演,获得了观测点高度以下的大气折射率剖面,以及电波弯曲角.实验结果和原理研究表明,山基掩星观测技术是一种潜在的低层大气环境监测新技术. 相似文献
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In the present reported study, the vertical distributions of local atmospheric refractivity were retrieved from ground- based GPS observations at low elevation angles. An improved optimization method was implemented at altitudes of 0-10 km to search for a best-fit refractivity profile that resulted in atmospheric delays most similar to the delays calculated from the observations. A ray-tracing model was used to simulate neutral atmospheric delays corresponding to a given refractivity profile. We initially performed a ＂theoretical retrieval＂, in which no observation data were involved, to verify the optimization method. A statistical relative error of this ＂theoretical retrieval＂ （-2% to 2%） indicated that such a retrieval is effective. In a practical retrieval, observations were obtained using a dual-frequency GPS receiver, and its initial value was provided by CIRA86aQ_UoG data. The statistical relative errors of the practical retrieval range from -3% to 5% were compared with co-located radiosonde measurements, Results clearly revealed diurnal variations in local refractivity prc,files, The results also suggest that the general vertical distribution of refractivity can be derived with a high temporal resolution. However, further study is needed to describe the vertical refractivity gradient clearly. 相似文献
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中性大气折射延迟是激光测距技术的主要误差源.本文基于国际大地测量与地球物理联合会（IUGG）1999决议推荐的光学和近红外波段的大气折射率差理论模型,在Mendes（2004）理论的基础上,对某些理论公式进行了重新推导,给出了大气折射率差静力学和非静力学分量的实用表达式.推导出了大气折射率差的级数展开式,并保留至波长的负6次方项;同时在水气引起的折射率差上加上了频率改正项.计算发现,水气项中的频率改正对折射率差的贡献是不可忽略的.本文工作可为空间大地测量,特别是激光测距技术的研究提供一定的参考和依据. 相似文献
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