北半球区域对流层延迟模型研究

发布时间：2018-08-14 18:25

【摘要】：在卫星导航精密定位中,对流层延迟是影响其精度的主要因素之一。对于对流层延迟误差的消除和削弱,目前国内外主要有外部修正法、差分法、模型修正法以及参数估计法四种方法。而在实际应用中,模型修正法应用最广泛。本文在详细分析时空变化对对流层延迟影响的基础上,基于Hopfield模型建立了北半球区域对流层延迟函数模型。主要内容与成果如下:(1)基于美国怀俄明大学网站提供的全球探空站实测气象数据提取北半球对流层延迟。详细阐述了北半球区域大气折射率指数,分析其随高度变化特征。实验分析发现折射率指数随高度变化呈现明显分段负指数关系,因此利用分段负指数函数对大气折射率指数进行拟合,求出对流层延迟。(2)基于VMF1全球格网对流层延迟产品对全球探空气象站进行插值得到对流层延迟,与探空数据求得的对流层延迟比较,分析对流层延迟近似真值的可靠性。研究发现,利用探空数据提取的对流层延迟精度在4mm左右,而目前经验模型的精度大约为3-7cm,因此探空数据提取的对流层延迟可视为近似真值,利用该近似真值进行后期对流层延迟区域建模。(3)顾及纬度参数的HL对流层模型研究。分析北半球不同空间上对流层延迟的差异,发现纬度对对流层延迟具有显著影响,相同纬度,不同经度对对流层延迟的影响不大。同时研究对流层延迟的季节性变化发现,对流层延迟随着时间的推移呈现出明显的周期性或半周期性特征。在此基础上,基于Hopfield模型提出一种顾及纬度参数的新改正模型HL模型,并给出了HL模型的具体函数表达式。(4)HIL模型精度分析。以探空数据提取的对流层延迟作为真值,对比分析Hopfield、Saastamoinen、HL三种模型,实验结果表明:Hopfield模型、Saastamoinen模型以及HL模型的平均精度分别为±31.85mm、±34.37mm以及±25.58mm,HL模型相对于Hopfield模型平均提高了 19.7%,在11月份提高了 27.5%;HL模型相对于Saastamoinen模型平均提高了 25.6%,在3月份提高了 30.1%。
[Abstract]:Tropospheric delay is one of the main factors affecting the precision of satellite navigation. For the elimination and weakening of tropospheric delay error, there are four main methods at home and abroad: the external correction method, the difference method, the model correction method and the parameter estimation method. In the practical application, the model modification method is the most widely used. Based on the detailed analysis of the effect of temporal and spatial changes on tropospheric delay, a regional tropospheric delay function model in the Northern Hemisphere is established based on Hopfield model. The main contents and results are as follows: (1) the tropospheric delay in the Northern Hemisphere is extracted from the global sounding station meteorological data provided by the University of Wyoming website. The regional atmospheric refractive index in the Northern Hemisphere is described in detail, and its variation characteristics with height are analyzed. The experimental results show that the index of refractive index varies with the height, so the piecewise negative exponent function is used to fit the index of refraction index of the atmosphere. (2) based on the VMF1 global grid tropospheric delay product, the tropospheric delay is obtained by interpolating the global sounding meteorological station. Compared with the tropospheric delay obtained from the sounding data, the reliability of the tropospheric delay approximation is analyzed. It is found that the accuracy of tropospheric delay extracted from sounding data is about 4mm, but the accuracy of empirical model is about 3 ~ 7 cm, so the tropospheric delay extracted from sounding data can be regarded as an approximate true value. The approximate true value is used to model the late troposphere delay region. (3) HL tropospheric model considering latitude parameters is studied. By analyzing the difference of tropospheric delay in different space in the Northern Hemisphere, it is found that latitude has a significant effect on tropospheric delay, and at the same latitude, different longitude has little effect on tropospheric delay. At the same time, the seasonal variation of tropospheric delay is studied. It is found that tropospheric delay shows obvious periodic or semi-periodic characteristics with the passage of time. On this basis, based on the Hopfield model, a new correction model HL model considering latitude parameters is proposed, and the specific functional expression of HL model is given. (4) the accuracy analysis of HIL model. Taking the tropospheric delay extracted from the sounding data as the true value, three models of Hopfield Saastamoinen HL are compared and analyzed. The experimental results show that the average accuracy of Saastamoinen model and HL model are 卤31.85 mm, 卤34.37mm and 卤25.58 mm respectively, which are 19.7mm higher than that of Hopfield model, 25.6mm higher than Saastamoinen model in November and 30.1mm higher than that of Saastamoinen model in March.
【学位授予单位】：东南大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：P228.4

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