地基GPS层析水汽三维分布研究

发布时间：2018-10-24 08:39

【摘要】：水汽是大气中最活跃的部分,而且水汽分布是动态变化的,它和长时间持续性降水,热带气旋,中纬度气旋风暴,雷电暴雨等气象现象密切相关。这些灾害性的天气现象可能给社会经济造成巨大的损失。因此,获得高精度的,高时空分辨率的水汽信息对气象学和天气预报具有非常重要的意义。本文使用四川区域的GPS数据对水汽三维分布展开了一系列的实验研究。主要内容如下： (1)西南交通大学徐韶光博士自主研发了精密定位与定轨软件(PLAOD软件),利用PLAOD软件解算得到的天顶总延迟精度较高,满足水汽反演的精度要求。验证了PLAOD软件作为本论文后续研究工作的解算软件是可靠且可行的。 (2)实验对比了事后精密星历和事后精密钟差,快速精密星历和快速精密钟差,超快速预报星历和快速精密钟差三种组合方案均能达到水汽反演的精度,根据本文情况选择了精度较高,时间延迟相对较小的快速精密星历和快速精密钟差的组合方案以满足近实时的水汽三维层析的要求。结合本文实际情况,设置高度角为100,采用NMF映射函数,选择投影法计算GPS斜路径延迟,选择Kalman滤波算法解算层析方程组。 (3)选择四川地区的巴中、达县、广安、南江、营山五个站点组成的GPS网络作为研究区域,水平方向划分为6×4=24个网格,分别以800m和1000m垂直分辨率的垂直均匀分层方法层析得到的水汽密度廓线与探空反演的水汽密度廓线很接近,初步表明,在相关系数都很高的情况下,两种分辨率得到的层析结果近似。对于低层对流层水汽的研究,800m的垂直分辨率反映的水汽特征更明显。 (4)研究了垂直分层方式对层析结果的影响,依据大气水汽随着高程变化的特点,提出了一种垂直不均匀分层方法。实验结果显示垂直不均匀分层方式层析获得的水汽密度廓线要好于垂直均匀分层方式,与探空计算的水汽密度廓线更吻合。考虑到水汽主要集中在对流层中低层,垂直不均匀分层时,对流层低层的垂直分辨率相对较高,得到的大气水汽的变化特征更加细致,更能反映出对流层低层大气水汽的变化特征。四川地区的水汽层析实验研究结果表明本文提出的垂直不均匀分层方法是可行的。 (5)通过实验研究了层析初值对层析结果的影响,层析初值存在±50%的偏差时,利用Kalman滤波解算得到的水汽垂直信息跟探空资料仍然能够较好的符合,得到正确可靠的水汽垂直方向的信息,说明Kalman滤波算法用于水汽三维分布层析对层析初值不敏感,其结果忠实于GPS的原始观测数据。实验分析了GPS站点数量对层析结果的影响,结果表明合理的格网划分和较多的测站数量是获得较好层析结果的前提条件。最后给出了四川地区构建的GPS网络的三维水汽层析分布图,从三维水汽层析分布图可以直观而清晰看出水汽主要集中在3km以下区域,中低层水汽量大,分布不均匀,高层水汽量较小,分布也较为均匀,3km以上总体上随着高度增加水汽量逐渐减少,但其中也可能会出现逆湿的反复现象。
[Abstract]:Water vapor is the most active part of the atmosphere, and the distribution of water vapor is dynamic. It is closely related to long-term persistent precipitation, tropical cyclone, middle latitude cyclone storm, thunder storm and other meteorological phenomena. These disastrous weather phenomena may cause huge losses to the socio-economic. Therefore, it is very important to obtain high-precision and high-spatial resolution water vapor information for meteorology and weather forecast. In this paper, a series of experimental studies have been carried out on the three-dimensional distribution of water vapor using GPS data in Sichuan area. The main contents are as follows: (1) Dr. Xu Shaoguang, Southwest Transportation University, independently developed precise positioning and orbit determination software (PLAOD software). The total delay accuracy of zenith total delay calculated by PLAOD software is high, and the accuracy of water vapor inversion is satisfied. Requirement. Verify that PLAOD software is reliable and can be used as a solution to the follow-up work of this paper In this paper, the accuracy of the water vapor inversion can be achieved by comparing the accurate ephemeris and the accurate clock difference, the fast precise ephemeris and the fast precision clock difference, the ultra-fast forecast ephemeris and the fast precision clock difference, and according to the situation, the accuracy of the water vapor inversion can be achieved. The combination scheme of fast precise ephemeris and fast precise clock difference with higher precision and relatively small time delay can be used to meet the three-dimensional water vapor in the near real-time. According to the actual situation of the paper, the height angle is set to 100, the NMF method is adopted, the projection method is adopted to calculate the GPS oblique path delay, and the Kalman filtering algorithm is selected to solve the problem. The chromatographic equation system. (3) Select the GPS network composed of five stations in Badzhong, Dxian, Guang 'an, Nanjiang and Yingshan in Sichuan area as the research area, and the horizontal direction is divided into 6. The water vapor density profile line obtained by the vertical homogeneous delamination method with 800m and 1000m vertical resolution is very close to the water vapor density profile of the sounding inversion. The results show that the two resolutions are very high when the correlation coefficients are very high. The chromatographic results obtained are approximate. The vertical resolution of 800m is reflected for the study of low-layer tropospheric water vapor (4) The influence of vertical layering on the chromatographic results is studied, and the characteristics of atmospheric water vapor along with the elevation change are studied. The invention relates to a vertical non-uniform layering method, and the vertical resolution of the lower layer is relatively high when the water vapor is mainly concentrated in the lower layer and the vertical non-uniform layer in the middle layer, so that the obtained atmospheric water vapor has more detailed characteristics, The changes of atmospheric water vapor in lower layers. The experimental results of water vapor chromatography in Sichuan area show that this paper is vertical. The method is feasible. (5) Through the experiment, the influence of the initial value on the chromatographic results is studied, and when the initial value of the chromatographic initial value is less than 50%, the vertical information and the sounding data obtained by Kalman filtering can still be well met and obtained. The accurate and reliable information about the vertical direction of water vapor shows that the Kalman filtering algorithm is applied to the three-dimensional distribution chromatography of water vapor and is insensitive to the initial value of chromatography, The effect of the number of GPS stations on the chromatographic results is analyzed, and the results show that the reasonable grid division and the larger number of columns It is the precondition of obtaining better chromatographic results. Finally, the three-dimensional water vapor chromatographic profile of the GPS network built in Sichuan area is given. From the three-dimensional water vapor chromatographic profile, it can be seen clearly and clearly that the water vapor is mainly concentrated in the area below 3km, and the water vapor in the middle layer is large and the distribution is uneven, the amount of high-rise water vapor is small, the distribution is even more uniform,
【学位授予单位】：西南交通大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：P228.4;P412.13

【参考文献】