中国区域融合地基GNSS等多种资料水汽反演、变化分析及应用

发布时间：2018-05-02 03:24

本文选题：全球导航系统 + 水汽　；参考：《武汉大学》2016年博士论文

【摘要】：水汽是大气中含量最为丰富的一种温室气体,在维持地球适宜生命生存的温度环境和水文循环中扮演着至关重要的角色。水汽在大气中含量的分布与变化深刻地影响着全球各地的气候环境和天气特征。然而不同于大气中的其他温室气体(如二氧化碳),水汽在大气中的含量具有复杂的空间和时间变化,因此难以精确测定、建模及预报。中国位于世界上最大的大陆板块(欧亚大陆板块)和最大的海洋(太平洋)交接处,地域跨度大且地形变化复杂,气候类型丰富,天气变化多端,因此中国区域上空的水汽含量分布与变化具有其独特性和复杂性。一些大尺度的气候现象(如厄尔尼诺和东亚季风等)对中国区域大气状况影响显著,加之每年频发的自然灾害天气(如台风和暴雨等)的发生、发展和消亡均与水汽含量的变化息息相关。因此对中国区域上空水汽分布和变化的研究和监测对进一步地理解中国区域气候变化特征、推动中国区域气候研究及改进天气预报等方面有十分重要的科学价值和现实意义。地基GNSS水汽反演技术是一种利用GNSS卫星信号在大气中的传播延迟来反演大气中水汽含量的技术,相比于其他水汽观测手段,地基GNSS具有高精度、全天候、低成本、高时间分辨率且长时间测量结果一致性好的优势。本文以中国陆态网GNSS基准站观测数据为主,综合利用地面气象站记录、气象再分析资料和radiosonde资料等,从中国区域上空水汽分布特征、各种时间尺度周期信号、水汽变化主导因素、水汽变化与其他气候天气现象关联、对radiosonde资料和气象再分析资料水汽误差评定、对流层相关模型建模以及地基GNSS在极端灾害天气研究和预报中的应用等方面进行细致深入的研究。主要的研究成果和内容有：(1)采用武汉大学开发的PANDA软件PPP模块处理了中国陆态网1999～2015年的GNSS观测数据,获得了中国区域各测站上空该时段的ZTD时间序列,平均精度约为3.9mm(与IGS事后ZTD产品精度相当)。由于陆态网测站气象观测不完整,论文综合利用了GNSS测站处的气象观测、.GNSS测站周边气象站气压记录和气象再分析资料获取各GNSS测站处的气压,并基于气象再分析资料获取各测站上空的水汽加权平均温度Tm,两者误差RMS分别为0.7hPa和1.8K。将ZTD转换为PW,并根据PW误差估计模型估计得到PW产品的平均误差约为0.98mm。(2)基于所获PW产品,研究了中国区域1999～2015年间水汽的地理分布和变化：水汽的平均含量与地表气温分布有很强的正相关,在华南地区含量最为丰富(PW约为50mm),而在青藏高原地区最低(PW小于20mm)；周年变化振幅和半周年变化振幅峰值分别在长江中下游区域和华北平原,而最小值分别在青藏高原和西南地区；天变化方面,水汽在一天当中的峰值时刻相对较为固定,而最低值时刻随四季有所变化。(3)基于所获PW产品,通过分析实测PW与仅考虑温度变化的模型PW之间的相关性,研究了不同气候类型区域水汽变化的主导因素(热力学或动力学因素)。结果表明南海南沙附近水汽变化几乎仅由动力学因素主导,而亚热带和温带季风气候区域主要由热力学因素所主导；而其他区域两种因素的作用相当。通过分析中国沿海地区测站水汽长期变化信号与SOI指数之间的相关性,研究了水汽变化与ENSO现象的关联,结果表明了ENSO现象主要对中国热带地区上空水汽含量的长期变化有较直接的影响。(4)基于所获PW产品,对中国区域1999～2015年期间的radiosonde水汽观测资料按类型(GZZ2、GTS1、GTS1-1和GTS1-2)进行了误差评估。结果显示早期广泛使用的GZZ2类型测量的水汽普遍偏湿,而后期更换的GTS1和GTS1-1普遍偏干,GTS1-2未表现出明显干湿偏差。因此,同一radiosonde测站由于仪器的更换会给基于radiosonde历史观测资料获得的水汽长期变化趋势估值引入虚假的下降信号。气象再分析资料(ERA-Interim)由于同化了未经修复的radiosonde资料,其水汽长期变化趋势估值同样受到了不一致问题的影响。(5)利用ERA-Interim产品,充分考虑了模型复杂性和模型精度,建立了CPT模型,相比于目前国际上通用的GPT和GPT2(5°和1°)模型,在中国区域先验气压误差RMS由5.92、5.14和5.04hPa减小为3.76hPa,先验温度误差RMS由5.95、4.25和4.14K减小为4.07K。而相比于ITG模型,CPT模型参数个数减少了一半。建立了中国区域先验Tm模型和Tm-Ts转换模型,相比于Bevis转换模型和GPT2先验模型,Tm误差RMS从4.45和4.19K减小为3.81和2.97K。(6)构建了中国区域实时ZTD格网产品,能够为中国区域任意测站提供平均精度约为1.5cm的实时ZTD先验改正,可显著加快实时PPP用户的收敛速度：对于BDS实时PPP用户,三维方向收敛时间可缩短20%,高程方向更加明显(可缩短约50%)。(7)针对2016年6月23日江苏阜宁超强龙卷风事件,使用地基GNSS观测资料分析了此次事件发生前后测站上空ZTD的时空变化特征。利用WRF3DVAR数据同化系统,讨论了地基GNSS观测在改善此次事件发生的天气背景相关变量(累积降雨量)短期预报可靠性的作用。
[Abstract]:Water vapor is the most abundant greenhouse gas in the atmosphere, which plays a vital role in maintaining the temperature and hydrological cycle of the earth's suitable life. The distribution and change of water vapor in the atmosphere profoundly affect the climate and weather characteristics around the world. However, it is different from other greenhouse gases. Gas (such as carbon dioxide), the content of water vapor in the atmosphere has complex spatial and temporal variations, so it is difficult to accurately determine, model and predict. China is located at the junction of the largest continental plate (Eurasian plate) and the largest ocean (Pacific) in the world, with large spans and complex topographic changes, rich climate types and weather changes. The distribution and variation of water vapor content over China's region has its unique characteristics and complexity. Some large scale climate phenomena, such as the El Nino and East Asian monsoon, have a significant impact on the regional atmospheric conditions in China, and the occurrence of frequent natural disasters (such as typhoon and rainstorm), development and extinction are all with water vapor. Therefore, it is of great scientific and practical significance to study and monitor the distribution and change of water vapor over the region of China. It is of great scientific and practical significance to further understand the characteristics of regional climate change in China, promote the study of regional climate and improve the weather forecast in China. The technology of GNSS water vapor inversion is a kind of use of GNSS Wei. In comparison with other methods of water vapor observation, the foundation GNSS has the advantages of high precision, all-weather, low cost, high time resolution and good consistency of the long time measurement results. This paper uses the observation data of the Chinese terrestrial network GNSS datum station as the main method, and makes comprehensive use of the ground gas. Image station records, meteorological reanalysis data and radiosonde data, from the characteristics of water vapor distribution over the region of China, a variety of time scale periodic signals, water vapor change leading factors, water vapor changes associated with other climate weather phenomena, water vapor error assessment for radiosonde data and meteorological reanalysis data, modeling of tropospheric correlation models and ground The main research results and contents are as follows: (1) the PANDA software PPP module developed by Wuhan University has been used to deal with the GNSS observation data of China land network for 1999~2015 years, and the ZTD time series over the period of each station in the central region is obtained. The average accuracy is about 3.9mm (equivalent to the IGS ZTD product precision). Because the meteorological observation of the land network station is incomplete, the paper comprehensively uses the meteorological observation at the GNSS station, and obtains the gas pressure at the GNSS stations at the meteorological stations around the.GNSS station, and obtains the above stations on the basis of the meteorological reanalysis data. The weighted average temperature of water vapor is Tm, and the error RMS is 0.7hPa and 1.8K. to convert ZTD to PW respectively. According to the PW error estimation model, the average error of PW product is estimated to be 0.98mm. (2) based on the PW products obtained, and the geographical distribution and change of water vapor in China region for 1999~2015 years are studied: the average content of water vapor and the surface temperature are divided. It has a strong positive correlation. In Southern China, the most abundant (PW is 50mm), and the lowest (PW less than 20mm) in the Qinghai Tibet Plateau; the amplitude and peak amplitude peak of the annual variation amplitude and the half year anniversary are respectively in the middle and lower reaches of the Yangtze River and the North China Plain respectively, and the minimum values are in the Qinghai Xizang Plateau and the southwest region respectively. The peak time is relatively fixed and the minimum time varies with the four seasons. (3) based on the correlation between the measured PW and the model PW only considering the temperature change, the dominant factors (thermodynamic or kinetic factors) in different climate types are studied based on the obtained PW products. The results show that the water near Nansha in the South China Sea is water. The variation of steam is dominated by the dynamic factors, while the subtropical and temperate monsoon climate regions are dominated by the thermodynamic factors, while the two factors in other regions are the same. By analyzing the correlation between the long change signals of water vapor and the SOI index in the coastal areas of China, the correlation between the water vapor change and the ENSO phenomenon is studied. The results show that the ENSO phenomenon has a direct impact on the long-term changes in the water vapor content over the tropical regions of China. (4) based on the PW products obtained, the radiosonde water vapor observation data for the period of 1999~2015 years in China were evaluated by type (GZZ2, GTS1, GTS1-1 and GTS1-2). The results showed the early widely used GZZ2 type measurement. The amount of water vapor is generally wet, and the later replacement of GTS1 and GTS1-1 is generally dry, and the GTS1-2 does not show obvious dry and wet deviations. Therefore, the same radiosonde station will introduce a false descent signal to the estimation of the long term variation trend of water vapor based on the historical observation data based on radiosonde. The meteorological reanalysis data (ERA-Interim) Because of the assimilation of unrepaired radiosonde data, the estimation of the long-term variation trend of water vapor is also affected by the inconsistency. (5) using the ERA-Interim products, the model complexity and model accuracy are fully considered, and the CPT model is established. Compared to the current international GPT and GPT2 (5 and 1 degrees) model, the regional transcendental gas is in China. The pressure error RMS is reduced from 5.92,5.14 and 5.04hPa to 3.76hPa, and the prior temperature error RMS is reduced from 5.95,4.25 and 4.14K to 4.07K., and the number of CPT model parameters is reduced by half. The regional priori Tm model and the Tm-Ts conversion model in China are established. Compared with the transition model and the prior model, the error decreases from 4.45 and decreases. Small for 3.81 and 2.97K. (6), a Chinese regional real-time ZTD grid product is built, which can provide a real time ZTD prior correction of an average precision of about 1.5cm for any regional station in China. It can significantly speed up the convergence rate of real-time PPP users. For BDS real-time PPP users, the convergence time of three-dimensional direction can be shortened by 20% and the direction of elevation is more obvious (can be shortened approximately. 50%) (7) according to the super Tornado Event in Funing, Jiangsu, Jiangsu in June 23, 2016, the temporal and spatial variation characteristics of ZTD over the station before and after the event were analyzed by using the ground-based observation data. The WRF3DVAR data assimilation system was used to discuss the short-term weather background related variables (accumulated rainfall) in the improvement of this event. The function of predicting reliability.

【学位授予单位】：武汉大学
【学位级别】：博士
【学位授予年份】：2016
【分类号】：P228.4;P412

【参考文献】