针对天顶对流层干延迟(ZHD)的3种通用模型,即Saastamoinen模型、Hopfield模型和Black模型,构建基于探空数据的Radiosonde方法来解算ZHD并将其作为真值,在北美夏季中纬度地区真实大气和标准大气两种条件下,通过对比Radiosonde方法与3种通用模型计算的ZHD结果,对3种通用模型进行高程适用性分析.结果表明,3种通用模型都适用于0～30 km的高度,Black模型和Saastamoinen模型的精度相近,Hopfield模型精度最差.最后,构建高气压变化范围的本地化短期ZHD-P模型.

Wi-Fi indoor positioning algorithms experience large positioning error and low stability when continuously positioning terminals that are on the move. This paper proposes a novel indoor continuous positioning algorithm that is on the move, fusing sensors and Wi-Fi on smartphones. The main innovative points include an improved Wi-Fi positioning algorithm and a novel positioning fusion algorithm named the Trust Chain Positioning Fusion (TCPF) algorithm. The improved Wi-Fi positioning algorithm was designed based on the properties of Wi-Fi signals on the move, which are found in a novel "quasi-dynamic" Wi-Fi signal experiment. The TCPF algorithm is proposed to realize the "process-level" fusion of Wi-Fi and Pedestrians Dead Reckoning (PDR) positioning, including three parts: trusted point determination, trust state and positioning fusion algorithm. An experiment is carried out for verification in a typical indoor environment, and the average positioning error on the move is 1.36 m, a decrease of 28.8% compared to an existing algorithm. The results show that the proposed algorithm can effectively reduce the influence caused by the unstable Wi-Fi signals, and improve the accuracy and stability of indoor continuous positioning on the move.

水汽含量是大气的最重要变量之一.本文对地基GPS数据反演的PWV(Precipitable Water Vapor,可降水量,单位mm或cm)和MODIS数据反演的PWV结果进行了对比研究,得出了两者线性相关的结论.并对地基GPS数据反演的PWV和探空数据反演的PWV进行对比研究,验证了地基GPS数据反演PWV的精度在mm级别的结论.最后,本文应用最小二乘回归法,构建了一种基于GPS数据的MODIS大气PWV实时精度提高模型.

This paper introduces the basic situation of Groundbased GNSS-R Remote Sensing Experiment for Retrieval of Soil Moisture Content in China, including the experiment principles, experiment site, experiment equipment, data processing and accuracy analysis. During past two years, Peking University carried out a series of ground-based GNSS-R experiments for retrieval of SMC in Henan Zhengzhou (Jan. 2012), Sichuan Ruoergai (Aug. 2012), Sichuan Shifang (Aug. 2013) and Beijing (Sept. 2013). The results show that the retrieval accuracy of this series of experiments is approximately 85%. Therefore, it could be stated that this experiment in China is very successful and the data is reliable.

The new retrieval algorithm of MODIS atmospheric precipitable water vapor(PWV) was established to improve the retrieval precision based on the relationship between high-precision GPS PWV and MODIS near-IR three-channel ratio transmittance.With the use of MODIS data in Kansas State and Oklahoma State of USA between April and September 2009 and the corresponding SuomiNet GPS PWV,it's concluded that the MODIS PWV retrieved by Kaufman and Gao Bo-Cai algorithm was systematically lower than GPS PWV with a relatively large error.Setting the high-precision GPS PWV as the standard,the relationship between GPS PWV and MODIS near-IR three-channel ratio transmittance of the 19th channel was researched,and the MODIS PWV new retrieval algorithm was established.Data of the study area was used for experimental verification,which showed that the new algorithm can greatly improve the retrieval precision of MODIS PWV.

Set the high-precision GPS PWV as the standard,the MODIS near-IR water vapor new retrieval algorithms were researched and established to improve the retrieval precision.With the comparison research of MODIS near-IR water vapor in Kansas State and Oklahoma State of USA between April and September 2009 and the corresponding SuomiNet GPS PWV,it′s concluded that MODIS PWV retrieved by Kaufman and Gao Bo-Cai algorithm changed consistently with GPS PWV but was systematically lower than GPS PWV,with a relatively large error.Based on the linear regression relationship between GPS PWV and MODIS PWV retrieved by the Kaufman and Gao Bo-Cai algorithm,relationship between GPS PWV and MODIS near-IR two-channel ratio transmittance of the 19th channel,the improved retrieval algorithms based on MODIS near-IR two-channel ratio were established.Data of the study area were used for experimental verification,which showed that the improved algorithms can greatly improve the retrieval precision of MODIS PWV.