An initial investigation of the non-isotropic feature of GNSS tropospheric delay  

作　　者：Ying Xu Zaozao Yang Hongzhan Zhou Fangzhao Zhang 

机构地区：[1]College of Geodesy and Geomatics,Shandong University of Science and Technology,579 Qianwangang Road,Qingdao,266590,Shandong,China

出　　处：《Satellite Navigation》2024年第1期155-167,共13页卫星导航（英文）

基　　金：supported by the National Natural Science Foundation of China(No.42174035).

摘　　要：Tropospheric delay is a significant error source in Global Navigation Satellite Systems(GNSS)positioning.Slant Path Delay(SPD)is commonly derived by multiplying Zenith Tropospheric Delay(ZTD)with a mapping function.However,mapping functions,assuming atmospheric isotropy,restrict the accuracy of derived SPDs.To improve the accuracy,a horizontal gradient correction is introduced to account for azimuth-dependent SPD variations,treating the atmosphere as anisotropic.This study uncovers that,amidst atmospheric dynamics and spatiotemporal changes in moisture content,the SPD deviates from that based on traditional isotropy or anisotropy assumption.It innovatively introduces the concept that SPD exhibits non-isotropy with respect to azimuth angles.Hypothesis validation involves assessing SPD accuracy using three mapping functions at five International GNSS Service(IGS)stations,referencing the SPD with the ray-tracing method.It subsequently evaluates the SPD accuracy with horizontal gradient correction based on Vienna Mapping Function 3(VMF3)estimation.Lastly,the non-isotropic of SPD is analyzed through the ray-tracing method.The results indicate the smallest residual(1.1–82.7 mm)between the SPDs with VMF3 and those with the ray-tracing.However,introducing horizontal gradient correction yields no significant improvement of SPD accuracy.Considering potential decimeter-level differences in SPD due to non-isotropic tropospheric delay across azimuth angles,a precise grasp and summary of these variations is pivotal for accurate tropospheric delay modeling.This finding provides vital support for future high-precision tropospheric delay modeling.

关 键 词：Tropospheric delay GNSS Non-isotropy Mapping function RAY-TRACING Horizontal gradient ERA5 

分 类 号：TN967.1[电子电信—信号与信息处理]