SHAtrop：基于陆态网GNSS数据的中国大陆区域ZTD模型

SHAtrop:Empirical ZTD Model Based on CMONOC GNSS Network

对陆态网223个全球导航卫星系统(Global Navigation Satellite System,GNSS)测站6 a实测对流层天顶延迟(zenith total delay, ZTD)的时空特性进行了分析,结果表明,各测站ZTD平均值随大地高指数递减,衰减因子与纬度近似线性关系,其时域变化呈现年周期和半年周期,周期、振幅、初相位与地域分布有关。综合采用周期函数及格网函数,建立了中国大陆区域ZTD经验模型SHAtrop。模型提供区域内分辨率为2.5°×2.0°的格网,用户使用时,先在相应格网内插得到对应参数,再利用三角函数得到椭球面ZTD,最后利用指数函数计算ZTD。实测ZTD的数据验证结果表明,SHAtrop的均方根误差(root mean square,RMS)为3.4 cm,优于常见经验模型。SHAtrop采用较多测站,对高程改正更精细;使用时只需要输入经纬度与时间,使用方便,能满足中国区域GNSS用户实时定位导航的ZTD改正需求。

Modelling errors of tropospheric delay have much impact on the application of the Global Navigation Satellite System(GNSS). Temporal and spatial characteristics of the zenith tropospheric delay(ZTD)over China's Mainland are analyzed using the Crustal Movement Observation Network of China(CMONOC)GNSS network over 6 years. Annual ZTD of each site exhibits an exponential function of sites altitude in spatial frame, and the temporal variation exhibits both annual and semi-annual periods. Therefore, we establish a new empirical ZTD model: SHAtrop. It combines the exponential and periodical functions and is provided as grids covering China's Mainland with a resolution of 2.5°×2.0°. Using the SHAtrop model, the ZTD over the ellipsoid is firstly calculated using the gridded parameters, and then the sites true ZTD is derived using the exponential function. The validation using 220 GNSS sites over 6 years shows that the precision of SHAtrop is of 3.4 cm in root mean square(RMS) quantity. The SHAtrop is easy to implement,where the input parameters are the station’s location and time. Thanks to the use of the long ZTD time series of the densified GNSS network in China's Mainland, the SHAtrop has better performance and finer regional resolution.