亚洲地区EGNOS天顶对流层延迟模型的精度评估

PRECISION ASSESSMENT OF ZENITH TROPOSPHERIC DELAY CALCULATED FROM EGNOS MODEL OVER ASIAN AREA

基于亚洲地区48个IGS站2009—2011年实测的天顶对流层延迟(ZTD)数据,对利用EGNOS模型计算的ZTD的精度进行评估,结果表明:1)在亚洲地区,相对于IGS站实测的ZTD,EGNOS模型计算的ZTD的偏差和均方根分别为-0.18 cm和5.98 cm,在中国地区分别为0.81 cm和6.13 cm;2)偏差和均方根差呈现明显的季节变化,偏差表现为夏季最大,秋季最小,而均方根夏季最大,冬季最小;3)在空间分布上,偏差与纬度和高程变化无明显规律,但均方根随着高程或者纬度的增加总体上呈递减趋势,西部和北部高纬度地区,年均偏差和均方根变化相对较小;4:)亚洲南部低纬度地区和东部地区夏季日平均偏差和均方根差变化相对较大。

The tropospheric delay is a main error source for the global satellite navigation and positioning, and the EGNOS model can be used to calculate the zenith tropospheric delay. The Zenith Tropospheric Delay （ZTD） data observed from 48 International GNSS system （IGS） sites which distributed in Asian area are used to assess the effectiveness and accuracy of ZTD calculated from EGNOS model in 2009-2011, and the application of the EGNOS model is also analyzed in Asian area. The results show：l ） relative to IGS observed ZTD, the bias and Root Mean Square （RMS） for ZTD calculated from the EGNOS model are -0.18 cm and 5.98 cm respectively in Asian area, and the bias and RMS are 0.81 cm and 6.13 cm respectively in China. 2） The bias and RMS show a obvious sea- sonal variation. The bias generally shows the largest value in the summer and the smallest values in the autumn, while the RMS shows the largest value in the summer and the smallest values in the winter. 3 ） The relation between the bias and the altitude or latitude is not obvious, but the RMS decreases with the increasing altitude or latitude, and the bias and RMS show a relative smaller valves in high latitude of the northern and western areas. 4） The daily bias and RMS at low latitude of southern area and eastern area in the summer have a relatively larger variation.