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对流层延迟是卫星导航定位的主要误差源,气象观测的数值预报资料可用来计算对流层延迟改正量.本文通过分布于亚洲地区的49个GPS台站一年的实测ZTD资料,对利用欧洲中尺度天气预报中心(ECMWF)分析资料、美国国家环境预报中心(NCEP)再分析资料和NCEP预报资料,计算对流层天顶延迟(ZTD)改正的有效性和可能达到的精度进行了评估,分析了ECMWF和NCEP在亚洲地区的适用程度和其分辨率对计算ZTD精度的影响.研究结果表明:(1)相对于GPS实测ZTD,用ECMWF资料计算ZTD的bias和rms分别为-1.0cm和2.7cm,优于NCEP再分析资料,可用于高精度ZTD研究和应用;NCEP预报数据计算ZTD的bias和rms分别为2.4cm和6.8cm,足以满足广大GNSS实时导航定位用户对流层延迟改正的需要.(2)bias和rms呈现明显的季节性变化,总体上夏季大,冬季小;在空间分布上随着纬度的变化不明显,但随高度的增加rms总体上有递减趋势.另外还发现,亚洲东部地区夏季日平均bias和rms和南部热带地区冬季的日平均bias和rms变化相对较大.(3)ECMWF2.5°和0.5°的资料进行了对比分析,发现0.5°分辨率资料的rms比2.5°减小1～5mm.这些结果,为在亚洲地区的空间大地测量、导航定位和INSAR等工作中,应用ECMWF/NCEP的资料进行对流层大气延迟改正的有效性和可能达到的精度提供了重要参考.
Tropospheric delay is the main source of error for satellite navigation and location, and the meteorological observation data can be used to calculate the tropospheric delay correction.Through one year’s measured ZTD data of 49 GPS stations distributed in Asia, (ECMWF), NCEP reanalysis data and NCEP forecast data to evaluate the validity and possible accuracy of tropospheric zenith delay (ZTD) correction, and analyzed the relationship between ECMWF and NCEP The application degree of ZTD in Asia and the resolution of ZTD.The results show that: (1) The bias and rms of ZTD calculated from ECMWF data are -1.0cm and 2.7cm, respectively, compared with the measured ZTD of GPS, which is better than NCEP reanalysis data can be used for high-precision ZTD research and application. The bias and rms of ZTD calculated by NCEP forecast data are 2.4cm and 6.8cm, respectively, which are enough to meet the needs of users of GNSS real-time navigation tropospheric delay correction. (2) bias and rms showed obvious seasonal changes, the overall summer big, small winter; spatial distribution with the latitude is not obvious, but with the increase of height rms overall decreasing trend. In addition, the average daily bias and rms in summer in eastern Asia and the average daily bias and rms in winter in southern tropical regions are relatively large. (3) The data of ECMWF 2.5 ° and 0.5 ° have been compared and found to be 0.5 ° resolution The rms of the rate data is reduced by 1 ~ 5 mm from 2.5 °. These results are intended to validate and possibly reach the application of ECMWF / NCEP data to atmospheric tropospheric delay correction in space geodesy, navigation and positioning and INSAR in Asia Accuracy provides an important reference.