中文摘要：

地区性的 ionospheric 模特儿被收养到 determinesatellite-plus-receiver 微分延期。satel-lite-plus-receiver 微分延期作为经常的价值被估计为每天。双频率的 GPS 伪范围 observ-ables 是 usedtocompute 垂直侦探(VTEC ) 。所有每月吝啬的 VTEC 侧面被在 2000 和 2004 之间的北京 IGS 地点的图 usingGPS 数据代表。VTEC 的每月平均的价值和振幅被图也代表。结果显示 VTEC 有季节的相关性。在 2000 的 VTEC 的每月平均的价值和振幅比那 in2004 大大约 2 倍。最大的 VTEC 价值在三月和 4 月被观察，当最小的 VTEC 价值在 12 月被观察时。季节的变化趋势被发现在多项式在 2000 和 2004 之间适合以后类似。

英文摘要：

The regional ionospheric model is adopted to determine satellite-plus-receiver differential delay. The satellite-plus-receiver differential delay is estimated as constant values for each day. Dual-frequency GPS pseudo-ranges observables are used to compute vertical TEC （VTEC）. All the monthly mean VTEC profiles are represented by graphs using GPS data of the Beijing IGS site between 2000 and 2004. The monthly averaged values and amplitudes of VTEC are also represented by graphs. The results indicate that the VTEC has seasonal dependency. The monthly averaged values and amplitudes of VTEC in 2000 are about 2 times larger than that in 2004. The maximum VTEC values are observed in March and April, while the minimum VTEC values are observed in December. The seasonal variations trend is found to be similar after polynomial fitting between 2000 and 2004.