利用全球大地观测系统（Global Geodetic Observing System，GGOS）大气（Atmosphere）的加权平均温度（瓦。）数据和欧洲中尺度天气预报中心（European Centre for Medium—Range Weather Forecasts，ECMWF）的地表温度数据在全球范围内计算了利用全球导航卫星系统（Global Navigation Satellite System，GNSS）反演水汽中的关键参数加权平均温度瓦，，与地表温度瓦的相关系数，结果显示二者的相关性主要受纬度影响，在高纬度地区较强，在低纬度地区较弱．虽然二者的相关性在赤道地区较弱，但这些区域的温度变化幅度较小，在这些区域利用线性回归模型建模依然可以取得较好的结果．在此基础上，本文利用2005～2011年的全球大地观测系统大气的L数据和欧洲中尺度天气预报中心的瓦数据按纬度建立了全球分区域线性回y-3模型．来自全球大地观测系统，气象、电离层和气候的星座观测系统（Constellation Observing System of Meteorology，Ionosphere and Climate，COSMIC）以及无线电探空（Radiosonde）的数据对模型的检验表明，新模型与这3种不同源数据都能较好吻合，分别取得了3．2，3.3和4．4K的均方根误差，精度明显优于BevisEl广瓦关糸模型．
The importance of water vapor in research of global climate change and weather forecast cannot be over emphasized; therefore substantial efforts have been made in exploring the optimal methods to measure water vapor. It is well-established that with a conversion factor, zenith wet delays can be mapped onto precipitable water vapor(PWV). However, the determination of the exact conversion factor depends heavily on the accurate calculation of a key variable, weighted mean temperature of the troposphere(T_m). As a critical parameter in Global Positioning System(GPS) meteorology, T_m has recently been modeled into a global grid known as GWMT. The GWMT_model only requires the location and the day of year to calculate T_m. Despite the advantages that the GWMT_model offers, anomalies still exist in oceanic areas due to low sampling resolution. In this study, we refine the GWMT_model by incorporating the global T_m grid from Global Geodetic Observing System(GGOS) and obtain an improved model, GWMT-G. The results indicate that the GWMT-G model successfully addresses the anomaly in oceanic areas in the GWMT_model and significantly improves the accuracy of T_m in other regions.
反距离加权内插法是一种普遍使用的电离层总电子含量(total electron content,TEC)内插方法,但其受站间距影响较大,大范围内插值所需站点数量较多。针对同经向分布下的站点,利用电离层在同经度分布下具有从高纬度到低纬度递减的特征,对电离层TEC进行经向多项式拟合并内插。经统计,插值偏差的均方根(root mean square,RMS)在3 TECU以内,满足定位过程中对电离层延迟估计的要求,同时该方法扩大了站间距,实现了大范围内实时TEC内插。
