基于地基GPS与MODIS遥感影像的映射函数与大气可降水汽分析

Analysis of Mapping Function and Atmospheric Precipitable Water Vapor Based on Ground GPS and MODIS Remote Sensing Image

为了提高短期和中小尺度灾害性天气可降水汽预报的准确性和实时性,利用西安地基GPS数据和MODIS遥感影像,采用NMF、GMF和VMF1映射函数设计了4种获取天顶干延迟初始值的方案,探讨了映射函数对计算天顶总延迟的影响。结果表明:在卫星高度角为10°时,VMF1映射函数反演效果和精度最佳,GMF映射函数次之,NMF映射函数最弱,而在卫星高度角为15°时,上述3种映射函数效果相当。最后,结合综合水汽含量与可降水汽的关系,通过计算地基GPS和MODIS遥感影像综合水汽含量,得到了地基GPS和MODIS遥感影像可降水汽(PPWV-GPS,PPWV-MODIS),并拟合了二者之间的线性关系,结果为PPWV-MODIS=1.421 7PPWV-GPS-2.143,相关系数为0.952 1。

In order to improve the accuracy and real-timing for forecasting precipitable water vapor of disastrous weather in mesoscale and microscale,ground GPS data and MODIS remote sensing image in Xi＇an were used to design four schemes for obtaining the original value of zenith dry delay with NMF,GMF and VMF1 mapping functions,and the effect of mapping function on calculating zenith total delay was discussed.The results showed that when the elevation of satellite was 10°,retrieval effect and precision of VMF1,GMF and NMF mapping functions were best,middle and weak,respectively;however,the three mapping functions were considerable when the elevation of satellite was 15°.Finally,integrate water vapors of ground GPS and MODIS remote sensing image were calculated,and then precipitable water vapors（PPWV-GPS,PPWV-MODIS） were calculated according to the relationship between integrate and precipitable water vapors;the relationship of precipitable water vapor between ground GPS and MODIS remote sensing image were fitted into linear function PPWV-MODIS=1.421 7PPWV-GPS-2.143,and the related coefficient was 0.952 1.