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星载激光测高仪发射的激光脉冲在通过地球大气层时发生折射,导致激光路径的延长,为了获得高精度的测距结果,必须对大气延迟进行修正;而大气干项延迟在大气延迟中占主导作用,仅由测量位置的地表大气压力决定。通过推导静态大气在非理想气体条件下的流体静力学方程,得出地表气压与位势高度有关的大气压力模型,结合NCEP基于标准大气压层的气象数据和GLAS测量的时间经纬度和高程数据,对位势高度使用4阶Runge-Kutta算法进行数值积分得出地表气压,进而计算大气干项延迟。通过该方法和NCEP地表气压估计得出的干项延迟分别与GLAS官方公布的干项延迟对比,该方法计算结果的趋势与准确程度均占优,且最大干项延迟误差小于2 cm。证明通过流体静力学方程数值积分计算地表气压的方法能够得出对星载激光测高仪较为准确的大气干项延迟。
The laser pulse emitted by the spaceborne laser altimeter refracts when passing through the Earth’s atmosphere, resulting in the extension of the laser path. In order to obtain a high-precision ranging result, the atmospheric delay must be corrected; while the atmospheric dry delay accounts for the atmospheric delay Leading role, only by measuring the location of the surface atmospheric pressure. By deriving the hydrostatic equations of static atmosphere under non-ideal gas conditions, the atmospheric pressure model of surface pressure and geopotential height is obtained. Based on the data of NCEP based on the atmospheric data of standard atmosphere and the time, latitude and longitude of GLAS, The geopotential height uses the 4th-order Runge-Kutta algorithm for numerical integration to obtain the surface pressure and then calculates the atmospheric dry delay. Compared with the dry delay officially announced by GLAS, the dry delay obtained by this method and NCEP surface air pressure estimation respectively, the trend and accuracy of the calculated results are dominant, and the maximum dry delay error is less than 2 cm. It is proved that the method of calculating the surface pressure through the numerical integration of the hydrostatic equations can obtain the more accurate atmospheric dry delay of the satellite laser altimeters.