一种基于多项式函数的中国区域ZTD垂直改正模型

Development of ZTD vertical correction model based on different polynomial functions over China

针对已有中国区域对流层天顶延迟(ZTD)垂直改正模型常采用指数函数表达,而指数函数在低高程范围内的精度较差的问题,该文利用ERA5数据基于多项式函数进行模型构建,探讨了二次多项式、三次多项式和四次多项式函数的模型精度以探索在垂直方向上最优的表达效果。结果表明:以陆态网全球导航卫星系统(GNSS)ZTD数据为外符合参考值,三次多项式函数模型在ZTD垂直改正中具有较好的性能,相对于二次多项式函数和四次多项式函数,其平均均方根误差(RMS)分别减少了0.48 cm(26%)和0.43 cm(24%)。此外分析了在不同月份各多项式函数模型的误差变化情况,三次多项式函数模型在夏季月份中精度提升效果最为明显,表现出稳定的性能。该文建立的模型能为中国区域提供高精度的ZTD垂直改正服务。

In view of the existing zenith tropospheric delay(ZTD) vertical correction models over China developed based on exponential functions, the accuracy of exponential functions is poor in the low altitude, the ERA5 data was used to develop the ZTD vertical correction model based on different polynomial functions in this paper. The accuracy of quadratic polynomial, cubic polynomial and quartic polynomial function was discussed to explore the optimal expression effect in the vertical direction. The results showed that taking the ZTD data of crustal movement observation network of China as the reference value, the cubic polynomial function model had better performance in ZTD vertical correction. Compared to the quadratic polynomial function and quartic polynomial function models, the cubic polynomial function model had improved by 0.48 cm(26%) and 0.43 cm(24%) respectively. In addition, the error variation of each polynomial function model in different months was analyzed. The accuracy improvement of cubic polynomial function model was the most obvious in summer months, showing stable performance. The model established in this paper could provide high-precision ZTD vertical correction services over China.