Jason-2高度计电离层GIM误差分析及修正研究

Analysis and correction of GIM error about Jason-2 altimeter

基于Jason-2高度计2015年地球物理数据集(GDR)38个周期太平洋海域的全球电离层图(GIM)电离层校正值和双频校正值的数据,分不同季度和不同纬度区域比较二者的差异,结果表明:GIM值与双频校正值之间存在明显的差异,GIM校正值普遍高于双频校正值,说明GIM高估了电离层路径延迟,GIM校正值与双频校正值的差异与季节和纬度区间有关。用梯度下降法得到GIM值的修正方程,将修正方程应用于2016年Jason-2的全年数据,修正后的GIM值与双频校正值十分接近,在各年份中均具有良好的适用性。在单频高度计不能使用电离层双频校正算法的情况下,可以利用不同季度和不同纬度区域的修正方程对同等高度的高度计GIM值进行修正以达到双频校正值的精度水平。

Based on the ionospheric correction data of Global Ionospheric Map (GIM) and dual-frequency, extracting the Pacific Ocean dataset from the Jason-2 Altimeter’s Geophysical Data Set (GDR) including 38-period in 2015. The dataset is divided into small twelve cell according to the features of ionosphere over seasons and in latitude. The result shows that there is a significant difference between the GIM and the dual-frequency correction value, and the GIM correction value is generally higher than the dual-frequency correction value, indicating that GIM overestimates the ionosphere path delay, also, the difference between the GIM and the dual-frequency is related to the season and latitude. Applying the modified equation to the 2016 Jason-2 annual data, the corrected GIM value is very close to the dual-frequency correction value, and the applicability of the modified equation remains the same over time. In the case where the single-frequency altimeter cannot use the ionospheric dual-frequency correction algorithm, the GIM value of the altimeter of the same height can be corrected by using the correction equations of different quarters and different latitude regions to achieve the accuracy level of the dual-frequency correction value.