IRI2016参考电离层模型在高度60～100km的精度分析

Accuracy analysis of IRI2016 international reference ionosphere at altitude of 60～100km

60~100 km低电离层对无线电传播、测量具有重大影响。IRI2016作为目前最新的国际参考电离层模型,研究其提供的电子密度在高度60~100 km的精度具有重要实际意义。本文以廊坊中频雷达(位于中纬度地区)提供的电子密度资料(2014—2016年)为基准,利用偏差、绝对差、相关系数、相对偏差和Lomb-Scargle周期图方法,定量分析了IRI2016模型电子密度在中纬度地区60~100 km高度范围内的精度特征。结果表明,在中纬度地区60~100 km高度范围内:①电子密度偏差、绝对差、相对偏差与季节有密切关系,在高度86~100 km,随高度增加均快速增大;相关系数同样与季节有密切关系,但随高度增加表现出增大、减小的交替变化特征;②IRI2016模型电子密度精度与太阳活动、地磁条件有关,在太阳活动低年、磁宁静条件下的电子密度精度最高;③中频雷达和IRI2016模型电子密度在82~84 km均显著(通过90%显著性检验)含有准全日潮汐波、准8 h重力波,同时IRI2016模型还显著含有准半日潮汐波,而中频雷达未显著含有准半日潮汐波;在86~92 km均显著含有准全日潮汐波、准半日潮汐波,无准8 h重力波;④中频雷达、IRI2016模型电子密度在同一高度层显著含有的波周期及功率谱存在差异,不同高度层之间显著含有的波周期及功率谱也存在差异;⑤对于高度82~92 km的中频雷达、IRI2016模型电子密度变化特征,准全日潮汐波均为主要作用,准8 h重力波在82 km为次要作用,而准半日潮汐波在86~92 km为次要作用。

The low-altitude ionosphere(60~100 km)has great influence on radio propagation and measurement.IRI2016 is a widely used international reference ionospheric model.Therefore,it is of great practical significance to analyze the reliability of its electron density at an altitude of 60~100 km.Based on electron density data(2014—2016)provided by medium-frequency(MF)radar in Langfang,the reliability of electron density of IRI2016 model at an altitude of 60~100 km in the mid-latitude was quantitatively analyzed in this study using deviation,absolute difference,correlation coefficient,relative deviation and Lomb-Scargle periodogram.At the altitude of 60~100 km in the mid-latitude,the results showed as follows:①The deviation,absolute difference and relative deviation of electron density was closely related to season.At the altitude of 86~100 km,they increased rapidly with the increase of altitude.In addition,correlation coefficient was also closely related to season,but presented an alternation of increasing and decreasing with the increase of altitude.②The electron density accuracy of the IRI2016 model was related to solar activity and geomagnetic conditions,and had the highest accuracy under low solar activity and magnetic tranquility.③The electron density of MF radar and IRI2016 model at the altitude of 82~84 km both showed significant(verified by 90%significance test)quasi-diurnal tidal wave and quasi-8-hour gravity wave.Meanwhile,IRI2016 model presented significant quasi-semidiurnal tidal wave,which was not found in MF radar.At the altitude of 86~92 km,the electron density of both MF radar and IRI2016 model had significant quasi-diurnal tidal wave and quasi-semidiurnal tidal wave,but no quasi-8-hour gravity wave.④The electron density of both MF radar and IRI2016 model showed differences in significant wave period and power spectrum at the same altitude,and the significant wave period and power spectrum had differences among different altitudes.⑤Quasi-diurnal tidal wave played a main role in the change of the electron density of both MF radar and IRI2016 model at the altitude of 82~92 km.Quasi-8-hour gravity wave played a secondary role at the altitude of 82 km,and quasi-semidiurnal tidal wave played a secondary role at the altitude of 86~92 km.