曲靖非相干散射雷达电离层F区日间电子温度变化特征初步分析

利用曲靖非相干散射雷达2017-2018年春夏季观测数据首次分析了电离层日间150~450km电子温度的地方时与高度变化特征及其与电子密度的相关性.发现hmF2及以上的电子温度在日出日落时具有两个峰值,在11∶00-16∶00LT之间变化较小,高度越高午后上升的时间越早;从150km开始迅速增加,在约220km达到最大值,然后开始降低,在约300~350km达到最小值,最后单调上升;200km以下电子温度与电子密度成正相关(主要由热传导控制),200~450km之间存在明显的反相关(光电离过程占主导),电子-离子温度差与电子密度对数之间存在近似线性关系,电子温度逐日变化与光电离因子的变化趋势相似,这种相关性在中午与午后更明显;以上结果与其他非相干散射雷达观测和电离层模型计算结果基本一致,但也存在一些差别,需要结合更多数据深入分析.

Preliminary analysis of the ionospheric electron temperature variations of F layer in daytime using the Qujing incoherent scatter radar measurements

The daily and altitudinal variations of electron temperature (T_e) of ionospheric F layer in daytime using the Qujing incoherent scatter radar (ISR) measurement in 2017 and 2018 are investigated. Also the relation between the electron temperature and electron density is presented. It is found that there exist the morning and sunset enhancement with the maximum about 3000 K above the F₂ peak height. The variation of T_e in daytime 11:00-16:00 LT is not obvious. The rise of T_e during sunset occurs earlier with the higher altitude. T_e increases from about 150 km, reaches the maximum at about 220 km, then decreases slowly to the minimum at 300~350 km, finally rises slowly again. T_e increases with the enhancement of electron density (N_e) below 200 km, which shows the positive correlation between the T_e and N_e. T_e increases with the decreasing of N_e between 200 and 450 km, which shows the negative inverse relationship. There seems the linear correlation between the difference of T_e and ion temperature and the logarithm N_e with the correlation coefficient 0.5 independent of the month. The variability profiles of T_e follow well with the variation of photo-ionization factor. Combing the electron energy equation, the thermal conduction dominates the photo-ionization below 200 km and photo-ionization is the dominant heating source for electron between the 200 and 450 km. These results show the electron density and the thermal characteristic are interrelated. The above results are in accordance with that from other ISR measurements in middle latitude, the calculated results from the international reference ionosphere (IRI) and the Arecibo ISR model but also some disagreements exist including the sunrise and sunset peak values. This is the first time to describe the thermal characteristic of T_e in Qujing, and also suggests the existence of difference in T_e variation in different latitudes which need more data and analysis.