中低纬电离层—热层中非迁移潮汐对太阳活动的依赖性

发布时间：2018-05-26 22:44

本文选题：电离层-热层 + 非迁移潮汐　；参考：《武汉大学》2017年硕士论文

【摘要】：电离层-热层系统是地球空间环境的重要区域,是空间天气研究的重要对象。电离层-热层系统变化显著,且具有不同的时空尺度,这种变化受到多方面的影响,其中太阳辐射、起源于太阳风的能量输入、大气中各种波动等是引起电离层-热层变化的重要因素。电离层电子密度和热层中性大气密度是表征电离层-热层系统特征的重要参数,研究它们的变化对于理解电离层-热层系统具有重要的科学意义。由于受热和波-波相互作用等影响,地球大气中产生潮汐现象,通过直接传播或E层发电机机制传播,电离层-热层系统中各参数产生随经度变化的波状结构。本文利用CHAMP卫星和GRACE卫星观测的电子密度和大气密度数据,在了解背景电子密度与大气密度与太阳活动性的关系后,分析研究了中低纬地区电子密度和大气密度随经度变化特征,利用傅里叶拟合的方法,提取中低纬度地区电子密度和大气密度中的潮汐信号,着重分析了电离层-热层系统中的非迁移潮汐对太阳活动的依赖性。论文的主要结果如下:1.电离层F区电子密度经度平均值和热层中大气质量密度的日均值与太阳活动紧密相关。太阳活动高年,电子密度经度平均值和大气质量密度日均值较高;太阳活动低年,电子密度和大气质量密度较低。2.电离层F区电子密度经度平均值呈现明显的赤道电离异常(EIA)现象。峰区通常位于磁纬±8-20°,在太阳活动低年,峰区位置向赤道方向移动。电离层电子密度经度平均值呈现明显的季节特征,二分季节电子密度最大,夏季电子密度最低。3.在23/24太阳活动周,秋季低纬地区F层电子密度在白天具有明显的随经度分布的四波结构,夜间低纬地区四波结构消失。随着太阳活动的降低,四波结构的幅度降低。4.在中纬当地夏季,电离层F区电子密度在南半球具有一波结构,在北半球呈现二波结构;且上述波状结构没有地方时的差异。中纬热层大气质量密度随经度分布也具有一波结构。5.秋季低纬地区,F层电子密度中的DE3分量的绝对幅度,以及夏季中纬区域电子密度中的DE1、DO、DW2分量的绝对幅度都与太阳活动密切相关。在太阳活动高年,这些潮汐分量具有较大的绝对幅度,而它们的相对幅度对太阳活动的依赖性不强。中纬热层大气质量密度中的D0、DW2、SPW1分量的绝对幅度有与太阳活动密切相关,在太阳活动高年,这些潮汐分量具有较大的绝对幅度,它们的相对幅度与太阳活动没有清晰的相关性。6.秋季低纬区,电子密度中的DE3分量的相对幅度具有明显的QBO调制效应,这与之前报道的E层中的QBO效应类似。该现象表明低纬E区和F区中非迁移潮汐存在耦合现象。然而,在中纬地区的非迁移潮汐分量DE1、D0、DW2中则没有发现QBO效应,这意味着这些潮汐分量在F层产生。
[Abstract]:The ionospheric-thermospheric system is an important area of the Earth's space environment and an important object of space weather research. The ionospheric thermosphere system changes significantly and has different space-time scales. This change is influenced by many aspects, in which solar radiation originates from the solar wind energy input. All kinds of fluctuations in the atmosphere are important factors that cause the ionospheric-thermosphere change. Ionospheric electron density and thermospheric neutral atmospheric density are important parameters to characterize the characteristics of ionospheric and thermospheric systems. The study of their changes is of great scientific significance in understanding the ionospheric and thermospheric systems. Due to the effects of heat and wave-wave interaction, tidal phenomena occur in the earth's atmosphere. By direct propagation or by the mechanism of the E layer generator, the parameters in the ionospheric thermosphere system produce wave-like structures varying with the longitude. Based on the data of electron density and atmospheric density observed by CHAMP and GRACE satellites, the relationship between background electron density and atmospheric density and solar activity is studied. The variation characteristics of electron density and atmospheric density with longitude in middle and low latitudes are analyzed and studied. The tidal signals of electron density and atmospheric density in middle and low latitudes are extracted by Fourier fitting method. The dependence of non-migrating tides on solar activity in the ionospheric-thermospheric system is emphatically analyzed. The main results of this paper are as follows: 1: 1. The mean longitude of electron density in F region of the ionosphere and the daily average value of atmospheric mass density in the thermosphere are closely related to solar activity. The mean longitude of electron density and the daily average of atmospheric mass density are higher in the high year of solar activity, and the electron density and atmospheric mass density are lower in the low year of solar activity. The mean longitude of electron density in the F region of the ionosphere shows obvious equatorial ionization anomaly (EIA) phenomenon. The peak region is usually located in the magnetic latitude 卤8-20 掳, and the position of the peak region moves toward the equator in the low year of solar activity. The mean longitude of the ionospheric electron density shows obvious seasonal characteristics, the bipartite seasonal electron density is the largest, and the summer electron density is the lowest. During the cycle of 23 / 24 solar activity, the electron density of F layer in low latitudes in autumn has a four-wave structure with longitude distribution in the daytime, and disappears in the low-latitude region at night. With the decrease of solar activity, the amplitude of the four-wave structure decreases by .4. In the middle latitude local summer, the electron density in the F region of the ionosphere has one wave structure in the southern hemisphere and two wave structure in the northern hemisphere, and there is no local difference in the above wave structure. The distribution of atmospheric mass density with longitude in the middle latitude thermosphere also has a wave structure of .5. The absolute amplitude of the DE3 component in the F layer electron density in autumn and the absolute amplitude of the DE1 DO DW2 component in the middle latitude area in summer are closely related to solar activity. In the solar active years, these tidal components have a large absolute amplitude, but their relative amplitude is not strongly dependent on solar activity. The absolute amplitude of the D0 DW2 ~ (2 +) SPW1 component in the atmospheric mass density of the mid-latitude thermosphere is closely related to the solar activity. In the high year of solar activity, these tidal components have a large absolute amplitude, and their relative amplitude has no clear correlation with the solar activity. In autumn, the relative amplitude of DE3 component in electron density has obvious QBO modulation effect, which is similar to the QBO effect in E layer reported previously. This phenomenon indicates that there is a coupling phenomenon between the non-migrating tides in the E and F regions in the low latitudes. However, the QBO effect is not found in the non-migrating tidal components DE1D0D0DW2 in the mid-latitude region, which means that these tidal components are produced in the F layer.
【学位授予单位】：武汉大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：P353.7

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