The Thermospheric Semiannual Density Response to Solar EUV Heating
The Thermospheric Semiannual Density Response to Solar EUV Heating
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DOI：
10.1016/j.jastp.2008.04.020
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发表时间：
2008-08
期刊：
影响因子：
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通讯作者：
B. Bowman;W. Tobiska;M. Kendra
中科院分区：
文献类型：
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作者：
B. Bowman;W. Tobiska;M. Kendra
这项研究的目的是描述过去35年来热层密度对太阳加热的半年响应。对历史雷达观测数据进行了处理，对近地点高度在200至1100公里之间的28颗卫星进行了特殊轨道摄动。利用轨道能量耗散率，获得了所有卫星在近地点的大约225，000个非常准确的日平均密度值。半年变化已被发现是非常可变的，每年。从7月最小值到10月最大值的最大年度差异的大小被用来表征每年的半年变率。已经发现，这种最大差异可以从一年到下一年变化多达100%。在这个最大差异和太阳EUV数据之间发现了高度的相关性。每一年的半年变化的特点是基于分析的年度和半年周期，使用傅立叶分析，并已开发出方程来表征这种每年的变化。在EUV和FUV波长的新的太阳能指数的使用被证明是非常准确地描述半年7月最小相移和观测到的每年半年振幅的变化。
The goal of this study was to characterize the thermospheric semiannual density response to solar heating during the last 35 years. Historical radar observational data have been processed with special orbit perturbations on 28 satellites with perigee heights ranging from 200 to 1100km. Approximately 225,000 very accurate average daily density values at perigee have been obtained for all satellites using orbit energy dissipation rates. The semiannual variation has been found to be extremely variable from year to year. The magnitude of the maximum yearly difference, from the July minimum to the October maximum, is used to characterize the yearly semiannual variability. It has been found that this maximum difference can vary by as much as 100% from one year to the next. A high correlation has been found between this maximum difference and solar EUV data. The semiannual variation for each year has been characterized based on analyses of annual and semiannual cycles, using Fourier analysis, and equations have been developed to characterize this yearly variability. The use of new solar indices in the EUV and FUV wavelengths is shown to very accurately describe the semiannual July minimum phase shifting and the variations in the observed yearly semiannual amplitude.