An improved expected temperature formula for identifying interplanetary coronal mass ejections
An improved expected temperature formula for identifying interplanetary coronal mass ejections
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DOI：
10.1029/2004ja010794
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发表时间：
2005-04
影响因子：
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通讯作者：
H. Elliott;D. McComas;N. Schwadron;J. Gosling;R. Skoug;G. Gloeckler;T. Zurbuchen
中科院分区：
文献类型：
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作者：
H. Elliott;D. McComas;N. Schwadron;J. Gosling;R. Skoug;G. Gloeckler;T. Zurbuchen
[1]在这项研究中，我们比较了近5年的太阳风质子速度和温度测量太阳风电子质子阿尔法监测器（SWEPAM）的高级成分探测器（ACE），推导出一个改进的预期温度公式，以确定行星际日冕物质抛射（ICME）。异常低的质子温度长期以来一直与ICME有关。当瞬态ICME不存在时，太阳风的速度和温度高度相关，以前的研究已经得出了这些测量的拟合。使用这些拟合，从太阳风速度确定预期温度。异常低温已被确定为测量温度与预期温度之比低于0.5的时间。在这项研究中，我们在拟合剩余数据之前删除ICME。当太阳风远离太阳时，太阳风中的快包和慢包相互作用，导致压缩和稀疏。由于这种相互作用导致这些包裹的速度和温度发生变化，我们分别拟合压缩和稀疏。我们发现，以这种方式推导出的预期温度公式提供了一个更好的方式来识别ICME比以前的公式，特别是在压缩区域。
[1] In this study we compare nearly 5 years of solar wind proton speed and temperature measurements from the Solar Wind Electron Proton Alpha Monitor (SWEPAM) on the Advanced Composition Explorer (ACE) to derive an improved expected temperature formula to identify interplanetary coronal mass ejections (ICMEs). Anomalously low proton temperatures have long been associated with ICMEs. When transient ICMEs are not present, the solar wind speed and temperature are highly correlated, and previous studies have derived fits to these measurements. Using these fits, an expected temperature is determined from the solar wind speed. Anomalously low temperatures have been identified as times when the ratio of the measured to expected temperature is below 0.5. In this study we remove ICMEs before fitting the remaining data. Fast and slow parcels in the solar wind interact and cause compressions and rarefactions as the solar wind moves away from the Sun. Since such interaction causes the speed and temperature of these parcels to change, we separately fit compression and rarefactions. We find that the expected temperature formula derived in this way provides a better way of identifying ICMEs than previous formulas, particularly in compression regions.