Quasi‐periodic Fluctuations Detected in Mars Express Coronal Radio Sounding Observations
Quasi‐periodic Fluctuations Detected in Mars Express Coronal Radio Sounding Observations
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火星快车日冕射电探测观测中检测到的准周期波动
DOI：
10.1063/1.3395972
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发表时间：
2010
期刊：
影响因子：
--
通讯作者：
S. Tellmann
中科院分区：
文献类型：
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作者：
A. Efimov;L. Lukanina;L. Samoznaev;V. K. Rudash;I. Chashei;M. Bird;M. Pätzold;S. Tellmann
对欧洲航天局火星快车号航天器上的无线电探测实验 MaRS 获得的高质量双频数据进行光谱分析，揭示了日心距离为 4 至 10 个太阳半径的准周期分量 (QPC)。 QPC 通常在以 3.7mHz<ν<5.3mHz 范围内的频率为中心的时间频率涨落谱中出现宽最大值，有时可能比相同频率下的背景幂律谱强四倍。 QPC 功率水平在大约 18% 的光谱中偶尔出现，可以在大约 30 分钟内迅速增加，但在相同的时间尺度上再次消失。在一些选定的光谱中，两个不同的 QPC 很明显，可能是主波及其二次谐波。据推测，太阳风加速区持续存在周期接近4分钟（ν≈4 mHz）的MHD波，并且在有利的观测几何条件下，偶尔可以在射电探测数据中检测到。这 ...
Spectral analysis of the high‐quality dual‐frequency data obtained with the radio sounding experiment MaRS on the ESA spacecraft Mars Express has revealed a quasi‐periodic component (QPC) at heliocentric distances from 4 to 10 solar radii. The QPC typically appears as a broad maximum in the temporal frequency fluctuation spectrum centered at a frequency in the range 3.7 mHz<ν<5.3 mHz, and can sometimes be as much as four times stronger than the background power‐law spectrum at the same frequency. Occurring sporadically in about 18% of the spectra, the QPC power level can increase rapidly within about 30 minutes, only to vanish again on the same time scale. Two distinct QPCs are evident in a few selected spectra, possibly a main wave and its second harmonic. It is conjectured that MHD waves with periods near 4 minutes (ν≈4 mHz) are continuously present in the solar wind acceleration region and can be occasionally detected in radio sounding data under conditions with a favorable observational geometry. The ...