冕洞演化与太阳活动周的关系及在日地预报中的应用

冕洞的研究在近二十多年里取得了丰硕的成果。本文回顾了冕洞的发现及观测历史，系统阐述了冕洞的结果特征，形成及演化规律，讨论了冕洞对日地空间产生的影响，冕洞与超级活动区的关系以及冕洞在太阳活动预报中所起的作用，在此基础上利用１９７０－１９９５年的晚洞资料听时空分 布和磁极性演化规律与太阳活动区的关系以及冕洞的时空分布和磁极性演化 规律与太阳活性周的得出以下结论：（１）冕洞在南北半球的分布在形态上基本是     

冕洞的地磁效应

分析了２２太阳活动周（１９８６．１—１９９５．６；ＣＲ１７７１—ＣＲ１８９８）冕洞对地磁扰动的长期效应和短期效应。作为长期效应，赤道冕洞数和面积指数随太阳活动周的演化与同期的地磁Ａｐ指数的长期变化基本一致，二者在α＝０．０１的信度水平上密切相关，表明赤道冕洞不仅对低年的磁扰有贡献，而且对峰年期间地磁扰动的贡献也是不可忽视的。对冕洞的短期地磁效应的研究表明，不论哪种类型的冕洞，在它们过中经后的１—４天，地磁Ａｐ指数都有不同程度的增长；大冕洞比小冕洞引起的地磁效应较强烈；跨越赤道的冕洞比未跨越赤道的同级冕洞引起的地磁效应较强烈     

冕洞的地磁效应

分析了２２太阳活动周（１９８６．１－１９９５．６；ＣＲ１７７１－ＣＲ１８９８）冕洞对地磁扰动的长期效应和短期效应。作为长期效应，赤道冕洞数和面积指数随太阳活动周伦与同期的地磁ＡＰ指数的长期变化基本一致，二者在ａ＝０．０１扒度水平上密度相关，表明赤道冕洞不仅对低年的磁扰有贡献，而且对峰年期间地磁拓动的贡献不可忽视的。对冕洞的短期地磁效应的研究表明，不论哪种类型的冕洞，在它们过中经后的１－４天，地磁４     

冕洞与太阳活动周及地磁活动的演化关系

本文用1970－1995年的冕洞资料，分析了冕洞的分布规律，磁场极性的演化特征和冕洞的地磁效应，以及它们与太阳黑子周期的演化关系，得到了一些有意义的结论。特别指出赤道冕洞和极区冕洞具有相反的演化规律和不同的特征。     

太阳活动22周以来的冕洞和地磁指数

本文对２２太阳活动周以来的中低纬冕洞和地磁指数Ａｐ进行了统计。对以月，年及２２周以来不同时段冕洞和地磁指数的时段合成图进行了分析。     

太阳活动22周以来的冕洞和地磁指数

本文对２２太阳活动用以来的中低纬冕洞和地磁指数Ａｐ进行了统计。对以月、季、年及２２周以来不同时段冕洞和地磁指数（Ｐｌａｎｅｔａｒｙ的Ａ指教）的时段合成图进行了分析。     

冕洞的演化规律

本文利用自有冕洞系统观测以来（１９７０－１９９５）的冕洞资料，分析了冕洞的时空分布演化规律，冕洞磁场的演化特征，以及它们与太阳黑子周期的演化关系。得到了一些有意义的新结论。特别是赤道冕洞和极区冕洞与太阳活动周的演化关系具有截然相反的演化规律和不同特征。前者与太阳活动周的演化规律基本一致；后者截然相反     

冕洞边界区磁结构的探讨—Ⅱ.太阳活动20,21周的冕洞及其边界区磁结构的变

本文分析讨论了太阳活动２０、２１周的冕洞及其边界区磁结构的变化，它包括：冕洞区光球磁场强度、磁极性的变化；冕洞面积与高速太阳风风速的关系，冕洞边界周围的环境，重点探讨太阳活动下降，极小相低纬，赤道冕洞区与其边界区磁结构的变化。     

冕洞边界区磁结构的探讨──Ⅱ．太阳活动20、21周的冕洞及其边界区磁结构的变化

本文分析讨论了太阳活动２０、２１周的冕洞及其边界区磁结构的变化。它包括：冕洞区光球磁场强度、磁极性的变化；冕洞面积与高速太阳风风速的关系；冕洞边界周围的环境。重点探讨太阳活动下降、极小相低纬、赤道冕洞区与其边界区磁结构的变化。     

Periodic Appearance of Coronal Holes and the Related Variation of Solar Wind Parameters

We compared the variability of coronal hole (CH) areas (determined from daily GOES/SXI images) with solar wind (daily ACE data) and geomagnetic parameters for the time span 25 January 2005 until 11 September 2005 (late declining phase of solar cycle 23). Applying wavelet spectral analysis, a clear 9-day period is found in the CH time series. The GOES/SXI image sequence suggests that this periodic variation is caused by a mutual triangular distribution of CHs ∼120° apart in longitude. From solar wind parameters a 9-day periodicity was obtained as well, simultaneously with the 9-day period in the CH area time series. These findings provide strong evidence that the 9-day period in solar wind parameters, showing up as higher harmonic of the solar rotation frequency, is caused by the “periodic” longitudinal distribution of CHs on the Sun recurring for several solar rotations. The shape of the wavelet spectrum from the Dst index matches only weakly with that from the CH areas and is more similar to the wavelet spectrum of the solar wind magnetic field magnitude. The distinct 9-day period does not show up in sunspot group areas which gives further evidence that the solar wind modulation is strongly related to CH areas but not to active region complexes. The wavelet power spectra for the whole ACE data range (∼1998 – 2006) suggest that the 9-day period is not a singular phenomenon occurring only during a specific time range close to solar minimum but is occasionally also present during the maximum and decay phase of solar cycle 23. The main periods correspond to the solar rotation (27^d) as well as to the second (13.5^d) and third (9^d) harmonic. Electronic Supplementary Material The online version of this article () contains supplementary material, which is available to authorized users.     

Statistical Analysis of the Relationships among Coronal Holes,Corotating Interaction Regions,and Geomagnetic Storms

We have examined the relationships among coronal holes (CHs), corotating interaction regions (CIRs), and geomagnetic storms in the period 1996?–?2003. We have identified 123 CIRs with forward and reverse shock or wave features in ACE and Wind data and have linked them to coronal holes shown in National Solar Observatory/Kitt Peak (NSO/KP) daily He i 10?830 Å maps considering the Sun?–?Earth transit time of the solar wind with the observed wind speed. A sample of 107 CH?–?CIR pairs is thus identified. We have examined the magnetic polarity, location, and area of the CHs as well as their association with geomagnetic storms (Dst≤?50 nT). For all pairs, the magnetic polarity of the CHs is found to be consistent with the sunward (or earthward) direction of the interplanetary magnetic fields (IMFs), which confirms the linkage between the CHs and the CIRs in the sample. Our statistical analysis shows that (1) the mean longitude of the center of CHs is about 8°E, (2) 74% of the CHs are located between 30°S and 30°N (i.e., mostly in the equatorial regions), (3) 46% of the CIRs are associated with geomagnetic storms, (4) the area of geoeffective coronal holes is found to be larger than 0.12% of the solar hemisphere area, and (5) the maximum convective electric field E _y in the solar wind is much more highly correlated with the Dst index than any other solar or interplanetary parameter. In addition, we found that there is also a semiannual variation of CIR-associated geomagnetic storms and discovered new tendencies as follows: For negative-polarity coronal holes, the percentage (59%; 16 out of 27 events) of CIRs associated with geomagnetic storms in the first half of the year is much larger than that (25%; 6 out of 24 events) in the second half of the year and the occurrence percentage (63%; 15 out of 24 events) of CIR-associated storms in the southern hemisphere is significantly larger than that (26%; 7 out of 27 events) in the northern hemisphere. Positive-polarity coronal holes exhibit an opposite tendency.     

Short-Period Fluctuations in Coronal Mass Ejection Activity during Solar Cycle 23

We have constructed a time series of the number of coronal mass ejections (CMEs) observed by SOHO/LASCO during solar cycle 23. Using spectral analysis techniques (the maximum entropy method and wavelet analysis) we found short-period (< one year) semiperiodic activity. Among others, we found interesting periodicities at 193, 36, 28, and 25 days. We discuss the implications of such short-period activity in terms of the emergence and escape of magnetic flux from the convection zone, through the low solar atmosphere (where these periodicities have been found for numerous activity parameters), toward interplanetary space. This analysis shows that CMEs remove the magnetic flux in a quasiperiodic process in a way similar to that of magnetic flux emergence and other solar eruptive activity.     

冕洞边缘结构对日冕物质抛射的可能贡献

分析了１９８０ 、１９８４ 和１９８９ 年 Ｓ Ｍ Ｍ 卫星观测到的１４０ 次日冕物质抛射（ Ｃ Ｍ Ｅ） 事件在时空分布上与“冕洞边缘结构”、耀斑爆发和爆发日珥等事件的相关关系。结果表明, Ｃ Ｍ Ｅ 事件与日冕边缘结构的关系最密切。此外, Ｃ Ｍ Ｅ 与赤道冕洞具有同步的长期演化关系。由此认为, 冕洞边缘结构对 Ｃ Ｍ Ｅ 的可能贡献是不可忽视的     

Coronal mass ejection of 4 April 2000 and associated space weather effects

The effects of a Halo Coronal Mass Ejection (CME) erupted on 4 April 2000 are studied and reported here. The effect of such CME on the interplanetary medium (IPM) is sensed by the Interplanetary Scintillation (IPS) recorded at Rajkot. The Solar Observations of this CME and associated events, like Solar Energetic Particles (SEP) and flare, are presented. CME events with high speeds and negative magnetic field components have higher possibility of penetrating the earth's shield, viz. the magnetosphere. The 4 April 2000 CME with a high speed and southward component of IMF produced a big geomagnetic storm with D_st reaching . Simultaneous ionospheric effects in F layer heights and auroral observations are reported. Such events are important in Space Weather Studies as these pose hazards to space operations including satellite communications and surveillance systems.