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排序方式: 共有128条查询结果,搜索用时 46 毫秒
121.
M.I. Tyasto O.A. Danilova L.I. Dorman V.M. Dvornikov V.E. Sdobnov 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2008,42(9):1556-1563
We report on a study of cosmic ray cutoff rigidity variations during the strong geomagnetic storm of 18–24 November 2003. We employed the most recent Tsyganenko magnetospheric model to represent the very strong disturbed Magnetosphere. We used this magnetic field for the cosmic ray trajectory calculations to determine the geomagnetic cutoff rigidity throughout this period of severe geomagnetic disturbance. We determine the cutoff rigidity changes during this period by two methods, by trajectory calculations and by the spectrographic global survey method. The values of the change of cutoff rigidities obtained by two different methods are correlated with the Dst and interplanetary magnetic field and plasma parameters and result in correlation coefficients in the range 0.63–0.84 for the various cosmic ray stations. The result of this study indicates that the most significant contributions to the cutoff rigidity changes are due to Dst variation although the influence of solar wind density and Bz and By components of IMF variations is significant. 相似文献
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123.
The combined observations of Double Star and Cluster missions allow for, for the first time, six-point measurements of the main plasma parameters in the key scientific regions of the near-Earth environment. In the past two years, a great number of works were made based on the data from DSP and Cluster missions, advancing remarkably the research of magnetospheric physics in China. This paper briefly reviews these important scientific results based on 51 selected publications. 相似文献
124.
J. Uwamahoro L.-A. McKinnell 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2013
Estimating the magnetic storm effectiveness of solar and associated interplanetary phenomena is of practical importance for space weather modelling and prediction. This article presents results of a qualitative and quantitative analysis of the probable causes of geomagnetic storms during the 11-year period of solar cycle 23: 1996–2006. Potential solar causes of 229 magnetic storms (Dst ? −50 nT) were investigated with a particular focus on halo coronal mass ejections (CMEs). A 5-day time window prior to the storm onset was considered to track backward the Sun’s eruptions of halo CMEs using the SOHO/LASCO CMEs catalogue list. Solar and interplanetary (IP) properties associated with halo CMEs were investigated and correlated to the resulting geomagnetic storms (GMS). In addition, a comparative analysis between full and partial halo CME-driven storms is established. The results obtained show that about 83% of intense storms (Dst ? −100 nT) were associated with halo CMEs. For moderate storms (−100 nT < Dst ? −50 nT), only 54% had halo CME background, while the remaining 46% were assumed to be associated with corotating interaction regions (CIRs) or undetected frontside CMEs. It was observed in this study that intense storms were mostly associated with full halo CMEs, while partial halo CMEs were generally followed by moderate storms. This analysis indicates that up to 86% of intense storms were associated with interplanetary coronal mass ejections (ICMEs) at 1 AU, as compared to moderate storms with only 44% of ICME association. Many other quantitative results are presented in this paper, providing an estimate of solar and IP precursor properties of GMS within an average 11-year solar activity cycle. The results of this study constitute a key step towards improving space weather modelling and prediction. 相似文献
125.
利用2004年海南DPS-4数字测高仪观测到的强区域扩展F(SSF)数据,分析研究了5个强磁暴(Dst<-100 nT)事件期间海南SSF的响应特征.结果发现,在海南地区,5个强磁暴事件中有3个磁暴Dst最小值位于2200-0200 LT之间,在磁暴主相及恢复相初期均出现了SSF现象,这种触发作用可能源于磁层直接渗透电场的作用,而另两个磁暴Dst最小值均发生在白天,一个SSF现象出现在磁暴的恢复相晚间,另一个SSF现象出现在超强磁暴的初相晚间,后者可能由该超强磁暴的急始造成的直接渗透电场所触发;5个强磁暴期间发生的SSF现象或者仅出现在午夜前,或者先出现在午夜前并持续到午夜后;同时,还就这些观测结果与Dabas等人有关磁暴对ESF影响的结论进行对比和讨论. 相似文献
126.
127.
《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2023,71(5):2240-2251
This study examines the occurrences rate of geomagnetic storms during the solar cycles (SCs) 20–24. It also investigates the solar sources at SCs 23 and 24. The Disturbed storm time (Dst) and Sunspot Number (SSN) data were used in the study. The study establishes that the magnitude of the rate of occurrences of geomagnetic storms is higher (lower) at the descending phases (minimum phases) of solar cycle. It as well reveals that severe and extreme geomagnetic storms (Dst < -250 nT) seldom occur at low solar activity but at very high solar activity and are mostly associated with coronal mass ejections (CMEs) when occurred. Storms caused by CME + CH-HSSW are more prominent during the descending phase than any other phase of the solar cycle. Solar minimum features more CH-HSSW- associated storms than any other phase. It was also revealed that all high intensity geomagnetic storms (strong, severe and extreme) are mostly associated with CMEs. However, CH-HSSW can occasionally generate strong storms during solar minimum. The results have proven that CMEs are the leading cause of geomagnetic storms at the ascending, maximum and the descending phases of the cycles 23 and 24 followed by CME + CH-HSSW. The results from this study indicate that the rate of occurrence of geomagnetic storms could be predicted in SC phases. 相似文献
128.
《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2023,71(5):2299-2306
The paper presents an analysis of the ionospheric variability as a function of local time, month, and geomagnetic activity level. The 2003–2020 dataset of peak electron densities (NmF2) from the Irkutsk DPS-4 Digisonde (52.3°N, 104.3°E) was converted into the dataset of the NmF2 disturbances (ΔNmF2) representing the relative (percentage) deviations of the NmF2 from the 27-day running median. The ΔNmF2 dataset was used to calculate root mean square values of ΔNmF2 (σNmF2) by 27-day running averaging. These σNmF2 values were considered as a measure of ionospheric variability. The σNmF2 as function of local time, day of year, and year was the input for building the local empirical model of ionospheric variability based on the linear regression of σNmF2 on the 27-day average daily Ap-index of geomagnetic activity. The paper demonstrates the diurnal-seasonal variations in σNmF2 under low geomagnetic activity (linear regression intercept) as well as the rate of increase/decrease in σNmF2 with increasing Ap (linear regression slope). The obtained diurnal, seasonal, and geomagnetic activity behavior of σNmF2 is compared with previous studies of ionospheric variability. 相似文献