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881.
I. Braun J. Engler J.R. Hörandel J. Milke 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2009
Since 1993, a muon telescope located at Forschungszentrum Karlsruhe (Karlsruhe Muon Telescope) has been recording the flux of single muons mostly originating from primary cosmic-ray protons with dominant energies in the 10–20 GeV range. The data are used to investigate the influence of solar effects on the flux of cosmic rays measured at Earth. Non-periodic events like Forbush decreases and ground level enhancements are detected in the registered muon flux. A selection of recent events will be presented and compared to data from the Jungfraujoch neutron monitor. The data of the Karlsruhe Muon Telescope help to extend the knowledge about Forbush decreases and ground level enhancements to energies beyond the neutron monitor regime. 相似文献
882.
883.
Rajesh K. Mishra Rekha Agarwal Mishra 《空间科学学报》2007,27(5):353-359
In the present work the cosmic ray intensity data recorded with ground-based neutron monitor at Deep River has investigated taking into account the associated interplanetary magnetic field and solar wind plasma data during 1981—1994.A large number of days having abnormally high/low amplitudes for successive number of five or more days as compared to annual average amplitude of diurnal anisotropy have been taken as high/low amplitude anisotropic wave train events(HAE/LAE).The amplitude of the diurnal anisotropy of these events is found to increase on the days of magnetic cloud as compared to the days prior to the event and it found to decrease during the later period of the event as the cloud passes the Earth.The High-Speed Solar Wind Streams(HSSWS)do not play any significant role in causing these types of events. The interplanetary disturbances(magnetic clouds)are also effective in producing cosmic ray decreases.Hαsolar flares have a good positive correlation with both amplitude and direction of the anisotropy for HAEs, whereas PMSs have a good positive correlation with both amplitude and direction of the anisotropy for LAEs. The source responsible for these unusual anisotropic wave trains in CR has been proposed. 相似文献
884.
885.
利用行星际监测数据进行地磁暴预报 总被引:2,自引:0,他引:2
利用全连接神经网络方法应用于地磁Dst指数的预报中.对ACE卫星探测的太阳风和行星际磁场及其变化对未来几小时的Dst指数的影响进行了统计分析,发现在这些行星际实测参数中,对Dst指数作用较为明显的是太阳风速度、太阳风质子密度和行星际磁场南向分量,同时,当前Dst指数实测值对今后几小时的Dst指数已有很强的制约作用.在统计分析的基础上,建立了全连接神经网络预报模型.由于采用了全连接神经网络结构,模式能够反映出太阳风、行星际磁场等参数与地磁Dst指数参数的复杂联系,可以自动建立输入参量的最佳组合方式,提高了预报精度.通过利用大量实测数据对神经网络模式进行训练,最终建立了利用优选的ACE卫星行星际监测数据提前2 h对Dst指数进行预报.通过检测,预报的误差为14.3%. 相似文献
886.
本文研究了太阳帆航天器在光压因子、锥角和钟角共同作用下的三维人工平动点的变化特性。在光压因子较小的时候,五个平动点会拓展成五个不相连的“人工”平动点面。随着光压因子增大,平动点面SL 3 ,SL 4 和SL5将逐渐扩大并互相融合,最终延展至SL 1 与之融合。而平动点面SL2则始终保持独立的球面,只随着光压因子的增大而扩大但不与其它平动点面发生融合。平动点位置的改变,意味着对应的周期轨道也随之改变,这为平动点周期轨道的转移等任务提供了有效参考。 相似文献
887.
Baolin Tan 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2019,63(1):617-625
Is Solar Cycle 24 anomalous? How do we predict the main features of a forthcoming cycle? In order to reply such questions, this work partitions quantitatively each cycle into valley, ascend, peak, and descend phases, statistically investigate the correlations between valley phase and the forthcoming cycle. We find that the preceding valley phase may dominate and can be predictor of the forthcoming cycle: (1) The growth rate in ascend phase strongly negatively correlates to valley length and strongly positively correlates to cycle maximum. (2) The cycle maximum strongly negatively correlates to valley length, and strongly positively correlates to cycle minimum. (3) The cycle period strongly negatively correlates to the valley variation. Based on these correlations, we conclude that the solar cycle 24 is a relatively weak and long cycle which is obviously weaker than Cycle 23. The similarity analysis also presents the similar result. The Cycle 25 is also inferred possibly to be a weak cycle. These results can help us understanding the physical processes of solar cycles. 相似文献
888.
R.N. Boroyev 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2019,63(1):302-308
In the present paper dependences of substorm activity on the solar wind velocity and southward component (Bz) of interplanetary magnetic field (IMF) during the main phase of magnetic storms, induced by the CIR and ICME events, is studied. Strong magnetic storms with close values of Dstmin?≈??100?±?10?nT are considered. For the period of 1979–2017 there are selected 26 magnetic storms induced by the CIR and ICME (MC?+?Ejecta) events. It is shown that for the CIR and ICME events the average value of the AE index (AEaver) at the main phase of magnetic storm correlates with the solar wind electric field. The highest correlation coefficient (r?=?0.73) is observed for the magnetic storms induced by the CIR events. It is found that the AEaver for magnetic storms induced by ICME events, unlike CIR events, increases with the growth of average value of the southward IMF Bz module. The analysis of dependence between the AEaver and average value of the solar wind velocity (Vswaver) during the main phase of magnetic storm shows that in the CIR events, unlike ICME, the AEaver correlates on the Vswaver. 相似文献
889.
Characterization of GPS-TEC over African equatorial ionization anomaly (EIA) region during 2009–2016
Temitope Seun Oluwadare Chinh Nguyen Thai Andrew Oke-Ovie Akala Stefan Heise Mahdi Alizadeh Harald Schuh 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2019,63(1):282-301
This study characterizes total electron content (TEC) measured by Global Positioning System (GPS) over African equatorial ionization anomaly (EIA) region for 2009–2016 period during both quiet geomagnetic conditions (Kp?≤?1) and normal conditions (1?>?Kp?≤?4). GPS-TEC data from four equatorial/low-latitude stations, namely, Addis Ababa (ADIS: 9.04°N, 38.77°E, mag. lat: 0.2°N) [Ethiopia]; Yamoussoukro (YKRO: 6.87°N, 5.24°W, mag. lat: 2.6°S) [Ivory Coast]; Malindi (MAL2; 3.00°S, 40.19°E, mag. lat: 12.4°S) [Kenya] and Libreville (NKLG; 0.35°N, 9.67°W, mag. lat: 13.5°S) [Gabon] were used for this study. Interesting features like noontime TEC bite-out, winter anomaly during the ascending and maximum phases of solar cycle 24, diurnal and seasonal variations with solar activity have been observed and investigated in this study. The day-to-day variations exhibited ionospheric TEC asymmetry on an annual scale. TEC observed at equatorial stations (EIA-trough) and EIA-crest reach maximum values between ~1300–1600 LT and ~1300–1600 LT, respectively. About 76% of the high TEC values were recorded in equinoctial months while the June solstice predominantly exhibited low TEC values. Yearly, the estimated TEC values increases or decreases with solar activity, with 2014 having the highest TEC value. Solar activity dependence of TEC within the EIA zone reveals that both F10.7?cm index and EUV flux (24–36?nm) gives a stronger correlation with TEC than Sunspot Number (SSN). A slightly higher degree of dependence is on EUV flux with the mean highest correlation coefficient (R) value of 0.70, 0.83, 0.82 and 0.88 for quiet geomagnetic conditions (Kp?≤?1) at stations ADIS, MAL2, NKLG, and YKRO, respectively. The correlation results for the entire period consequently reveals that SSN and solar flux F10.7?cm index might not be an ideal index as a proxy for EUV flux as well as to measure the variability of TEC strength within the EIA zone. The estimated TEC along the EIA crest (MAL2 and NKLG) exhibited double-hump maximum, as well as post-sunset peaks (night time enhancement of TEC) between ~2100 and 2300 LT. EIA formation was prominent during evening/post-noon hours. 相似文献
890.
Melinda Nagy Alexandre Lemerle Paul Charbonneau 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2019,63(4):1425-1433
The solar dipole moment at activity minimum is a good predictor of the strength of the subsequent solar cycle. Through a systematic analysis using a state-of-the-art D solar dynamo model, we found that bipolar magnetic regions (BMR) with atypical characteristics can modify the strength of the next cycle via their impact on the buildup of the dipole moment as a sunspot cycle unfolds. In addition to summarizing these results, we present further effects of such “rogue” BMRs. These have the ability to generate hemispheric asymmetry in the subsequent sunspot cycle, since they modify the polar cap flux asymmetry of the ongoing cycle. We found strong correlation between the polar cap flux asymmetry of cycle i and the total pseudo sunspot number asymmetry of cycle . Good correlation also appears in the case of the time lag of the hemispheres of cycle . 相似文献