利用神经网络预报短期电离层TEC变化     

李淑慧  彭军还  徐伟超  杨红磊 《测绘科学》2013,38(1):8-9,12

利用神经网络,基于IGS提供的(40°N,115°E)网格点TEC数据,本文构造了该点处提前一天的TEC预报模型。神经网络模型的预测目标是待预测日一天内的12个TEC数值。输入参数包括预测日前一日的太阳黑子数、地磁Kp指数、预测日前27天的太阳黑子数三角函数拟合参数,以及预测日前2天16个Kp指数的多项式拟合参数。实验结果表明训练后的神经网络模型可以反映出不同季节的TEC周日变化以及地磁暴情况下的TEC特征。  相似文献   

由对地全晕状日冕物质抛射诱发的地磁感应电流统计研究     

王开让  林隽  刘连光  刘春明  高冠男 《天文学报》2012,53(1):9-27

太阳活动会引起输变电系统异常,特别是对超长距离输变电系统的危害尤其明显.根据SOHO/LASCO (Solar and Heliospheric Observatory/Large Angle and Spectrometric Coronagraph)的日冕物质抛射(Coronal Mass Ejection,CME)数据、华北电力大学和芬兰气象研究所获得的地磁感应电流(Geomagnetically Induced Current,GIC)数据以及地磁暴数据,分析研究了与GIC事件有关的对地晕状CME的重要观测特征和物理性质.按照对称性将晕状CME进行分类后,发现造成GIC事件的晕状CME主要有3类:完全对称型、亮度不对称型和外形不对称型.不同类型的全晕状CME驱动的GIC事件在强度、持续时间等方面特征各不相同.其中,亮度不对称型晕状CME很有可能对GIC事件影响最为严重.同时注意到GIC与地磁场随时间的变化率也具有较好的相关性.  相似文献   

A Statistical Analysis of the Type-III Bursts in Centimeter and Decimeter Wavebands     

Yuan Ma  Rui-xiang Xie  Xiang-min Zheng  Min Wang  Yan Yi-hua 《Chinese Astronomy and Astrophysics》2012

A statistical analysis of the type-III bursts observed by the spectrographs in the ranges of 625∼1500 MHz, 2600-3800 MHz, and 5200-7600 MHz during the 23rd solar cycle (from 2000 July to 2004 September) is carried out. The distribution of the type-III bursts, and their durations, frequency drift rates, polarization degrees and frequency bandwidths are given in this paper. The results indicate that the average values of the frequency drift rates and frequency bandwidths increase with the frequency. The average values of the durations and polarization degrees are neither constant nor uniformly varied over a broad frequency range. Most of type-III bursts are distributed in the range from 625 to 3800 MHz, and decrease with the frequency in number. This analysis shows that the places of electron acceleration and energy release are mainly in the decimetric range, and the characteristic of this frequency range is possibly related with the magnetic configuration at the decimeter wavelengths, as well as the electron acceleration in the magnetic reconnection site close to the main flare. However, there are also a considerable number of type-III bursts in the range of 5200-7600 MHz, it means that the sites of electron acceleration are widely distributed in the coronal region. The radiation mechanisms of type-III bursts at the centimeter-decimeter wavelengths include most probably the coherent plasma radiation and the emission process of electron cyclotron maser.  相似文献   

An Observational Study on Coronal Hard X-ray Sources in Flares     

BAI Wei-dong  LI You-ping  GAN Wei-qun 《Chinese Astronomy and Astrophysics》2012

Observational studies on solar ?ares with footpoints partially occulted by the solar limb provide an important method for diagnostics of coronal hard X-ray emissions. The statistics of hard X-ray sources in 71 such ?ares observed by RHESSI (Reuven Ramaty High-Energy Solar Spectroscopic Imager) show that the two kinds of hard X-ray sources proposed in previous studies (i.e., the sources with respectively a smaller and larger spatial separations between the thermal and non-thermal sources of coronal hard X-ray emissions) have no evident difference in the aspects of their photon spectra, images, light curves, GOES durations, etc. The area of the radiation region, the ?are's total thermal energy and GOES duration are well correlated with the distance of separation. These results support some uni?ed models of solar ?ares proposed in recent years, and indicate that the Masuda ?are is only a kind of special event, which does not possess the general features of coronal hard X-ray emissions  相似文献   

An Analysis of the Variation of Solar Activity     

Li-sheng Hao  Bao-gui Bi  Xue-xiang Yao 《Chinese Astronomy and Astrophysics》2008

Using the method of Morlet wavelet transform, we analysed the sunspot relative numbers and obtained some meaningful results. The solar activity possesses the periods of 10.7a and 101a, and the period of 10.7a is very prominent. The variation of intensity of the solar activity exhibits certain stages. In 1950 there occurred abrupt changes of climate, and since then the solar activity has become more and more intense. It is predicted that it would be weaker for some time interval in the future.  相似文献   

Non-adiabatic effects in the solar p-mode oscillations     

Shao-lan Bi  Ru-feng Li 《Chinese Astronomy and Astrophysics》1997,21(4):474-480

Non-adiabatic effects associated with radiative loss and convective transfer add small imaginary parts to solar p-mode eigenfrequencies. An asymptotic approximation is developed to study the non-adiabatic effects. For the outermost layer where the approximation is not valid, an exact solution of the equation of non-adiabatic oscillation which results in an cigenfunction equation, is used. The inclusion of the non-adiabatic effects reduces the discrepancy between the theory and observations particularly for frequencies above 3.1 mHz.  相似文献   

Global Oscillations at Low Frequency from the SOHO mission (GOLF)     

A. H. Gabriel  G. Grec  J. Charra  J. -M. Robillot  T. Roca Cortés  S. Turck-Chièze  R. Bocchia  P. Boumier  M. Cantin  E. Cespédes  B. Cougrand  J. Crétolle  L. Damé  M. Decaudin  P. Delache  N. Denis  R. Duc  H. Dzitko  E. Fossat  J. -J. Fourmond  R. A. García  D. Gough  C. Grivel  J. M. Herreros  H. Lagardère  J. -P. Moalic  P. L. Pallé  N. Pétrou  M. Sanchez  R. Ulrich  H. B. van der Raay 《Solar physics》1995,162(1-2):61-99

The GOLF experiment on the SOHO mission aims to study the internal structure of the sun by measuring the spectrum of global oscillations in the frequency range 10^–7 to 10^–2 Hz. Bothp andg mode oscillations will be investigated, with the emphasis on the low order long period waves which penetrate the solar core. The instrument employs an extension to space of the proven ground-based technique for measuring the mean line-of-sight velocity of the viewed solar surface. By avoiding the atmospheric disturbances experienced from the ground, and choosing a non-eclipsing orbit, GOLF aims to improve the instrumental sensitivity limit by an order of magnitude to 1 mm s^–1 over 20 days for frequencies higher than 2.10^–4 Hz. A sodium vapour resonance cell is used in a longitudinal magnetic field to sample the two wings of the solar absorption line. The addition of a small modulating field component enables the slope of the wings to be measured. This provides not only an internal calibration of the instrument sensitivity, but also offers a further possibility to recognise, and correct for, the solar background signal produced by the effects of solar magnetically active regions. The use of an additional rotating polariser enables measurement of the mean solar line-of-sight magnetic field, as a secondary objective.  相似文献   

内蒙古干旱区赛乌素金矿氧化带及金表生地球化学研究     

马民涛  关广岳 《地质学报》1996,70(3)

该矿是内蒙古干旱草原气候区典型的含金硫化物石英脉型矿床。研究表明:自全新世以来该氧化带一直处于干旱气候控制之下;金的表生演化除具有颗粒增大、形态复杂、品位变富和成色增高外,金、银出现双峰富集且基本处同一深度;这与潮湿气候区金、银以“单峰”富集及“上金下银”规律形成鲜明对比。太阳泵是金、银“双峰”富集的主要成因;金的下部富集与较低pH环境有关;伊利石2M_1是金、银上部富集峰主要成因之一。  相似文献   

上海及其邻区地震活动与某些“天,地”因子关系初探     

何正檀 《上海国土资源》1991,(2):22-25

本文报导了上海及其邻区M_s≥4 3/4级地震活动与地球自转速率和太阳黑子活动周期有关。据此可望找到该地区地震中期预报的指标。  相似文献   

太阳黑子与全球强震活动   总被引：1，自引：0，他引：1  

方炜  刘春  张春生  邵辉成 《高原地震》2003,15(4):27-31

根据NGDC提供的太阳黑子资料,分析了太阳黑子活动与地球上巨震活动的关系。一般来说,强震发生的平均相位角大致在69 5°～103 7°和256 3°～290 5°之间,在每个太阳黑子活动的双周中,强震容易在黑子活动的峰值出现,而在太阳黑子活动的单周中,强震较易在黑子活动的谷值出现,并指出在今后3～4年内,欧亚大陆发生8级以上巨震的可能性很大。  相似文献