Equatorial F-region vertical ion drifts during quiet solar maximum

Median values of ionosonde h′F data acquired at Ibadan (Geographic:7.4°N, 3.9°E, Magnetic: dip 6°S, and magnetic declination, 3°W), Nigeria, West Africa, have been used to determine vertical ion drift (electric field) characteristics in the postsunset ionosphere in the African region during a time of high solar activity (average F_10.7 −208). The database spans from January and December 1958 during the era of International Geophysical Year (IGY) for geomagnetic quiet conditions. Bimonthly averaged diurnal variations patterns are very similar, but differ significantly in magnitude and in the evening reversal times. Also, monthly variations of F-region vertical ion drift reversal times inferred from the time of h′F maximum indicates early reversal during equinoxes and December solstice months except for the month of April. Late reversal is observed during the June solstice months. The equatorial evening prereversal enhancement in vertical ion drift (V_zp) occurs largely near 1900 LT with typical values 20–45 m/s. Comparison of Ibadan ionosonde V_zp with the values of prereversal peak velocity reported for Jicamarca (South America), Kodaikanal (India), and Scherliess and Fejer global model show considerable disparity. The changes of postsunset peak in virtual height of F-layer (h′F_P) with prereversal velocity peak V_zp are anti-correlated. Investigation of solar effects on monthly values of V_zp and h′F_P revealed that these parameters are independent of monthly averaged solar flux intensity during quiet-time sunspot maximum conditions.     

PAMELA observational capabilities of Jovian electrons

PAMELA is a satellite-borne experiment that has been launched on June 15th, 2006. It is designed to make long duration measurements of cosmic radiation over an extended energy range. Specifically, PAMELA is able to measure the cosmic ray antiproton and positron spectra over the largest energy range ever achieved and will search for antinuclei with unprecedented sensitivity. Furthermore, it will measure the light nuclear component of cosmic rays and investigate phenomena connected with solar and earth physics. The apparatus consists of: a time of flight system, a magnetic spectrometer, an electromagnetic imaging calorimeter, a shower tail catcher scintillator, a neutron detector and an anticoincidence system. In this work a study of the PAMELA capabilities to detect electrons is presented. The Jovian magnetosphere is a powerful accelerator of electrons up to several tens of MeV as observed at first by Pioneer 10 spacecraft (1973). The propagation of Jovian electrons to Earth is affected by modulation due to Corotating Interaction Regions (CIR). Their flux at Earth is, moreover, modulated because every 13 months Earth and Jupiter are aligned along the average direction of the Parker spiral of the Interplanetary Magnetic Field.PAMELA will be able to measure the high energy tail of the Jovian electrons in the energy range from 50 up to 130 MeV. Moreover, it will be possible to extract the Jovian component reaccelerated at the solar wind termination shock (above 130 MeV up to 2 GeV) from the galactic flux.     

On the effect of near-equatorial thunderstorms on the global distribution of ionospheric potential

We develop our earlier attempts to perform an indirect quantitative examination of the hypothesis that electric currents flowing up from thunderstorms to the ionosphere (also known as Wilson currents) charge the ionosphere to a large positive potential with respect to the Earth. First, we take the electrostatic potential arising from the interaction of the solar wind with the Earth’s magnetosphere derived from an experimental data-based model of the high-latitude field-aligned currents. We then obtain the global distribution of ionospheric potential, utilizing a thin shell model, based on integration along field lines of the current continuity equation with a realistic model of ionospheric conductivity. Next, we include additional upward currents to simulate the effect of the three main thunderstorm regions over equatorial Asia/Oceania, Africa and the Americas. We compare the local time variation of the eastward electric field in the ionosphere produced by these three equatorial sources separately, and seek to understand the substantial differences between them. Finally, we examine the variation with local time of the eastward electric field in the ionosphere at low latitudes.     

Variations of quasi-electrostatic fields and ionosphere potential above lightning discharge at equatorial latitudes

Lightning discharges by thunderstorms cause generation of electromagnetic pulses and of quasi-electrostatic fields (QESF) in the atmosphere above, which occur in different time-scales. QESF penetrate into the mesosphere and the lower ionosphere where they are big enough to generate considerable electric charge transfer there and, in some cases, to cause red sprites. These processes may have an important contribution to the global atmospheric electric circuit. Significant transient variations of the ionospheric potential above the thunderstorm take place as well. QESF depend on the atmospheric conductivity and in the ionosphere they are affected also by its anisotropy determined by geomagnetic field orientation. QESF after a lightning discharge are investigated theoretically in this work in the case of equatorial latitudes (by horizontal geomagnetic field), where thunderstorms are important contributors to the global circuit. Results for DC electric fields in the lower equatorial ionosphere above a thundercloud obtained by earlier models demonstrate some specific features of the spatial distribution of these fields, which appear due to geomagnetic field orientation. Thus, the electric fields can be shifted by tens or more kilometers to east of the cloud charge region; also their horizontal scale is much bigger than in the case of middle latitudes. Here, a presence of similar specific features of quasi-electrostatic field distributions and ionospheric potential variations caused by a lightning stroke is studied. A situation when no secondary ionization is generated is considered. A model based on the Maxwell equations for potential electric fields is proposed. Computations of QESF in the middle atmosphere and of the ionospheric potential variations are provided as dependent on conductivity and its anisotropy in D-region. The obtained results for the ionosphere show that the electric fields in the equatorial lower ionosphere are comparable to these formed in the case of middle latitudes. However, their horizontal scales are much bigger and depend on conductivity profiles. Similar features are valid also for the ionospheric potential variations and for their horizontal scales.     

Dark matter search with the CALET detector on-board ISS

The CALorimetric Electron Telescope, CALET, mission is proposed for the observation of high-energy electrons and gamma-rays at the Exposed Facility of the Japanese Experiment Module on the International Space Station. The CALET has a capability to observe the electrons (without separation between e⁺ and e⁻) in 1 GeV–10 TeV and the gamma-rays in 20 MeV–several TeV with a high-energy resolution of 2% at 100 GeV, a good angular resolution of 0.06 degree at 100 GeV, and a high proton-rejection power of nearly 10⁶. The CALET has a geometrical factor of 1 m²sr, and the observation period is expected for more than three years. The very precise measurement of electrons enables us to detect a distinctive feature in the energy spectrum caused from WIMP dark matter in the Galactic halo. The excellent energy resolution of CALET, which is much better than GLAST or air Cherenkov telescopes over 10 GeV, enables us to detect gamma-ray lines in the sub-TeV region from WIMP dark matter annihilations. The CALET has, therefore, a unique capability to search for WIMP dark matter by the hybrid observations of electrons and gamma-rays.     

Fractal analysis of short and intermediate GRB and the fireball model

In the present work the possibility of the fractal analysis application for GRB temporal profiles was studied. We have analysed the 4B revised BATSE catalog: temporal profiles of GRB with t₉₀ < 3 s (287 short and 100 intermediate) were studied on TTE data, a sample of 278 intermediate GRB with t₉₀  3 s were studied on DISCSC data. An analysis of the background fractal dimension distributions obtained using TTE and DISCSC data (143 and 110 background regions, respectively), indicates that for both datasets background fractal dimensions D_bgr = 1.5 that the fractal dimension distributions obtained by using these data can be processed simultaneously. The change of the fractal index D_bgr for Poisson statistics – dominated sets with different coefficients of error in counting (up to 10) was studied and D_bgr = 1.5. The ranges of fractal dimension (0.80  D  2.25 for short and 0.85  D  2.01 for intermediate GRB) are shifted over range for theoretical fractal curve (1 < D < 2) due to the finite detector time resolution. There are four subgroups in fractal dimension distribution for short GRB (D = 1.05 ± 0.03, D = 1.31 ± 0.05, D = 1.51 ± 0.04, D = 1.90 ± 0.03) and six subgroups for intermediate one (D = 1.05 ± 0.09, D = 1.24 ± 0.08, D = 1.44 ± 0.07, D = 1.51 ± 0.08, D = 1.64 ± 0.07, D = 1.91 ± 0.1). Time profiles with fractal dimension smaller then background can be obtained by using models with many short chaotic processes in sources, for example, fireball model with shock waves. The range of fractal dimensions for the modelled temporal profiles is 1.213  D  1.400, which can correspond to subgroups of short and intermediate GRB with D = 1.31 and D = 1.24; moreover, the fractal dimension of a simulated indented event and GRB990208 are equal within the error limits for some model parameters and it is possible to obtain smooth temporal profiles with D = D_bgr.     

Geomagnetic effects on mid-latitude railways: A statistical study of anomalies in the operation of signaling and train control equipment on the East-Siberian Railway

Intense geomagnetically induced currents (GIC) can hamper rail traffic by disturbing signaling and train control systems. GIC threats have been a concern for technological systems at high-latitude locations due to geomagnetic disturbances driven by substorm expansion electrojet or convection electrojet intensifications. However, other geomagnetic storm processes such as storm sudden commencement (SSC) and geomagnetic pulsations can also cause GIC concerns for technological systems. We present in this paper the first evidence based on statistical data for links between geomagnetic disturbances and faulty operations (anomalies) in the functioning of railway automatics and telemetry. We analyze anomalies of automatic signaling and train control equipment which occurred in 2004 on the East-Siberian Railway (corrected geomagnetic latitude _m = 46–51°N and longitude λ_m = 168–187°E). Our results reveal a seasonal effect in the number of anomalies per train similar to the one observed in geomagnetic activity (Kp, Ap, Dst indices). We also found an increase by a factor of 3 in the total duration of daily anomalies during intense geomagnetic storms (local geomagnetic index specific to Siberian Observatory A_max > 30), with a significant correlation between the daily sum of durations of anomalies with geomagnetic activity. Special attention was paid to failures not related to recognized technical malfunctions. We found that the probability of these failures occurring in geomagnetically disturbed periods was 5–7 times higher than the average anomaly occurrence.     

Study of correlations between waves and particle fluxes measured on board the DEMETER satellite

The topic of relativistic electron dynamics in the outer radiation belt has received considerable attention for many years. Nevertheless, the problem of understanding the physical phenomenon involved is far from being resolved. In this paper, we use DEMETER observations to examine the variations of the energetic electron fluxes and ELF/VLF wave intensities in the inner magnetosphere during the intense 8 November 2004 magnetic storm. Electron flux spectra and associated wave intensity spectra are analysed throughout the magnetic storm and common characteristics or differences to other storm events are retained. The overall objective of this study is to identify and derive parameters that are relevant for particle flux modelling; the time constant characterizing the persistent decay after particle enhancement was found to be one of these important model parameters.The analysis of the 8 November 2004 event reveals that for L-shell parameter higher than 4, an electron flux dropout is observed during the storm’s main phase for electrons in the energy range 0.1–1 MeV, as has been reported from other measurements. Characteristic wave spectra accompanying this phase are analysed. They show a typical enhancement in the frequency range 0.3–10 kHz at onset for all L-shell values under consideration (2 < L < 5). During the first stage of the recovery phase, the electron fluxes are increased to a level higher than the pre-storm level, whereas the level of wave intensity in the frequency range observed below 300 Hz is at its highest. In the second stage, the particle flux decrease goes hand in hand with a global wave activity decline, the relaxation time of the latter being smaller than the former’s one. In some other cases, long-lasting electron enhancement associated with constant wave activity has been observed during this latter stage. For the above mentioned storm, while at low L values the decay time constants are higher for low energy electrons than for high energy electrons, this order is reversed at high L values. At about L = 3.6 the time constant is independent of electron energy.     

雷暴云准静电场和夜间低电离层的电离

用点电荷模型计算雷暴云突然放电后形成的准静电后形成的准静电场随高度的分布，以E/N（E的电场大小，N为大气密度）为输入参量，在一定条件下，对Boltzmann方程数值求解，计算电离层电子数密度的扰动。计算结果表明，在约70-90km之间，在约放电后的10ms内，准静电场大于中性大气的击穿电场，将引起大气的雪崩电离，从而引起夜间低电离层电子密度的显著增加，但这种电子密度的增加是暂的，在很短的时期内就恢复到平静时的水平，恢复时间随高度的变化而不同。     

The PAMELA experiment: A space-borne observatory for heliospheric phenomena

PAMELA is a multi-purpose apparatus composed of a series of scintillator counters arranged at the extremities of a permanent magnet spectrometer to provide charge, time-of-flight and rigidity information. Lepton/hadron identification is performed by a silicon–tungsten calorimeter and a Neutron detector placed at the bottom of the device. An Anticounter system is used offline to reject false triggers coming from the satellite. The device was put into orbit on June 15th 2006 in a pressurized container on board the Russian Resurs-DK1 satellite. The satellite is flying along a high inclination (70°), low Earth orbit (350–600 km), allowing to perform measurements in different points and conditions of the geomagnetosphere. PAMELA main goal is a precise measurement of the antimatter ( 80 MeV–190 GeV, e⁺ 50 MeV–270 GeV) and matter (p 80–700 GeV, e⁻ 50 MeV–400 GeV) component of the galactic cosmic rays. In this paper we focus on the capabilites of observations of heliospheric cosmic rays: trapped and semi-trapped particles in the proton and electron belts, solar particle events, Jovian electrons will be studied in the three years of expected mission.     

Consequences of the application of the streamer fluid model to the study of the sprite inception mechanism

We present the results of a streamer-fluid model used to investigate the electrodynamical coupling between the troposphere and upper atmosphere due to the penetration of lightning electric fields into the mesosphere and the lower ionosphere, generating sprites. The model solves the continuity equation for electrons and ions coupled to Poisson equation. The dominant physical response of the atmosphere is the formation of a screening-ionization wave. The wave shields the atmosphere above it from the action of the lightning field and, together with the conductivity reduction below it due to attachment, the wave amplifies the total field below it, allowing for the penetration of intense electric fields in the mesosphere as it propagates downwards into regions of higher density that compress the wave. This is the key physical mechanism for sprite inception. We evaluated the effects of the thundercloud charge geometry, lightning current waveshape, atmospheric conductivity, via different electron density profiles, and the effect of ionization, attachment and electron mobility coefficients in the electrical breakdown process, related to halo production, and sprite streamer initiation. The results showed that electrons with higher mobility are more efficient in shielding the lightning electric field before breakdown, causing delay, and they contribute to the formation of the streamer seed after breakdown, anticipating the sprite streamer inception. Similarly, a higher effective ionization rate, produced by modifications in the attachment and ionization coefficients, anticipates sprite inception. The simulations with 6 different electron density profiles, and therefore conductivities, spanning 4 orders of magnitude, showed that the altitude of breakdown and sprite initiation, as well as their time delays from the lightning discharge are directly related to atmospheric conductivity: higher conductivities produce halo and sprite inception at lower altitudes with longer delays and may hinder sprite formation. We document that variations of 30 times in the lightning current leads to sprite initiation altitudes in the range 66.0–73.5 km, with delays between 1.550 and 34.500 ms, while variations of 4 orders of magnitude in the conductivity profile lead to initiation altitudes 61.0–70.6 km, with delays in the range 3.825–9.825 ms. Consequently, we suggest that lightning characteristics dominate over atmospheric parameters in determining sprites’ initiation altitude and delay. The simulation of a −CG, with a constant current of 30 kA, did not produce a sprite seed, confirming an asymmetry in the response of the atmosphere to positive and negative lightning. This is due to the free electron drift direction that is away from the screening ionization wave, preventing the formation of the streamer seed for the great majority of −CGs. The same does not apply to halos, which depend on the occurrence of breakdown and can be produced by discharges of both polarities.     

Solar wind low-energy energetic ion enhancements: A tool to forecast large geomagnetic storms

Predicting the occurrence of large geomagnetic storms more than an hour in advance is an important, yet difficult task. Energetic ion data show enhancements in flux that herald the approach of interplanetary shocks, usually for many hours before the shock arrival. We present a technique for predicting large geomagnetic storms (Kp  7) following the arrival of interplanetary shocks at 1 AU, using low-energy energetic ions (47–65 keV) and solar wind data measured at the L1 libration point. It is based on a study of the relationship between energetic ion enhancements (EIEs) and large geomagnetic storms by Smith et al. [Smith, Z., Murtagh, W., Smithtro, C. Relationship between solar wind low-energy energetic ion enhancements and large geomagnetic storms. J. Geophys. Res. 109, A01110, 2004. doi:10.1029/ 2003JA010044] using data in the rise and maximum of solar cycle 23 (February 1998–December 2000). An excellent correlation was found between storms with Kp  7 and the peak flux of large energetic ion enhancements that almost always (93% of time in our time period) accompany the arrival of interplanetary shocks at L1. However, as there are many more large EIEs than large geomagnetic storms, other characteristics were investigated to help determine which EIEs are likely to be followed by large storms. An additional parameter, the magnitude of the post-shock total magnetic field at the L1 Lagrangian point, is introduced here. This improves the identification of the EIEs that are likely to be followed by large storms. A forecasting technique is developed and tested on the time period of the original study (the training data set). The lead times, defined as the times from the arrival of the shock to the start of the 3-h interval of maximum Kp, are also presented. They range from minutes to more than a day; the average for large storms is 7 h. These times do not include the extra warning time given when the EI flux cross the high thresholds ahead of the shock. Because the data-stream used in the original study is no longer available, we extended the original study (1998–2000) to 2001, in order to: (a) investigate EIEs in 2001; (b) present a validation of the technique on an independent data set; (c) compare the results based on the original (P1) energy channel to those of the replacement (P1′) and (d), determine new EIE thresholds for forecasting geomagnetic storms using P1′ data. The verification of this P1′ training data set is also presented, together with lead times.     

雷暴充电对大气电位的影响

本文在指数导电率大气中,在给定电离层电位情况下,考虑雷暴充电电流源以后,解析地求解了稳态电流守恒方程,获得了大气电位分布的解析表达式.考察这一表达式可以看到,雷暴充电对大气电位的影响和电离层电位对大气电位的影响主要都是垂直地起作用的.从观测到的雷暴充电电流密度的数值以及其他性质出发,利用本文得到的解析表达式进行计算可看到,雷暴充电作用能够使电层高度上的电位上升到由观测所推出的电层电位应具有的数值.数例结果还表明,电离层电位能通过对雷暴上空电层电位值的显著影响而对晴天区低层大气电状态发生作用.      

Propagation and origin of ultra high-energy cosmic rays

Propagation of UHE protons through CMB radiation leaves the imprint on energy spectrum in the form of Greisen–Zatsepin–Kuzmin (GZK) cutoff, bump (pile-up protons) and dip. The dip is a feature in energy range 1 × 10¹⁸–4 × 10¹⁹ eV, caused by electron–positron pair production on CMB photons. Calculated for power-law generation spectrum with index γ_g = 2.7, the shape of the dip is confirmed with high accuracy by data of Akeno-AGASA, HiRes, Yakutsk and Fly’s Eye detectors. The predicted shape of the dip is robust: it is valid for the rectilinear and diffusive propagation, for different discreteness in the source distribution, for local source overdensity, deficit, etc. This property of the dip allows us to use it for energy calibration of the detectors. The energy shift λ for each detector is determined by minimum χ² in comparison of observed and calculated dip. After this energy calibration the absolute fluxes, measured by AGASA, HiRes and Yakutsk detectors remarkably coincide in energy region 1 × 10¹⁸–1 × 10²⁰ eV. Below the characteristic energy E_c ≈ 1 × 10¹⁸ eV the spectrum of the dip flattens for both diffusive and rectilinear propagation, and more steep galactic spectrum becomes dominant at E < E_c. The energy of transition E_tr < E_c approximately coincides with the position of the second knee E_2kn, observed in the cosmic ray spectrum. The dip-induced transition from galactic to extragalactic cosmic rays at the second knee is compared with traditional model of transition at ankle, the feature observed at energy 1 × 10¹⁹ eV.     

Real-time global MHD simulation of the solar wind interaction with the earth’s magnetosphere

We have developed a real-time global MHD (magnetohydrodynamics) simulation of the solar wind interaction with the earth’s magnetosphere. By adopting the real-time solar wind parameters and interplanetary magnetic field (IMF) observed routinely by the ACE (Advanced Composition Explorer) spacecraft, responses of the magnetosphere are calculated with MHD code. The simulation is carried out routinely on the super computer system at National Institute of Information and Communications Technology (NICT), Japan. The visualized images of the magnetic field lines around the earth, pressure distribution on the meridian plane, and the conductivity of the polar ionosphere, can be referred to on the web site (http://www2.nict.go.jp/y/y223/simulation/realtime/).The results show that various magnetospheric activities are almost reproduced qualitatively. They also give us information how geomagnetic disturbances develop in the magnetosphere in relation with the ionosphere. From the viewpoint of space weather, the real-time simulation helps us to understand the whole image in the current condition of the magnetosphere. To evaluate the simulation results, we compare the AE indices derived from the simulation and observations. The simulation and observation agree well for quiet days and isolated substorm cases in general.     

Microwave specular scattering response of soil texture at X-band

Soil texture is an important soil parameter that is useful for meteorology, climatology, hydrology, ecology, etc. Therefore, it is important to classify soil based on soil texture (i.e., sand, silt and clay). A lot of studies with radar remote sensing have been carried out to estimate soil moisture and surface roughness, but less attention has been given to study the effect of individual soil texture on radar scattering, especially in specular direction. The main aim of this paper is to check the behavior of specular scattering with change in soil texture. This effect has also been analyzed in presence of soil moisture and surface roughness. Scattering coefficient has been retrieved for various soil texture fields with indigenously designed X-band bistatic scatterometer for a range of incidence angles (from 30° to 70° in steps of 10°) in both like polarizations, i.e., HH-polarization and VV-polarization. Observations were made at 10 GHz frequency. Four different fields were considered on the basis of soil texture variations; especially changes in sand percentage were made. Roughness (smooth soil to 1.4 cm rms surface height) and moisture (dry soil to 0.21 cm³ cm⁻³ volumetric soil moisture) conditions of these fields were varied for observations. Strong change in specular scattering coefficient is observed by changing the sand percentage in soil for HH-polarization, while in case of VV-polarization a lesser change is observed. Also a high change in specular scattering coefficient is noticed once moisture is added to the soil. It is difficult to observe the change in specular scattering coefficient with change in soil texture when surface is considered as rough. Therefore, it is important to minimize the roughness effect while observing the texture with specular scattering. For this purpose, polarization study was carried out to see how polarization can be helpful to minimize the roughness effect. The effect of soil texture on copolarization ratio is critically analyzed, and it is observed that for higher incidence angle (50°), the distinction in soil texture fields are clearly observable on the basis of copolarization ratio. This type of study will be helpful in near future to design the bistatic radar system for soil parameter monitoring, especially for cartwheel satellite system.     

A linear stability analysis of large-Prandtl-number thermocapillary liquid bridges

A linear stability analysis is applied to determine the onset of oscillatory thermocapillary convection in cylindrical liquid bridges of large Prandtl numbers (4  Pr  50). We focus on the relationships between the critical Reynolds number Re_c, the azimuthal wave number m, the aspect ratio Γ and the Prandtl number Pr. A detailed Re_c–Pr stability diagram is given for liquid bridges with various Γ. In the region of Pr > 1, which has been less studied previously and where Re_c has been usually believed to decrease with the increase of Pr, we found Re_c exhibits an early increase for liquid bridges with Γ around one. From the computed surface temperature gradient, it is concluded that the boundary layers developed at both solid ends of liquid bridges strengthen the stability of basic axisymmetric thermocapillary convection at large Prandtl number, and that the stability property of the basic flow is determined by the “effective” part of liquid bridge.     

Schumann resonance frequency and conductivity in the nighttime ionosphere of Mars: A source for lightning

We have solved the Maxwellian equations of electromagnetic waves which oscillate within the cavity formed in the lower ionosphere of Mars between 0 and 70?km. The electrical conductivity and Schumann Resonance (SR) frequencies are calculated in the lower ionosphere of Mars, in the presence of a major dust storm that occurred in Martian Year (MY) 25 at low latitude region (25°–35°S). It is found that the atmospheric conductivity reduced by one to two orders of magnitude in the presence of a dust storm. It represents a small dust layer at about 25–30?km altitudes where lightning can occur. We also found that the SR frequencies peak at?～18?km with values 19.9, 34.5 and 48.8?Hz for the modes l?=?1, 2 and 3, respectively, in the non-homogeneous medium. Our results indicate that practical or measurable values of SR are dependent on the altitudes.     

北京和东北地区雷暴与太阳活动的关系

太阳活动对于大气电性能可能会产生影响,而大气电性能在雷暴形成过程中可能会起着重要作用.因此,太阳活动对于大气电性能的影响,最终将有可能影响到雷暴的形成.本文用1957年到1978年北京地区和东北地区的10个气象站的13000多个雷暴资料,用时序迭加法分析了雷暴数与太阳磁扇形界面通过、太阳耀斑及太阳黑子11年周期变化等的关系.结果表明,有些年分的雷暴数当行星际磁场方向由指向太阳变为离开太阳的磁扇形界面扫过地球时有相关影响,在界面通过前后3天内或7天后雷暴数明显增大.从季节来看,上半年的界面通过比下半年的界面通过对雷暴的影响大.在各种太阳耀斑分类统计分析中,看到出现在日面上西区特别是西一区(0°-30°)的耀斑对雷暴的影响显著.雷暴数与太阳黑子11年周期变化则没有很显著的相关关系.