Schumann resonance amplitude during the Forbush effect

The time variations in the galactic cosmic ray (GCR) intensity at Apatity stations have been compared to the amplitude of the first Schumann resonance (as an indicator of the global thunderstorm activity power) for 12 cases of Forbush decreases in GCRs. A performed analysis indicated that the amplitude of the first Schumann resonance decreased only once during a Forbush decrease in GCRs as compared to the quiet conditions (during the strongest event in January 2005). In the remaining cases, a statistically significant effect was not observed.     

Effect of cosmic rays on atmospheric pressure under mountain conditions

The phenomenological model of condensation interaction between galactic cosmic rays (GCRs) and water vapor, which makes it possible to estimate atmospheric pressure variations at different altitudes with changing GCR flux, has been developed. It has been indicated that pressure should increase at all altitudes in the considered interval (0–5 km above sea level) during Forbush decreases. Therefore, the correlation between pressure and GCR flux under mountain conditions can be negative as near sea level. However, the performed calculation of the cross-correlation function of the series of daily data, obtained at Jungfraujoch station (3475 m) in 1968–1992, indicated that this correlation is positive and statistically significant with a maximum leading the GCR variation onset by two days. As usual, pressure increased during Forbush decreases due to the condensation mechanism. The obtained results can be explained by the manifestation of the optical mechanism related to solar flares, which operates together with the condensation mechanism and causes a decrease in pressure at high altitudes. It has been indicated that the effectiveness of this mechanism substantially changes with the phase of the quasibiennial cycle.     

Effect of solar and galactic cosmic rays on the duration of macrosynoptic processes

The effect of solar and galactic cosmic ray variations on the duration of elementary synoptic processes (ESPs) in the Atlantic-European sector of the Northern Hemisphere has been studied. It has been found that solar cosmic ray (SCR) bursts result in an increase in the duration of ESPs, which belong to the western and meridional forms of atmospheric circulation. Forbush decreases in galactic cosmic rays (GCRs) are accompanied by an increase in the duration of ESPs, which belong to the meridional atmospheric circulation form, and in a decrease in the duration of ESPs, which are related to the western and eastern circulation forms. It has been assumed that the observed variations in the ESP duration are caused by the effect of short-period cosmic ray variations on the intensity of cyclonic processes at middle and high latitudes, namely, the regeneration of cyclones near the southeastern coast of Greenland after SCR bursts and the development of blocking anticyclones over the northeastern Atlantic, Europe, and Scandinavia during GCR Forbush decreases.     

Galactic Cosmic Ray Intensity in the Upcoming Minimum of the Solar Activity Cycle

During the prolonged and deep minimum of solar activity between cycles 23 and 24, an unusual behavior of the heliospheric characteristics and increased intensity of galactic cosmic rays (GCRs) near the Earth’s orbit were observed. The maximum of the current solar cycle 24 is lower than the previous one, and the decline in solar and, therefore, heliospheric activity is expected to continue in the next cycle. In these conditions, it is important for an understanding of the process of GCR modulation in the heliosphere, as well as for applied purposes (evaluation of the radiation safety of planned space flights, etc.), to estimate quantitatively the possible GCR characteristics near the Earth in the upcoming solar minimum (~2019–2020). Our estimation is based on the prediction of the heliospheric characteristics that are important for cosmic ray modulation, as well as on numeric calculations of GCR intensity. Additionally, we consider the distribution of the intensity and other GCR characteristics in the heliosphere and discuss the intercycle variations in the GCR characteristics that are integral for the whole heliosphere (total energy, mean energy, and charge).     

Relation between the atmospheric characteristics in the antarctic regions and the space weather factors

Considerable variations in the cloud cover level and air temperature, related to the variations in GCRs and IMF, have been revealed based on an analysis of the meteorological and aerological data obtained at Vostok station from 1974 to 1994. It has been found out that the cloud cover at Vostok decreased, on average, by 35% a day after powerful Forbush decreases in GCRs following a considerable increase in the southward IMF component. In the years of solar activity minimum, when the variations in SCRs and GCRs are insignificant, the cloudiness and surface temperature increase on a day of B _z minimum and decrease on a day of maximum as compared to the average level. On days of B _z minimum, the air temperature rises at altitudes of h = 3.5–7 km, remains almost unchanged at an altitude of h = 8 km, and slightly decreases at higher altitudes. An increase in cloudiness at altitudes below 8 km causes warming, probably due to the greenhouse effect, because the temperature of the Earth’s surface decreases.     

Estimation of the effect of solar activity on the intensity of galactic cosmic rays

The observations of solar activity (average monthly values of the international sunspot numbers and areas, solar radioemission flux at a wavelength of 10.7 cm) and galactic cosmic ray (GCR) intensity (average monthly values of the count rate of an omnidirectional Geiger counter at a maximum of the transition curve in the regions of Moscow and Murmansk and differences between these values) have been studied. The main aim of the studies was to assess the possibility of using the series of GCR values as an additional type of instrumental observations to predict solar activity. The results of an analysis made it possible to assess the degree of interrelation between the studied time series and, thereby, to confirm that GCRs, together with the characteristics of sunspot formation and solar radioemission flux at a wavelength of 10.7 cm, can be used to predict solar activity. The development of the current solar cycle has been predicted. It is assumed that the duration of this cycle will exceed the average value.     

气溶胶对雷暴云电过程影响的数值模拟研究

本文在已有的三维雷暴云起、放电模式中加入了一种经典的气溶胶活化参数化方案,结合一次长春雷暴个例,进行了雷暴云起放电数值模拟试验.研究显示气溶胶浓度改变对雷暴云微物理、起电及放电过程都有重要影响.结果表明:(1)污染型雷暴云中气溶胶浓度增加时,云滴数目增多,上升风速加强;云中冰晶与霰粒子数浓度增加但尺度减小;(2)相对于清洁型雷暴云,污染型雷暴云非感应起电过程弱,感应起电过程强,起电持续时间长;(3)污染型雷暴云中首次放电时间延迟,闪电持续发生的时间长,总闪电频次增加,正地闪频次增加明显.     

Frequency characteristic of response of surface air pressure to changes in flux of cosmic rays

We compare the series of daily-average values of the surface air pressure for De Bilt and Lugano meteorological stations with subtracted linear trends and seasonal harmonics, as well as the series of the flux of galactic cosmic rays (GCRs) at Jungfraujoch station with subtracted moving average over 200 days. Using the method of superposed epochs, we show that the Forbush decreases at both stations are accompanied by increased pressure. Spectral analysis allows us to conclude that the analyzed series are characterized by nonzero coherence in almost the entire frequency range: from 0.02 day^?1 day up to the Nyquist frequency of 0.5 day^?1. Using changes in the GCR flux as a probing signal, we obtain amplitude-frequency characteristics of the pressure reaction. For both stations, these characteristics are in qualitative agreement with each other and indicate that the atmospheric response can be described by a second-order linear dynamic system that has wide resonance with a maximum at a frequency of 0.15 day^?1.     

闪电放电过程的近红外光谱及温度沿放电通道的演化特征

利用无狭缝红外光谱仪, 获得山东地区闪电放电过程760~970 nm范围的近红外光谱.光谱特征分析得出: 近红外光谱主要是峰值电流之后、放电后期的辐射, 谱线主要是中性原子的贡献.首次讨论了放电后期的通道温度和光谱总强度沿放电通道的演化特征.结果表明, 通道温度较回击电流上升至峰值阶段降低, 约为16000 K; 不同闪电的光谱结构、通道温度差异不大, 反映了放电等离子体复合阶段的特性; 地闪通道的温度和光谱总强度沿放电通道略呈单调变化趋势, 接地点附近最大; 云闪通道的温度和光谱总强度沿放电通道非单调变化, 在通道的拐弯、分叉以及结点附近发生突变.     

Source of runaway electrons in a thundercloud field caused by cosmic radiation

The volumetric generation rate of secondary electrons, produced by cosmic radiation in the Earth’s atmosphere and able to accelerate in a thundercloud electric field, has been calculated as a function of height above sea level. It is recommended to use the obtained function as a source when modeling atmospheric breakdown in thunderstorm fields with the participation of relativistic runaway electron avalanches. It has been indicated that ionization of the atmosphere by a cosmic particle with an energy of 10¹⁶ eV cannot initiate lightning.     

The rigidity spectrum of the harmonics of the 27-day variation of the galactic cosmic ray intensity in different epochs of solar activity: 1965–2002

We study temporal changes of the rigidity (R) spectrum of the harmonics of the 27-day variation of the galactic cosmic ray (GCR) intensity using neutron monitors (NM) data for the period 1965–2002. We show that the rigidity spectrum of the third harmonic (9 days) of the 27-day variation of the GCR intensity changes in a similar way as the spectra of the first and second harmonics, being hard in the maximum epochs and soft in the minimum epochs of solar activity. We ascribe this finding to the alternation of the sizes of the modulation regions of the 27-day variation of the GCR intensity in different epochs of solar activity. The average size of the vicinity of the corotating interaction regions, causing the 27-day variation of the GCR intensity, is less in the minimum epochs than in the maximum epochs of solar activity. A vicinity of the corotating interaction regions of larger size involves in modulation higher rigidity particles of GCR than the vicinity of smaller size; thus, this statement can be considered as one of the reasons leading to the hardening of the rigidity spectrum of the harmonics of the 27-day variation of the GCR intensity in maximum epochs compared with minimum epochs of solar activity.We also show that the temporal changes of the power rigidity spectrum of the third harmonic of the 27-day variation of the GCR intensity are negatively correlated with the rigidity spectrum of the 11-year variation of the galactic cosmic ray intensity.We found a recurrence in the temporal changes of the amplitudes of the first harmonic of the 27-day variation of the GCR intensity and in some parameters of solar activity and solar wind.     

Wavelet image of the fine structure of the 11-year cycle based on studying cosmic ray fluctuations during cycles 20–23

A non-stationary transient oscillating process of the solar magnetic field polarity reversal of ≈3 years in duration has been established: a U-shaped dynamics in the wavelet representation of variations in the scintillation index of galactic cosmic rays (GCRs) (≈7, 13–14, and ≈7 solar rotations). The transient oscillating process of the field reversal is concluded with a sharp and deep decrease in the GCR intensity at the branch of 11-year cycle decline (1972, 1982, 1991, and 2003). The duration of the transient process inversely depends on the 11-year cycle amplitude. Retardation of relaxation oscillations during “weak” cycles (20 and 23) explains “anomalous” solar activity in 1972 and 2003. A decrease in the amplitude of the current cycle 23 is accompanied by an increase in its duration, which can mean that the 11-year cyclicity has become anomalous. The constancy of the energy released in a single cycle indicates that the 11-year cycle is the mechanism of energy regulation preventing the Sun from “overheating” at the critical temperature.     

Numerical simulations of the bi-level and branched structure of intracloud lightning flashes

Intracloud (IC) lightning is used to mean those lightning flashes which channels do not strike the ground. It is an important scientific problem to inves-tigate the IC flash features and the discharge physics.Measurements from the electric field change arrange-ment[1,2] and VHF radiation events[3,4] have provided ample evidence that IC flashes have branches with substantial horizontal extents. The VHF interferomet-662 Science in China: Series D Earth Sciences ric observations[5] also s…     

Spectrographic analysis of events in cosmic rays in October–November 2003

Based on the multiplied neutron registration with the Magadan neutron monitor, the parameters of the spectrum of variations in the cosmic ray hardness and variation in geomagnetic cutoff rigidity for Forbush decreases and intensity increases, related to registration at a level of solar cosmic ray observation, have been determined using the spectrographic method. Results of an analysis indicate that the spectral index (represented in the power form) increases for Forbush decreases and decreases for increases in CR intensity. In the analyzed cases, geomagnetic cutoff rigidity decreases for intensity increases and Forbush decreases.     

Study on the characteristics of earthquake’s impact on cities

Firstly, the impact of historical earthquakes on 34 China province-level capital cities is evaluated by using historical earthquake catalog. The distribution of affected intensity shows, about 53% of cities have even not been affected by earthquake intensity VI, and 44% of cities have been hit by earthquake intensity VII to IX. For most of the cities, occurrence frequency of affected intensity VI is usually higher than that of affected intensity larger than VI, and the value of affected intensity with maximal occurrence frequency may be very different among cities. So both the maximal affected intensity and the affected intensity with maximal occurrence frequency should be taken into account when the prevention seismic intensity needs to be determined. Secondly, considering the incompleteness of records of historical earthquakes, a method of earthquake catalog computer simulation is introduced to study the features of affected intensity of big cities. 69 county-level cities of Fujian Province are selected to be statistical objects. The statistical result shows, for different risk levels the seismic intensity changes greatly among cities, the seismic intensity of 2% probability of exceedance in 50 years can be regarded as the characteristic affected intensity of city, and can be the basis of determining the city special earthquake prevention level and a proper indicator of future earthquake’s impact on cities. Foundation item: A Public Benefit Foundation of the Ministry of Science and Technology of China. Contribution No. 04FE1005, Institute of Geophysics, China Earthquake Administration.     

Study on the characteristics of earthquake''''s impact on cities

Introduction With rapid development of national economy, urbanization has been speeded up in China, and several city groups or city belts with extra-large cities as their centers have been formed. For example, Pearl River Delta urbanized area surrounds Guangzhou City, Shenzhen City, Zhuhai City; Yangtze River Delta urbanized area surrounds Shanghai City, Suzhou City, Wuxi City, Nanjing City, Hangzhou City; Beijing-Tianjin-Tangshan urbanized area surrounds Beijing City, Tianjin City…     

Numerical calculation of cosmic ray ionization rate profiles in the middle atmosphere and lower ionosphere with relation to characteristic energy intervals

Numerical calculations of galactic cosmic ray (GCR) ionization rate profiles are presented for the middle atmosphere and lower ionosphere altitudes (35–90 km) for the full GCR composition (protons, alpha particles, and groups of heavier nuclei: light L, medium M, heavy H, very heavy VH). This investigation is based on a model developed by Velinov et al. (1974) and Velinov and Mateev (2008), which is further improved in the present paper. Analytical expressions for energy interval contributions are provided. An approximation of the ionization function on three energy intervals is used and for the first time the charge decrease interval for electron capturing (Dorman 2004) is investigated quantitatively. Development in this field of research is important for better understanding the impact of space weather on the atmosphere. GCRs influence the ionization and electric parameters in the atmosphere and also the chemical processes (ozone creation and depletion in the stratosphere) in it. The model results show good agreement with experimental data (Brasseur and Solomon 1986, Rosenberg and Lanzerotti 1979, Van Allen 1952).     

Lightning activity and precipitation structure of hailstorms

By using the cloud-to-ground (CG) lightning location data from the lightning detection network of He- nan Province, surface Doppler radar data and standard orbit data of PR, TMI and LIS on TRMM satellite, the spatial and temporal characteristics of CG lightning flashes in 10 severe hailstorms are analyzed. The results show that the percentage of CG lightning in these hailstorms is high with an average value of 45.5%. There is a distinct increase in CG flash rate during the rapid development stage of hailstorms. The hailstone falling corresponds to an active positive flash period, and the increase of CG flash rate is generally accompanied with a decrease of –CG flash rate. The flash rate declines rapidly during the dissipating stage of hailstorms. The precipitation structure and lightning activity in two typical hail- storms are studied in detail. It is found that strong convective cells with reflectivity greater than 30dBZ mainly are situated in the front region of hailstorms, whereas the trailing stratiform region is in the rear part of the hailstorms. The maximum heights of echo top are higher than 14 km. Convective rain con- tributes much more rainfall to the total than stratiform rain, and the convective rain takes about 85% and 97% of the total in the two cases, respectively. Total lightning in the hailstorms is very active with the flash rate up to 183 fl/min and 55 fl/min, respectively. The results also indicate that most lightning flashes occurred in the echo region greater than 30 dBZ and its immediate periphery. The probability of lightning occurrence is 20 times higher in the convective region than in the stratiform region. The result suggests that the lightning information is helpful to the identification of convective rain region. The linear relationship between flash rate and ice water content is disclosed primarily.     

A new index of solar activity: An index of cosmic ray scintillation

An index of cosmic ray scintillation introduced previously is verified. This procedure has been performed within the scope of the long-term full-scale monitoring of galactic cosmic rays (GCRs) in the real time regime. The 5-min data of the global network of high-latitude neutron monitors at Tixie Bay (Apatity) and Oulu (Finland) stations during the last four solar cycles (cycles 20–23), i.e., during the entire period of data registration with a high (5 min) resolution, have been used. The relationship between the amplitude-frequency-time structure of a precursor in the GCR scintillation index and the soliton-like structure of the heliospheric current sheet during the disturbed period has been established. This indicates that the precursor is of a coherent origin. Only the presence of a coherent process—quasi-week variation—makes it fundamentally possible to predict heliospheric storms. Finally, the justifiability of the effective prediction of heliospheric storms (～80%) has been obtained based on the long-term cosmic ray monitoring during cycle 23.     

Petro-Sonde法场源研究

美国的Petro-Sonde（简称PS）法,对地层有很高的分辨力和一定的识别物性的能力,从而引起我国地球物理学界的重视,国内研究者相继开展了对该方法的研究。但由于对PS法的场源机制并不清楚,这妨碍了对方法原理的研究,因而对场源机制的探讨至关重要。本文提出PS法所利用的场源是起因于雷暴闪电的天然电磁场,且主要是电型场或TM场,而TM零阶模和TM一阶模为其主要的初始场形式,这明显不同于Cagniard模型。