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 研究了雷达导引头的交班误差以及截获概率与交班时刻弹目几何位置的关系,提出了单个误差角的导引头天线指向角误差模型,它与两个误差角的导引头指向角误差模型相比可以更好地分析天线指向角误差,并得到使指向角误差最小的弹目几何位置;然后进一步得到使多普勒频率误差最小的弹目几何位置;给出了最终的截获概率的表达式,截获概率由目标处于导引头天线主波束的概率、目标回波多普勒频率落入接收机频带内的概率和目标的检测概率组成的;最后分析了一种典型的中末交班情况.     

陀螺仪短周期性能测试方法研究

讨论了陀螺仪短周期重复性能的标定测试方法，即极轴翻滚试验方法。该方法以地球极轴为基准，通过对一周过程的电流值进行离散傅立叶分析，经过相应的运算处理求出误差模型参数的估计值。试验结果表明，该方法辨识参数多，全面反映了陀螺仪性能，可以科学地考察陀螺仪的短周期重复性。     

Comparison of the magnetic field before the subsolar magnetopause with the magnetic field in the solar wind before the bow shock

Crossings of the magnetopause near the subsolar point are analyzed using data of THEMIS mission. Variations of the magnetic field near magnetopause measured by one of THEMIS satellites are studied and compared with simultaneous measurements in the solar wind by another THEMIS satellite. The time delay of the solar wind arrival at the subsolar point of the magnetopause is taken into account. 30 and 90 s averaging of the magnetic field in the magnetosheath is produced. The results of averaging are compared with the results of measurements in the solar wind before the bow shock and foreshock. It is shown, that _Bx$B_x$ component of the magnetic field near magnetopause is near to zero, which supports the possibility to consider the magnetopause as the tangential discontinuity. Comparatively good correlation of _By$B_y$ component in the solar wind and near the magnetopause is observed. The correlation of _Bz$B_z$ component near the magnetopause and IMF is practically absent, the sign of the _Bz$B_z$ near the subsolar point does not coincide with the sign of IMF _Bz$B_z$ in ∼$\sim$30% cases.     

Influence of the Ionosphere on the Observation of the Mid-Latitude Pi2 Pulsations at the Global Scale

Results of our investigation showed that occurrence frequency of Pi2 over a 24 hour period undergoes seasonal variations in time coincidence with f0F2. In the winter months, at sunrise and sunset (when f0F2 gradients are the largest) the observation probability of these oscillations is minimal. At periods of summer solstice when the F2-layer persists almost round the clock, no effect of Pi2 pulsation attenuation is observed at sunrise and sunset. The pulsation amplitudes behave in a similar manner. Results of this study suggest the conclusion that the propagation of signal from the Pi2 sourse into the mid-latitudes, and also the parameters of these pulsations are essentially affected by electron density in the ionospheric F2-layer.     

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.     

Method for the prediction of the effective dose equivalent to the crew of the International Space Station

This paper describes a methodology for assessing the pre-mission exposure of space crew aboard the International Space Station (ISS) in terms of an effective dose equivalent. In this approach, the PHITS Monte Carlo code was used to assess the particle transport of galactic cosmic radiation (GCR) and trapped radiation for solar maximum and minimum conditions through an aluminum shield thickness. From these predicted spectra, and using fluence-to-dose conversion factors, a scaling ratio of the effective dose equivalent rate to the ICRU ambient dose equivalent rate at a 10 mm depth was determined. Only contributions from secondary neutrons, protons, and alpha particles were considered in this analysis.     

地磁暴恢复相中间层低热层高纬温度响应

利用TIMEGCM模拟了2005年9月10日至20日由日冕物质抛射引起的地磁暴事件，研究了此地磁暴恢复相高纬度中间层低热层（MLT）区域温度的变化，揭示了磁暴恢复相时温度、垂直风、总加热项和NO辐射冷却的内在联系.结果表明:地磁暴恢复相刚开始时，温度对磁暴的响应在晨侧为负扰动（降温），在其他地区都为正扰动（增温）；随着磁暴的恢复，整个北半球都变为正的温度扰动（增温）.这种高纬MLT区域的温度响应主要与垂直风密切相关.当垂直风为正时，总加热为负，增温减弱；当垂直风为负时，总加热为正，增温变强.辐射冷却特别是NO辐射冷却作用在热层被称为恒温器，降低了磁暴期间80%的热层增温.但是，在MLT区域NO辐射冷却作用不明显，一般比总加热项小一个量级，对温度响应造成的影响较小.      

On the correlation of the solar wind observed at the L5 point and at the Earth

The L5 point is a promising location for forecasting co-rotating high-speed streams in the solar wind arriving at the Earth. We correlated the solar wind data obtained by the Nozomi spacecraft in interplanetary space and by the Advanced Composition Explorer (ACE) at the L1 point, and found that the correlation is significantly improved from that of the 27-day recurrence of ACE data. Based on the correlation between the two spacecraft observations, we estimated the correlation of the solar wind velocity between the L5 point and at the Earth, and found that the correlation coefficient was about 0.78 in late 1999, while that of the 27-day recurrence was 0.51. Eighty-eight percent of the velocity difference falls within 100 km/s between the L5 point and the Earth. This demonstrates the potential capability of solar wind monitoring at the L5 point to forecast the geomagnetic disturbances 4.5 days in advance.     

太阳风-磁层相互作用的磁流体力学数值模拟研究

磁层位于地球空间的最外层,太阳风与磁层的相互作用是空间天气变化因果链中承上启下的关键环节,是揭示地球空间天气基本规律的关键科学课题．地球空间由于时变、多成分、多自由度的关联相互作用,使得传统的理论分析变得非常困难．数值模拟作为近几十年发展起来的一个新的研究手段,对地球空间的理论和应用研究产生了深刻的影响．国际上磁层的全球MHD数值模拟工作开始于20世纪70年代末,最初的研究局限于二维空间．由于磁层内在的三维特性,20世纪80年代三维MHD数值模拟工作兴起．本文简要说明了三维全球磁层MHD（磁流体力学）研究的特点及现状,给出了三维全球磁层模型的基本框架,综述了行星际激波与磁层相互作用、大尺度电流体系、重联电压和越极电位、磁层顶K—H不稳定性等方面的太阳风—磁层相互作用的MHD数值模拟的研究进展．     

Possible physical properties of the flow in the vicinity of the heliopause

An interface between the fully ionized hydrogen plasma of the solar wind (SW) and the partially ionized hydrogen gas flow of the local interstellar medium (LISM) is formed as a region where there is a strong interaction between these two flows. The interface is bounded by the solar wind termination shock (TS) and the LISM bow shock (BS) and is separated on two regions by the heliopause (HP) separating the solar wind and charged component of the LISM (plasma component below). The BS is formed due to the deceleration of the supersonic LISM flow relative to the solar system. Regions of the interface between the TS and HP and between the HP and BS were in literature named as the inner and outer heliosheaths, respectively. An investigation of the structure and physical properties of the heliosheath is at present especially interested due to the fact that Voyager-1 and Voyager-2 have crossed the TS in December 2004 (Burlaga, L.F., Ness, N.F., Acuna, M.Y., et al. Crossing the termination shock into the the heliosheath. Magnetic fields. Science 309, 2027–2029, 2005; Fisk, L.A. Journey into the unknown beyond. Science 309, 2016–2017, 2005; Decker, R.B., Krimigis, S.M., Roelof, E.C., et al. Voyager 1 in the foreshock, termination shock and heliosheath. Science 309, 2020–2024, 2005; Stone, E.C., Cummings, A.C., McDonald, F.B., et al. Voyager 1 explores the termination shock region and the heliosheath beyond. Science 309, 2017–2020, 2005) and in September 2007 (Jokipii, J.R. A shock for Voyager 2. Nature 454, 38–39, 2008; Gurnett, D.A., Kurth, W.S. Intense plasma waves at and near the solar wind termination shock. Nature 454, 78–80, 2008. doi: 10.1038/nature07023; Wang, L., Lin, R.P., Larson, D.E., Luhmann, J.G. Domination of heliosheath pressure by shock-accelerated pickup ions from observations of neutral atoms. Nature 454, 81–83, 2008. doi: 10.1038/nature07068.14; Burlaga, L.F., Ness, N.F., Acuna, M.H., et al. Magnetic fields at the solar wind termination shock. Nature 454, 75–77, 2008. doi: 10.1038/nature07029; Richardson, J.D., Kasper, J.C., Wang, C., et al. Cool heliosheath plasma and deceleration of the upstream solar wind at the termination shock. Nature 454, 63–66, 2008. doi: 10.1038/nature07024; Stone, E.C., Cummings, A.C., McDonald, F.B., et al. An asymmetric solar wind termination shock. Nature 454, 71–74, 2008. doi: 10.1038/nature07022; Decker, R.B., Krimigis, S.M., Roelof, E.C., et al. Mediation of the solar wind termination shock by non-thermal ions. Nature 454, 67–70, 2008. doi: 10.1038/nature 07030), respectively, and entered to the inner heliosheath.