神经网络方法在太阳质子事件短期预报中的应用

在大量统计结果的基础上,深入研究了太阳质子事件预报机理．总结了质子事件爆发与太阳活动区面积、位置、McIntosh结构、磁结构以及前两天活动区爆发耀斑事件数目之间的关系．然后,在神经网络的基础上建立了太阳质子事件短期预报模型,并对2000年以后12个未参加训练的样本进行测试,结果对事件预报的准确率为83％．此外,我们还利用该模型对2002年1-4月发生的几次质子事件进行了预报试验,结果发现,这期间发生的6次事件都被预报．其中3次质子事件系统预报提前了3天,两次事件预报提前了2天,一次事件提前1天预报．     

太阳微波爆发频谱事件

国家天文台1.0-2.0GHz,2.6-3.8GHz太阳射电频谱仪从1994年1月和1996年9月投入观测至2000年4月10日记录到太阳射电爆发分别为297个和316个，取得了高质量的高时间分辨率，高频率分辨率的动态谱资料，为研究耀斑各种尺度的时间及空间演化过程提供了丰富的信息，1998年4月15日的共同事件在时间和频率上显示了丰富的幅度和结构的变化。     

模拟地球同步轨道辐照环境对光学太阳反射镜性能的影响

研究了模拟地球同步轨道辐照环境对卫星用温控涂层-光学太阳反射镜(OSR)性能的影响。对所研制的两类OSR 片进行的辐照试验项目有,真空紫外辐照、低能电子和两种能量的质子辐照。此外还进行了等离子体环境条件下的表面充/放电效应试验。经过相当于安装在地球同步轨道卫星南北极位置处,在空间七年所受到的电子、质子和紫外辐照总剂量的辐照后,导电型OSR 的太阳光谱吸收率α_s 由0.068增加到0.078,法向发射率ε_n 由0.83降低到0.72;而非导电型OSR的α_s 由0.066增加到0.085,ε_n 由0.82降低到0.76。表面充/放电试验的结果表明:导电型OSR 的充电电位仅在15～40V 之间,而非导电型OSR 的充电电位则可高达13kV。因此导电型OSR能有效地控制表面的充/放电现象。     

The characteristics of sharp (small-scale) boundaries of solar wind plasma and magnetic field structures

We investigate properties of large (>20%) and sharp (<10 min) solar wind ion flux changes using INTERBALL-1 and WIND plasma and magnetic field measurements from 1996 to 1999. These ion flux changes are the boundaries of small-scale and middle-scale solar wind structures. We describe the behavior of the solar wind velocity, temperature and interplanetary magnetic field (IMF) during these sudden flux changes. Many of the largest ion flux changes occur during periods when the solar wind velocity is nearly constant, so these are mainly plasma density changes. The IMF magnitude and direction changes at these events can be either large or small. For about 55% of the ion flux changes, the sum of the thermal and magnetic pressure are in balance across the boundary. In many of the other cases, the thermal pressure change is significantly more than the magnetic pressure change. We also attempted to classify the types of discontinuities observed.     

低纬地磁Z分量的半年变化

利用武汉、广州、泉州和琼中等4个低纬地磁站连续多年的地磁资料，计算了各月5个磁静日Z分量日均值与中午1100---1300时段平均值之差(Dz)，对每年12个Dz采用多元回归分析方法，得到各年的半年变化幅度和相位．结果表明：4个站的Dz每年都有半年变化现象；半年变化幅度与太阳活动有关，一般来说，太阳活动高年Dz半年变化幅度明显大于太阳活动低年；太阳活动本身的半年变化，对Dz半年变化幅度有显著的调制作用；Dz半年变化的相位在3—4月(或9—10月)，即极大值出现在分季；低纬地区地磁Z分量存在显著的半年变化，能够反映赤道电急流也有明显的半年变化，这再一次证明，赤道电急流幅度的半年变化，通过“喷泉效应”使得电离层，f0F2产生半年变化，其是产生，f0F2半年变化的一个主要因素．     

神舟2号大气密度探测器的探测结果(Ⅰ)日照和阴影区域热层大气密度变化

选用了神舟2号（SZ-2）大气密度探测器在2001年2—4月间的探测数据,进行日照和阴影区域热层大气密度变化的探讨.结果表明:在高度410km附近,日照和阴影区域大气密度变幅为2—3倍,变幅的大小与地磁活动程度呈负相关关系.日照面大气密度峰区位于星下点地方时1400—1500LT的纬度处,峰值大小与太阳活动程度呈正相关关系.阴影面大气密度谷区位于星下点地方时0400-0500的纬度处,同时在±10°纬度区域中还出现了阴影面峰区.     

MONITORING OF ENERGETIC PARTICLE ENVIRONMENT INSIDE THE CHINA-BRAZIL EARTH RESOURCE SATELLITE

On 14 October 1999, the Chinese-Brazil earth resource satellite (CBERS-1) was launched in China. On board of the satellite there was an instrument designed at Peking University to detect the energetic particle radiation inside the satellite so the radiation fluxes of energetic particles in the cabin can be monitored continuously. Inside a satellite cabin, radiation environment consists of ether penetrated energetic particles or secondary radiation from satellite materials due to the interactions with primary cosmic rays.Purpose of the detectors are twofold, to monitor the particle radiation in the cabin and also to study the space radiation environment The data can be used to study the radiation environment and their effects on the electronics inside the satelhte cabin. On the other hand, the data are useful in study of geo-space energetic particle events such as solar proton events, particle precipitation and variations of the radiation belt since there should be some correlation between the radiation situation inside and outside the satellite.The instrument consists of two semi-conductor detectors for protons and electrons respectively. Each detector has two channels of energy ranges. They are 0.5-2MeV and ≥2MeV for electrons and 5-30MeV and 30-60MeV for protons. Counting rate for all channels are up to 104/(cm2@s)and power consumption is about 2.5 W. There are also the additional functions of CMOS TID (total integrated dose) effect and direct SEU monitoring. The data of CBMC was first sent back on Oct. 17 1999 and it's almost three years from then on. The detector has been working normally and the quality of data is good.The preliminary results of data analysis of CBMC not only reveal the effects of polar particle precipitation and radiation belt on radiation environment inside a satellite, but also show some important features of the geo-space energetic particle radiation.As one of the most important parameters of space weather, the energetic charged particles have great influences on space activities and ground tech nology. CBMC is perhaps the first long-term on-board special equipment to monitor the energetic particle radiation environment inside the satellite and the data it accnmulated are very useful in both satellite designing and space research.     

太阳质量损失对行星轨道的影响

本文利用Ｇｙｌｄｅｎ－Ｍｅｓｈｃｈｅｒｓｋｉｉ方程和Ｅｄｄｉｎｇｔｏｎ－Ｊｅａｎｓ定律，讨论太阳质量损失对行星轨道的影响，结果表明由于太阳质量损失会产生轨道半长径α的一阶周期项和二阶混合项；近日点角距ω的一阶周期项、二阶长期项和混合项，行星轨道半长径的长期变化会影响太阳系的稳定性。     

Acceleration of interplanetary pick-up ions and anomalous cosmic rays

It may not be doubted anymore that anomalous cosmic rays (ACRs) are produced in the heliosphere from interplanetary pick-up ions through their acceleration at the solar wind termination shock. However, there is no general agreement in the community of heliospheric researchers concerning the mechanism of injection of the pick-up ions into the shock acceleration. We discuss here three possible ways for pick-up ions to be involved into the acceleration process at the termination shock: (1) preacceleration of pick-up ions in the whole region from the Sun up to the termination shock by solar wind turbulences and interplanetary shock waves, (2) local preacceleration of pick-up ions in a vicinity of the termination shock by shock surfing, and (3) formation of high-velocity tails in pick-up ion spectra consisting of secondary pick-up ions which are produced in the supersonic solar wind due to ionization of energetic neutral atoms entering from the inner heliosheath.     

Noise in wireless systems from solar radio bursts

Solar radio bursts were first discovered as result of their interference in early defensive radar systems during the Second World War (1942). Such bursts can still affect radar systems, as well as new wireless technologies. We have investigated a forty-year record of solar radio burst data (1960–1999) as well as several individual radio events in the 23rd solar cycle. This paper reviews the results of a portion of this research. Statistically, for frequencies f  1 GHz (near current wireless bands), there can be a burst with amplitudes >10³ solar flux units (SFU; 1 SFU = 10⁻²² W/m²) every few days during solar maximum conditions, and such burst levels can produce problems in contemporary wireless systems.