Simulation Research on the Solar Hard X-Ray Imaging Telescope     

Teng Teng  Jian Wu  Jin Chang 《Chinese Astronomy and Astrophysics》2012

The hard X-ray imaging telescope of the modulation collimator type is widely used in current solar observations. The spatial modulation telescope is the telescope which keeps its central axis not rotate, suitable for the satellite of 3-axis attitude stabilization. For the possible Chinese solar mission in the near future, we make a design of hard X-ray imaging telescope, and simulate the photon counting using the common simulation software GEANT4. Then we implement the image reconstruction with MATLAB, and compare the reconstructed image of the photons simulated by GEANT4 with that of the photons calculated by the geometric algorithm. The results show that the simulated one by GEANT4 is more closer to the reality than that obtained by the geometric algorithm. An executable design is also proposed at last.  相似文献   

The Calculation of Solar Gamma-Rays by TALYS     

Wei Chen  Wei-Qun Gan 《Chinese Astronomy and Astrophysics》2012

Solar gamma-ray lines, produced from nuclear reactions of accelerated particles interacting with the solar atmospheric medium, are the most direct diagnosis for the acceleration and transportation of energetic electrons and ions in solar flares. Much information about composition, spectrum, and angular distribution of the accelerated ions, as well as the elemental abundances of the ambient solar atmosphere can be derived from solar gamma-ray line spectra. A new gamma-ray calculation program has been developed by using an efficient nuclear code − TALYS. The theory of gamma-ray production in solar flares is treated in detail. The characteristics of gamma-ray spectrum are also presented.  相似文献   

太阳活动极大和极小期太阳磁场周期变化研究     

叶妮  祝凤荣  周雪梅  贾焕玉 《天文学报》2012,53(1):28-35

利用Wilcox天文台1975年到2010年间的太阳磁场数据,分析了太阳平均磁场在太阳活动极大和极小时期的短时周期性.结果显示太阳磁场主要具有9 d、13.5 d、27 d左右的周期.在太阳活动极大时期,27 d左右周期最为显著,而在太阳活动极小时期最显著的周期为13.5 d左右(1984～1986年间的太阳活动极小时期除外).这些结果说明太阳的活动区域在活动极大和极小时期具有明显不同的分布.  相似文献   

利用台站资料定标太阳光度计效果评估   总被引：4，自引：1，他引：3  

李霞 《气象科技》2009,37(1):79-84

运用Langley方法、采用法国CE318太阳光度计在台站的观测记录为光度计定标,提出一种较客观的数据处理方法,主要分为4步：①利用Langley法对全年资料进行预处理,得到各通道定标常数、Langley法线性拟合相关系数、550nm的气溶胶光学厚度等;②以线性拟合相关系数的阈值大小（如440nm相关系数大于等于0．99）、定标期间550nm的平均气溶胶光学厚度小于等于0．15、半天（上午或下午）参与拟合的数据个数大于等于8组为条件,对预处理数据进行筛选;③根据光度计电压信号图像、最大值再次选取定标常数;④对最终选出的多组定标常数取平均值。对2002、2005年,乌鲁木齐、塔中、哈密、和田4个站点光度计资料进行试验,定标系数与出厂定标值（2002年）、北京定标值（2005年）比较后,4个站点的定标误差基本控制在8．5％以内（和田除外）,说明这种定标步骤有一定的参考价值。  相似文献   

黄土高原半干旱地区气溶胶光学厚度变化特征的初步分析   总被引：3，自引：2，他引：1  

张玉洁  张武  陈艳  常倬林  史晋森 《高原气象》2008,27(6)

利用"兰州大学半干旱气候与环境观测站"2006年8月至2007年4月的CE-318全自动跟踪太阳光度计观测资料,分析了黄土高原半干旱地区气溶胶光学厚度(AOD)的变化特征。结果表明,黄土高原半干旱地区气溶胶光学厚度谱基本满足Angstrom关系;在可见光和近红外波段,随着波长的增大,气溶胶光学厚度是减小的;黄土高原半干旱地区AOD日变化类型主要有单峰型、稳定型、上升型3种。逐日变化特征显示,降水对气溶胶粒子具有明显的湿清除作用,霾的出现导致AOD明显增大;AOD日均值主要集中在0.1~0.4之间,日极大值在08~11时(北京时,下同)出现的频率最多,日极小值在12~13时、14~17时出现的频率最多。气象条件对AOD有明显的影响,在南风情况下AOD大,东风情况下AOD小,霾与晴天相比,AOD明显增大;对同一波段,风向差别引起的AOD的差异较晴天与霾相比引起的AOD的差异要小。  相似文献   

The non-uniform pattern in full-disc vector magnetograms and its correction     

Xiaofan Wang  Jiangtao Su  Hongqi Zhang 《Monthly notices of the Royal Astronomical Society》2008,387(4):1463-1469

The Solar Magnetism and Activity Telescope (SMAT) has been operational at Huairou Solar Observing Station since the end of 2005. Its scientific projects are the observational study of full-disc vector magnetic field and Hα chromospheric activities. In this paper, the Fourier low-frequency passing filter and the large-scale polynomials fit methods have been employed to analyse and remove the non-uniform pattern (NUP) in the full-disc Stokes V image. These methods are useful to effectively improve the quality of SMAT's data. The following main results have been obtained. (1) An intrinsic large-scale spatial distribution of NUP appears in SMAT's full-disc Stokes V image and its average amplitude accounts for 2 per cent of sunspots' field of kG. (2) NUP is testified as instrumental polarization through data reduction and observational explanation (passband shift). There are pseudo-passband shift in the wide field of view of SMAT due to NUP, and the maximum shifting value from the solar disc centre to the solar disc limb is 0.12 Å. (3) As an example, after removing SMAT's NUP in the Stokes V image, the correlation coefficients of the magnetograms become 78 per cent between SMAT and MDI (Michelson Doppler Imager project) on the SOHO ( Solar and Heliospheric Observatory ) satellite, and 92 per cent between SMAT and the SMFT (Solar Magnetic Field Telescope) at Huairou.  相似文献   

A Statistical Study on the Filament Eruption Caused by New Emerging Flux     

Xiao-yan Xu  Cheng FangPeng-fei Chen 《Chinese Astronomy and Astrophysics》2008

Observations indicated that solar coronal mass ejections (CMEs) are closely asociated with reconnection-favored new flux emergence. By means of numerial simulations, a physical model of the emerging flux trigger mechanism for CMEs is proposed and explained well the observational results. Based upon this model, leaving the gravity and heat conduction out of consideration, the theoretical results of 2.5 dimensional numerical simulations indicate that whether a CME can be triggered depends on both the amount and the location of an emerging flux, besides its polarity orientation. Furthermore, the eruption and non-eruption regimes are presented in parameter space. By use of 15 filament eruption events in 2002 and 2003 and 44 non-eruption events in 2002, the results of a statistical study on the properties of emerging flux including its polarity orientation, its location and the amount of flux show that not all the emerging flux can make a filament to lose equilibrium and trigger the onset of a CME, The statistic results basically support the theoretical results of numerical simulations. This research provides useful information for the space weather forecast.  相似文献   

郑州地区气溶胶光学厚度反演与分析     

田宏伟  郑有飞  陈怀亮  邓伟  杜子璇 《气象科技》2010,38(4):515-520

利用CE-318太阳光度计,采用Bouguer-Lamber定律,反演郑州地区2008年气溶胶光学厚度,分析该地区气溶胶光学厚度的日变化和月变化特征,并进一步分析天气条件对气溶胶光学厚度的影响。结果表明:2008年郑州地区气溶胶光学厚度与2007年持平,波长指数有所增大。气溶胶光学厚度存在明显的季节变化,春夏高,秋冬低,最低值出现在12月,郑州地区气溶胶光学厚度主要受工业烟尘影响。工作日和非工作日气溶胶光学厚度日变化趋势存在差异,交通负荷的变化可能对气溶胶光学厚度的日变化影响较大。轻雾和霾均能引起气溶胶光学厚度的显著增大,并且轻雾对气溶胶光学厚度的影响大于霾。沙尘过程中,气溶胶光学厚度急剧增大,而后逐渐下降,并逐渐恢复到正常水平,波长指数会减小。  相似文献   

朵云信息辅助卫星影像扫描区域的概略定位     

潘申林  赵杰  黄小波  王仁礼 《测绘学院学报》2007,(2)

利用卫星遥感影像中朵云与其阴影的成像差异以及扫描区域与成像时刻太阳方位角的关系,建立了3种云朵高度的计算公式。在此基础上,进一步提出了概略计算扫描区域坐标的方法。实验结果表明,该方法有效地解决了在缺乏传感器摆角的情况下对扫描区域的概略定位问题。根据推导的公式,利用物体与阴影在太阳赤纬角上的分量,还可以解决摄影时间不精确情况下的物体高度计算。该方式比用太阳高度角在时间上的敏感程度要小,因而降低了对时间的要求,尤其对单片航空摄影测量中物体高度计算更有利。  相似文献   

CE318太阳光度计观测资料应用前景及其解读   总被引：8，自引：0，他引：8  

任宜勇 李霞吕鸣  胡秀清 《气象科技》2006,34(3):349-352

2002年中国气象局在沙尘暴各观测站点安装了CE318太阳光度计,用于探测大气气溶胶。为了使研究人员了解CE318太阳光度计工作原理、数据存储格式及解读方法,使这批观测数据很好地发挥作用,该文介绍了气溶胶气候效应的研究现状,分析了应用太阳光度计这种地基手段探测气溶胶的优势以及探测数据的应用前景。同时,针对光度计原始观测资料直接应用的瓶颈问题———资料解读方案进行了讨论,包括定标、气溶胶光学厚度的计算、光度计数据质量控制方法等。结合新疆塔中站光度计观测资料,列举了采用Langley法进行定标和计算气溶胶光学厚度的步骤。  相似文献