月球光学遥感与制图研究进展

在月球探测活动中,光学成像探测是任务重点,也是信息量最大的数据源。航天技术和传感器技术的发展促进了月球光学遥感的发展,月球科学研究也越来越依赖于高分辨率遥感数据,对月球光学遥感与制图的研究是月球探测的关键问题之一。本文扼要论述了其中的几个方面,包括月球光学遥感数据获取系统、月球遥感立体测绘和制图,以及月球控制网构建等方面的研究进展。     

基于遥感的上海地区雾霾监测研究

以中分辨率成像光谱仪(MODIS)遥感数据为数据源,综合利用6S传输模型与NASA V5.2算法对2013年12月4日至8日上海地区雾霾污染进行了连续性监测,并对其形成原因进行分析。结果表明,此次雾霾污染主要是由本地生产和外地迁移来源共同作用形成,上海地区气溶胶光学厚度在12月6日达到最大,雾霾污染区域逐渐从上海地区的西北向东南扩散,污染等级也逐渐降低。     

利用MODIS可见光波段反演陆地气溶胶光学厚度

利用Herold等建立的地表反射率库及MODIS遥感影像研究城市区和非城市区典型地物在可见光红蓝波段地表反射率的比值特性。在此基础上,利用MODIS 1km分辨率遥感影像红蓝可见光波段实现了气溶胶光学厚度的反演,采用卫星过境时间前后半小时北京和香河AERONET站的气溶胶光学厚度观测平均值作为验证参考。结果显示,66.67%的反演结果处于±0.05±0.15τ的误差界限内,反演算法不受地表反射率的限制,而且只利用了可见光红蓝波段,避免缺少近红外波段数据的限制。     

多回击负地闪先导通道的辐射和光学特征

利用闪电VHF窄带干涉仪辐射源定位系统和高速摄像系统,对青海大通地区一次有5次回击的负地闪放电过程进行了同步观测,对比分析了通道传输过程的辐射和光学特征.结果表明,光学通道亮度能补充VHF干涉仪定位先导通道的电流特征,VHF干涉仪定位弥补了光学设备拍摄弱放电和云内流光通道的不足;在通道分枝结构上,干涉仪定位的通道和光学通道呈现出很好对应.干涉仪定位分枝通道的辐射源点较明显,但分枝光学通道的出现明显落后于干涉仪定位辐射源通道.对用两种不同观测手段探测的先导通道进行速度计算,发现两者计算的直窜先导和直窜梯级先导速度量级一致,均为106m·s-1,但干涉仪在时间的获取及精确量化上有优势,干涉仪定位计算先导速度的精确度高于光学通道定位.     

CINRAD/CC型雷达数据传输系统故障分析与改进方案

对甘肃省3部CINRAD/CC型雷达近4年的雷达故障进行统计分析,作为雷达系统的主要故障部件,随着使用年限的增加,雷达数据传输系统的故障有明显的增多趋势.对引起故障的主要因素进行统计分析,提出了改进方法:基于标准网络的数据传输方式舍弃了原来的光纤系统;取消了基于光端机和复分接的通信方式,代以采用标准网络传输的通信方式;采用四创电子研发的终端软件(2.0版本),新增了集成的网络功能、用户权限功能、数据产品和图像产品全自动生成、数据文件的检索能力、语音报警等功能.改进后的雷达数据传输系统运行情况表明:网络型光纤通信系统减少了雷达数据传输故障,增强了系统的可靠性和稳定性;雷达数据的传输率和有效性也得到一定的提高,确保了新一代天气雷达的正常业务观测.     

Aeolian activity in northern Amazonia: optical dating of Late Pleistocene and Holocene palaeodunes

Palaeodunes were examined on the eastern margin of the Rio Branco–Rupununi savanna, northeast Amazonia. Optical dating suggests that the onset of aeolian activity was between 17 000 and 15 000 yr ago, just after the Last Glacial Maximum. Both the palaeodune axes and modern dominant wind directions have northeast to east‐northeast directions, implying no significant shift in atmospheric circulation patterns over northeast Amazonia during the Late Pleistocene to Holocene. Major regional climate change events, such as the Younger Dryas, do not appear to have had any effect on the rates of aeolian deposition at the study site. Aeolian activity appears to have continued to the present day, showing a remarkably constant deposition rate of around 0.13 m kyr^?1 initially, increasing smoothly to the present. Until more palaeodunes in northern Amazonia are dated, it is impossible to determine if this record of gradual aeolian deposition is a reliable regional palaeoclimate indicator, rather than being the result of local bioclimatic and geomorphological effects. Copyright © 2004 John Wiley & Sons, Ltd.     

实时相关跟踪图像处理系统

文章介绍了怀柔太阳观测基地最近完成的一套实时高分辨太阳磁场观测系统。系统采用局部相关跟踪算法来提高磁场观测数据的空间分辨率，同时对相关跟踪算法的实现程序进行了优化以满足常规太阳磁场观测的要求。通过对试观测和常规观测数据的分析，我们发现：1）该系统能够大大提高单色像、磁场数据的对比度和空间分辨率；2）对相关跟踪算法的优化大大提高了系统的时间分辨率，系统可以投入常规观测使用。     

Optical Spectroscopy of Comet C/2000 WM1 (LINEAR) at the Guillermo Harro Astrophysical Observatory in Mexico

We present a preliminary analysis of medium resolution optical spectra of comet C/2000 WM1 (LINEAR) obtained on 22 November 2001. Theemission lines of the molecules C₂, C₃, CN, NH₂,H₂O⁺ and presumably CO (Asundi and triplet bands) and C₂ ^-were identified in these spectra. By analysing the brightnessdistributions of the C₂, C₃, CN emission lines along theslit of the spectrograph we determined some physical parameters of theseneutrals, such as their lifetimes and expansion velocities inthe coma. The Franck–Condon factors for the CO Asundi bands and C₂ ^- bands were calculated using a Morse potential model.     

近10年我国天体测量的发展

简述天体测量学研究的内各以及与各相关学科之间的关系；描述近10年来国际天体测量研究的进展和前沿课题；叙述我国天体测量研究的历史背景和研究基础，以及近10年来在国家自然科学基金委员会和其他科学组织支持下取得的成果，并对今后10～20年我国天体测量的发展提出初步看法。     

Shock temperatures in anorthite glass

Summary. Temperatures of CaAl₂Si₂O₈ (anorthite glass) shocked to pressures between 48 and 117 GPa have been measured in the range from 2500 to 5600 K, using optical pyrometry techniques. The pressure dependence of the shock temperatures deviates significantly from predictions based on a single high-pressure phase. Either a variable specific heat, or the existence of three phase transitions, at pressures of about 55, 85 and 100 GPa and with transition energies of about 0.5 MJ kg⁻¹ each (∼ 1.5 MJ kg⁻¹ total) can explain the shock-temperature data. The proposed phase transition at 100 GPa can possibly be identified with the stishovite melting transition. Theoretical models of the time dependence of the thermal radiation from the shocked anorthite based on the geometry of the experiment and the absorptive properties of the shocked material yield good agreement with observations, indicating that it is not necessary to invoke intrinsic time dependences to explain the data in many cases. Observed time dependences were used to calculate absorption coefficients of the shocked material of from about 2 mm⁻¹ to greater than 24 mm⁻¹– an increasing function of shock pressure. The assumption that the shocked material radiates as a black body is supported by the theoretical model, and by the close agreement between measured and calculated black body spectral radiance as a function of wavelength.