新亚欧大陆桥新疆段暴雨灾变事件的灰色预测   总被引：1，自引：1，他引：0  

陈亚宁  杨思全 《干旱区地理》1999,22(4):77-82

通过对新亚欧大陆桥新疆段水害严重区段暴雨灾变事件的分析,确定暴雨灾变事件的临界雨强,并运用灰色灾变预测方法,根据暴雨灾变序列确立相应的灾变年份序列,运用ＧＭ（１,１）模型,分别求出灾变年份序列的ＧＭ（１,１）序号响应式和灾变年份预测式。  相似文献   

The “susceptibility factor” in the atmospheric response to periodic forcing     

William H. Campbell  Reid A. Bryson 《Journal of Earth System Science》1993,102(1):157-173

Evidence is presented of a periodic component in the inter-annual variability of precipitation and pressure data for India during June, the month of the onset of the Indian southwest monsoon. Two frequencies that explain a statistically significant percent of the variance in these data sets are the same as the two that explain most of the variance of the average monthly lunar tidal potential for June. Not only are the frequencies the same but they are also in phase which strongly suggests that lunar tides in the atmosphere do, in fact, produce an element of climatic variability. The amplitude of the atmospheric response to this periodic forcing was not constant in time but was found to be related to the long term change in northern hemispheric surface temperature. This susceptibility of the atmosphere to an external forcing results in a nonlinear relationship between forcing and response. As a result, nonlinear regression had to be used in order to adequately define the magnitude of the response at a given frequency. The ramifications of this nonlinear response are discussed. The nonlinear interaction of the northern hemisphere temperature and the 18.6 year lunar nodal cycle results in a modulation of the frequency which appears in a linear spectral analysis near 22 years. Thus, the 22-year cycle often found in meteorological data sets may instead be the result of the modulated nodal cycle.  相似文献   

月球地形测绘和月球大地测量(5)   总被引：8，自引：1，他引：8  

陈俊勇 《测绘科学》2004,29(6):7-10

主要介绍月球地形测绘和月球大地测量的情况。第一部分论述了月球大地测量(Selenodesy)的定义和方法。月球大地测量的一个特点是它的观测数据绝大部分都要依靠航天探测器或环月、绕月卫星来获取。月球大地测量的内容可以考虑有三个方面:一是在月球上给出一个有确定定义的坐标参考系,并在其中布测一个控制网;二是确定这一月球参考系的大地测量几何和物理常数;三是求定月球的外部重力场。第二部分介绍月球地形测绘。重点介绍了月球地形的特点,它大体分为月海、月陆、环形山等三种类型。  相似文献   

Low energy trajectories for the Moon-to-Earth space flight     

V. V. Ivashkin 《Journal of Earth System Science》2005,114(6):613-618

The Moon-to-Earth low energy trajectories of ‘detour’ type are found and studied within the frame of the Moon-Earth-Sun-particle system. These trajectories use a passive flight to the Earth from an initial elliptic selenocentric orbit with a high aposelenium. The Earth perturbation increases the particle selenocentric energy from a negative value first to zero and then to a positive one and therefore leads to a passive escape of the particle motion from the Moon attraction near the translunar libration pointL ₂. This results in the particle flight to a distance of about 1.5 million km from the Earth where the Sun gravitation decreases the particle orbit perigee distance to a small value that leads to the particle approaching the Earth vicinity in about 100 days of the flight. A set of the Moon-to-Earth ‘detour’ trajectories is defined numerically. Characteristics of these trajectories are presented. The ‘detour’ trajectories give essential economy of energy (about 150 m/s in Delta V) relative to the usual ones.  相似文献   

Luna-Glob project in the context of the past and present lunar exploration in Russia     

E. M. Galimov 《Journal of Earth System Science》2005,114(6):801-806

The Russian Luna-Glob project has been conceived with a view to understand the origin of the Earth-Moon system. The objectives and main features of the Luna-Glob mission, which will mainly study the internal structure of the Moon by seismic instruments, are described in the context of the past and current program of lunar exploration in Russia.  相似文献   

An analysis of near-circular lunar mapping orbits     

R. V. Ramanan  V. Adimurthy 《Journal of Earth System Science》2005,114(6):619-626

Numerical investigations have been carried out to analyse the evolution of lunar circular orbits and the influence of the higher order harmonics of the lunar gravity field. The aim is to select the appropriate near-circular orbit characteristics, which extend orbit life through passive orbit maintenance. The spherical harmonic terms that make major contributions to the orbital behaviour are identified through many case studies. It is found that for low circular orbits, the 7th and the 9th zonal harmonics have predominant effect in the case of orbits for which the evolution is stable and the life is longer, and also in the case of orbits for which the evolution is unstable and a crash takes place in a short duration. By analysing the contribution of the harmonic terms to the orbit behaviour, the appropriate near-circular orbit characteristics are identified.  相似文献   

环月飞行器精密定轨的模拟仿真   总被引：11，自引：2，他引：11  

胡小工  黄珹  黄勇 《天文学报》2005,46(2):186-195

以中国正在实施的探月计划“嫦娥1号”工程为背景，分析了在中国联合S波段(USB)测控网和甚长基线射电干涉(VLBI)跟踪网的现有空间分布、观测精度水平下的环月飞行器精密定轨．采用的方法是模拟仿真计算，即首先模拟观测数据，然后在计入各误差源的影响后进行求解，并对解算结果进行比较．模拟仿真的工具是美国宇航局哥达德飞行中心的空间数据分析软件系统GEODYN．环月飞行的主要误差源是月球重力场，为此首先讨论了目前精度最高的月球重力场模型JGL165P1的(形式)误差．在模拟了测距、测速以及VLBI的时延、时延率数据后，计入月球重力场的误差进行精密轨道确定．定轨时采用了减缩动力学(reduced dynamic)方法，即选用合适的经验加速度参数吸收重力场误差对定轨的影响．结果表明对于一个不将月球重力场作为主要科学目标的探月计划(如“嫦娥1号”)，减缩动力学方法是一个简单、有效地提高环月飞行器定轨精度的方法．  相似文献   

2010～2017年激光测月研究进展     

张明月  钟敏 《大地测量与地球动力学》2019,39(4):382-386

简要介绍近几年激光测月(lunar laser ranging, LLR)的研究进展,包括设施建设、月球轨道、多源数据联合探测月球等。激光测月技术使我们能够全方位地了解地月系统,并且其用途广泛;下一代单棱镜反射器会将激光测月的精度提高1～2个量级;云南天文台站实现了中国激光测月零的突破,新台站的加入将帮助我们得到更准确的月球轨道;探测月球技术手段的增加、多种数据联合分析将使我们更加全面地认识月球。  相似文献   

Improving the Definition and Algorithms of China’s Coastline Considering the Diversity of Tidal Characteristics     

Chenhu Huang  Meiping Wu  Weikang Sun  Gang Bian  Jianlun He 《Marine Geodesy》2019,42(4):382-405

Two commonly used definitions of coastline are compared and analyzed in this article. To build a more perfect digital tide-coordinated coastline model in China, we should first solve the problems of the existing definition and unclear algorithms of China’s coastline. On the basis of defining the coastline in China as the intersection of coastal land and the mean high water spring (MHWS), it should be further revised, and defined either as an intersection of coastal land and the MHWS or as a mean higher high water level (MHHWL) considering the diversity of tidal characteristics in China Sea areas. Since MHWS is related to the extreme of the lunar phase and MHHWL is related to the extreme of the angle of the lunar declination elevation, the algorithms to obtain them are more complicated than that of mean high water (MHW) used in the United States. We should consider the specific law of tidal movement in different tide types of the predominantly semidiurnal or diurnal sea areas in China when studying the precise algorithms for MHWS and MHHWL. Several experiments show that the difference between the two types of calculations of coastal height, such as water level observations and tidal predictions, is within centimeter level. The research results of this article have a certain reference value for countries with similar coastline features as in China.  相似文献   

玉兔号月球车巡视点矿物丰度及粒径分布高光谱反演     

林红磊  张霞  杨亚洲  郭弟均  吴兴  戚文超 《遥感学报》2019,23(5):831-840

矿物的类型、丰度及其粒径分布对理解月球和行星表面曾经存在过怎样的地质演化过程具有重要的意义。本文提出基于辐射传输模型和稀疏分解模型反演矿物丰度及其粒径分布的方法,利用辐射传输模型计算各矿物端元不同粒径的单次散射反照率以构建解混光谱库,然后基于稀疏分解算法得到在每个可观测像元的端元最优丰度和粒径分布。利用实验室测量数据进行验证,表明本文方法具有较高的精度。最后根据玉兔号月球车的实地测量光谱数据,利用本文方法获得了其矿物的丰度及粒径分布,结果显示,辉石、橄榄石、斜长石、熔融玻璃和钛铁矿的丰度在4个观测点的平均丰度分别为28.1%、4.5%、39%、28%、0.4%,辉石的平均粒径为166.02μm,橄榄石为8.34μm,斜长石为196.31μm,熔融玻璃为44.21μm,一定程度上表明在这些观测点不同矿物对太空风化的响应不同。  相似文献