共查询到20条相似文献，搜索用时 190 毫秒
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空间科学技术的蓬勃发展 ,特别是各类应用卫星对地球的观测、空间探测器对太阳活动的系统探测和对月球及行星的全面而综合的勘测 ,以及天体化学和比较行星学研究的兴起 ,大大扩展了人类的视野。借助于空间探测的成就 ,也即在更大的时空尺度上来研究地球生态环境的变化 ,并深化对全球变化的认识 ,已经成为一种必然的发展趋势。太阳活动是引起太阳系空间和地球环境变化及扰动的主要控制因素 ,太阳活动以巨大的能量和物质抛向地球 ,引起空间环境发生长期持续性变化和短期灾害性影响 ,给人类活动带来巨大损失。“蓬勃发展的空间天气学”、“‘地… 相似文献
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2003年度国家自然科学基金项目指南（地球科学部分） 总被引：3，自引：0，他引：3
国家自然科学基金委员会地球科学部 《地球科学进展》2002,17(6):791-805
地球科学是人类认识、利用和改造人类目前唯一生存环境———地球的基础科学。地球科学通过对地球系统包括大气圈、水圈、岩石圈、生物圈和日地空间的过程与变化以及这些过程之间相互作用等研究,以提高对地球的认识水平,并利用这种知识为解决人类生存与持续发展中的资源供给,环境优化、减轻灾害等重大问题提供科学与技术的支持。地球科学在21世纪初叶的发展强烈地反映出以下趋势:⑴以整体系统的观念认识地球、强化学科间的交叉与渗透、广泛应用与发展高新技术,以及社会功能日益增强为时代特征。⑵形成以不同空间尺度、时间尺度的基本地… 相似文献
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2004年度国家自然科学基金项目指南(地球科学部分) 总被引：5，自引：1，他引：4
国家自然科学基金委员会地球科学部 《地球科学进展》2004,19(1):1-011
地球科学是人类认识、利用和改造人类目前唯一生存环境———地球的基础科学。地球科学通过对地球系统包括大气圈、水圈、岩石圈、生物圈和日地空间的过程与变化以及这些过程之间相互作用等研究,以提高对地球的认识水平,并利用这些知识为解决人类生存与持续发展中的资源供给、环境优化、减轻灾害等重大问题提供科学与技术的支持。地球科学在21世纪初叶的发展强烈地反映出以下趋势:(1)以整体系统的观念认识地球、强化学科间的交叉与渗透、广泛应用与发展高新技术以及社会功能日益增强为时代特征。(2)形成以不同空间尺度、时间尺度的基本… 相似文献
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空间物理学的回顾和展望 总被引：5，自引：1，他引：5
空间物理学是一门重要的迅速发展的学科。回顾了过去百年中发生的重大空间物理学事件。空间物理学已成功地迈过了探索阶段 ,未来是要搞清一些基本的科学问题。这些问题的解决需要观测研究、理论分析、数值模拟和环境预报的紧密合作 ,才能促成空间物理学的飞跃发展。 相似文献
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中高层大气研究的空间探测 总被引：9，自引：2，他引：7
中高层大气研究对于深入理解全球变化和日地关系十分重要,也为有关航天与临近空间飞行的环境保障提供基础。中高层大气研究的目的是要深入了解其中发生的主要过程及其耦合,并发展各种模式。在现代中高层大气研究中,地基、高空飞机、高空气球、火箭和空间观测提供了动力、热力和化学成分结构与变化的资料,其中空间观测起到至关重要的作用。将对用于中高层大气研究的卫星任务和传感器载荷进行综述,同时列举一些中高层大气空间观测的科学结果。 相似文献
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网络信息空间的城市地理学研究：综述与展望 总被引：16，自引：2，他引：16
20世纪90年代,互联网飞速发展,不仅深刻地影响了我们的社会系统和经济结构,同时也重构了全球城市的物理和虚拟空间结构形式。近几年,在西方发达国家,网络信息空间的相关研究已经成为多学科研究的热点,有关城市网络信息空间的地理学研究也不断涌现。从技术与经济的角度入手,在已有文献资料基础上,对西方地理学界关于网络信息空间与城市发展的研究进展进行了评述。首先界定网络信息空间的概念及其相对于物理空间的各种特征,然后总结城市学者研究网络信息空间的几种理论方法,并从三个空间层次分别评述现有的实证研究成果。在此基础上,对网络信息空间的测量方法和关于城市地理学的研究内容进行了进一步展望。 相似文献
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中国空间物理学学科发展战略研究组 《地球科学进展》1996,11(2):140-150
从战略高度论述了空间物理学在认识人类生存环境、航天活动、经济发展中的重要地位和战略意义；以科学的态度分析了空间物理的发展史、现状和趋势；根据学科发展与我国国情相结合的原则提出了长期、中期和近期空间物理学的战略目标、战略重点和鼓励研究的课题以及实现战略目标的基本措施。 相似文献
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总结中国工程水利、环境水利、资源水利、生态水利发展沿革，分析国内外生态水利研究进展、发展趋势及其特点，指出生态水利是人类社会发展到生态文明时代水资源利用的一种新途径和方式，以尊重和维护生态环境为主旨，开发水利、发展经济，为人类社会可持续发展服务。阐述了广义生态水利的内涵、定义和发展模式及其过程和维度，并提出以下结论和观点:①生态水利将水资源和水循环调控作为重要生态要素，从流域生态系统能量交换、生物链接、结构平衡、循环转化全视角开展研究，探索既能满足人类社会需求，又能兼顾水生态系统健康和良性发展的生态水利措施和方法。②建立了水利工程"规划设计—建设管理—运行调度"全过程、全生命周期的工程安全和生态安全保障体系，特别是将生态调度纳入水利工程全"服役期"，其中"后坝工时代"实施全流域大尺度生态调度，是生态保护和恢复最有效的措施。③从"生态环境-社会经济-水循环调控"三个维度，在生态文明视野下的国土空间规划治理体系中，科学把控生态水利的空间定位，促进"三生空间"优化布局，保障"三生用水"合理配置，优化"三生关系"耦合协调，实现生态保护和高质量发展，推动生态水利事业创新发展。 相似文献
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总结中国工程水利、环境水利、资源水利、生态水利发展沿革，分析国内外生态水利研究进展、发展趋势及其特点，指出生态水利是人类社会发展到生态文明时代水资源利用的一种新途径和方式，以尊重和维护生态环境为主旨，开发水利、发展经济，为人类社会可持续发展服务。阐述了广义生态水利的内涵、定义和发展模式及其过程和维度，并提出以下结论和观点：①生态水利将水资源和水循环调控作为重要生态要素，从流域生态系统能量交换、生物链接、结构平衡、循环转化全视角开展研究，探索既能满足人类社会需求，又能兼顾水生态系统健康和良性发展的生态水利措施和方法。②建立了水利工程"规划设计—建设管理—运行调度"全过程、全生命周期的工程安全和生态安全保障体系，特别是将生态调度纳入水利工程全"服役期"，其中"后坝工时代"实施全流域大尺度生态调度，是生态保护和恢复最有效的措施。③从"生态环境-社会经济-水循环调控"三个维度，在生态文明视野下的国土空间规划治理体系中，科学把控生态水利的空间定位，促进"三生空间"优化布局，保障"三生用水"合理配置，优化"三生关系"耦合协调，实现生态保护和高质量发展，推动生态水利事业创新发展。 相似文献
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Studies of the extreme solar proton event of January 20, 2005 intensified the contest over of a long-standing problem: are solar cosmic rays arriving at the Earth accelerated by solar flares or by shocks preceding rapidly moving coronal mass ejections? Among the most important questions is the relationship between the energy spectra of the solar cosmic rays and the frequency spectra of flare microwave bursts. Some studies of previous solar-activity cycles have shown that such a relationship does exist, in particular, for protons with energies of tens of MeV. The present work analyzes this relation using data for 1987–2008. For flare events observed in the western half of the disk, there is a significant correlation between the index δ, which is equivalent to the power-law index of the integrated energy spectrum of 10–100 MeV protons detected near the Earth’s orbit, and radio burst parameters such as a ratio of peak fluxes S at two frequencies (for example, at 9 and 15 GHz) and a microwave peak frequency f m . Proton fluxes with hard (flat) energy spectra (δ ≤ 1.5) correspond to hard microwave frequency spectra (S 9/S 15 ≤ 1 and f m ≥ 15 GHz), while flares with soft radio spectra (S 9/S 15 ≥ 1.5 and f m ≤ 5 GHz) result in proton fluxes with soft (steep) energy spectra (δ ≥ 1.5–2). It is also shown that powerful high-frequency bursts with the hardest radio spectra (f m ≈ 30 GHz) can point at acceleration of significant proton fluxes in flares occurring in strong magnetic fields. These results argue that solar cosmic rays (or at least their initial impulses) are mainly accelerated in flares associated with impulsive and post-eruptive energy release, rather than in shocks driven by coronal mass ejections. 相似文献
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小行星深空探测的科学意义和展望 总被引：11，自引：0，他引：11
太阳系深空探测活动方兴未艾,小行星探测已成为主要发展方向。通过回顾近年来几个主要的国际小行星空间探测计划以及取得的研究成果,总结了小行星深空探测从早期的近距离飞越到小行星低空绕轨勘探,到目前的表面软着陆和采集样品返回的发展进程。同时深空探测也给行星科学研究者提出了新的挑战,鉴于目前行星科学的研究热点,详细叙述了小行星深空探测急需解决的重大科学问题及其科学意义,随后简单介绍了未来小行星深空探测计划的科学目标,为小行星深空探测的具体任务提供了科学目标选择方向。最后呼吁我国及时介入小行星深空探测,提升航天能力,开拓深空领域。 相似文献
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This work continues earlier statistical analyses of catalogued proton events in cosmic rays. The spectra of proton enhancements identified from the logarithm of the ratio of the proton fluxes with energies exceeding 100 and 10 MeV, δ = log(F 100/F 10), are studied focusing on 172 powerful events with favorable conditions for escaping from the corona and subsequent propagation in the interplanetary space. The δ distribution for the flares is Gaussian, with a comparatively weak spread in δ. The distribution maximum corresponds to an excess of the 10 MeV flux over the 100 MeV flux by a factor of 30. The fact such a frequent spectrum does exist supports the idea that both soft and hard protons are efficiently accelerated, probably by a single mechanism that operates during the explosive phases of the flares. The sizes of the loops of M2-X4 flares observed by the Yohkoh Hard X-Ray Telescope at energies exceeding 50 keV indicate low heights for the main acceleration regions. There is some excess over the Gaussian distribution for “softer” events. Some post-eruptive phenomena can be clearly distinguished in these events, and they display a correlation between δ and the total flare duration. Thus, there are two sources of the particle acceleration operating at low and high altitudes during the explosive and post-eruptive phases of the solar flares, respectively. The second source, which is manifested through some prolonged flares and filament-ejection phenomena, accelerates protons only to energies of 10–30 MeV. 相似文献
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地球物理学的回顾与展望 总被引：13，自引：0，他引：13
简要回顾了 2 0世纪地球物理学的发展。指出 2 0世纪是地球物理学发展的重要历史阶段 ,在此期间实施的一系列大型的全球性的研究计划深化了人类对地球本体的认识 ,提供了有关资源、能源、灾害和环境的形成、分布与发展的深层过程和空间信息 ,扩大了人类对地球整体研究的视野 ,激励了对空间和地球 (包括大陆和海洋 )以及生态环境之间耦合的研究 ,并在造福人类的过程中取得了辉煌的成就。展望了 2 1世纪地球物理学的发展 ,认为 2 1世纪的地球物理学必将担负起地球科学中一系列重大科学问题的先导角色。在深化对地球本体和日地空间及其相互作用的认识 ,量化地球内部各圈的耦合和深部物质状态及物质组成的错综组构 ,解决水、资源、环境 (包括空间资源环境 )等问题中做出贡献。 相似文献
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Recent observations indicate that relatively strong plasma ejections are accompanied by the formation of systems of coronal loops with two glowing ribbons near their footpoints. However, while two-ribbon flares can sometimes last for many hours, for example, soft X rays, they sometimes decay within tens of minutes. We study here factors affecting the durations of flares using four major flares occurring in July 15–18, 2002, as examples. Various ground-based and satellite observations are used to show that short-duration events involved collimated (narrow) plasma ejections directed to the north and the subsequent formation of compact loops in the leading part of the active region. During one event, a powerful eastward ejection in a wide solid angle was followed by the formation of an extended arch system in the trailing part, which determined the long duration of the flare. It is proposed that in events involving collimated jets and corresponding narrow features in coronal mass ejections (CMEs), systems of coronal loops do form, but post-eruptive energy release either does not occur or is expressed very faintly. So the energy does not go downward from this region, and the plasma is emitted free in the coronal loops. In contrast to such rapid flares, wide ejections and bright, large-scale CMEs are accompanied by the formation and prolonged existence of an extended arch system. Thus, powerful nonstationary solar processes involve a large-scale CME and the flare itself, with the pattern of a particular event determined by the reconnection scenario and the evolution of the ejected plasma. 相似文献
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An analysis of the dynamics of the electron temperature of the solar atmosphere in regions where solar flares appear is presented. The temperatures are estimated from the emission in spectral lines of ions with various degrees of ionization. The emission of ionized helium and highly ionized iron was used. Images of preflare states and of flares from the archive of the American SDO spacecraft are analyzed. A solar flare is usually preceded by the registration of a bright glowing structure above the action region, with a temperature exceeding that of the corona. This preflare structure (~1010 cm) is identified with the development of a system of currents, which, according to numerical simulations, is responsible for the accumulation of energy above the active region before the flare. After several tens of hours of a slow increase in the brightness of the preflare glow in the 94 Å iron (FeXVIII) line, the emission in the 193 Å line of FeXXIV increases sharply, indicating a flare-like growth of the temperature up to at least 20 MK. This growth of the emission coincides with the onset of the solar flare. The observed dynamics of the emission in spectral lines of highly ionized ions is consistent with an electrodynamic model of a solar flare based on the accumulation of magnetic energy in a current sheet above the active region and the explosive release of the stored energy. Studies of mechanisms for solar flares are of special importance in connection with the discovery of solar cosmic rays. Information from the worldwide network of neutron monitors and from the GOES spacecraft has made it possible to firmly state that the source of solar rays is solar flares, not shocks generated by such flares. It cannot be ruled out that a similar mechanism, not shocks, is also responsible for the acceleration of cosmic rays in the Galaxy. 相似文献
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R. V. Vasil’ev D. S. Kushnarev L. K. Kashapova V. P. Lebedev A. V. Medvedev N. I. Nevedimov K. G. Ratovskii 《Astronomy Reports》2013,57(11):872-881
Using the Irkutsk Incoherent Scattering Radar, it is demonstrated that the high sensitivity of such radars, which are usually used for studies of the Earth’s ionosphere, also enables their use in a passive mode for observations of astronomical radio sources. Observations of solar flares accompanied by coronal mass ejections and of quasi-stationary radio sources on the Sun have been carried out. In addition, scintillations of several of the brightest discrete radio sources (Cygnus A, Cassiopeia A, and the Crab Nebula) have been studied over several months. These data can also be useful for studies of the ionosphere and interplanetary space. 相似文献
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Space weather prediction involves advance forecasting of the magnitude and onset time of major geomagnetic storms on Earth. In this paper, we discuss the development of an artificial neural network-based model to study the precursor leading to intense and moderate geomagnetic storms, following halo coronal mass ejection (CME) and related interplanetary (IP) events. IP inputs were considered within a 5-day time window after the commencement of storm. The artificial neural network (ANN) model training, testing and validation datasets were constructed based on 110 halo CMEs (both full and partial halo and their properties) observed during the ascending phase of the 24th solar cycle between 2009 and 2014. The geomagnetic storm occurrence rate from halo CMEs is estimated at a probability of 79%, by this model. 相似文献
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M. A. Livshits V. A. Chernetskii I. G. Mitrofanov A. S. Kozyrev M. L. Litvak A. B. Sanin V. I. Tret’yakov W. Boynton K. Shinohara D. Hamara 《Astronomy Reports》2005,49(11):916-931
We present the first results of data on solar flares detected by the HEND instrument onboard the 2001 Mars Odyssey interplanetary spacecraft during its flight to Mars and in orbit around Mars. The instruments carried by the spacecraft, which was developed at the Space Research Institute of the Russian Academy of Sciences, included a scintillation detector with two crystals, enabling the detection of photons with energies from tens of keV to 2.5 MeV with high time resolution. Several dozen flares were detected on both the sides visible from the Earth and back side of the Sun, supplementing other available data in a number of cases. A joint analysis of the HEND data together with data obtained in near-Earth orbits enabled the detection of variations in the integrated fluxes of photons with energies exceeding 80 keV during observations of flares near the limb from various directions. Two events were analyzed in great detail: the setting of a region displaying frequent very short flares on May 20, 2001, and the rising of the group 10486, which displayed numerous flare phenomena on the limb followed by extremely high activity in October–November 2003. These variations appear in simultaneous observations of limb M flares made at angles differing by only 8°–10°. Analyses of observations of rising sources obtained on two spacecraft lead to similar results. This indicates that the vast majority of emission at energies exceeding 80 keV arises at altitudes of no higher than seven to ten thousand kilometers. We briefly consider the powerful solar-disk gamma-ray flare of August 25, 2001. In this case, there are some differences in the behavior of the hard radiation in the decay phase for observations made at angles differing by 25°, which is most likely due to differences in the instrumental responses to radiation with this spectrum. The absence of hard radiation at great heights in the region of the “cusp” places some constraints on our picture of the physical processes occurring in powerful solar flares. 相似文献