全球Ms≥7￣3／4级地震的定向迁移

对全球尺度的６条大地震带内１９００～１９９０年中１８４次Ｍｓ≥７３／４级地震进行了沿地震带方向定向迁移的分析，获得了全球统一的地震定向迁移规律，总体是由西向东，迁移速度由７００ｋｍ／ａ变为１５０ｋｍ／ａ，此现象可以作多种暂态地球动力作用过程的推论，如以大西洋脊间歇式张裂引起上地幔软流物质自西向东运动，呈现纵波式的振荡传播；也可解释为非洲板块、阿拉伯板块和印度板块自西南向东北对欧亚地震带依次的推压引起向东的应变波的传播；太平洋脊两侧洋底板块向西北和东北两侧的斜向推压，可能是造成两侧地震带地震向北迁移的触发源     

对我国西南地区河谷深厚覆盖层成因机理的新认识

近年来,在我国水能资源开发过程中,发现各河流现代河床以下普遍堆积厚达数十米甚至上百米的松散堆积物。河谷深厚覆盖层的存在,不仅严重制约了工程坝址的选择,影响相关流域水电资源的开发利用,也给坝工设计带来巨大的困难。由于深厚覆盖层埋藏于现代河床之下,其形成年代一般先于一二级阶地,有悖于河流发育演化的常理,其成因一直令人费解。首次将河谷深切和深厚堆积事件与全球气候变化、海平面升降运动、地壳运动等有机地联系起来,并提出冰期、间冰期全球海平面大幅度升降,是导致河流深切成谷并形成深厚堆积的主要原因的新观点。在此基础上,引入层序地层学原理,从理论上较好地解释了全球气候变化导致海平面和河流侵蚀基准面大幅变化,并产生河谷深切和深厚堆积的原因和过程。最后,进一步将沿河大型古滑坡的孕育和发生与河谷深切事件相联系,提出沿河大型古滑坡是在河谷深切期因前缘临空较好而形成的新观点,从而对沿河古滑坡前缘剪出口高程往往低于现代河床数十米的原因给出了较合理的解释。     

GPS在计算导弹脱靶量中的应用研究

将GPS技术应用于导弹靶试脱靶量测量,并对计算过程作了较为详细的分析和探讨。试验证明：利用GPS测定脱靶量,测量精度高,简单易行,可以在靶场逐步试验推广。     

GNSS three carrier ambiguity resolution using ionosphere-reduced virtual signals

This paper presents a general modeling strategy for ambiguity resolution (AR) and position estimation (PE) using three or more phase-based ranging signals from a global navigation satellite system (GNSS). The proposed strategy will identify three best “virtual” signals to allow for more reliable AR under certain observational conditions characterized by ionospheric and tropospheric delay variability, level of phase noise and orbit accuracy. The selected virtual signals suffer from minimal or relatively low ionospheric effects, and thus are known as ionosphere-reduced virtual signals. As a result, the ionospheric parameters in the geometry-based observational models can be eliminated for long baselines, typically those of length tens to hundreds of kilometres. The proposed modeling comprises three major steps. Step 1 is the geometry-free determination of the extra-widelane (EWL) formed between the two closest L-band carrier measurements, directly from the two corresponding code measurements. Step 2 forms the second EWL signal and resolves the integer ambiguity with a geometry-based estimator alone or together with the first EWL. This is followed by a procedure to correct for the first-order ionospheric delay using the two ambiguity-fixed widelane (WL) signals derived from the integer-fixed EWL signals. Step 3 finds an independent narrow-lane (NL) signal, which is used together with a refined WL to resolve NL ambiguity with geometry-based integer estimation and search algorithms. As a result, the above two AR processes performed with WL/NL and EWL/WL signals respectively, either in sequence or in parallel, can support real time kinematic (RTK) positioning over baselines of tens to hundreds of kilometres, thus enabling centimetre-to-decimentre positioning at the local, regional and even global scales in the future.     

Rodent paleofaunas as indicators of climatic change in Europe during the last 125,000 years

This paper presents a quantitative reconstruction of the European late Pleistocene paleoclimate based on 72 rodent assemblages of five sequences from France, Germany and Bulgaria, covering the last interglacial-glacial cycle. They show a pattern of severe changes in temperature, with reduced precipitation during the coldest periods. A tentative correlation between the isotopic and palynological records and the paleotemperature changes is shown. These changes are consistent with variations in atmospheric circulation patterns in response to an expanding-retracting Fennoscandian ice-sheet. They can be attributed to the enhancement-weakening of the Scandinavian-Polar anticyclone and its associated dry winds, the south-north shifting of the North Atlantic Polar Front, and the varying supply of moist air from the Atlantic. Qualitative paleoenvironmental analysis shows broadleaved-deciduous forests in France and Bulgaria during most of the studied period. Taiga and tundra appeared in eastern France during the lower Würm. The German sequence indicates the presence of coniferous forests. These results are broadly consistent with other paleobiological records (mammalian, avian and insect faunas, isotopic record in dental tissue, palynology). The main discrepancies with the paleoclimate inferred from the palynological record are found during the coldest periods and are probably due to the interaction between vegetation, climate, and atmospheric CO₂ levels.     

类脂化合物单体碳稳定同位素在古气候环境研究中的意义

类脂化合物极大地扩展了全球变化研究的深度，尤其是单体碳稳定同位素技术在古气候、古环境重建上有着重要作用。基于近些年来国内外的最新研究成果，就类脂化合物单体碳同位素在古气候环境方面的应用研究进行了较为全面的评述。已有研究表明利用类脂化合物单体碳同位素组成可以追溯到海洋和湖泊环境中陆源有机质的物源，其母源区历史时期 C3、C4植被的变迁以及区域性的古气候、古环境重建。     

A parametric study on the impact of satellite attitude errors on GOCE gravity field recovery

In the recent design of the Gravity field and steady-state Ocean Circulation Explorer (GOCE) satellite mission, the gravity gradients are defined in the gradiometer reference frame (GRF), which deviates from the actual flight direction (local orbit reference frame, LORF) by up to 3–4°. The main objective of this paper is to investigate the effect of uncertainties in the knowledge of the gradiometer orientation due to attitude reconstitution errors on the gravity field solution. In the framework of several numerical simulations, which are based on a realistic mission configuration, different scenarios are investigated, to provide the accuracy requirements of the orientation information. It turns out that orientation errors have to be seriously considered, because they may represent a significant error component of the gravity field solution. While in a realistic mission scenario (colored gradiometer noise) the gravity field solutions are quite insensitive to small orientation biases, random noise applied to the attitude information can have a considerable impact on the accuracy of the resolved gravity field models.     

ELF propagation parameters for uniform models of the Earth–ionosphere waveguide

Uniform models for the Earth–ionosphere cavity are considered with particular attention to the physical properties of the ionosphere for the extremely low frequency (ELF) range. Two consistent features have long been recognized for the range: the presence of two distinct altitude layers of maximum energy dissipation within the lower ionosphere, and a “knee”-like change in the vertical conductivity profile representing a transition in dominance from ion-dominated to electron-dominated conductivity. A simplified two-exponential version of the Greifinger and Greifinger (1978) technique widely used in ELF work identifies two slopes in the conductivity profile and, providing accurate results in the ELF communication band (45–75 Hz), simulates too flat a frequency dependence of the quality factor within the Schumann resonance frequency range (5–40 Hz). The problem is traced to the upward migration, with frequency increasing, of the lower dissipation layer through the “knee” region resulting in a pronounced decrease of the effective scale height for conductivity. To overcome this shortcoming of the two-exponential approximation and still retain valuable model analyticity, a more general approach (but still based on the Greifinger and Greifinger formalism) is presented in the form of a “knee” model whose predictions for the modal frequencies, the wave phase velocities and the quality factors reasonably represent observations in the Schumann resonance frequency range.     

The global rainforest mapping project JERS-1:a paradigm of international collaboration for monitoring land cover change

The Global Rainforest Mapping (GRFM) project was initiated in 1995 and, through a dedicated data acquisition policy by the National Space Development Agency of Japan (NASDA), data acquisitions could be completed within a 1.5-year period, resulting in a spatially and temporally homogeneous coverage to contain the entire Amazon Basin from the Atlantic to the Pacific; Central America up to the Yucatan Peninsular in Mexico; equatorial Africa from Madagascar and Kenya in the east to Sierra Leone in the west; and Southeast Asia, including Papua New Guinea. To some extent, GRFM project is an international endeavor led by NASDA, with the goal of producing spatially and temporally contiguous Synthetic Aperture Radar (SAR) data sets over the tropical belt on the Earth by use of the JERS-1 L-band SAR, through the generation of semi-continental, 100m resolution, image mosaics. The GRFM project relies on extensive collaboration with the National Aeronautics and Space Administration (NASA), the Joint Research Center of the European Commission (JRC) and the Japanese Ministry of International Trade and Industry (MITI) for data acquisition, processing, validation and product generation. A science program is underway in parallel with product generation. This involves the agencies mentioned above, as well as a large number of international organizations, universities and individuals to perform field activities and data analysis at different levels.     

1991年江淮暴雨时期的能量和水汽循环研究

通过对 1991年 5～ 7月江淮暴雨期全球范围的水汽输送和不同降水过程中江淮暴雨区及其临近区域的水汽收支和视热源和视水汽汇的计算分析得到了以下结论 :( 1)从水汽输送的机制来看 ,一方面 ,有大量的水汽以定常涡动的方式从孟加拉湾及南海输送到中国江淮地区 ;另一方面 ,江淮地区的瞬变涡动水汽向北输出 ,这可能与江淮地区频繁活动的α和β中尺度系统有关 ,它们将江淮地区汇集的充沛的水汽除了大部分以降水形式降下外 ,剩余部分继续向水汽较少的高纬地区输出 ,以维持全球水汽的平衡。( 2 )在降水过程中 ,局地蒸发项在水汽的供应中或再循环中十分重要 ,其数值一般为降水量的 13 ～ 12 ,这与1998年的降水情况相似。( 3 )在降水过程中 ,暴雨区的水汽主要是从南边界和西边界流入的 ,东边界和北边界则流出 ,并且水汽的流入、流出主要在中低层进行。 (a)在流入边界上 ,水汽通量的垂直分布存在差异 ,暴雨区西边界和南边界的水汽流入的垂直差异可能与其所在的地理位置有密切关系。 (b)对于暴雨区 ,不同强度的降水过程水汽的主要来源有所不同。( 4)在 5次降水过程中 ,视热源和视水汽汇的较大值对应降水的大值区 ,表明了水汽凝结加热对大气加热所起的主要作用。梅雨期降水 ,以对流性降水为主 ,对流活动随季节变化