基于构造的测震学参数在鲁东-黄海地块的应用

以基于构造的测震学参数分析为思路,利用地震构造分区和地质构造单元的划分结果,检验了基于活动边界带的测震学参数方法的可行性;将活动地块内部（地质构造复杂且地震活动频繁）构造单元与测震学参数相结合,研究中强震前震源区所在的构造单元测震学参数的变化特征,提取具有中期预测意义的震兆标志,为中强震的预测提供理论依据。结果显示：中强地震前,郯庐断裂带（鲁东-黄海地块西边界带）及扬子地块（鲁东－黄海地块内部构造单元）D、C值异常过程明显,且各有特点,证明了基于活动地块内部构造单元的测震学参数方法具有良好的可行性。     

A response spectrum approach for seismic performance evaluation of actively controlled structures

To evaluate and measure the effectiveness of active control schemes in reducing the response of structures subjected to earthquake excitations, it is common to use recorded or artificially generated earthquakes as input motions. This paper introduces the response spectrum analysis to evaluate linear control systems for seismic inputs defined by code‐prescribed or site‐specific ground response spectra. Using such a method one can evaluate a control system in a single analysis for the ensemble of time histories that are represented by the input response spectra. The response spectrum analysis can also facilitate the implementation of comprehensive parametric studies. A generalized response spectrum method is used to analyse systems with non‐symmetrical matrices that are caused by the general nature of the control actions imposed on the structure. The application of the method is demonstrated on several numerical examples of a building structure where the control force is applied through an active tuned‐mass damper. Copyright © 2000 John Wiley & Sons, Ltd.     

International and national climate policies for aviation: a review

Aviation constitutes about 2.5% of all energy-related CO₂ emissions and in addition there are non-CO₂ effects. In 2016, the ICAO decided to implement a Carbon Offsetting and Reduction Scheme for International Aviation (CORSIA) and in 2017 the EU decided on faster emission reductions in its Emissions Trading System (EU ETS), which since 2012 includes the aviation sector. The effects of these policies on the expected development of air travel emissions from 2017 to 2030 have been analyzed. For the sample country Sweden, the analysis shows that when emissions reductions in other sectors are attributed to the aviation sector as a result of the EU ETS and CORSIA, carbon emissions are expected to reduce by ?0.8% per year (however if non-CO₂ emissions are included in the analysis, then emissions will increase). This is much less than what is needed to achieve the 2°C target. Our analysis of potential national aviation policy instruments shows that there are legally feasible options that could mitigate emissions in addition to the EU ETS and CORSIA. Distance-based air passenger taxes are common among EU Member States and through increased ticket prices these taxes can reduce demand for air travel and thus reduce emissions. Tax on jet fuel is an option for domestic aviation and for international aviation if bilateral agreements are concluded. A quota obligation for biofuels is a third option.

Key policy insights

• Existing international climate policies for aviation will not deliver any major emission reductions.

• Policymakers who want to significantly push the aviation sector to contribute to meeting the 2°C target need to work towards putting in place tougher international policy instruments in the long term, and simultaneously implement temporary national policy instruments in the near-term.

• Distance-based air passenger taxes, carbon taxes on jet fuel and quota obligations for biofuels are available national policy options; if they are gradually increased, and harmonized with other countries, they can help to significantly reduce emissions.

     

近20年海南岛森林生态系统碳储量变化

热带森林在碳循环研究中有重要作用。根据目前森林碳储量的计算方法和海南森林资源二类调查数据 ,估算了不同时段的碳储量 ,并分析其动态变化特点。结果表明 :海南森林碳储量从 1979年的 30 4 5TgC增加到 1998年的 37 74TgC ,年均增加 0 36 4 5TgC ,增长率为1 19% ,是全国平均增长率的 2 5倍 ;海南森林在碳循环中起不断增强的碳汇作用 ;森林碳密度呈加速减少趋势 ,储碳潜力将很大 ;随着海南全面禁止采伐和封育等林业措施的实施 ,森林面积扩大 ,林龄结构改善 ,储碳能力将进一步提高 ,海南森林在全国或全球碳循环中的作用和社会价值与意义将日渐突出。通过对碳储量计算不确定性的分析和讨论 ,提出应加强对森林群落各层次生物量的实测与实地监测研究 ,统一计算方法 ,以提高碳储量计算的精度     

中国区域气溶胶对东亚夏季风的可能影响(Ⅱ)：黑碳气溶胶及其与硫酸盐气溶胶的综合影响

 利用NCAR的新一代GCM CAM3.0模式耦合一个气溶胶同化系统,研究了中国区域黑碳气溶胶的直接气候效应。结果显示,中国区域黑碳气溶胶引起全球平均辐射强迫为0.13 W/m2,导致除了青藏高原和广西以外的中国大部分地区降温,其中东北、四川和内蒙古中北部降温最显著。由此造成海陆温差缩小,气压差降低,从而总体上使东亚夏季风减弱。但与硫酸盐气溶胶的影响相比,黑碳气溶胶使季风减弱的程度较小,长江中下游地区的降水有所增加。黑碳气溶胶加强了中国东南部地区的对流活动,这与硫酸盐气溶胶的作用相反。同时,探讨了中国区域硫酸盐和黑碳气溶胶的综合直接气候效应。结果表明,硫酸盐和黑碳气溶胶的综合作用与仅有硫酸盐气溶胶的情形十分相似,降水变化的区域也和硫酸盐的保持一致。     

Mercury partition in the interface between a contaminated lagoon and the ocean: The role of particulate load and composition

After having estimated the patterns of flow to the ocean and found some seasonal and tidal differences, mainly with regard to the relative importance of dissolved and particulate fractions, mercury partitioning at the interface between a contaminated lagoon and the Atlantic Ocean was investigated during four tidal cycles in contrasting season and tidal regimes. Mercury was found to be located predominantely in the particulate fraction throughout the year, contributing to its retention within the system. Seasonal conditions, variations in marine and fluvial signals and processes affecting bed sediment resuspension influenced the character and concentration of suspended particulate matter in the water column. Variation in the nature, levels and partitioning of organic carbon in the particulate fraction affected levels of particulate mercury as well as mercury partitioning. These results highlight the dominant role of suspended particulate matter in the distribution of anthropogenic mercury and reinforce the importance of competitive behavior related to organic carbon in mercury scavenging.     

A short introduction to broad and variable iron lines around black holes

Accreting black holes often show iron line emission in their X‐ray spectra. When this line emission is very broad or variable then it is likely to originate from close to the black hole. The theory and observations of such broad and variable iron lines are briefly reviewed here. In order for a clear broad line to be found, one or more of the following have to occur: high iron abundance, dense disk surface and minimal complex absorption. Several excellent examples are found from observations of Seyfert galaxies and Galactic Black Holes. In several cases there is strong evidence that the black hole is rapidly spinning. Further examples are expected as more long observations are made with XMM‐Newton, Chandra and Suzaku. Intriguing instances of rapid variability of some narrow iron lines, both emission and absorption, have been reported. These may reflect variations in the irradiation or motion of physical structures on the accretion disk. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Magnetic Field Strengths and Structures from Radio Observations of Solar Active Regions

Radio observations of some active regions (ARs) obtained with the Nobeyama radioheliograph at λ=1.76cm are used for estimating the magnetic field strength in the upper chromosphere, based on thermal bremsstrahlung. The results are compared with the magnetic field strength in the photosphere from observations with the Solar Magnetic Field Telescope (SMFT) at Huairou Solar Observing Station of Beijing Astronomical Observatory. The difference in the magnetic field strength between the two layers seems reasonable. The solar radio maps of active regions obtained with the Nobeyama radioheliograph, both in total intensity (I-map) and in circular polarizations (V-map), are compared with the optical magnetograms obtained with the SMFT. The comparison between the radio map in circular polarization and the longitudinal photospheric magnetogram of a plage region suggest that the radio map in circular polarization is a kind of magnetogram of the upper chromosphere. The comparison of the radio map in total intensity with the photospheric vector magnetogram of an AR shows that the radio map in total intensity gives indications of magnetic loops in the corona, thus we have a method of defining the coronal magnetic structure from the radio I-maps at λ=1.76 cm. Analysing the I-maps, we identified three components: (a) a compact bright source; (b) a narrow elongated structure connecting two main magnetic islands of opposite polarities (observed in both the optical and radio magnetograms); (c) a wide, diffuse, weak component that corresponds to a wide structure in the solar active region which shows in most cases an S or a reversed S contour, which is probably due to the differential rotation of the Sun. The last two components suggest coronal loops on different spatial scales above the neutral line of the longitudinal photospheric magnetic field.     

辽宁营口虎皮峪地区古元古代岩浆事件及地质意义

辽宁营口虎皮峪地区存在3期古元古代侵入岩浆活动:早期虎皮峪辽吉花岗岩成岩时代为2119±16Ma,富硅、富碱、低铝、低钙及负Eu异常显示其具有类似A型花岗岩的地球化学特征,非常低Sr高Yb的特点指示其形成压力很低,与减薄的地壳有关;第二期后松树沟奥长花岗岩成岩时代为1892±16Ma,富硅、富钠、高铝,Na2O/K2O1.35及无Eu异常或正Eu异常显示其具有埃达克质岩石的特征,中—高Sr低Yb的特点指示其形成压力较高、深度较大,与碰撞后加厚地壳底侵玄武岩的部分熔融有关;晚期南台子石英二长岩成岩时代为1850±11Ma,富碱(Na2O+K2O=11.32%~11.93%),里特曼指数δ=4.78~7.20,属碱性岩,低Sr低Yb的特点指示其形成压力中等,深度大概40~50km,是造山作用完成后板内伸展背景下的产物。上述3期岩浆事件对整个辽吉古元古代活动带的构造演化具有重要指示意义:早期辽吉花岗岩可能形成于辽吉古元古代活动带早期弧后伸展阶段;后松树沟奥长花岗岩则代表古元古代晚期碰撞后地壳加厚阶段的产物;南台子石英二长岩属后造山花岗岩,标志着辽东地区克拉通化的完成,开始进入后造山伸展演化阶段。     

青藏高原北缘哈拉湖近800年来 湖泊沉积及其环境意义*

文章以青藏高原北缘高山祁连山湖泊——哈拉湖作为研究对象,利用放射性核素²¹⁰ Pb和¹³⁷ Cs测年资料,通过对此高海拔湖泊沉积碳酸盐氧碳同位素、碳酸盐含量、总有机碳含量、磁化率等环境代用指标的分析,揭示了这一地区近800年来的气候环境变化过程。分析表明哈拉湖记录的气候环境变化经历了3个阶段:1206~1700A.D.环境较为寒冷、湿润,并有持续变湿的趋势;1700~1920A.D.环境由冷湿的状况趋向温暖干旱,1771年之后,环境保持相对稳定;1920~2002A.D.是自1206年以来最为温暖干旱的阶段。