CTBTO国际数据中心地震数据处理软件研究进展

全球台网地震震相有效关联与快速精确定位是地震监测和禁核试核查的核心问题之一。禁核试条约组织（CTBTO）筹备委员会临时技术秘书处（PTS）国际数据中心（IDC）自成立以来,一直致力于台网震相自动关联有效率及自动处理公报质量的提高,以减轻分析员的工作量。NET-VISA作为IDC下一代全球震相自动关联和事件检测定位软件,使用概率模型和贝叶斯方法找到解释检测观测结果的最佳事件集,进而从这些观测结果中生成自动处理地震公报。测试结果表明,NET-VISA产生的公报要比IDC目前使用的全球关联方法生成的自动处理公报SEL3更加完整和精准。本文介绍了NET-VISA方法的基本原理和测试进展,最后对CTBT北京国家数据中心参加NET-VISA测试中朝鲜6次核试验的NET-VISA关联结果作了分析对比。     

恩施剖面栖霞组下部贫氧-缺氧环境成因模式

我国华南地区二叠系栖霞组沉积了多套富有机碳的暗色岩系,是华南地区油气勘探的潜在烃源岩。其形成主要与水体的氧化还原以及古特提斯海洋洋流系统有关。然而,栖霞期水体的缺氧-贫氧的成因模式还需要更多的地质证据。本文选择湖北省恩施剖面栖霞组下部臭灰岩段钙质页岩及碳酸盐岩夹层为研究对象,开展稀土元素REE、微量元素Th/U比值以及碳酸盐矿物晶格内微量硫酸盐硫同位素组成分析。研究结果表明,栖霞组下部臭灰岩段的下部沉积水体主要为缺氧至贫氧条件,而臭灰岩段上部主要为贫氧至氧化条件。这些缺氧至贫氧沉积主要是由洋流的上涌造成。洋流的上涌将深水环境中缺氧、贫氧的底部水体涌至陆棚斜坡地带,造成斜坡浅水地带形成一个近似倒三角的缺氧-贫氧水体带,从而沉积了栖霞组暗色薄层石灰岩或钙质页岩。     

PREDICTABILITY LEVELS OF MONTHLY FORECAST BASED ON TIME-AVERAGED OCEAN/ATMOSPHERE VARIABLES —A NATURALLY OCCURRING ANALOGUE STUDY

Naturally occurring analogues between the monthly averaged data of 1000,500 and 100 hPa geopotential height and the sea surface temperature (SST) in the Pacific,Atlantic and Indian Oceans during the period January 1956-December 1972 are used to study the potential predictability levels of forecasting the monthly mean ocean/atmosphere variables.It is found that in the ocean-atmosphere system the forecast of geopotential height may be more difficult than SST,and that the predictability level of monthly mean geopotential height anomaly calculated from the corresponding monthly mean SST appears relatively poor,but it can be improved by using the past observational data of monthly mean SST/geopotential fields.     

电磁波井间CT成象技术及其在岩土工程中的应用

简要叙述了电磁波ＣＴ成象技术的基本原理、工作方法及其在岩土工程中诸如机场跑道、隧道工程和高层建筑地基评价中的应用。通过井下激发和观测电磁波能量的衰减，利用ＣＴ技术重建了地下介质在观测平面内相对吸收系数的二维分布图象，这些图象直观准确地反映出地下介质的构造形态、地层界面、风化壳以及破碎带的分布特征，在岩土工程探测中发挥了重要作用。     

利用MSU序列研究高空大气温度变化的进展

美国NOAA卫星上搭载的微波大气探测仪MSU以及后续继承改进仪器AMSU,自1978年投入运行以来,已经积累了超过30年的全球大气温度的观测资料。近年来,国外学者通过仪器定标误差订正、卫星轨道衰减订正、观测时间差异导致的温度日变化订正、仪器间的相互定标处理等技术,发现并剔除了一些影响较大的非气候因素,提高了该序列资料的质量,并用于全球气候变化研究,特别是对流层和平流层近30年的温度变化研究,研究结果是对常规地面和探空资料分析结果的重要补充。本文对目前国际上3种常用的MSU序列资料集的定标误差、偏差订正和不同卫星上仪器观测序列的一致化处理方法进行了综合介绍,并比较分析了3种资料用于30年高空大气温度变化趋势分析的异同。     

从全波段太阳直射辐射确定大气气溶胶光学厚度 II：实验研究

本文通过比较太阳直射表和太阳光度计探测的大气柱气溶胶光学厚度，分析了从太阳直射表探测的全波段太阳直射光强信息确定大气柱气溶胶光学厚度的误差，并应用北京观象台的太阳直射表观测资料，反演得到了 1990—1993年北京大气柱气溶胶光学厚度，分析了该光学厚度月与年变化规律以及1991年菲律宾皮纳图博火山爆发对北京大气气溶胶含量的影响。本文还提出了关于有效水汽含量的一个经验关系式，用于确定水汽对太阳辐射的吸收率。     

甘肃河西地区植被资源的现状及其开发利用途径的探讨

河西地区的植被资源由于人们对它开发利用和管理不当已产生了明显的衰退, 例如: 森林植被资源、灌丛植被资源、草原植被资源分布面积的缩小和质量的下降, 荒漠植被资源变得愈来愈稀少, 草甸植被资源产生明显的衰退以至植物大量死亡, 等等。为了改善河西地区植被资源的质量和防止衰退, 必须对它进行合理利用、治理和保护, 积极种草种树, 合理地利用, 严禁乱砍滥伐和毁草毁林开荒, 适当进行封育和建立自然保护区等措施。     

Vertical variations and transport mechanism of soil moisture in response to vegetation restoration on the Loess Plateau of China

Soil moisture is essential for vegetation restoration in arid and semi-arid regions. Ascertaining the vertical distribution and transportation of soil moisture under different vegetation types has a profound effect on the ecological construction. In this study, the soil moisture at a depth of 500 cm for four typical vegetation types, including Robinia pseudoacacia, Caragana korshinskii, Stipa bungeana, and corn, were investigated and compared in the Zhifanggou watershed of the Loess plateau. Additionally, hydrogen and oxygen stable isotopes were detected to identify the transport mechanism of soil moisture. The results showed vertical distribution and transportation of soil moisture were different under different vegetation types. Depth-averaged soil moisture under S. bungeana and corn generally increased along the profile, while C. korshinskii and R. pseudoacacia showed weakly increasing and relatively stable after an obvious decreasing trend (0–40 cm). The soil moisture under R. pseudoacacia was lower than that under other vegetation types, especially in deep layer. However, the effect of R. pseudoacacia on soil moisture in the topsoil (< 30 cm) could be positive. For R. pseudoacacia (160–500 cm), C. korshinskii (0–500 cm), and S. bungeana (0–100 cm), the soil moisture declined with increased in vegetation age. Planting arbor species such as R. pseudoacacia intensified the decline of soil moisture on the Loess Plateau. The capacity of evaporation fractionation of soil moisture followed the sequence: corn > S. bungeana > R. pseudoacacia > C. korshinskii. The δ¹⁸O values in soil water fluctuated across the profile. The δ¹⁸O values changed sharply in upper layer and generally remained stable in deep layer. However, in middle layer, the vertical distribution characteristics of the δ¹⁸O values were different under different vegetation types. We estimated that piston flow was the main mode of precipitation infiltration, and the occurrence of preferential flow was related to vegetation types. These results were helpful to improve the understanding of the response of deep soil moisture to vegetation restoration and inform practices for sustainable water management.     

Comparative assessment of nitrogen fixation rate by 15N2 tracer assays in the South China Sea

Nitrogen fixation is one of the most important sources of new nitrogen in the ocean and thus profoundly affects the nitrogen and carbon biogeochemical processes. The distribution, controlling factors, and flux of N₂ fixation in the global ocean remain uncertain, partly because of the lack of methodological uniformity. The 15N₂ tracer assay (the original bubble method → the 15N₂-enriched seawater method → the modified bubble method) is the mainstream method for field measurements of N₂ fixation rates (NFRs), among which the original bubble method is the most frequently used. However, accumulating evidence has suggested an underestimation of NFRs when using this method. To improve the availability of previous data, we compared NFRs measured by three 15N₂ tracer assays in the South China Sea. Our results indicate that the relationship between NFRs measured by the original bubble method and the 15N₂-enriched seawater method varies obviously with area and season, which may be influenced by incubation time, diazotrophic composition, and environmental factors. In comparison, the relationship between NFRs measured by the original bubble method and the modified bubble method is more stable, indicating that the N₂ fixation rates based on the original bubble methods may be underestimated by approximately 50%. Based on this result, we revised the flux of N₂ fixation in the South China Sea to 40 mmol/(m2·a). Our results improve the availability and comparability of literature NFR data in the South China Sea. The comparison of the 15N₂ tracer assay for NFRs measurements on a larger scale is urgently necessary over the global ocean for a more robust understanding of the role of N₂ fixation in the marine nitrogen cycle.     

深弹自导过程的波束相关处理仿真

深弹精确自导受测向测距精度影响,为探究自导全过程算法,采用波束域相关处理方法,开展深弹自导过程中自导算法的测向测距性能研究.首先,对方法的可行性进行分析,确定噪声背景下有效混响抑制方法.进而,假设深弹运动态势和弹目的初始位置,根据几何态势推算出运动过程中的弹目位置和目标俯仰角,并加入随机误差模拟弹体旋转.最后,仿真计算...