热带对流季内振荡强度异常特征及其与海表温度的关系

利用外逸长波辐射 (outgoing longwave radiation, OLR) 资料分析了热带对流季内振荡 (ISO) 强度的季节变化及年际异常特征, 重点研究其与海表温度的关系。结果表明:最强的OLR季内振荡主要位于高海表温度 (SST) 区, 即热带印度洋和热带西太平洋区域, 终年存在, 冬、春季最强, 振荡中心偏于夏半球。OLR季内振荡强度年际异常显著区域是热带中东太平洋区域、西北太平洋区域和西南太平洋区域, 它与SST年际异常存在局地正相关关系, 伴随环流的辐合辐散, 并与ENSO事件关系密切。另外, El Ni?o事件发生之前, 热带印度洋和热带西太平区域OLR季内振荡增强, 其中心随事件的发展逐渐东移, 事件发生后这两个区域ISO减弱, 这与OLR季内振荡强度年际异常显著的区域具有内在连贯性。海表温度是决定OLR季内振荡强度季节变化、年际异常的一个关键因子。     

中国地震电磁现象的岩石实验研究

介绍了近年来中国岩石电磁辐射实验的一些现象和结果。     

现浇楼板参与工作后框架结构的pushover分析研究

为了研究现浇楼板对钢筋混凝土框架结构抗震性能的影响,本文利用pushover方法对框架结构进行了分析研究,在分析中分别考虑和不考虑现浇楼板及其钢筋对梁抗弯承载力的贡献,通过对计算结果进行分析比较得出了一些结论,并对框架结构抗震设计提出了一些建议。     

Building GIS web services on JXTA network

In recent years, Web services and Peer-to-Peer (or simply P2P) appear as two of the hottest research topics in network computing. On the one hand, by adopting a decentralized, network-based style, P2P technologies can make P2P systems enhance overall reliability and fault-tolerance, increase autonomy, and enable ad-hoc communication and collaboration. On the other hand, Web services provides a good approach to integrate various heterogeneous systems and applications into a cooperative environment. This paper presents the techniques of combining Web services and P2P technologies into GIS to construct a new generation of GIS, which is more flexible and cooperative. As a case study, an ongoing project JGWS is introduced, which is an experimental GIS Web services platform built on JXTA. This paper also explores the schemes of building GIS Web services in a P2P environment.     

Remains of trilobites and other species discovered in a volcanic ash bed of the end-Permian,Yangtze craton,South China

The remains of trilobites and other species were unexpectedly discovered in a volcanic ash layer beneath the Permian–Triassic Boundary (PTB). Based on a biostratigraphic investigation of the Zhongliangshan section in Chongqing, South China, the quantity of the species gradually decreased with subsequent volcanism. This finding provides an opportunity to further understand the disappearance of trilobites and the evolution of the mass extinction event. The temporal coincidence between the volcanic eruption event and the loss of trilobites and other species supports the idea of a cause-and-effect relationship. The species remains in the ash bed appeared before the disappearance of Clarkina yini and the climax of the negative carbon isotope excursion, which implies that the onset of the mass extinction occurred at the end-Permian. The explosive volcanic events caused massive releases of CO₂, toxic gases and volcanic ash and resulted in loss of habitat for certain species in the Tethys domain. This phenomenon may have led to the abrupt death of trilobites and the catastrophic collapse of biodiversity.     

基于GF-1卫星遥感影像的海岸线生态化监测与评价研究——以营口市为例

海岸线是海洋与陆地的分界线,也是重要的生态交错线。本文采用GF-1卫星遥感影像,通过监测大潮高潮时刻和小潮低潮时刻海岸水陆边界线,构建了潮间带完整性系数,以此为依据将海岸线划分为自然海岸线、具有基本生态功能的人工海岸线、具有部分生态功能的人工海岸线、具有有限生态功能的人工海岸线、具有少量生态功能的人工海岸线和无生态功能的人工海岸线。在此基础上,结合潮间带完整性系数及其毗邻海岸线长度,构建了海岸线生态化指数,用以评价区域海岸线的生态化程度。营口市海岸线以无生态功能的人工海岸线、自然海岸线和具有少量生态功能的人工海岸线为主,分别占到海岸线总长度的45.74%、18.31%和15.53%。营口市总体海岸线生态化指数为0.29,其中西城区、老边区、盖州北、鲅鱼圈区和盖州南分别为0.55、0.17、0.40、0.10和0.55。     

Analysis of current–topography interaction in remote sensing imaging procedures for shallow water topography

Underwater topography can be imaged using remote sensing methods. Numerous studies have been conducted to understand the imaging mechanism of shallow water topography. However, current–topography interaction constitutes the weakest link in the remote sensing imaging mechanism of underwater topography. In addition, few studies focused on different topography patterns. Current velocity is highly correlated with bathymetry, and velocity gradient is used as an indicator of sea surface roughness. In this research, we analyzed the distribution characteristics of current velocity and velocity gradient in different cases using a 3-dimensional (3-D) hydrodynamic model to discuss the current–topography interaction part of the remote sensing imaging mechanism, especially the modulation by current parallel or normal to the underwater topography, both positive and negative. Results showed remarkable agreement between 3-D current analysis and surface velocity analysis. Parallel and normal currents had different responses to different topography types. The distribution of surface current gradient showed opposite features over negative and positive topography in parallel and normal current fields. This can be used to distinguish negative topography from positive topography with different current directions to a certain extent.     

Spatiotemporal distributions of δD in atmospheric water vapor based on TES Data during 2004–2009

The spatial and temporal distributions of the stable isotopes such as HD¹⁶O (or ¹H²H¹⁶O, or HDO) and H₂ ¹⁸O in atmospheric water vapor are related to evaporation in source places, vapor condensation during transport, and vapor convergence and divergence, and thus provide useful information for investigation and understanding of the global water cycle. This paper analyzes spatiotemporal variations of the content of isotope HDO (i.e., δ _D), in atmospheric water vapor, namely, δ _{D v}, and the relationship of δ _{D v} with atmospheric humidity and temperature at different levels in the troposphere, using the HDO and H₂O data retrieved from the Tropospheric Emission Spectrometer (TES) at seven pressure levels from 825 to 100 hPa. The results indicate that δ _{D v} has a clear zonal distribution in the troposphere and a good correspondence with atmospheric precipitable water. The results also show that δ _{D v} decreases logarithmically with atmospheric pressure and presents a decreasing trend from the equator to high latitudes and from lands to oceans. Seasonal changes of δ _{D v} exhibit regional differences. The spatial distribution and seasonal variation of δ _{D v} in the low troposphere are consistent with those in the middle troposphere, but opposite situations occur from the upper troposphere to the lower stratosphere. The correlation between δ _{D v} and temperature has a similar distribution pattern to the correlation between δ _{D v} and precipitable water in the troposphere. The stable isotope HDO in water vapor (δ _{D v}), compared with that in precipitation (δ _{D p}), is of some differences in spatial distribution and seasonal variation, and in its relationship with temperature and humidity, indicating that the impacts of stable isotopic fractionation and atmospheric circulation on the two types of stable isotopes are different.     

1988-2009年全球地面风速变化趋势研究

利用来自ESE的1988-2009年高精度、高分辨率的CCMP风场资料,对全球0.25°×0.25°每个网格点上地面风速的逐年变化趋势进行分析.研究发现:近22 a期间,全球大部分区域的地面风速以显著性递增趋势为主导,递增趋势较强的区域主要分布于南极大陆的临海区域、格陵兰岛的临海区域;显著性逐年线性递减以及地面风速无明显变化趋势的区域主要散布于全球各地的一些零星区域,且不同地区地面风速的变化趋势由不同季节主导.     

Intercomparison of stable isotopes in precipitation simulated by GCMs with GNIP survey over East Asia

Using the isotope enabled ECHAM4, GISS E and HadCM3 GCMs, the spatial distribution of mean δ¹⁸O in precipitation, mean seasonality and the correlations of δ¹⁸O in precipitation with temperature and precipitation amount are analyzed. The simulated results are in agreement with stable isotopic features by GNIP observations. Over East Asia, the distribution of δ¹⁸O in precipitation is of marked latitude effect and altitude effect. The latitude effect is covered by the continent effect in some regions. The largest seasonality of δ¹⁸O in precipitation appears in eastern Siberia controlled by cold high pressure, and the smallest seasonality is in the western Pacific controlled by the subtropical high. Relatively weak seasonality appears in middle latitudes where oceanic and continental air masses frequently interact. However, three GCMs show significant systematic lower δ¹⁸O for inland mid-high latitudes than GNIP data, which is related to the used isotopic scheme in GCMs. Temperature effect occurs mainly in inland mid-high latitudes. The higher the latitude and the closer the distance to inland is, then the stronger the temperature effect. Amount effect occurs mainly in low-mid latitudes and monsoon areas, with the strongest effect in low-latitude coasts or islands. However, three GCMs provide virtually non-existent amount effect in arid regions over Central Asia. The enrichment action of stable isotopes in falling raindrops under a cloud base, which is enlarged by these modes, is responsible for such a result. A significant difference between spatial distributions of δ¹⁸O statistics by GCMs simulations and by GNIP observations is that the standard deviation of GCMs statistics is greater than that of GNIP statistics. In contrast, by comparing parallel time series at a single station, the standard deviations of GCMs simulations are smaller than that of GNIP observations.