南极中山站Pc3地磁脉动特征

根据1992年2月9日军1993年2月9日南极中山站地磁脉动观测资料,选出Pc3脉动事件进行分析研究,重点研究南极中山站Pc3脉动的出现频次、频率特性和振幅特性,并对南极中山站记录的Pc3脉动的激发和传播机制进行理论研究.     

南极中山站Pc3地磁脉动特征

根据1992年2月9日军1993年2月9日南极中山站地磁脉动观测资料,选出Pc3脉动事件进行分析研究,重点研究南极中山站Pc3脉动的出现频次、频率特性和振幅特性,并对南极中山站记录的Pc3脉动的激发和传播机制进行理论研究.     

北京地区Pc3地磁脉动与K指数的相关性

本文分析了北京地区Pc3脉动和K指数的关系,研究了Pc3脉动出现频次对不同K指数的分布和日变化,得到了平均周期和K指数之间的经验公式,分析了不同K指数下的Pc3脉动平均周期的日变化。此外,我们把所得的结果和其他人的结果作了比较,并且做了初步的理论解释。     

北京地区Pc3地磁脉动与K指数的相关性

本文分析了北京地区Pc3脉动和K指数的关系,研究了Pc3脉动出现频次对不同K指数的分布和日变化,得到了平均周期和K指数之间的经验公式,分析了不同K指数下的Pc3脉动平均周期的日变化。此外,我们把所得的结果和其他人的结果作了比较,并且做了初步的理论解释。     

北京地区Pc3地磁脉动的偏振特征

本文对1986年1月北京地区Pc3地磁脉动进行了偏振特征的分析,分别找出了北京地区Pc3地磁脉动在磁静日期间和磁扰日期间偏振旋转方向随地方时变化的规律,以及偏振主轴方向随地方时变化的规律。 根据Pc3地磁脉动的偏振分析,可以了解北京地区Pc3脉动的激发机制,为进一步磁层诊断提供科学依据。     

北京地区Pc3地磁脉动的偏振特征

本文对1986年1月北京地区Pc3地磁脉动进行了偏振特征的分析,分别找出了北京地区Pc3地磁脉动在磁静日期间和磁扰日期间偏振旋转方向随地方时变化的规律,以及偏振主轴方向随地方时变化的规律。 根据Pc3地磁脉动的偏振分析,可以了解北京地区Pc3脉动的激发机制,为进一步磁层诊断提供科学依据。     

中国南极长城站地磁脉动记录的分析

中国首次南极考察队于1985年1月至2月在南极洲中国长城站进行了地磁脉动观测。作者采用微型计算机和数字声图仪对记录的资料进行了处理,得到Pc1-4以及Pi2等类型脉动的形态和动态谱。同时,统计了Pc1脉动发生频次的日变化特征以及与K_p指数的相关性。最后,讨论了Pc1脉动中H和D分量的不对称性等某些不常见的现象。     

中国南极长城站地磁脉动记录的分析

中国首次南极考察队于1985年1月至2月在南极洲中国长城站进行了地磁脉动观测。作者采用微型计算机和数字声图仪对记录的资料进行了处理,得到Pc1—4以及Pi2等类型脉动的形态和动态谱。同时,统计了Pc1脉动发生频次的日变化特征以及与K_p指数的相关性。最后,讨论了Pc1脉动中H和D分量的不对称性等某些不常见的现象。     

极隙区纬度Pc 5脉动的传播和起源

南极中山站和戴维斯站均位于极隙区纬度附近,均安装了完全相同的感应式磁力计.选择两站的数据,1997年3月和1996年6、9、12月,运用信号互谱技术进行统计分析,结果得到:在中山站-戴维斯站,Pc5脉动出现时间范围较广,但以地方时中午/磁中午及磁午夜附近出现频次多,其振幅、传播及发生率季节变化不大.振幅白天变化小,中午有小峰,夜间有时有大值.传播方向白天以磁中午为界,晨侧向西传播,直至磁凌晨;昏侧向东传播,约在5:00MLT处转向.夜间约以20:00 MLT为界,之前向西传播,之后向东传播,磁黄昏附近,Pc5脉动传播方向变化较多,显得不规则.这些特征,反映了Pc5脉动在不同地方时段有不同的起源.     

极隙区Pc 3脉动特性的短基线研究

南极中山站和戴维斯站(不变磁纬74.5°)白天中午位于磁层极隙区,两站均安装了完全相同的感应式磁力计,选择1997年3月和1996年6、9、12月两站的数据,运用快速傅里叶变换和波形检查方法选择Pc3脉动事件,然后用信号互谱技术进行统计分析.结果如下:在中山站-戴维斯站,Pc3脉动主要出现于白天,尤其是中午/磁中午附近;Pc3脉动振幅及发生率均在6月份最小,在其他月份大些;Pc3脉动传播方向,白天主要向西.这些可能反映了电离层电导率和日侧电离层电流系统对Pc3脉动的影响.     

A Monte Carlo study of rainfall forecasting with a stochastic model

A procedure for short-term rainfall forecasting in real-time is developed and a study of the role of sampling on forecast ability is conducted. Ground level rainfall fields are forecasted using a stochastic space-time rainfall model in state-space form. Updating of the rainfall field in real-time is accomplished using a distributed parameter Kalman filter to optimally combine measurement information and forecast model estimates. The influence of sampling density on forecast accuracy is evaluated using a series of a simulated rainfall events generated with the same stochastic rainfall model. Sampling was conducted at five different network spatial densities. The results quantify the influence of sampling network density on real-time rainfall field forecasting. Statistical analyses of the rainfall field residuals illustrate improvement in one hour lead time forecasts at higher measurement densities.     

Earthquake Engineering and Engineering Vibration Aims And Scope

正This journal is established by the Institute of Engineering Mechanics(IEM),China Earthquake Administration,to promote scientific exchange between Chinese and foreign scientists and engineers so as to improve the theory and practice of earthquake hazards mitigation,preparedness,and recovery.To accomplish this purpose,the journal aims to attract a balanced number of papers between Chinese and     

Foreword

Destructive earthquakes have caused great damage in China and the United States and collapsing buildings havecaused many deaths and injuries. The field of earthquake engineering studies earthquake hazards, the occurrence ofearthquakes of various magnitudes, the nature of the ground shaking during an earthquake, the vibration of structuresduring earthquakes, the strengthening of existing structures and the design of new structures to be earthquake resistant,and finally, how to cope with earthquake damage and restore a city to normal functioning. Such efforts are in progressin both countries, but unfortunately, the language barrier interferes with the free flow of information between China andthe Untied States. It would be mutually beneficial if some means could be developed to promote the exchangeof information across the Pacific Ocean. This new journal has been established for this purpose and its success willbe an important step in promoting earthquake engineering in China and the United States.     

WORLD ASSOCIATION FOR SEDIMENTATION AND EROSION RESEARCH(WASER)

正President:Giampaolo Di Silvio,Italy Vice Presidents:Ulrich C.E.Zanke,Germany Zhao-yin Wang,China The World Association for Sedimentation and Erosion Research(WASER),inaugurated on Oct.19,2004,is an independent non-governmental,non-profit organization.The mission of WASER is to promote international co-operation on the study     

Enhancing remote sensing research on global change to improve our understanding on Earth system processes

正Global Change includes climate change and other environmental changes caused by the joint interaction among various layers of Earth. From the positive side, global change provides new opportunities to human and other living forms on Earth. In the meantime, it creates tremendous challenges and negative impact. At present, the negative impacts have reached all primary processes of the global ecosystem and every aspect of human society, especially causing degradation of the ecosystem. For instance, intensive deforestation causes decline of biodiversity; global warming causes sea level rise and increases     

Solute concentrations in the lower niger river and the source rock contribution

Water quality analyses for the Niger River for the 1980/81 hydrological year are presented. The samples were collected from the main river at Lokoja, and from two main tributaries, the Kaduna and the Benue Rivers. Different water types were distinguished by the concentrations of major ions. The type Ca > Na > Mg > K - HCO₃ > SO₄ > Cl was represented at all stations during at least part of the year. Chloride was found to dominate the sulphate ion in the Kaduna and Niger, while the Benue maintained a higher concentration of sulphate relative to chloride all year round. Distinct patterns of seasonal variation in the ion concentrations were observed, particularly for the samples collected at Lokoja. Low ion concentrations were prominent during periods of high discharge, while low flow periods coincided with high dissolved ion concentrations. The contribution of rainwater to the total dissolved solids in the river waters was assessed indirectly using rainwater chemistry data from the Gulf of Guinea. The estimated rainwater contribution to the Lower Niger amounts to 5.15 mg 1^?1. Geochemical weathering calculations involving reactions of the four major minerals of granitic rocks - anorthite, biotite, albite, and K-feldspar - with carbon dioxide and water, can account for the average water composition of the Lower Niger. The proportion of the ionic components was also related to the occurrence of the respective element in the minerals.