地面VLF波穿透电离层的能量衰减变化

地面VLF人工源可以导致辐射带高能粒子沉降.为研究辐射带粒子加速和沉降机制,乃至实现对辐射带电子"人工控制"的设想,需要在精确计算得到VLF人工源在电离层激发电磁场能量分布的基础上,计算哨声波对辐射带电子的调制作用.以往计算VLF人工源在电离层中激发的电磁场能量分布多基于Cary给出的波导中VLF波衰减率和Helliwell提出的经典电离层吸收曲线,但近期研究表明,这些模型结果存在较为明显的误差.本研究建立了地面VLF信号穿透电离层传播的全波计算模型,将计算结果与DEMETER卫星记录的NWC通讯台激发的电磁响应进行对比.虽然模型没有考虑电离层参数水平不均匀性,但模型计算结果与卫星观测值也有较好的一致性.利用经过验证的全波模型计算了不同地磁参数、电离层参数情况下,不同辐射特性的地面VLF辐射在波导中的衰减和穿透电离层时D/E区的吸收值,探讨了上述参数对电磁波能量在波导和D/E区中衰减的影响规律.     

Seasonality of the Lagged Relationship between ENSO and the Northern Hemispheric Polar Vortex Variability

〈Abstract〉This paper reports the seasonal feature of the relationship between ENSO and the stratospheric Polar Vortex Oscillation （PVO） variability in the Northern Hemisphere.It is shown that the lagged ENSO-PVO coupling relationship exhibits distinct seasonal feature,due to the strong seasonality of PVO and ENSO.Specifically,the PVO variability not only during winter,but also in autumn and spring months,is significantly correlated with ENSO anomalies leading by seasons;however,no significant effect of ENSO is found on the PVO variability in winter months of November and February.Although a significant ENSO effect is primarily observed when ENSO leads PVO by about one year,a significant correlation is also found between PVO in the following spring months （M ＋1 A ＋1） and ENSO anomalies in the previous autumn （A-1 S-1 O- 1 N -1） when ENSO anomalies lead by about 18 months.The significant correlation between PVO in various seasons and the corresponding ENSO anomalies leading by seasons could be explicitly verified in most of the individual years,confirming that the lagged ENSO effect can largely modulate the seasonal timescale variability of PVO.Moreover,the composite spatial patterns of the zonal-mean temperature anomalies further show that the ENSO effect on the PVO in various seasons is related to the interannual variability of the seasonal timescale PVO events.     

大气掩星反演误差特性初步分析

GPS大气掩星探测技术可以获得全球大气折射率、气压、密度、温度和水汽压等气象参数,该技术基本原理是基于几何光学近似的Abel积分反演.地球扁率、电离层传播时间延迟、大气大尺度水平梯度、多路径传播现象等因素在某些高度范围影响大气反演的精度.本文采用模拟的方法,分析其中地球扁率及电离层对反演结果的影响,并讨论局部圆弧修正及电离层修正的效果.利用CHAMP掩星实测轨道数据和有关电离层和大气经验模式、采用三维射线追踪方法模拟计算几种情形下的GPS掩星观测附加相位数据,对模拟数据进行反演,将反演气象参量剖面与模拟时给定模式剖面进行比较,得到了0～60 km高度范围内的反演误差.误差统计分析结果表明,局部圆弧中心的修正以及电离层修正,对于高精度的GPS掩星反演是非常重要的;电离层修正残差仍是制约30～60 km高度范围内反演精度的重要因素,进一步完善和优化大气掩星反演需要发展新的电离层修正算法.     

冰层取心回转钻进模拟实验台的设计与测试

极地钻探实践表明,冰盖底部冰岩交界附近地质情况异常复杂,不但可能存在暖冰、基底融水,甚至还存在厚度不等的冰岩夹层,取心钻探异常困难,而优选钻头类型、确定合理的钻进参数是保证其安全、快速钻进的重要因素。本文设计了一套能够模拟冰层回转钻进的实验台,其技术参数为：钻压、转速分别可在0～10 kN、0～300 r/min范围内调节,最大扭矩约100 N·m。该实验台能够测量钻头切削具温度、钻孔深度及钻进速度等参数,为深入研究钻头类型及结构参数、钻进参数对扭矩、钻速和切削温度的影响规律提供了手段。采用PDC复合片钻头进行了冰钻实验,结果表明,实验台能够准确调节钻压和转速,可满足实验要求。     

A Possible Detection of the 26 December 2004 Great Sumatra-Andaman Islands Earthquake with Solution Products of the International GNSS Service

The main goal of this work is to critically review the IGS solution products and Precise Point Positioning (PPP) in order to demonstrate their potential to contribute to studies of large earthquakes such as the one that devastated Southeast Asia on December 26th, 2004. In view of a possible detection of the Mw 9.0 Sumatra-Andaman Islands Earthquake of December 26, 2004, position solutions, ranging from intervals of years to one second, of four International GNSS Service (IGS) stations within 3000 km of the epicenter were examined. The IGS combined, cumulative solution product (IGS04P51), consisting of epoch and station velocity solutions and based on data spans of several years prior to the earthquake, was used as a reference. Four IGS combined weekly position solutions (igs04P1301-4), two weeks before and after the earthquake, were utilized for the weekly solution resolution. PPP static and kinematic solutions with IGS Final combined orbits and clocks were used for the mean daily and instantaneous 5-min and 1-sec epoch solutions, respectively. The most significant changes, detected by both weekly and daily solutions occurred in longitude. The nearest IGS station ntus, about 1000 km east of the epicenter, moved westward about 15 mm, while the more distant Indian station iisc (∼ 2300 km NW from the epicenter), shifted about 15 mm eastward. In spite of position errors caused by interpolation of the 5-min IGS clocks, the 1-sec solutions, based on separate data sets, available only for two stations (iisc, dgar), still showed seismic surface waves, in particular at the Indian station iisc. Precise daily IGS combined polar motion and length-of-day products, after correcting for the atmospheric effects, also likely detected, statistically significant, anomalistic excitations on December 26, 2004 that could be caused by this great earthquake.     

石崆山Ⅱ段岩质高边坡稳定性的工程地质系统分析研究

岩质高边坡稳定性的分析评价涉及工程地质学、岩体力学、计算科学等多学科交汇的问题,是一较为复杂的系统工程问题。在系统分析岩质高边坡赋存的地质背景和环境条件的基础上,采用系统分析评价、综合集成的方法应是研究分析和解决该问题的有效和最佳方法。针对漳龙高速公路石崆山Ⅱ段岩质高边坡工程,在系统分析边坡工程地质特性的基础上,采用赤平极射投影法和有限单元(FEM)法等,进行综合评价和系统分析,获得的稳定性结论,已正常运营使用若干年,反映了系统分析,综合评价方法是成功和有效的。它表明,综合评价、系统分析应是岩质高边坡稳定性评价分析的重要途径;它的综合内容和集成方式及其完善与工程实用性,有待进一步深入的研究和工程实践的运用及其经验的积累。     

ANALYSIS OF CAUSATION OF ABNORMAL MOTION OF LANDING TROPICAL CYCLONES IN GUANGDONG

1 INTRODUCTION It is doubtless that TCs making landfalls on Guangdong are one of the important aspects of the research on and prediction of short-term climate changes for the province. With regard to the climate patterns of TCs motion and factors governin…     

北半球500百帕极地环流与厄尔尼诺、南方涛动及我国气温场的遥相关

本文用1951—1984年的资料对500百帕、65°N以北的高度场作自然正交展开,用模糊聚类对典型场归类。指出,极涡月平均场有三种形态,1月份平均场形态较特殊;大尺度距平场也有三种形态,4月份距平场形态较特殊。此外,研究了典型场的时间权重系数与厄尔尼诺、南方涛动的关系。指出,厄尔尼诺现象发生的当年4月、10月极地大尺度距平场有明显的异常特征。这种极地环流异常已明显影响到我国4月份、10月份的气温场。因而,可能是厄尔尼诺年我国气温4月偏低、10月偏高的一个重要原因。     

鲫鲤杂交一代（F_1）自交的受精细胞学观察

采用人工催产、波恩氏液固定、石蜡切片和Ｈ·Ｅ染色等方法，研究了杂交一代（Ｆ１）自交的受精细胞学过程。结果表明，鲫鲤杂交一代自交时有正常的受精细胞学过程。受精后，卵子完成第二次成熟分裂，排出第二极体；１５ｍｉｎ，雌雄性原核形成，２０ｍｉｎ，两性原核完全融合，形成二倍体的合子，４０ｍｉｎ，开始进行卵裂；１ｈ，两个分裂球出现，本实验为Ｆ２代是二倍体提供了证据。     

A climatological study of nocturnal equatorial F-region irregularities at the west Pacific longitudes by using phase fluctuations of the global positioning system

This study investigated a long-term climatology of nocturnal equatorial F-region irregularities by using phase fluctuations of the global positioning system during the solar cycle of 1996–2006 at the west Pacific longitudes. The results showed that the distribution of the occurrence of irregularities is a two-peak pattern, which peaks in equinoxes with a shallow/deep dip in June/December solstice during high solar activity but with two about the same dips in magnitude in both June and December solstices during low solar activity. Moreover, the most interesting longitudinal effect in the area is in solstice occurrences of irregularities during high solar activity that the irregularities in December solstice months develop easier in the west area but those in June solstice months develop easier in the east area.