利用COSMIC低轨卫星对GPS信号的顶部TEC观测资料研究等离子体层电子含量的变化特征   总被引：1，自引：0，他引：1       下载免费PDF全文

张满莲  刘立波  万卫星  宁百齐 《地球物理学报》2016,59(1):1-7

本文尝试利用COSMIC低轨卫星对GPS信号的顶部TEC观测资料研究等离子体层电子含量(简称PEC)的变化规律.首先介绍从低轨卫星对GPS的顶部TEC观测资料提取等离子体层垂直电子含量的方法,然后利用该方法提取2008年全年的PEC数据,进而研究了2008年这一太阳活动低年PEC随地磁纬度(MLAT)、磁地方时(MLT)以及不同季节的变化规律.此外,还利用提取的120°E和300°E经度链上的数据对比研究了PEC的经度变化情形.研究结果表明:(1)PEC主要集中分布在磁赤道±45°之间的一个绕地球的环带状区域中;(2)PEC表现出以下的昼夜变化规律特征:白天时段之值高于夜间,约在12—16MLT之间达到最高峰值,而最小PEC值出现在日出前大约4—5MLT左右的时段;(3)相比其他季节月份而言,PEC在北半球夏季月份(5—8月)具有最小值;(4)PEC存在明显的经度变化,不同经度链上的PEC存在不同的季节变化特征.  相似文献   

2002年10月Millstone Hill地区电离层暴时特性研究          下载免费PDF全文

王露露  刘立波  陈一定  乐会军  张瑞龙 《地球物理学报》2019,62(7):2355-2365

磁暴期间电离层行为是电离层物理的重要研究内容.本文利用美国Millstone Hill非相干散射雷达以及GPS-TEC数据资料,分析了2002年10月13-17日和22-26日磁暴事件期间电离层电子密度响应在不同高度存在的差异.结果表明：正、负相暴电子密度的变化幅度随高度变化趋势相同,但不同高度上响应的时间、相位和幅度存在差异;负相暴最大变化幅度所在高度值同静时峰高值非常吻合,二者有很好的线性关系,但正相暴最大变化幅度所在高度值同静时峰高值无关,波动较大,意味着电离层正相暴响应更易到达各个高度上;特别地,22-26日负相暴在能量初次耦合进入电离层时高高度有极小的变化,其最大绝对变化量仅为低高度的4%.大气成分和风场的共同作用是两次负相暴发生的主要原因,但前者成分效应明显,后者动力学作用明显,有时甚至700 km以上电离层的贡献也是不可忽略的.  相似文献   

Detection of two pathogenic marine ciliates Ancistrum haliotis and A. crassum (Ciliophora: Scuticociliatia) by fluorescence in situ hybridization     

Zifeng Zhan  Kuidong Xu 《海洋学报(英文版)》2020,39(12):90-94

The scuticociliatid ciliates Ancistrum haliotis and A. crassum are parasites that may cause high mortality in the cultured abalone Haliotis spp. and the bivalve Ruditapes philippinarum. Traditional identification with silver staining methods is hampered by their morphological similarities to closely related species and the complicated procedures of morphological analysis. We designed two SSU rRNA-targeted oligonucleotide probes labeled with a fluorochrome, and optimized the fluorescence in situ hybridization (FISH) protocols for identification of A. halioti and A. crassum, respectively. The assays resulted in a clear identification by strong fluorescence signals from the oligonucleotide probes. The method can be used for quick and accurate quantitative analysis of A. haliotis and A. crassum infections on host molluscs.  相似文献   

Microstructures of structure I and II gas hydrates from the Gulf of Mexico     

Stephan A. Klapp  Gerhard Bohrmann  Werner F. Kuhs  M. Mangir Murshed  Thomas Pape  Helmut Klein  Kirsten S. Techmer  Katja U. Heeschen  Friedrich Abegg 《Marine and Petroleum Geology》2010

Gas hydrate samples from various locations in the Gulf of Mexico (GOM) differ considerably in their microstructure. Distinct microstructure characteristics coincide with discrete crystallographic structures, gas compositions and calculated thermodynamic stabilities.  相似文献   

Identification of Prorocentrum minimum and Takayama pulchella by fluorescence in situ hybridization through epifluorescence microscopy and flow cytometry     

HOU Jianjun          LAI Hongyan  HUANG Bangqin  CHEN Jixin College of Fisheries  Huazhong Agricultural University  Wuhan  China College of Life Sciences  Hubei Normal University  Huangshi  China State Key Laboratory of Marine Environmental Science  Environmental Science Research Center  Xiamen University  Xiamen  China Key Laboratory of Freshwater Fish Germplasm Resources  Biotechnology  Yangtse River Fisheries Research Institute  Jinzhou  China State Key La... 《海洋学报(英文版)》2009,28(2)

Partial rDNA sequences of Prorocentrum minimum and Takayama pulchella were amplified, cloned and sequenced, and these sequence data were deposited in the GenBank. Eight oligonucleotide probes (DNA probes) were designed based on the sequence analysis. The probes were employed to detect and identify P. minimum and T. pulchella in unialgal and mixed algal samples with a fluorescence in situ hybridization method using flow cytometry. Epifluorescence micrographs showed that these specific probes labeled with flu...  相似文献   

Attitude and angular rates of planetary probes during atmospheric descent: Implications for imaging     

Ralph D. Lorenz 《Planetary and Space Science》2010,58(5):838-846

Attitude dynamics data from planetary missions are reviewed to obtain a zeroth-order expectation on the tilts and angular rates to be expected on atmospheric probes during descent: these rates are a strong driver on descent imager design. While recent Mars missions have been equipped with capable inertial measurements, attitude measurements for missions to other planetary bodies are rather limited but some angular motion estimates can be derived from accelerometer, Doppler or other data. It is found that robust camera designs should tolerate motions of the order of 20-40°/s, encountered by Mars Pathfinder, Pioneer Venus, Venera and the high speed part of the Huygens descent on Titan. Under good conditions, parachute-stabilized probes can experience rates of 1-5°/s, seen by the Mars Exploration Rovers and Viking, Galileo at Jupiter, and the slow speed parts of the Huygens descent. In the lowest 20 km of the descent on Titan, the Huygens probe was within 2° of vertical over 95% of the time. Some factors influencing these motions are discussed.  相似文献   

Modeling of solute transport and biological sulfate reduction using low cost electron donor     

Osama Eljamal  Kenji Jinno  Tosao Hosokawa 《Environmental Geology》2009,56(8):1605-1613

Serial data from soil–sawdust column experiments were used to develop a mathematical model to describe the biological sulfate reduction processes in porous media. The mathematical model numerically solves the equation of solute transport in one-dimensional saturated state. Solute transport is coupled to sulfate reducing bacteria sub model. Bacterial growth is assumed to follow double Monod kinetic equation. Two bacterial groups (X1 and X2) were described. Bacterial group X1 uses under aerobic conditions oxygen and under anaerobic conditions nitrate as electron acceptor. Under anaerobic conditions bacterial groups X2, use sulfate as an electron acceptor. Sulfate rich wastewater is usually deficient in electron donor and requires external addition of electron donors in order to achieve complete sulfate reduction. The organic carbon as electron donor is one of the most important factors that affect sulfate reduction bacterial activity. In this study the possible source of organic carbon is the solid organic carbon supplied to the system in the form of sawdust. The results of this study indicate that sawdust could be employed as low-cost materials to enhance the biological sulfate reduction processes in porous media. While the availability of organic carbon as electron donor is one of the most important factors that affect the sulfate reducing bacterial activity in porous media, this study demonstrates that using sawdust as a carbon source can improve the bacterial activity and increase the column permeability.  相似文献   

Disproportionation of Fe<Superscript>2+</Superscript> in Al-free silicate perovskite in the laser heated diamond anvil cell as recorded by electron probe microanalysis of oxygen     

Michel Fialin  Gilles Catillon  Denis Andrault 《Physics and Chemistry of Minerals》2009,36(4):183-191

Experimental evidence is reported for Fe²⁺ disproportionation in Al-free perovskite (Pv), when submitted to large temperature gradients (i.e., under off-equilibrium conditions) in a laser heated diamond anvil cell (LHDAC). To enable this effect, the experimental procedure was designed to produce large radial and axial temperature gradients. In the Pv and ferropericlase (Fp) assemblage synthesized after dissociation of natural olivine, the three chemical states of iron (i.e., Fe⁰, Fe²⁺ and Fe³⁺) could be evidenced by electron probe microanalysis (EPMA), through variations of oxygen contents attached to the Fe cations. Despite inherent difficulties for determination of O-contents and Fe³⁺/ΣFe ratios using EPMA, we recorded significant changes in iron oxidation state across the laser-heated strip. These changes are correlated with variations in composition for the major elements (Fe, Mg, and Si), which evidences that the Pv/Fp assemblage experienced large segregation under the strong temperature gradients. Grains of metallic iron were detected in parts of the laser-heated strip coexisting with a Pv phase with Fe/(Mg + Fe) = 6 at% and most of its iron as Fe³⁺. This Fe²⁺-disproportionation reaction involves insertion of Fe³⁺-defects in the Pv lattice. This Fe³⁺-bearing Pv phase is presumably unstable and decomposes into a mineral assemblage including magnesioferrite, which is detected at the border of the laser-heated strip.  相似文献   

一次闪电回击过程的通道辐射特性     

张华明  袁萍  吕世华  欧阳玉花 《高原气象》2008,27(1):143-147

用无狭缝摄谱仪获得了山东省一次云对地闪电回击过程的光谱,根据光谱信息,计算了闪电通道等离子体温度和电子密度,并分析了闪电通道内部的辐射机制,讨论了闪电通道等离子体中的箍缩效应。由此推断:闪电通道等离子体中的箍缩效应是闪电产生X射线的主要辐射源。最后讨论了闪电通道与激光在大气中激发的等离子体通道的差异。  相似文献   

智利8.8级地震的震前电子浓度扰动   总被引：2，自引：1，他引：1       下载免费PDF全文

刘静  万卫星  黄建平  张学民  赵庶凡  欧阳新艳  泽仁志玛 《地球物理学报》2011,54(11):2717-2725

基于法国DEMETER卫星数据,在识别2级图像的基础上,通过对1级数据进行滑动中值处理、纬度变化分析以及空间差值研究,发现2010年2月27日智利8.8级地震的震前震中区上空附近有异常变化:20日距离震中1500 km处电子浓度升高,24日电子浓度降低;25、26日电场、磁场及部分等离子体参量呈现同步扰动; 26日2条...  相似文献