Evaluation of energetic particle parameters in the near-Earth magnetotail derived from flux asymmetry observations

The flux asymmetries measured by spectrometers on board spacecraft contain information on particle parameters. The net flux intensity (NFI) method provides a tool to evaluate these parameters. The NFI method is valid when both the spin period of the spacecraft and the time resolution of the particle spectrometers are much shorter than the characteristic time-scale of the particle flux variations. We apply the NFI analysis to the flux asymmetry measurements made by GEOS 2 at the nightside geosynchronous orbit in the late substorm growth phase. The cross-tail current of energetic ions, their pressure gradient and average drift velocity, as well as a field-aligned flows are investigated. Current disruption at substorm onset and the –convection surge mechanism during dipolarization of the magnetic field are directly observed.     

The equatorial and low-latitude ionosphere within the context of global modeling

The thermosphere–ionosphere–mesosphere-electrodynamics coupled model TIME-GCM, coupled to NCEP lower atmosphere data, is used to simulate the noontime ionospheric peak electron density NmF2 at low latitudes for year 2002. Model output are compared with observations a three ionosonde stations: Jicamarca, Ascension Island and Darwin, stations at geomagnetic latitudes of 3°S, 10°S and 22°S, respectively. The modeled electron density at the peak of the F2-layer (NmF2) matches the general trend of the data fairly well at noon throughout the year. The shapes of the diurnal curves of NmF2 vs. local time are not well produced in the model, and particularly so at the two stations away from the geomagnetic equator. At all sites the day-to-day variability of NmF2, assessed using the percent standard deviation about the monthly mean, is about twice the modeled variability. Possible sources of this shortfall in the model may be due to the under-representation of coupling from below and/or from auroral sources.     

基于MESSEGER观测对水星磁尾电流片磁场分布的统计研究

本文利用信使号飞船2011-2015年期间在轨磁场数据对水星磁尾电流片的磁场结构分布特征进行了统计分析.为探究磁场结构分布随水星径向距离的变化, 电流片划分为近磁尾(-1.5R_M > X > -2.0R_M)和远磁尾(-2.0R_M > X > -2.5R_M)两个区域.所得结果表明:(1)无论是近磁尾还是远磁尾, 电流片中的磁场都以+B_z分量为主, 磁场方向几乎与磁赤道面垂直.(2)相比近磁尾, 远磁尾电流片中磁场强度、B_z分量较弱, B_y分量较强, 而且-B_z信号出现概率相对较大, 这表明电流片中磁活动相对容易在远磁尾中发生.(3)磁场强度以及B_z分量在晨昏方向上的分布存在晨昏不对称性—在方位角120°~190°范围内相对较弱.弱B_z数据点(B_z < 5 nT)也在昏侧(Y>0)发生较为频繁.(4)与B_z分布相反, 磁场强B_y分量(|B_y|>5 nT)倾向于在晨侧(Y < 0)发生.统计分析还表明, 磁场B_y分量与行星际磁场B_y分量并无明显的相关性.对比地球磁尾电流片, 我们对水星磁尾电流片B_z分量、强B_y分量的晨昏不对称起源机制作了探讨分析.

     

Non-linear methods for event location in a global context

Directed search methods in four-dimensional hypocentre space do not require the differentiation of travel times and are particularly suitable for the use of information from multiple seismic phases including joint use of primary and depth phases (e.g. pP) for a reference model such as a k135. These approaches can be used with a wide range of measures of misfit between observed and estimated times. A very effective method of this class is the use of the neighbourhood algorithm that allows all previous hypocentre estimates to be employed to estimate the shape of the misfit surface. When used with a robust measure of misfit such as the sum of the absolute values of the residuals (L1 norm), the neighbourhood algorithm provides rapid convergence, and a measure of the uncertainty in the hypocentral estimate from the concentration of the points with low misfit in four-space. Such a procedure is well suited to the first pass analysis of observations since it is not distracted by occasional readings associated with other events. Phase association can then be improved and a more conventional procedure used to provide error ellipsoids around a well-defined depth.     

Detection of short-period global waves from nightglow observations

Atmospheric temperature oscillations at similar frequencies have been detected in the spectra of variations in the rotational temperatures of the OH and O₂ nighttime emissions, simultaneously observed at two spaced stations in the range of periods ～1–3 h. These oscillations are probably caused by global waves: short-period solar tides and/or free oscillations of the atmosphere.     

Multipoint observations of Pi2 pulsations and correlation with dynamic processes in the near-Earth magnetotail on March 18, 2009

Simultaneous measurements from THEMIS spacecraft,GOES-11 and ground stations(Canadian Array for Realtime Investigations of Magnetic Activity or CARISMA,and 210°magnetic meridian or MM)on March 18,2009 allow the study of dynamic processes in the near-Earth magnetotail and corresponding Pi2 pulsations on the ground in great detail.Fast earthward flows along with traveling Alfvén waves and fast mode waves in the Pi2 band were observed by three Time History of Events and Macroscale Interactions during Substorms(THEMIS)probes(P3,P4 and P5)in the near-Earth plasmasheet.At the mid-to high-latitude nightside,the CARISMA stations located near the foot points of the three probes recorded Pi2s with two periods,about 80 s after the earthward fast flows observed by the P4 probe.The long-period Pi2(140–150 s)belongs to the transient response Pi2(TR Pi2),since the travel time of the Alfvén waves between the plasma sheet and CARISMA stations is very close to half the period of the long-period Pi2.The short-period Pi2(60–80 s)has the same period band as the perpendicular velocity of the fast flows,which indicates that it may relate to the inertial current caused by periodic braking of the earthward fast flows.The 210°MM stations located at the low-latitude duskside also observed Pi2s with the same start time,waveform and frequency,about~120 s after the earthward fast flows.Strong poloidal oscillations are shown by GOES-11(~23 MLT)and the compressional component(Bb)is highly correlated with H components of the 210°MM stations,whereas the other two components(Br and Be)are not.These results confirm that the low-latitude Pi2s are generated by cavity mode resonance,which is driven by an impulsive broadband source in the near-Earth magnetotail.     

Structural control of volcanic ore deposits in the context of global tectonics

Structural control of the deposition of endogenic ores, among which the ores of volcanic affinity play an important role, has been studied by the author in several regions of four continents. Correlation of the results has revealed that generally there is a repetition of four sets of ore-controlling basement fracture zones. All the four sets of basement fracture zones are not always well developed in the sub-surface level and in the morphology of a region, and some of them usually play a dominant role depending on the geological development of the territory (Table 1). The strike of the ore-controlling basement fractures and their distribution have shown similarities with the pattern of fractures distribution in the floor of the adjoining oceans in three of the studied areas. The most important feature is the joint development of east-west trending fracture zones in both the oceanic areas and the basement of continental areas. One of these zones, defined as the «Fourty-north Fracture Zone » has been traced for a considerable distance on a global scale, the Mendocino fracture zone being considered as its prolongation. The results do not exclude the possibility of a continental drift in some areas, but require the presence of a rigid layer with a rather uniform global fracture pattern existing in the period before rifting and drifting apart of the plates.     

Quiet-time Pc 5 pulsations in the Earth’s magnetotail: IMP-8, ISEE-1 and ISEE-3 simultaneous observations

Quasi-periodic Pc 5 pulsations have been reported inside and just outside the Earth’s magnetotail during intervals of low geomagnetic activity. In order to further define their characteristics and spatial extent, we present three case studies of simultaneous magnetic field and plasma observations by IMP-8, ISEE-1 (and ISEE-2 in one case) in the Earth’s magnetotail and ISEE-3 far upstream of the bow shock, during intervals in which the spacecraft were widely separated. In the first case study, similar pulsations are observed by IMP-8 at the dawn flank of the plasma sheet and by ISEE-1 near the plasma sheet boundary layer (PSBL) near midnight local time. In the second case study, simultaneous pulsations are observed by IMP-8 in the dusk magnetosheath and by ISEE-1 and 2 in the dawn plasma sheet. In the third case study, simultaneous pulsations are observed in the north plasma sheet boundary layer and the south plasma sheet. We conclude that the pulsations occur simultaneously throughout much of the nightside magnetosphere and the surrounding magnetosheath, i.e. that they have a global character. Some additional findings are the following: (a) the observed pulsations are mixed mode compressional and transverse, where the compressional character is more apparent in the close vicinity of the plane Z_GSM=0; (b) the compressional pulsations of the magnetic field in the dusk magnetosheath show peaks that coincide (almost one-to-one) with similar peaks observed inside the dawn plasma sheet; (c) in the second case study the polarization sense of the magnetic field and the recurrent left-hand plasma vortices observed in the dawn plasma sheet are consistent with antisunward moving waves on the magneto-pause; (d) pulsation amplitudes are weaker in the PSBL(or lobe) as compared with those in the magneto-tail’s flanks, suggesting a decay with distance from the magnetopause; (e) the thickness of the plasma sheet (under extremely quiet conditions) is estimated to be \sim22 R_E at an average location of (X, Y)_GSM=(16, 17) R_E, whereas at midnight local time the thickness is \sim14 R_E. The detected pulsations are probably due to the pressure variations (recorded by ISEE-3) in the solar wind, and/or the Kelvin Helmholtz instability in the low-latitude boundary layer or the magnetopause due to a strongly northward IMF.     

TC-1在近磁尾观测到地向流的偏转

使用TC-1卫星在2004年到2007年磁尾探测数据,将以往高速流的研究拓宽到较低的速度,统计分析其从-13.4RE到-5RE地心距离内的空间演化. 研究发现: (1) 在向着地球运动的过程中,地向流发生率在日地连线附近减小,但在晨昏两翼的发生率增加,且在黄昏侧的发生率最高;这表明地向流在运动到近地时向着晨昏两翼偏转. (2) 越靠近地球,流速V和Vx越小,Vy和Vz的变化幅度较小并且具有明显的晨昏不对称性;所以地向流在近地运动过程中,不仅在晨昏方向上偏转,而且在南北方向上偏转. (3) 地向流期间,等离子体密度整体偏小;但是随地心距离的减小,密度整体上逐步增加. (4) 平行和垂直于磁场的流速具有明显的晨昏不对称性.在黎明侧的平行流速比黄昏侧大,在黄昏侧的垂直流速比黎明侧大. 鉴于较大的垂直流速易触发与电流中断关系密切的不稳定性,我们推测电流中断更容易出现在黄昏侧. (5) 除个别位置处的热压和磁压相当外, 磁压在总压中一直占据主导地位.日地连线附近的总压较大,晨昏两翼处的总压相对较小; 从而在晨昏向上产生较大的压力梯度,导致地向流在晨昏两翼偏转和发生率增大. 在晨昏两翼,距离地球较近的位置处观测到了较小的压力;而在日地连线附近,距离地球较远的位置才可以观测到较小的压力;压力分布的这个统计特征说明过去事例研究中电流中断出现在不同的位置可能是由近地磁尾的压力分布造成的.     

Estimation of global lightning activity and observations of atmospheric electric field

Variations in the global atmospheric electric circuit are investigated using a wide range of globally spaced instruments observing VLF (∼10 kHz) waves, ELF (∼300 Hz) waves, Schumann resonances (4–60 Hz), and the atmospheric fair weather electric field. For the ELF/VLF observations, propagation effects are accounted for in a novel approach using established monthly averages of lightning location provided by the Lightning Image Sensor (LIS) and applying known frequency specific attenuation parameters for daytime/nighttime ELF/VLF propagation. Schumann resonances are analyzed using decomposition into propagating and standing waves in the Earth-ionosphere waveguide. Derived lightning activity is compared to existing global lightning detection networks and fair weather field observations. The results suggest that characteristics of lightning discharges vary by region and may have diverse effects upon the ionospheric potential.     

The challenge of integrating the environment into policy-making Part 1: The German Governmental view

The paper discusses the recent trends in environmental protection within an industrial society. The potential conflict between environmental sustainability and economic development is discussed with particular reference to Germany. Environmentally orientated management is considered to be the most appropriate means of achieving this economical cost-efficiency and ecological sustainability. However, producers have a responsibility to achieve these aims against a framework of increasing environmental legislation, both national and international, and widely adopted philosophies such as the polluter pays and precautionary principles. Finally, the paper discusses the relevance of these aspects for both industrialized and developing countries.     

磁尾爆发性整体流与亚暴的关系

利用星簇Cluster的三颗卫星(C1, C3和C4)在2001年和2002年的数据,研究磁尾爆发性整体流（BBF, Bursty Bulk Flow）事件及其与亚暴的关系. 三颗卫星可以同时观测到同一次BBF事件, 有时只有一颗或两颗观测到BBF,其原因有:（1）等离子体整体流的速度峰值满足BBF选取原则中的峰值要求, 但卫星的运行轨道不满足;（2）卫星处于所要求的区域内,等离子体整体流的速度峰值不满足;（3）中性片的复杂结构及其运动使得选取条件不能同时满足;（4）BBF空间分布高度局域化. 统计研究结果表明：单颗卫星观测存在局限性, C1、C3和C4卫星独立观测到BBF的持续总时间分别占它们联合观测到的5507%、7748%和5552%; 大部分亚暴爆发期间都能观测到BBF, 甚至在一次亚暴爆发期间观测到多次BBF; 少数亚暴爆发期间没有观测到BBF.     

The challenge of integrating the environment into policy-making: Part 2: The Norwegian Governmental view

The paper briefly discusses the view and actions of the Norwegian Government in relation to environmental protection and development and the minimization of the effects of industry. Governments and supra-national bodies, industry, municipal bodies, science and training bodies and voluntary and non-governmental organizations all have a major and integrated role in protecting the environment. It is emphasized that as many of the problems are transboundary and trans-sectoral their solution requires an intersectoral approach.     

地球磁尾中重联产生的磁流通管的运动

本文通过MHD理论研究了细磁流通管在二维静止平衡介质中的运动.用地球磁尾中的一维细丝来表示流通管,通过数值模拟可以得到细丝随时间变化的一些性质.重联产生的细丝磁场比周围磁场偶极性更强,运动时表现出了很强的地向流.结果还显示了阿尔芬波、慢激波等MHD波从磁层的赤道面传播到地球电离层上并部分地反射回来.细丝在电离层上的足点的赤道向运动滞后于赤道面上的地向运动.虽然在模拟中细丝的初始等离子体压强低于周围压强,但是当它开始迅速向地球方向运动时,它的等离子体压强很快上升到与周围压强相当,甚至有时候大于周围压强的值.     

Actual state of European wetlands and their possible future in the context of global climate change

The present area of European wetlands is only a fraction of their area before the start of large-scale human colonization of Europe. Many European wetlands have been exploited and managed for various purposes. Large wetland areas have been drained and reclaimed mainly for agriculture and establishment of human settlements. These threats to European wetlands persist. The main responses of European wetlands to ongoing climate change will vary according to wetland type and geographical location. Sea level rise will probably be the decisive factor affecting coastal wetlands, especially along the Atlantic coast. In the boreal part of Europe, increased temperatures will probably lead to increased annual evapotranspiration and lower organic matter accumulation in soil. The role of vast boreal wetlands as carbon sinks may thus be suppressed. In central and western Europe, the risk of floods may support the political will for ecosystem-unfriendly flood defence measures, which may threaten the hydrology of existing wetlands. Southern Europe will probably suffer most from water shortage, which may strengthen the competition for water resources between agriculture, industry and settlements on the one hand and nature conservancy, including wetland conservation, on the other.     

Characterizing supraglacial meltwater channel hydraulics on the Greenland Ice Sheet from in situ observations

Supraglacial rivers on the Greenland Ice Sheet (GrIS) transport large volumes of surface meltwater toward the ocean, yet have received relatively little direct research. This study presents field observations of channel width, depth, velocity, and water surface slope for nine supraglacial channels on the south‐western GrIS collected between July 23 and August 20, 2012. Field sites are located up to 74 km inland and span 494–1485 m elevation, and contain measured discharges larger than any previous in situ study: from 0.006 to 23.12 m³/s in channels 0.20 to 20.62 m wide. All channels were deeply incised with near vertical banks, and hydraulic geometry results indicate that supraglacial channels primarily accommodate greater discharges by increasing velocity. Smaller streams had steeper water surface slopes (0.74–8.83%) than typical in terrestrial settings, yielding correspondingly high velocities (0.40–2.60 m/s) and Froude numbers (0.45–3.11) with supercritical flow observed in 54% of measurements. Derived Manning's n values were larger and more variable than anticipated from channels of uniform substrate, ranging from 0.009 to 0.154 with a mean value of 0.035 ± 0.027 despite the absence of sediment, debris, or other roughness elements. Ubiquitous micro‐depressions in shallow sections of the channel bed may explain some of these roughness values. However, we find that other, unobserved sources of flow resistance likely contributed to these elevated Manning's n values: future work should explicitly consider additional sources of flow resistance beyond bed roughness in supraglacial channels. We conclude that hydraulic modeling for these channels must allow for both subcritical and supercritical flow, and most importantly must refrain from assuming that all ice‐substrate channels exhibit similar hydraulic behavior, especially for Froude numbers and Manning's n. Finally, this study highlights that further theoretical and empirical work on supraglacial channel hydraulics is necessary before broad scale understanding of ice sheet hydrology can be achieved. Copyright © 2016 John Wiley & Sons, Ltd.     

ESW在磁尾磁场重联耗散区分形线附近的观测特性及其作用

磁场重联是空间能量释放和转换的重要机制.静电孤立波(ESW)虽然在空间中有广泛观测,但在磁场重联附近少有直接观测,对它在磁场重联附近的特性了解甚少.通过Geotail卫星对一个磁场重联事件的观测,仔细分析了其边界层上观测到的静电孤立波的特性,并讨论了它对磁场重联的影响.研究表明,亚暴期间在磁尾发生磁场重联,重联区域的分形线附近观测到了大量的静电孤立波,其特性与在其他地方观测到的并没有显著差别,但具有更明显的非线性和孤立性的特征.它们对电子加速和能量耗散有促进作用,加速磁场重联的进程.     

基于COSMIC卫星观测数据的平流层重力波的全球分布特征研究

本文利用2007年1月至2012年12月的COSMIC卫星温度剖线,从中提取了垂直波长在3~10 km的重力波扰动信息,进而分析了全球平流层大气重力波的分布特征.赤道地区低平流层重力波表现出明显的准两年变化,这种变化与风场的准两年变化具有明显的相关性,向下发展速度约为1 km/月;赤道地区高平流层(35 km以上区域)的重力波活动则存在明显的半年变化.中高纬度重力波活动主要表现为冬季强夏季弱.在南极地区存在着与急流的时间、空间以及强度变化密切相关的重力波分布特征,这说明在南极极夜急流是非常重要的一个重力波源;而在北极极夜急流的作用则没有那么强.此外,通过考察不同高度的重力波活动特征,我们发现:30 km以下重力波活动较强区域主要在赤道地区且与强对流区分布基本吻合,地形诱发的以及与天气系统相关的强重力波活动在该高度范围内同样出现;而在30 km以上的区域重力波活动强度分布则会出现与平流层爆发性增温以及极夜急流有关的变化.