Distribution of ionospheric O<Superscript>+</Superscript> ion in synchronous altitude region

Based on satellite observation data, using dynamics equation, the ionospheric O⁺ ion’s distribution in the synchronous altitude region for different geomagnetic activity indexK _p is studied by theoretical modeling and numerical analyzing, and semi-empirical models for the O⁺ ion’s density and flux versus longitude in the synchronous altitude region for differentK _p are given. The main results show that in the synchronous altitude region: (i) The O⁺ ion’s density and flux in day-side are larger than those in nightside. (ii) With longitude changing, the higher the geomagnetic activity indexK _p is, the higher the O⁺ ion’s density and flux, and their variation amplitude will be. The O⁺ ion’s density and flux whenK _{p ≥} 6 will be about ten times as great as that whenK _p = 0. (iii) WhenK _p = 0 orK _{p ≥} 6, the O⁺ ion’s density reaches maximum at longitudes 120° and 240° respectively, and minimum in the magnetotail. WhenK _p = 3−5, the O⁺ ion’s density gets to maximum at longitude 0°, and minimum in the magnetotail. However, the O⁺ ion’s flux reaches maximum at longitude 120° and 240° respectively, and minimum in the magnetotail for anyK _p value.     

电离层电导对地球磁层顶和舷激波尺度的影响

本文在如下假定下分析电离层电导对地球磁层顶和舷激波尺度的影响：（1）对电离层采用球壳近似,Pedersen电导ΣP均匀,Hall电导为零;（2）地磁偶极矩处于正南方向,行星际磁场（IMF）只有南向分量（BzBz和ΣP,通过三维全球MHD模拟获得系统的准定态.结果表明,在大约1～5 S范围内,ΣP值显著影响磁层顶和舷激波的尺度,而在该范围之外则几乎没有影响.随着ΣP的增加,磁层顶和舷激波整体向外扩张,前者的扩张程度低于后者,以至磁鞘区的范围扩大.磁层顶的侧翼点的位置随ΣP的变化与Bz的幅度有关：在弱南向IMF情况下磁层顶的侧翼点随ΣP的增加向内移动,而在强南向IMF情况下则向外移动.上述结果表明,在构建磁层顶和舷激波的经验模型时,有必要计入电离层电导的影响.     

The plasmasphere and advances in plasmaspheric research

A review is made of recent major advances in plasmaspheric research; important results have emerged from those concerning a variety of plasmasphere features. Both experiments and modeling efforts have progressed. A number of unknowns still persist, however, but research is underway toward their clarification. These clarifications are essential for obtaining a predictive capability of the near-Earth space weather in the plasmasphere region.     

水星内磁层等离子体带及电流体系

水星是太阳系中离主星最近的和最小的类地行星, 它具有独特的空间环境.水手10号(Mariner 10)确认水星拥有全球性内禀偶极磁场和磁层.但是由于早期观测有限, 人们通常将水星磁层简单地视作地球磁层的缩小版来研究.不过, 在信使号(MESSENGER)访问水星之后, 人们认识到水星和地球的空间环境有巨大差异.通过更深入的分析研究, 人们发现在水星内磁层中, 夜侧磁赤道面附近有带状的等离子体分布, 并且该等离子体带可能与多种磁层电流体系(分叉环电流、亚暴电流楔和东向电流等)密切相关.在贝彼哥伦布(BepiColombo)计划揭开水星研究的新篇章之际, 本文回顾近些年来与水星内磁层等离子体带及相关电流体系有关的研究, 并指出相关研究将是未来水星空间环境的前沿热点.

     

Asymmetric distribution of the ionospheric electric potential in the opposite hemispheres as inferred from the SuperDARN observations and FAC-based convection model

We compare the SuperDARN convection patterns with the predictions of a new numerical model of the global distribution of ionospheric electric potentials. The model utilizes high-precision statistical maps of field-aligned currents (FAC) derived from measurements made by polar-orbiting low-altitude satellites. Both the solar and auroral precipitation contributions are included in order to derive the ionospheric conductance. Taking into account the electrodynamic coupling of the opposite hemispheres, the model allows one to obtain the convection patterns developed simultaneously in both hemispheres for given input parameters. SuperDARN, with its database containing global northern and southern convection maps, provides the unique opportunity to compare the model predictions of electric fields with observations. In the present study we focus on the effect of significant interhemispheric asymmetry governed by the IMF clock angle and solar zenith angle. We calculate the convection patterns for specific cases caused by the sign of B_Y and season and demonstrate the capability of the FAC-based model reproduce the radar observations. The simulation confirms that the solar zenith angle should be linked to the IMF clock angle to fully characterize the convection patterns. The model predicts that the cross-polar cap potential drop is regularly larger in the winter hemisphere than in the summer hemisphere.     

Characteristics and quantitative of negative ion in salt aqueous solution by Raman spectroscopy at ?170°C

The results from Raman spectroscopy analysis of salt aqueous solutions at −170°C demonstrate that for those clearly sharp iron peaks whose Raman wavenumber is close to each other such as NO ₃ ⁻ and CO ₃ ²⁻ , their original shape could be restorable by the stripping technique, and that ice’s sharp characteristic peak 3090–3109 cm⁻¹) is steady, while the spectrum band of the complex compound (nCl⁻-[H⁺-OH⁻]_n) chlorine ion combined chemically with water molecule is 3401–3413 cm⁻¹. On the other hand, the research shows that the higher the negative iron concentration, the stronger its Raman characteristic peak intensity and the smaller the ice’s. Based on the number of data and theoretical work, the strong correlation of the molar concentration of negative ion with the S _i/S _{H 2}O band area ratio is built up. Moreover, the developed Raman method is successfully used in the component analysis of the field fluid inclusions from Silurian sandstone in Tarim basin.     

Net, actual, and potential sediment-water interface NH4 fluxes in the northern Gulf of Mexico (NGOMEX): Evidence for NH4 limitation of microbial dynamics

A new approach, combining ¹⁵NH₄⁺ isotope dilution and continuous-flow techniques, provided estimates of “actual” and “net” NH₄⁺ flux and sediment NH₄⁺ demand (SAD) at the sediment-water interface (SWI) of sites in the northern Gulf of Mexico (NGOMEX). The sites included a hypoxic site (C6), two sites with intermediate oxygen levels (B7 and F5), and a normoxic site (CT). Control cores without isotope addition and other cores from the same site treated with ¹⁵NH₄⁺ labeled overflowing water differentiated between net and actual regeneration flux and actual vs. potential uptake flux of NH₄⁺. Experiments were conducted in 2008 before (July) and after (September) two successive hurricanes (Gustav and Ike) and in January and August, 2009. Actual regeneration was significantly higher than net flux at most sites. Net flux did not differ significantly in most sites/dates, but the actual regeneration, and the actual and potential uptake, showed temporal and spatial variation; the flux at the hypoxic site was more active than non-hypoxic sites. SAD, the difference between potential and actual NH₄⁺ uptake flux, was higher at the hypoxic site than at non-hypoxic sites before and after the hurricanes in 2008 and during the hypoxia season in 2009. SAD related negatively to bottom water DO values. Conclusions: (1) net flux often underestimated actual regeneration, (2) hurricane activity decreased N dynamics, and (3) microbial N limitation status at the hypoxic site related to NH₄⁺ removal processes that were independent of oxygen (e.g., anaerobic heterotrophic uptake or anammox). These results indicate a rather consistent NH₄⁺ demand at the SWI during the hypoxic season and suggest that reduced nitrogen may limit microbial dynamics in the region.     

The impact of temporal ionospheric gradients in Northern Europe on relative GPS positioning

The effect of temporal ionospheric gradients on measured baselines was studied at mid and high latitudes. The experimental analysis was carried out from 14 to 17 July 2000 (day of year (DOY) from 196 to 199), which includes both quiet and stormy days for comparison purposes. Temporal ionospheric gradients caused by the geomagnetic storm affect the ambiguity resolution, resulting in unresolved ambiguities up to 61% for the time periods 21:00–24:00 UT on DOY 197 and 00:00–03:00 UT on DOY 198 for the Kiru-Soda and Kiru-Tro1 baselines (high-latitude, K_p>7). RMS of epoch by epoch coordinate residual change gradually increases from 1.45, 0.96 and 3.67 cm at 9:00–12:00 UT on DOY 197 to 1.79, 1.22 and 4.61 cm at 0:00–03:00 UT on DOY 198 (K_p>8) for the same baselines’ north, east and up coordinate components, respectively. There are no remarkable effects for the selected baselines in the mid-latitude region in both ambiguities and coordinate components.     

Morphological changes in branchial mitochondria-rich cells of the teleost Paralichthys olivaceus as a potential indicator of CO2 impacts

We studied the morphological and biochemical changes of mitochondria-rich cells (MRCs) of a demersal teleost, Paralichthys olivaceus, during exposure to 0.98, 2.97 and 4.95 kPa pCO₂. The apical opening area of MRCs increased 2.2 and 4.1 times by 24 h exposure to 2.97 and 4.95 kPa pCO₂, respectively, while the cross-sectional area or density of MRCs did not change. Gill Na⁺/K⁺-ATPase activity more than doubled at 72 h and then returned to the pre-exposure level at 168 h in 0.98 kPa pCO₂, while it increased 1.7 times at 24 h at 4.95 kPa. These results indicate that the apical opening area of MRCs and the gill Na⁺/K⁺-ATPase activity may be used as an indicator of acute (up to 72 h), but not chronic, impacts of high (>1 kPa) seawater CO₂ conditions in P. olivacues. Limitations of those parameters as indices of CO₂ impacts are discussed.     

Modern (<100 years) sedimentation in the Taiwan Strait: Rates and source-to-sink pathways elucidated from radionuclides and particle size distribution

A large number of sediment cores collected during 2005-2010 from the Taiwan Strait were analyzed for radionuclides (²¹⁰Pb, ¹³⁷Cs and ⁷Be) to elucidate sedimentation dynamics in this all-important gateway linking two largest marginal seas in the western Pacific (namely, the South China Sea and the East China Sea). Apparent sediment accumulation rates derived from ²¹⁰Pb and ¹³⁷Cs profiles vary from <0.1 to >2 cm/yr, averaging ∼0.4 cm/yr and showing a spatial pattern closely related to hydrodynamics and sediment source-to-sink pathways. Spatial-temporal variation of ⁷Be activity in surface sediments off Taiwan’s west coast indicates episodic deposition of flood layers and their mobility from river estuaries toward the north. In conjunction with particle size distribution in surface sediments and the structure of sediment strata revealed by sub-bottom echo images; the radionuclide data can be used to outline three different sediment source-to-sink dispersal systems. Based on sediment loads of surrounding rivers and the distribution of sediment accumulation rates, lateral transport is required to account for the budget and size distribution of sediments in the strait.     

青海湖泉湾镭同位素的空间分布与沿岸地下水排放评价

青海湖是青藏高原的重要组成部分,它是维系青藏高原东北部生态安全的重要水体.其沿岸地下水的排放直接影响了青海湖的水文生物地球化学过程,然而对该问题的研究仍然不充分.本研究于2014年对青海湖泉湾湖水、河水和地下水进行223Ra和224Ra活度的测定分析,并对泉湾湖水水平向和垂直向的Ra活度分布进行深入分析,最后估算并探讨了泉湾水体的停留时间和布哈河口沿岸地下水的排放通量.表层湖水、河水、地下水不同端元的水体223Ra和224Ra活度值分别为0.441和0.026 dpm/100 L、0.22和0.016 dpm/100 L以及0.061和1.30 dpm/100 L,最高值为地下水,其次湖水,河水最小;总体上泉湾湖水223Ra和224Ra活度随离岸距离增加分别由0.047到0.011 dpm/100 L和1.4到0.2 dpm/100 L的减小,垂向上Ra活度呈楔形分布,Ra活度在不同方向上的非保守性分布主要受到悬浮颗粒物解析的影响;通过水体滞留时间模型计算获得青海湖泉湾水体的平均停留时间为1.8天,进一步分析泉湾水体Ra的源汇项,应用镭同位素质量平衡模型获得泉湾布哈河口沿岸地下水排放通量为0.054～0.109 m3/(m2·d).     

基于Van Allen Probes EMFISIS波动仪器观测的内磁层上频带哨声合声波全球分布的统计分析

基于Van Allen Probes近三年的EMFISIS仪器波动观测数据,针对内磁层上频带哨声模合声波幅度的全球分布特性对地磁活动水平的依赖性进行了详细的统计分析,着重研究上频带合声波平均场强幅度随磁壳值（L）、磁地方时（MLT）、地磁纬度（MLAT）的分布特征及不同强度区间的合声波的发生概率.结果表明,上频带合声波的平均场强幅度与地磁活动条件密切相关,在强磁扰期,平均幅度可达到40 pT以上.在外辐射带中心区域（L=4~6）,上频带合声波的幅度最强;在L＜~3的区域,上频带磁层合声波没有分布.在夜侧至晨侧（22-09MLT）,上频带合声波幅度最强;在下午侧至昏侧（15-19MLT）,上频带合声波幅度最弱;日侧（10-14MLT）上频带合声波在不同地磁活动条件下都存在,幅度偏小.上频带合声波主要分布在|MLAT| < 10°,其中21-09MLT范围内、磁纬位于|MLAT| < 5°的平均场强幅度最强,磁扰期间可达约100 pT.另外,统计而言,中等幅度（10~30 pT）的上频带合声波在夜侧至晨侧（23-09MLT）靠近磁赤道区域的发生率最高,可达15%左右.强幅度（>30 pT）的上频带合声波普遍分布在夜侧（01-05MLT）,发生率最小.本文建立的上频带哨声模合声波的全球分布模型结合已经建立的下频带合声波的全球分布模型,将有助于进一步深入理解该重要磁层等离子体波动对地球等离子体片、辐射带、环电流动力学过程的定量贡献.

     

曝气充氧对城市污染河道内源铵态氮释放的控制

以城市污染河道沉积物和上覆水为研究对象,利用模拟实验方法,探讨不同曝气充氧方式(水曝气EW、底泥曝气ES)对污染河道內源铵态氮(NH4+-N)释放的影响.研究结果发现:从间隙水和沉积物中NH4+-N的削减效果来看,底泥曝气均要优于水曝气;实验结束后,底泥曝气组沉积物与间隙水中NH4+-N含量分别减少63.39%和43.33%,水曝气组分别减少了7.54%和13.98%;从沉积物-水界面NH4+-N的扩散通量变化来看,水曝气组界面通量高于对照组,其变化规律与对照组相似;底泥曝气组沉积物-水界面NH4+-N扩散通量变化过程完全不同于其它两组,在整个试验周期内(除第5 d以外),底泥曝气组的通量低于水曝气组,在第15 d最低,为13.73 mg/(m2.d),仅为水曝气组和对照组的14.68%和19.93%,表明底泥曝气组沉积物NH4+-N的释放潜力低于水曝气组沉积物.     

SuperDARN: An example of a network approach to geospace science in the twenty-first century

The study of Earth's space environment, or geospace, has made considerable advances in the 50 years since the start of the Space Age, which was coincident with the 1957 International Geophysical Year. Space probes have visited most parts of that environment providing a wealth of in situ and remote-sensing measurements. Equally important in contributing to the advances made over the last 50 years have been the many instruments, which have been distributed on the surface of the Earth. In particular, the development of networks for the specific purpose of studying the dynamics of geospace, energy redistribution within geospace, and fundamental physical processes in plasmas has been hugely successful. Ground-based instruments remotely sense processes and phenomena in geospace and since this volume is large, networks of such instruments are the best way of measuring the global state of geospace and its dynamics. In this paper, I describe ways in which the Super Dual Auroral Radar Network (SuperDARN) has contributed to the success of ground-based networks, concentrating on science results, which have required the network approach so well demonstrated by SuperDARN. Such science includes the remote sensing of the reconnection electric field and its dynamics, the study of processes where asymmetries in the geospace system are induced by the external driving forces, and MHD waves, which play an important role in the transfer of energy and momentum within geospace. In addition, I discuss open science questions, which can be addressed by SuperDARN in the future, in particular in conjunction with current and future space missions as well as other ground-based networks.     

Diagnosing the effective parameters of the ionospheric fine structure from statistical characteristics of radio waves in the vicinity of a regular caustic

This paper is concerned with the oblique propagation of decametric radio waves in the ionosphere with random electron density irregularities. Effective parameters are introduced for calculating the influence of irregularities on the wave field structure. A technique is proposed for determining these parameters from measurements of statistical characteristics of the signal in the vicinity of a regular caustic. The technique uses asymptotic expressions obtained using the interference integral method and perturbation theory, as well as matching them to the numerical solution on the basis of the method of characteristics. A global semi-empirical model that is updated for current ionospheric conditions is used to specify the background medium. The proposed technique has been tested using data from a number of mid-latitude paths. Results obtained in this study testify that the technique deserves a practical implementation.     

Free cupric ion concentrations and Cu complexation in selected Swiss lakes and rivers

[Cu²⁺] and Cu complexation parameters in some selected freshwater systems in Switzerland were determined by the technique of ligand-exchange and DPCSV. Results from the water columns of some eutrophic and oligotrophic lakes are presented and compared to small acid lakes. Cu is strongly complexed by organic ligands which with very high stability constants at low concentrations are probably biologically produced, as indicated by the seasonal variations in the eutrophic lakes and by the relationship between Cu complexation and algal activity in the eutrophic (pCu=15–16), oligotrophic (pCu=13–14) and acidic (pCu=9–10) lakes. The extent of Cu complexation in river waters was generally lower than in the eutrophic lakes, at similar DOC levels. No obvious correlation between Cu complexation and DOC was observed, indicating that Cu complexing ligands are specific organic compounds.     

Concentration and distribution of 210Po in the tissues of the scallop Chlamys varia and the mussel Mytilus edulis from the coasts of Charente-Maritime (France)

Polonium-210 (210Po) has been analysed in the soft parts of two bivalves species, the scallop Chlamys varia and the common mussel Mytilus edulis, from the Bay of La Rochelle and Ré Island, on the French Atlantic coast. Between those sites, the highest 210Po concentrations have been found in whole scallop soft parts from La Rochelle, reaching 1,181 +/- 29 Bq kg(-1) dry weight (dwt), a size effect being related to the highest 210Po concentration in the smallest scallops. The results show a significant difference in concentrations for similar size individuals between species in each site (C. varia > M. edulis) and between sites for each species (Ré Island > Bay of La Rochelle). Very high 210Po concentrations have been found in the digestive gland of C varia, ranging 3,150-4,637 Bq kg(-1) dwt. Thus, the digestive gland contains up to 60% of the radionuclide. Subcellular investigations have shown that approximately 40% of the 210Po contained in the digestive gland is in the cytosolic fraction, suggesting a high bioavailability of the 210Po from this fraction to the trophic upper level. Calculations will show that approximately 4 kg of scallops flesh intake would be necessary to reach the annual incorporation limit of 1 mSv.     

A large excess of 210Po in the overlying water of the Zhubi Coral Reef flat, in the South China Sea

The temporal variability of ²¹⁰Po and ²¹⁰Pb was examined in the overlying water of the Zhubi Coral Reef flat to detect nutrient-like behavior of ²¹⁰Po. Different mechanisms influencing their geochemical behaviors were observed. Excess ²¹⁰Po relative to ²¹⁰Pb revealed an additional input of ²¹⁰Po other than in situ production from ²¹⁰Pb. The ²¹⁰Po input comes from the reef flat sediment through diffusion. The diffusion contributes 62% of the total ²¹⁰Po. This diffusion of ²¹⁰Po directly highlights its nutrient-like behavior. No input, but the slight removal, of ²¹⁰Pb was observed. Fractionation factors indicate that particulate matter prefers to adsorb ²¹⁰Po rather than ²¹⁰Pb. In combination with particulate composition, ²¹⁰Po diffusion was closely related to organic matter. These results reveal that ²¹⁰Po might be a potential tracer for quantifying nutrient recycling in the Coral Reef system.     

Letter to the editor The ionospheric response during an interval of Pc5 ULF wave activity

A preliminary analysis of Pc5, ULF wave activity observed with the IMAGE magnetometer array and the EISCAT UHF radar in the post midnight sector indicates that such waves can be caused by the modulation of the ionospheric conductivity as well as the wave electric field. An observed Pc5 pulsation is divided into three separate intervals based upon the EISCAT data. In the first and third, the Pc5 waves are observed only in the measured electron density between 90 and 112 km and maxima in the electron density at these altitudes are attributed to pulsed precipitation of electrons with energies up to 40 keV which result in the height integrated Hall conductivity being pulsed between 10 and 50 S. In the second interval, the Pc5 wave is observed in the F-region ion temperature, electron density and electron temperature but not in the D and E region electron densities. The analysis suggests that the wave during this interval is a coupled Alfven and compressional mode.