利用太阳耀斑的电离层效应确定低纬度D层顶一氧化氮浓度

通过氧鎓离子化学计算了一次强太阳耀斑扰动期间低纬度(28°38′N)D层顶NO浓度。该方法适用于O+₂离子化学生存时间较短且负离子浓度与正离子相比可以忽略的80至87.5公里高度。计算结果表明,它相当好地符合Meira的实验观测剖面,只是85公里处的最小值特别弱。      

Positive ion composition and electron density in a combined auroral and NLC event

The positive ion composition and electron density were measured in the lower ionosphere above Kiruna in salvo A of CAMP (Cold Arctic Mesopause Project). The CAMP/P (S37/P) payload carrying a magnetic ion spectrometer, positive ion and electron probes, and propagation experiments was launched on 3 August 1982 2332 UT during extended Noctilucent Clouds (NLC) and auroral activities over Kiruna. The measured electron density was 5×10³cm^?3 at 80 km and 2.5×10⁵cm^?3 at 90 km. The increase of ion and electron densities in the D- and E-region during twilight was caused by precipitating auroral particles. The height distribution of the positive ions measured by the mass spectrometer in the mass range 19–280 amu is different from a winter flight with similar auroral conditions. Below 85.5 km proton hydrates H⁺(H₂O)₃ ? H⁺(H₂O)₈ were the dominant ions. The heaviest proton hydrates H⁺(H₂O)₇ and H⁺(H₂O)₈ were most abundant at 82–85.5 km, the altitude of visible NLC. Above 85.5 km O₂⁺ and NO⁺ became dominant. A small metal ion layer was observed between 90.5–93 km with a maximum ion density of 10% of the total positive ion density at 91 km altitude. The metal ion density disappeared within about a km below 90.5 km.     

Mesospheric H2O and H2O2 densities inferred from in situ positive ion composition measurement

The measurements of positive ion composition in the high latitude D-region have revealed an excess of 34⁺ under distrubed conditions which has been interpreted as H₂O₂⁺. At the same altitude range near the transition height oxonium ions were measured as well. This paper presents a new model for the production and loss of oxonium ions with their production from H₂O₂⁺ + H₂O → H₃O⁺ + HO₂ and their loss by attachment of N₂ and/or CO₂. A reaction constant of 8.5×10^?28 (300/T)⁴ cm⁶s^?1 has been obtained for the three body attachment H₃O⁺ + CO₂ + M → H₃O⁺.CO₂ + M from the measured density profile of 63⁺ in flight 18.1020. Mesospheric H₂O and H₂O₂ densities are inferred from measurements of four high latitude ion compositions based on the oxonium model. The mixing ratios of hydrogen peroxide are up to two orders of magnitude higher compared to previous model calculations. In order to explain the missing production of odd hydrogen, we consider larger O(¹D) densities, surface reactions of O(³P) on particles, and cathalytic photodissociation of water vapor on aerosol particles.     

Venus atmospheric circulation: Observations and implications of the thermal structure

Continued analysis of Pioneer Venus imaging and polarimetry data indicates that the average cloud-top level circulation is mainly zonal (east to west) with a small meridional component. Presence of planetary scale waves and a possible sun-related component are evident in the data. If the tracked features refer to the same vertical level, then some variability of the circulation would have to be present to account for the Pioneer and Mariner 10 cloud-tracking results. However, the implied balanced flow from the observed thermal structure analysis strongly suggests that at least some of the variations in these observations is due to apparent cloud-top variations and that the circulation itself is relatively stable.Direct cyclostrophic calculations based on the observed thermal structure of the atmosphere yield a balanced zonal circulation with distinct mid-latitude jets (peak velocities about 110–120 ms^?1) located between 50 and 40 mb in each hemisphere of the planet near 45° latitude. The calculations which extend to about 40 km altitude from 80 km above the surface agree well with the observed entry probe zonal components and indicate breakdown of the balance condition near the upper and lower boundaries at low latitudes.The balanced flow results are consistent with the Mariner 10 and Pioneer cloud tracked estimates of the zonal circulation provided the effective altitude of the tracked features is slightly different at different observation periods. The features in the Pioneer Venus data would then lie on a sloping surface that extends from about 68 km (40 mb) at low latitudes to about 75 km (10 mb) in mid-latitudes. The polarization features would occur on a roughly parallel surface that is 1–2 km above the effective cloud-height surface, and Mariner 10 features would have effective altitudes somewhat lower than the Pioneer ultraviolet features. A slight asymmetry is evident in the balanced zonal circulation arising out of an asymmetry in the thermal field.Finally, the solenoids formed by intersecting isobaric and isosteric (constant specific volume) surfaces deduced from the Pioneer Venus radio occultation data show distinct evidence of a direct meridional circulation that may be important in sustaining the Venus atmospheric circulation.     

Hybrid quadri-ionic model of the lower ionosphere

An ion model of the lower ionosphere is proposed. It consists of four positive ions: O₂⁺, NO⁺ and two cluster ions - a simpler CI₁ and a more complex CI₂. This model well explains the normal component of the winter anomaly (WA) in the D-region, which is recorded by absorption measurements on short radiowaves and rocket experiments at middle (40°N) and high (70°) latitudes. The higher values of the electron density during the winter appear as a result of the lower recombination because of smaller rates of cluster ion formation, i.e. the normal WA can be explained and modelled by the regular seasonal variations of composition, temperature and density.     

Mass spectrometric measurements of stratospheric ions

Recent in situ measurements with balloon borne quadrupole mass spectrometers, between 20 and 45 km altitude, are reviewed and discussed.The major stratospheric positive ions observed are proton hydrates [H⁺(H₂O)_n] and non proton hydrates of the form H⁺X_m(H₂O)₂. The data analysis allows a derivation of the vertical mixing ratio profile of X (most probably CH₃CN), which is compared with recent model calculations. From negative ion composition data, showing the presence of NO₃^? and HSO₄^? cluster ions, the density of sulfuric acid in the stratosphere is deduced. The implications of these findings on our understanding of the sulfur chemistry is briefly treated.Finally some other aspects such as contamination, cluster break up and the use of stratospheric ion mass spectra for determination of thermochemical data and other minor constituents are discussed.     

Super rogue wave catalysis in Titan’s ionosphere

Super rogue ion-acoustic waves are proposed as a physical catalyst for the heavy hydrocarbon ions formation in the Titan ionosphere. We justified that analytically and numerically by probing a Titan referenced plasma system, consists of the most abundant positive ions and superthermal electrons. A solution of the nonlinear Schrödinger equation (NLSE) has provided us by the plasma (un) stable regions at altitude 900–1200 km from the Titan surface with superthermal parameter values, relative ion to electron densities, and temperature ratio variations. Our results are not only agreed with the Cassini data but also predict a chemistry independent approach for the heavy hydrocarbons’ formation conditions.     

Latitudinal influences on the quiet daytime D-region

Four versions of a steady-state quiet D-region model are presented. They differ from each other as a result of latitudinal differences in total neutral particle concentrations, nitric oxide concentrations and cosmic ray ionization rates. The total ion concentration profiles of all four versions have minima near 70 km which range from about 10⁸ m^?3 at high latitudes to 3.5 × 10⁷ m^?3 at equatorial latitudes for a solar zenith angle of 60°. Neutral density differences among the four cases result in important vertical shifts for the respective D-region profiles relative to one another. A “C-layer” is evident for the high and mild-latitude models at large solar zenith angles. The altitude where the negative ion/electron concentrations ratio is unity varies from about 63 to 67 km. The computed results are compared briefly with the extensive data base in the literature.     

Energetic particles in the night-time middle- and low-latitude ionosphere

Data are presented on the zones of energetic particle precipitation at middle and low latitudes observed during and after magnetic storm injection events. Satellite measurements of the equatorial zone ion flux (～ 10³ - 10⁴ cm^?2 s^?1 sr^?1 for E > 45 keV at 240 km) are consistent with the development of a temporary low altitude ion radiation belt at the magnetic equator. In the midlatitude ion zone the flux (～ 10³ - 10⁵ ions cm^?2 s^?1 sr^?1 for E > 45 keV at 220 km) is directly related to magnetic activity while the midlatitude electron zone flux has a delayed response (～ 4 days).     

Comprehensive investigation of the basic parameters of the upper atmosphere at the time of the flight of the geophysical rocket “vertical-6”

Ion temperature and total ion concentration measured on 25th October 1977 during the flight of the geophysical rocket “Vertical-6” are analyzed. The solar EUV fluxes determined in five wave-length bands with a photoelectron analyzer are also given. The observed anomalous variation of ion temperature between 700 and 900 km and the measured ion concentration can be explained, if the charge exchange reactions H⁺ ? O⁺ and diffusion are taken into account.     

Ion formation by high- and medium-velocities dust impacts from laboratory measurements and Halley results

The ion formation processes by dust impacts have been studied qualitatively as well as quantitatively by dust accelerator laboratory measurements. Iron, carbon and metallized glass particles in the femto- to nano-gram mass range had been impacted on various metal targets in a velocity regime of v = 2 - 64 km/s. In the high velocity regime as relevant for the (retrograde) Halley encounter more than 99% of the ions produced are singly charged atomic, the rest molecular ones. The ion/atom ratios are apparently modified SIMS yields, the modification parameter being impact velocity dependent. A semiempirical formula was deduced for the determination of mass and density of the impacting particle from target and projectile ion yields. When evaluating the Halley encounter results, the elemental distribution of p/Halley dust appeared nearly to be solar; the organic fraction (CHON) could be characterized in a rough manner as fairly unsaturated. Oligomers of the monomers C₂H₂ (65%), CH₂O (25%), and HCN (10%) are probable.

With medium velocities (for prograde comet encounter), i.e. v = 15-30 km/s molecular ion types govern the mass spectra. Consequently, more chemical information of the projectile can be expected in this case, additional to the elemental distribution. Mass and density of the impinging dust particles can be determined as well.     

Counterstreaming hydrogen and oxygen ions observed in the magnetosphere on ISEE-1

Counterstreaming ions or ions travelling simultaneously both parallel and antiparallel to the magnetic field direction have been briefly noted in the literature but have not been studied previously in depth. We have studied over 60 counterstreaming ion (CSI) events observed on the ISEE-1 satellite. They were found to occur at altitudes of about 2 to 8 Earth radii on L shells of about 5 to 12 in the evening-to-morning sector from about 1700 - 0900 LT. Often both oxygen and hydrogen ions at a number of energy levels are counterstreaming but some events show only either oxygen or hydrogen ions involved. One particularly interesting event shows only counterstreaming oxygen ions with 417 eV energy; oxygen ions of lower energy (215 eV) and above (630–17000 eV) and all the hydrogen ions between 215–17000 eV energy have lower fluxes and/or nearly isotropic pitch angle distributions. This event correlates well with wave activity in the 17–100 Hz band and is also accompanied by 200 eV downgoing and 400 eV upgoing electrons. Details of this event and the other counterstreaming events are presented.     

平流层上部负离子成分的直接测量和硫酸离子热化学分析

本文报道了在法国南部(44°N)上空进行的两次气球飞行实验的部分负离子成分探测结果.利用自然负离子谱计算了某些硫酸离子的热化学常数ΔG, ΔH和ΔS.讨论了上升段测量中气球表面放气造成的离子化学污染.      

Photoionization balance and ion composition model in the equatorial D-region over Thumba

Positive and negative ion profiles, together with the λ-profile (ratio of negative ions to electrons), have been derived for Thumba (8°54′N) for noon conditions and for the height range 50–90 km, using the latest available input parameters.     

Recent results on the Venus atmosphere from pioneer Venus radio occultations

Radio occultation measurements of the temperature structure of the Venus atmosphere have been obtained during seven occultation “seasons” extending from December 1978 to December 1983. Approximately 123 vertical profiles of temperature from about 40 km to about 85 km altitudes have been derived. Since these measurements cover latitudes from both poles to the equator, they have shown the latitudinal dependence of thermal structure. There is a smooth transition from the troposphere to the mesosphere at latitudes below about 45°, with the tropopause at about 56 km. The troposphere then rises to about 62 km in the “collar cloud” region between about 60° and 80° latitude, where a strong temperature inversion (up to 30 K) is present. In the polar areas, 80°–90°, the mesosphere becomes isothermal and there is no inversion. This latitudinal behavior is related to the persistent circulation pattern, in which a predominantly zonal retrograde motion at latitudes below 45° gradually changes to a circumpolar vortex at the “collar cloud” latitudes. Indeed, the radio occultation data have been used in a cyclostrophic balance model to derive zonal winds in the Venus atmosphere, which showed a mid-latitude (50°–55°) jet with a speed of about 120–140 ms^?1 at about 70 km altitude /1,2/. The observations obtained in 1983 and 1984 have shown that above the tropopause there is considerable temporal variability in the detailed thermal structure, suggesting that the persistent circulation pattern is subject to weather-like variability.     

IR-spectroscopy of ionosphere from stratospheric balloons

The radiation spectra of the ionosphere in the 4–5 μm region have been determined from stratospheric balloons by means of the specially elaborated method of the registration of angular and spectral distribution of the radiation. The radiation bands of 4.4 μm and 4.8 μm which have 0.1–0.2 erg cm^?2 sr^?1s^?1. brightness obtained in two flights, are identified with the vibration-rotation transitions of the ion NO⁺ (0 - 1) and the molecules N¹⁴N¹⁵ (0 - 1) and CO (0 - 1) and (3 - 2) from altitudes between 120 and 500 km.     

Mesospheric ionisation over dip equator at sunrise

The electron density profile in the equatorial mesosphere was measured during sunrise time over Thumba(dip lat= 0.6°S). The measurements were carried out in the altitude range 60 to 100 km using rocketborne probes. A sharp layer of ionisation was observed around 80 km with electron density about 10⁸m^?3. It is suggested that hydrated ions are the main constituents of this layer.     

中层大气钠层的流星蒸发模式

本文计算了地球中层大气的钠层模式。在此模式中,流星蒸发是形成钠层的源而尘埃的吸附足汇。本文考虑和比较了有关钠层形成机制的已往工作中所出现过的所有光化学反应,选出了四十个合理而重要的化学反应作为本模式的化学基础。模式也考虑进了高度变化的涡流扩散和带电粒子受地磁场作用的向下飘移等机制。本文对各化学反应和模式中各个因素的重要性作了比较和评价。本文计算结果表明,在各高度上中层大气中的钠及其化合物的相对浓度主要取决于化学反应过程本身,与源、汇及各层间扩散机制等关系不大。虽然在钠层模式计算中必须考虑到十种钠成分,但105公里以上主要成分足钠离子(Na+)。80公里以下主要成分是氢氧化钠(NaOH)。80公里到105公里间主要成分是中性钠原子(Na)。所有成分的总浓度主要地取决于源和汇随高度的分布。大气背景及电离常数的变化可以引起钠层相当显著的季变化和周日变化。理论计算结果与历年来的观测结果作比较后可以看到两者大体上符合得相当好。      

Modulation of dayside ion and neutral distributions at Venus: Evidence of direct and indirect solar energy inputs

In-situ measurements of ion and neutral composition and temperature across the dayside of Venus during 1979–1980 exhibit long and short-term changes attributed to solar variations. Following solar maximum, dayside concentrations of CO⁺ and the neutral gas temperature are relatively smoothly modulated with a 28-day cycle reasonably matching that of the solar F_10.7 and EUV fluxes. Measurements some 6–8 months earlier show less pronounced and more irregular modulation, and short-term day-to-day fluctuations in the ions and neutrals are relatively more conspicuous than in the later period. During the earlier period, the solar wind at Venu exhibits relatively large velocity enhancements, which appear to be consistent with differences in solar coronal behavior during the two periods. It is suggested that through the solar wind variations and associated changes in the draping of the interplanetary magnetic field about the dayside, fluctuating patterns of joule heating may occur, producing the observed short term ion and neutral variations. This indirect energy effect, if verified, presents a complication for quantitatively analyzing the modulation in neutral temperature and ion concentration produced by changes in direct EUV radiation.     

Empirical model of the composition of the Venus ionosphere: Repeatable characteristics and key features not modeled

In-situ measurements of positive ion composition of the ionosphere of Venus are combined in an empirical model which is a key element for the Venus International Reference Atmosphere (VIRA) model. The ion data are obtained from the Pioneer Venus Orbiter Ion Mass Spectrometer (OIMS) which obtained daily measurements beginning in December 1978 and extending to July 1980 when the uncontrolled rise of satellite periapsis height precluded further measurements in the main body of the ionosphere. For this period, measurements of 12 ion species are sorted into altitude and local time bins with altitude extending from 150 to 1000 km. The model results exhibit the appreciable nightside ionosphere found at Venus, the dominance of atomic oxygen ions in the dayside upper ionosphere and the increase in prominence of atomic oxygen and deuterium ions on the nightside. Short term variations, such as the abrupt changes observed in the ionopause, cannot be represented in the model.