Upper atmospheric temperatures from Doppler line widths—V. Auroral electron energy spectra and fluxes deduced from the 5577 and 6300 Å atomic oxygen emissions     

H.H. Zwick  G.G. Shepherd 《Planetary and Space Science》1973,21(4):605-621

This is a report upon further data obtained from the auroral OI 5577 Å emission with a Wide Angle Michelson Interferometer (WAMI), and upon our first observations made with it on the 6300 Å emission. The method used for converting emission intensities and temperatures to auroral electron fluxes and energy spectra is described. Data for the 5577 Å emission are presented for the (lack of) heating in auroral forms, vertical temperature profiles in aurora, electron flux and energy spectrum variations in pulsating aurora, and a ‘cold’ subvisual auroral arc. Data from the OI 6300 Å emission are presented for the diurnal variation of exospheric temperature and for the thermalization of $\text{O}\text{(}{}^1\text{D)}$ in the F-region.  相似文献   

Auroral implications of recent measurements on O(1S) and O(1S) formation in the reaction of N+ with O2     

Andrew O. Langford  Veronica M. Bierbaum  Stephen R. Leone 《Planetary and Space Science》1985,33(10):1225-1228

Recent flowing afterglow measurements have shown that the reaction of N⁺ with O₂ produces 70 ± 30% of the oxygen atom product as $\text{O}\text{(}{}^1\text{D}\text{)}$ and < 0.1% as $\text{O}\text{(}{}^1\text{S}\text{)}$. These results indicate that this reaction does not contribute to the auroral green line emission (5577 Å), but can account for ～10% of the observed red line (6300 Å) auroral emission.  相似文献   

Auroral recombination of N and O: A possible source for emission in the γ and δ bands of NO     

Steven C. Wofsy  Michael B. McElroy 《Planetary and Space Science》1977,25(11):1021-1026

Radiative recombination of N and O provides a significant source for auroral emission in the γ and δ bands of NO with selective population of vibrational levels in the A²Σ⁺ and C²Π states. This mechanism may account for emissions detected near 2150 Å. Models are derived for the auroral ionosphere and include estimates for the concentrations of N and NO. The concentration of NO is estimated to have a value of about 10⁸ cm^?1 near 140 km in an IBC III aurora. The corresponding density for N is about 5 × 10⁷cm^?3 and the concentration ratio $\text{NO}{}^{\mathrm{+}}\text{O}{}_2{}^{\mathrm{+}}$ has a value of about 5.5.  相似文献   

Contamination of ground-based measurements of OI (6300 Å) and NI (5200 Å) airglow by OH emissions     

R.G. Burnside  J.W. Meriwether  M.R. Torr 《Planetary and Space Science》1977,25(10):985-988

High resolution spectra of the 6300 Å and 5200 Å regions of the night sky have been obtained using a 1 m spectrometer. Typical errors in measurements of $\text{O}\text{(}{}^1\text{D}\text{)}$ 6300 Å and $\text{N}\text{(}{}^2\text{D}\text{)}$ 5200 Å intensities due to contanimation by overlapping OH emissions have been calculated for a fixed-filter photometer, a tilting-filter photometer and a spectrophotometer. The importance of careful selection of certain instrumental parameters in order to minimize measurement errors is emphasized.  相似文献   

The problem of auroral NO+ concentration and the intensity of 1·27μ bands of O2     

S.S. Prasad  D.R. Furman  A.E.S. Green 《Planetary and Space Science》1975,23(9):1341-1343

The problem of the theoretical computation of the emission intensities and ion composition in a weak aurora which has been preceded by a stronger event is examined. For this purpose a model auroral precipitation consisting of biexponential primaries is considered. The softer of the two components is brighter, and begins to decay after remaining steady for ten to fifteen minutes. The other, harder component starts to build up at that instant. Our results suggest that at least a part of the high $\text{n(}\text{NO}{}^{\mathrm{+}}\text{)}\text{n(}\text{O}{}_2{}^{\mathrm{+}}\text{)}\text{or}\text{I}\text{(1·27 μ)}\text{I}\text{(3914}\text{A}\text{?}\text{)}$ ratios could be attributed to the retention, by the atmosphere, of the memory of previous auroral precipitations. Thus, the serious energy paradox in the context of 1·27 μ intensity need not arise, and, in the context of the large NO⁺ density, it may perhaps be unnecessary to invoke any major conversion of O₂ to NO thus avoiding the associated energy problem.  相似文献   

A global study of $\text{O}{}_2\text{(}{}^1\text{Δ}{}_{\mathrm{g}}\text{)}$ airglow: Day and twilight     

J.F. Noxon 《Planetary and Space Science》1982,30(6):545-557

Aircraft measurements of $\text{O}{}_2\text{(}{}^1\text{Δ}{}_{\mathrm{g}}\text{)}$ emission made over a 10-yr period provide information on the variation of ozone with latitude and season in the altitude region 50–90 km. Between 50 and 70 km there appears to be little variation (< ± 25%) whereas the abundance between 80 and 90 km exhibits a large seasonal change north of 30°N and much less at lower latitude. At mid and high latitude the column abundance above ～ 80 km changes from ? 1 × 10¹⁴ cm^?2 in summer to about 3 × 10¹⁴ cm^?2 in winter. There are occasional enhancements in both the day and twilight airglow which almost always occur in association with auroral activity or, at least, where such activity is statistically most likely. These enhancements appear to reflect a corresponding increase in the ozone mixing ratio in the upper stratosphere. While the gradient in ozone mixing ratio with latitude is generally small at altitudes between 50 and 90km there are occasions when a temporary latitude structure can be seen, particularly above 80 km.  相似文献   

A statistical study on Psc 4 and Psc 5 observed by geostationary satellites     

H. Nagano  T. Araki 《Planetary and Space Science》1985,33(4):365-372

Using magnetic data from the geostationary satellites of ATS 6 and SMS/GOES series, long-period geomagnetic pulsations, Psc 4 and Psc 5, associated with geomagnetic sudden commencements (SC's) were statistically analyzed. Local time and geomagnetic latitude dependence of the occurrence, and local time dependence of the period and the amplitude were examined for 218 SC's. For transverse Psc 5 pulsations which could be observed at all local times, the period was shorter and the amplitude was smaller near noon than in the morning and evening sides. Compressional Psc 5's, which were observed mainly from about 09.00 L.T. to midnight, had larger amplitude near noon. The period seemed to be longer near noon. As for Psc 4 pulsations the period tended to be shorter near noon. Psc 4's with the largest amplitude appeared near noon, but on the whole Psc 4's in the evening side had larger amplitude. The compressional Psc occurred more frequently near the geomagnetic equator (geomagnetic latitude $\text{φ}{}_{\mathrm{m}}\text{≌ 5°}\text{N}$) than at higher latitude ($\text{φ}{}_{\mathrm{m}}\text{≌ 9° ~ 12°}\text{N}$). We suggest that the transverse Psc 5 pulsations can be considered to be magnetic field-line resonant oscillations excited by impulsive waves, while the compressional Psc 5's may be oscillations localized near the geomagnetic equator.  相似文献   

An indirect mechanism for the production of O(¹S) in the aurora     

B.H. Solheim  E.J. Llewellyn 《Planetary and Space Science》1979,27(4):473-479

Recent laboratory measurements of the deactivation rate constants for O(¹S) have suggested that the dominant production mechanism for the green line in the nightglow is a two-step process. A similar mechanism involving energy transfer from an excited state of molecular oxygen is considered as a potential source of the OI (5577 Å) emission in the aurora. It is shown that the mechanism, $\text{O}{}_2\text{+ e → O}{}_2{}^1\text{+ e O}{}_2{}^1\text{+ O → O}{}_2\text{+ O(}{}^1\text{S}\text{)}$, is consistent with auroral observations; the intermediate excited state has been tentatively identified as the O₂(c¹∑^?_u) state. For the proposed energy transfer mechanism to be the primary source of the auroral green line, the peak electron impact cross-section for O₂¹ production must be approximately 2 × 10^?17 cm².  相似文献   

Observations and interpretation of spectra and rapid time variations of type-B aurora     

R.L. Gattinger  A.Vallance Jones 《Planetary and Space Science》1979,27(2):169-181

Observations of type-B red and normal aurora were made with a high-speed multichannel photometer and a digital grating spectrometer. The ratio $\text{I}\text{(}\text{O}{}_2{}^{\mathrm{+}}\text{1N; 2, 0 + 3, 1)}\text{I}\text{(}\text{N}{}_2{}^{\mathrm{+}}\text{1N; 0, 3)}$ measured in the 5200–5300 Å region with the spectrometer was found to increase by about 16% from normal to type-B aurora. This small change is difficult to reconcile with a height below 90 km for the red border. In the type-B aurora, λ 5577 was weakened by a factor between 1.9 and 3.8 while the ratio $\text{I}\text{(}\text{N}{}_2\text{1P; 5, 2)}\text{I}\text{(}\text{N}{}_2{}^{\mathrm{+}}\text{1N)}$ was enhanced less than 20%. Rapid intensity variations in the type-B lower border were observed in the λ 5577 and other channels of the photometer. A revised time dependent auroral excitation-ion chemistry model is used in an attempt to reproduce the observations. The observed weakening of λ 5577 could be produced at heights equal to or less than 100 km while the short observed time lag of λ 5577 on the N₂⁺ 1N emission is easier to explain at 100 km than at 80 km. It is concluded that some type-B lower borders may occur near 100 km although it is recognized that there is good evidence rare deep crimson lower borders lie at 80 km or below. The mechanism for the excitation of O(¹S) is considered in the light of these results. None of the mechanisms examined is satisfactory on the basis of currently accepted atmospheric models and quenching rate coefficients.  相似文献   

Further quantification of the sources and sinks of thermospheric O¹D) atoms     

D.G. Torr  P.G. Richards  M.R. Torr  V.J. Abreu 《Planetary and Space Science》1981,29(6):595-600

In this paper we confirm an earlier finding that the reaction constitutes a major source of OI 6300 Å dayglow. The rate coefficient for this reaction is found to be consistent with an auroral result, namely k₁ ≈ 6 × 10^?12cm³s^?1. We correct an error in an earlier publication and demonstrate that reaction (1) is consistent with the laboratory determined quenching rate for the reaction where $\text{k}{}_2\text{= 2.3 × 10}{}^{\mathrm{?11}}\text{cm}{}^3\text{s}{}^{\mathrm{?1}}$. Dissociative recombination of O⁺₂ with electrons is found to be a major daytime source in summer above ～220 km.  相似文献   

Non-thermal $\text{O}\text{(}{}^1\text{D}\text{)}$ produced by dissociative recombination of O₂⁺: A theoretical model and observational results     

G.A. Schmitt  V.J. Abreu  P.B. Hays 《Planetary and Space Science》1981,29(10):1095-1099

Thermal and non-thermal $\text{O}\text{(}{}^1\text{D}\text{)}$ number density profiles are calculated. The two populations are assumed to be coupled by a thermalization cross-section which determines the loss and production in the non-thermal and thermal populations, respectively. The sources, sinks and transport of the two populations are used to model volume emission rate profiles at 6300 Å. The 6300 Å brightness measured by the Visible Airglow Experiment is then used to establish the presence of the non-thermal population and to determine the thermalization cross-section.  相似文献   

Aeronomical determination of the efficiency of O¹D) production by dissociative recombination of O₂⁺     

L.L. Cogger  L.S. Smith  R.M. Harper 《Planetary and Space Science》1977,25(2):155-159

Simultaneous measurements of the 6300 Å airglow intensity, the electron density profile, and F-region ion temperatures and vertical ion velocities taken at the Arecibo Observatory in March 1971 are utilized in the height integrated continuity equation to extract the number of photons'of 6300 Å emitted per recombination. After accounting for quenching of $\text{O}\text{(}{}^1\text{D}\text{)}$ and the electrons lost via NO⁺ recombination, the efficiency of $\text{O}\text{(}{}^1\text{D}\text{)}$ production by the dissociative recombination of O₂⁺ is determined to be 0.6 ± 0.2 including cascading from the $\text{O}\text{(}{}^1\text{S}\text{)}$ state. The uncertainty includes both random measurement errors and estimates of possible systematic errors.  相似文献   

Airglow from the inner comas of comets     

T.E. Cravens  A.E.S. Green 《Icarus》1978,33(3):612-623

The intensities of radiation from the inner comas of comets which are composed primarily of water and carbon monoxide have been calculated. Only “airglow” emissions initiated by the absorption of extreme ultraviolet radiation have been considered. The photoionizations of H₂O, CO, CO₂, and N₂ are the most important emission sources, although photoelectron excitation is also considered. Among the emission features for which intensities were calculated are H₂O⁺ ($\text{A}\text{?}{}^2\text{A}{}_{\mathrm{1?}}\text{X}\text{?}{}^2\text{B}{}_1$), CO⁺ (first negative), CO (fourth positive), CO (Cameron), CO₂⁺ ($\text{B}\text{?}{}^2\text{?}{}_{\mathrm{u}}\text{?}\text{X}\text{?}{}^2\text{II}{}_{\mathrm{g}}$), N₂ (Vegard-Kaplan), N₂⁺ (first negative), and OI (1304 Å). In the inner coma (collision region) these airglow mechanisms are shown to be possible competitors with the usually assumed resonance scattering and flourescence excitation mechanisms which are appropriate for the outer coma and tail.  相似文献   

VLF-emissions associated with ring current electrons: Off-equatorial observations     

Kaichi Maeda  Paul H. Smith 《Planetary and Space Science》1981,29(8):825-835

The combination of a small inclination of the orbit (～4°) with the tilt angle (～11°) of the Earth's magnetic dipole axis enabled the S³-A satellite (Explorer 45) to make simultaneous observations of magnetospheric VLF-emissions and the associated enhancement of ring current electrons not only at the magnetic equator but also up to 15° geomagnetic latitudes. Microdensitometer scanning of the wideband data of these emissions reveals that the band of missing emission in the off-equatorial whistler mode emissions (chorus) appears at $\text{f}{}_{\mathrm{<mtext>Ho</mtext>}}\text{2}$ and that the intensities of the off-equatorial emission above $\text{f}{}_{\mathrm{<mtext>Ho</mtext>}}\text{2}$ are very weak in contrast to those of the near equatorial emissions, where $\text{f}{}_{\mathrm{<mtext>Ho</mtext>}}\text{2}$ is the equatorial electron gyrofrequency corresponding to the local gyrofrequency f_H at the satellite. Ray-tracing of whistler mode waves produced by the enhanced ring-current electrons at the geomagnetic equator just outside of the plasmapause has shown that some of these waves are reflected from high latitudes back to the Equator inside the source region. This process had been previously speculated to explain the formation of the bimodal intensity distribution with a gap at half the gyrofrequency (the two-band chorus) in the equatorial emission data. The intensities of those reflected waves, however, are shown to be insufficient to explain the observed emissions below $\text{f}{}_{\mathrm{<mtext>Ho</mtext>}}\text{2}$ at the Equator. These results indicate that the superposition of two types of emissions produced by the same processes but from different locations is not the main mechanism for the formation of the two-band chorus and that the dominant sources of these choruses are located around ± 5° geomagnetic latitude.  相似文献   

Measurements of the optical emission height profiles of medium intensity aurora     

A.Vallance Jones 《Planetary and Space Science》1979,27(3):307-312

Height profiles of auroral emissions at 3914 Å, 4861 Å, and 5577 Å were obtained in two rocket flights through medium intensity stable aurora. The 3914 Å N₂⁺ integral intensity data were compared with intensity variations predicted by an auroral model for a range of primary electron energy spectra. The observed profiles for the two flights were well reproduced respectively by a 5.6 keV mono-energtic flux and by a flux with an exponential spectrum cutting off around 12 to 15 keV. The data for 5577 Å (available only above 120 km) bear a constant ratio to that for 3914 Å. The emission profiles derived for 3914 Å, peak at 115 and 107 km respectively.  相似文献   

The excitation of the infrared atmospheric oxygen bands in the nightglow     

E.J. Llewellyn  B.H. Solheim 《Planetary and Space Science》1978,26(6):533-538

Simultaneous observations of the nightgiow emission profiles of $\text{O}{}_2\text{(}{}^1\text{Δ)}$ and the OH Meinel bands have been used to show that the excitation mechanism for $\text{O}{}_2\text{(}{}^1\text{Δ)}$ in the night-time is through the reaction between OH¹ and atomic oxygen and the recombination of atomic oxygen. These reactions, and the proposed rate constants, have been used to derive the atomic oxygen profile appropriate to the observations. It is suggested that the atomic oxygen profile may exhibit significant structure near the mesopause at high latitude. It is also suggested that the extent of this structure may be influenced by transport effects related to stratospheric warming events.  相似文献   

The excitation of atomic oxygen to the $\text{O(}{}^1\text{S)}$ level by energy transfer from N₂(A³∑_u⁺) molecules in aurora     

Kjell Henriksen 《Planetary and Space Science》1973,21(5):863-871

The part that the energy transfer reaction $\text{N}{}_2\text{(A}{}^3\text{∑}{}_{\mathrm{u}}{}^{\mathrm{+}}\text{) + O(}{}^3\text{P) → N}{}_2\text{(X}{}^1\text{∑}{}_{\mathrm{g}}{}^{\mathrm{+}}\text{) + O(}{}^1\text{S)}$ plays in the excitation of the auroral green line has been investigated. The contribution is estimated to be 40 per cent in this case, containing pulsating aurora in class IBC 1. Due to greater quenching of the A³∑_u⁺ state, the centroid of the VK emission is displaced 10 km upwards of the green line height, which is centred at 110 km.  相似文献   

Small-scale turbulence in the atmosphere of Venus     

Richard Woo  J.W. Armstrong  A.J. Kliore 《Icarus》1982,52(2):335-345

Previous studies based on radio scintillation measurements of the atmosphere of Venus have identified two regions of small-scale temperature fluctuations located in the vicinity of 45 and 60 km. A global study of the fluctuations near 60 km, which are consistent with wind-shear-generated turbulence, was conducted using the Pioneer Venus measurements. The structure constants of refractive index fluctuations c_n² and temperature fluctuations c_T² increase poleward, peak near 70° latitude, and decrease over the pole; c_n² varies from 2 × 10^?15 to 1.5 × 10^?14m^{$\text{2}\text{3}$} and c_T² from 4 × 10^?3 to 7 × 10^?2°K²m^{$\text{?2}\text{3}$}. These results indicate greater turbulent activity at the higher latitudes. In the region near 45 km the refractive index fluctuations and the corresponding temperature fluctuations are substantially lower. Based on the analysis of one representative occultation measurement, $\text{c}{}_{\mathrm{<mtext>n</mtext>}}{}^2\text{= 2 × 10}{}^{\mathrm{?16}}\text{m}{}^{\mathrm{<mtext>?2</mtext><mtext>3</mtext>}}\text{and}\text{c}{}_{\mathrm{<mtext>T</mtext>}}{}^2\text{= 7.3 × 10}{}^{\mathrm{?4}}\text{°}\text{K}{}^2\text{m}{}^{\mathrm{<mtext>?2</mtext><mtext>3</mtext>}}$ in the 45-km region. The fluctuations in this region also appear to be consistent with wind-shear-generated turbulence. The turbulence level is considerably weaker than that at 60 km; the energy dissipation rate ε is 4.9 × 10^?5m²sec^?3 and the small-scale eddy diffusion coefficient K is 2 × 10³ cm² sec^?1.  相似文献   

Changes in the concentration of mesospheric ozone during the total solar eclipse     

V.V. Agashe  S.M. Rathi 《Planetary and Space Science》1982,30(5):507-513

Measurements of dayglow radiance of $\text{O}{}_2\text{(}{}^1\text{Δ}{}_{\mathrm{g}}\text{)}$ and OH(7,2) bands are reported. Ground based photometers were used to monitor zenith radiance of 1270 and 694 nm emissions during the total solar eclipse of 16 February 1980. Altitude distribution of 1270 nm intensity was derived from ground based observations. A set of altitude distributions of $\text{O}{}_2\text{(}{}^1\text{Δ}{}_{\mathrm{g}}\text{)}$ were thus obtained throughout the eclipse. These altitude distributions were converted into ozone distributions using the rate equations for formation and loss of ozone and $\text{O}{}_2\text{(}{}^1\text{Δ}{}_{\mathrm{g}}\text{)}$ molecules. Results indicate an increase in the ozone concentration at mid-eclipse. OH(7,2) emission did not show enhancement during totality. This may mean that there was no increase in OH concentration during the eclipse.  相似文献   

Cross-section for the dissociative photoionization of hydrogen by 584 Å radiation: The formation of protons in the Jovian ionosphere     

K.M. Monahan  W.T. Huntress  A.L. Lane  J.M. Ajello  T.E. Burke  P. Le Breton  A. Williamson 《Planetary and Space Science》1974,22(1):143-149

The cross-section for dissociative photoionization of hydrogen by 584 Å radiation has been measured, yielding a value of 5 × 10^?20 cm². The process can be explained as a transition from the $\text{X}{}^1\text{Σ}{}_{\mathrm{g}}{}^{\mathrm{+}}$ ground state to a continuum level of the $\text{X}{}^2\text{Σ}{}_{\mathrm{g}}{}^{\mathrm{+}}$ ionized state of H₂ The branching ratio for proton (H⁺) vs molecular ion (H₂⁺) production at this energy is 8 × 10^?3. This process is quite likely an important source of protons in the Jovian ionosphere near altitudes where peak ionization rates are found.  相似文献