Rocket Observations Research Articles

Plasma Processes Driven by Current Sheets and Their Relevance to the Auroral Plasma

Satellite and rocket observations have revealed a host of auroral plasma processes, including large dc perpendicular electric fields (E⊥) associated with electrostatic shocks, relatively weak parallel electric fields (E║) associated with double layers, upflowing ions in the form of beams and conics, downflowing and upflowing accelerated electron beams, several wave modes such as the electrostatic ion-cyclotron (EIC), lower hybrid (LH), very low frequency (VLF), extremely low frequency (ELF), and high-frequency waves and associated nonlinear phenomena. Recently, we have attempted to simulate the various processes using a two-dimensional particle-in-cell code in which the plasma is driven by current sheets of a finite thickness. Striking similarities between the observed auroral plasma processes and those seen in the simulations are found. In this paper we give a review of the plasma processes dealing with dc and ac electric fields, formation of ion beams and conics, and electron acceleration. Electrostatic shock-type electric fields (E┴e) occur near the current sheet edges. Such fields arise because of the contact between the high-and low-density plasmas inside and outside the sheet, respectively. Double layers having upward electric fields form inside the sheet and they are distinguishable from the large perpendicular electric fields (E⊥e) only in wide sheets with thicknesses l >> ρi, the ion Larmor radius. Double layers with a reverse polarity form outside the sheet where downward currents flow. The most energetic ions are found to have pitch angles near 90°, implying a large perpendicular acceleration of the ions.

The excitation of O(1S) and O2 bands in the nightglow: a brief review and preview

Recent laboratory and in situ studies of the processes involved in the excitation of O(1S) and the five strongest systems of molecular oxygen in the terrestrial nightglow are reviewed. In spite of the significant advances that have been made during the last few years, it is not yet possible to reconcile rocket and satellite photometric observations with expectations based on laboratory kinetic data. Even in the most extensively studied O2 system, the Herzberg-I system, serious discrepancies exist between the kinetic parameters measured in the laboratory and those deduced from the airglow observations. It is only in the case of the O2 Atmospheric system that the laboratory and in situ studies have converged on a consistent view of the overall excitation mechanism. In the case of the O(1S) green line, most evidence would now appear to support the Barth mechanism, but progress towards a conclusive identification of the Barth precursor state, or states, is seriously hindered by the inadequacies in current understanding of the molecular oxygen systems.

Formation of sporadic E layers at low magnetic latitudes

Rocket observations of the electron density and neutral winds conducted during the morning, evening and night-times show that the sporadic E layers observed over an equatorial station, Thumba, cannot be explained in terms of the currently available version of the wind shear theory. These observations also suggest, strongly, that the modified version of the wind shear theory must include the effect of the vertical electric field and the shear in the meridional wind, in addition to the shear in the zonal wind.

Daytime high‐latitude rocket observations of the NO γ, δ, and ε bands

Observations of the Earth's thermospheric dayglow were obtained on August 10, 1982, from Poker Flat, Alaska, using a rocket‐borne spectrometer covering the wavelength range 1950 to 2170 Å. This part of the spectrum is dominated by emissions from the gamma, delta and epsilon bands of nitric oxide. Column densities of nitric oxide were determined by fitting these bands with synthetic spectra. At low altitudes the (1, 0) and (2, 0) gamma bands exhibit large self‐absorption. Three bands of the weak NO epsilon system, (0, 1), (0, 2), and (0, 3) were positively identified and used to determine NO densities between 105 and 125 km. The fluorescence efficiency of the NO delta bands was found to be ∼0.25 based on the fit to synthetic spectra. A one‐dimensional diffusive photochemical model of the earth's thermosphere was used for comparison with the rocket observations. The data was reproduced by the model using a 10 keV characteristic energy for the primary aurora electrons with a constant flux of 0.5 ergs cm−2 s−1. The production yield of N(²D) from the dissociation of N2 by electron impact used in this calculation was 0.6. An analysis was performed to show the sensitivity of the conclusions to the various model parameters.

Rocket and satellite observations of electric fields and ion convection in the dayside auroral ionosphere

Electric-field observations from two high-altitude rocket flights in the polar cusp have been combined with satellite observations of ion drifts and energetic particles to infer details of the electric field and convection pattern of the dayside auroral ionosphere. A region of shear flow reversal could be inferred from the electric-field observations on one flight near 1530 magnetic local time 20 min after the Dynamics Explorer 2 (DE-2) satellite crossed through the same region. The drift patterns observed by the two spacecrafts were very similar, although shifted by 0.5°, a shift that is expected from the observed change in the interplanetary magnetic-field (IMF) BZ component during this time. A region of rotational flow reversal was covered by the other flight shortly after magnetic noon, at the same time the DE-2 satellite travelled along roughly the dawn–dusk meridian. By joining points of equal potential, integrated from the two data sets, and assuming the reversal boundary to be an equipotential, we could draw the instantaneous convection pattern showing crescent-shaped convection contours in the dusk cell and more circular-shaped contours in the dawn cell. This pattern has been shown to be in qualitative agreement with the predictions of a geometrical model proposed by Crooker in 1979, when the IMF is oriented towards dawn. The same characteristic patterns but with the dusk and dawn cells reversed, as presented in a recent radar-satellite study for the IMF oriented towards dusk, may serve as additional evidence in favour of this model.

Rocket observations of ultraviolet and optical emissions in the dayside aurora

Observations of emissions extending from the extreme ultraviolet to the near-infrared region of the spectrum were obtained from a rocket payload flown from Cape Parry, N.W.T., Canada, during the CENTAUR campaign December 7, 1981. The flight, NASA 29.017CE (Terrier-Malemute), was launched near local magnetic noon during an electron-precipitation event in the dayside cleft region. Emission rates versus altitude and zenith angle were obtained for the principal atomic-oxygen emission features OI (989 Å), OI (1304 Å), OI (1356 Å), OI (6300 Å), OI (7774 Å), and OI (8446 Å), as well as HI (1216 Å) and OII (834 Å). Some data were also obtained for the [Formula: see text] (first negative) bands. The results suggest an emission layer peaked in the vicinity of 250 to 300 km. Temporal and spatial fluctuations were most pronounced at apogee and on the downleg portion of the flight. Emissions strongly affected by multiple scattering fluctuated less than optically thin emissions.In this paper, estimates of the input energy flux and characteristic energy are made based on the intensity of the OI (6300 Å) and OI (1356 Å) emissions and the altitude of the emission layer. A value of 0.3 to 0.4 erg/cm2∙s for the energy flux and a characteristic energy of approximately 200 eV are consistent with the observations (1 erg = 0.1 μJ).

AE‐D measurements of the NO geomagnetic latitudinal distribution and contamination by N+(5S) emission

Measurements of the NO γ (1, 0) band resonance scattering distribution obtained with the Atmosphere Explorer D satellite have been inverted to generate maps of the meridional distribution of nitric oxide between 90 and 160 km. It is shown that the results are better organized in terms of geomagnetic rather than geographic latitudes, especially at high latitudes. In particular, the presence of an E region maximum associated with the summer auroral zone is clearly demonstrated. The existence below the NO peak of larger concentrations in the winter than in the summer hemisphere is also observed. Comparison between calculations and rocket observations of the 2143‐Å doublet emission indicates that the quantum yield of N+(5S) is considerably less than unity. The possible contamination of the observations by this emission is shown to be negligible in these observations.

Solar absolute spectral irradiance 118–300 nm: July 25, 1983

The full‐disk solar absolute spectral irradiance in the spectral range 118–300 nm was obtained from a rocket observation above White Sands Missile Range, New Mexico, on July 25, 1983, halfway in time between solar maximum and solar minimum. Comparison with measurements made in May 1982 shows no changes within the absolute errors of the experiment. Comparison with measurements made during solar maximum in 1979 and 1980 indicates a large decrease in the absolute solar irradiance at wavelengths below 190 nm. The absolute calibration of the instruments for this flight was accomplished at the National Bureau of Standards Synchrotron Radiation Facility.

The perturbed neutral circulation in the vicinity of a symmetric stable auroral arc

The neutral response to changes in the energy source associated with the appearance of a symmetric stable auroral arc is simulated using a sophisticated two‐dimensional numerical model. The model is a time‐dependent one which describes nonlinear, nonhydrostatic viscous flow in a rotating atmosphere. The energy sources are the ion drag momentum source and the Joule and particle precipitation heating sources. The arc model is an idealization of rocket observations of a fairly wide intense arc. The distribution of ion production and electric potential were assumed to be symmetric about the center of the arc and constant along the arc. A significant feature of the forcing is the reduction and reversal of the electric field within the arc. The arc is embedded in a region of enhanced ionization associated with a diffuse aurora. The simulation was carried out for an interval of 1 hour after the onset of the changed forcing. The main findings of our study are as follows: (1) the zonal ion drag force drives strong (∼200 m s−1) counterstreaming zonal winds on opposite sides of the arc; (2) the zonal flow within the arc is accelerated to ∼40% of the electric field drift velocity in the region of high Pedersen conductivity; (3) the nonhydrostatic interplay of buoyancy and vertical pressure gradient forces sets up a large‐scale buoyancylike oscillation; (4) the adiabatic circulation driven by the meridional ion drag force contributes to a net cooling in the lower region of the arc during the first half of the simulation; (5) forced convection within the arc resembles convection due to particle heating alone, but particle heating contributed only ∼25% of the net warming; and (6) the lateral extent of the meridional circulation is much more extensive than the lateral extent of the arc and the diffuse aurora.

Rocket Observations of Kelvin Waves in the Upper Stratosphere over India

Abstract The upper atmospheric winds (20–40 km) at two Indian stations, Sriharikota Range (SHAR 13.7°N, 80.2°E) and Balasore (2 1.5°N, 86.93°E) during the years 1979–80 were analyzed for short scale vertical variations (6–16 km) of the zonal wind. The analysis involves high-pass filtering of the wind profiles to extract the short-scale wavelike perturbations and Fourier analysis of the wave disturbances. The results of the analysis are presented. The dominant vertical wavelengths are in the 6–12 km range in 67% of the observed cases, and the amplitudes are significantly larger during the easterly background wind. The amplitudes are systematically larger by about a factor of 2 at Sriharikota (13.7°N) than at 1Wasore (21.5°N). Corresponding wave perturbations are absent in the meridional wind in as much as 70% of the observations. These characteristics lead to the conclusion that the observed wavelike disturbances are the manifestation of Kelvin waves in the upper stratosphere. In some cases, the periods of...

Rocket observations of energetic particles at the geomagnetic equator

Energetic particle detectors were included in the payloads of two rockets launched in Peru during the CONDOR campaign of 1983. These night-time flights reached altitudes of 587 and 535 km, respectively. The pitch-angle distribution is anisotropic with the maximum at 90°. Each payload included two solid-state detectors differing in the thickness of the aluminum coating. Comparison of the fluxes measured by the two detectors leads to the conclusion that, on both occasions, the energetic particles are predominantly helium ions. The flux is small below 200 km, increases linearly to 350 km, and then more slowly to apogee. The east-west asymmetry of flux, noted at 200 km in a previous equatorial launch, is not seen at greater altitudes, consistant with the flux profile and the large gyroradius of the ions.

The ultraviolet dayglow at solar maximum: 3. Photoelectron‐excited emissions of N2 and O

Rocket observations of the far ultraviolet dayglow spectrum near solar cycle maximum are analyzed using laboratory cross sections, atmospheric composition models, and photoelectron production models. Photoelectron‐excited emissions of N2 and O are used to derive a self‐consistent description of the atmosphere at solar maximum. Spectral synthesis of the N2 Lyman‐Birge‐Hopfield bands shows a departure of a¹Πg state vibrational populations from the direct excitation theory. Observations of the N2 second positive (0, 0) 3371‐Å band and O I 1356‐Å emission indicate an exospheric temperature of 1600 K, 200 K higher than predicted by empirical models. The empirical models are also found to overestimate the O and O2 densities required to fit the data by a factor of 2 and 1.4, respectively. These results are compared to the results of an analysis of similar observations made in 1978 near solar minimum. The derived photoelectron flux at 290 km is a factor of 1.6 times larger than for the 1978 data.

Rocket observation of the EUV images of a solar flare and active regions

Images of a flare and active regions were obtained in the extreme ultraviolet emission lines such as CIII 977 A, Ne VIII 770 A, and HI Lβ, and hydrogen Lyman continua with a spatial resolution of less than ten seconds of arc together with one-dimensional scanning at 1650 A. A microchannel plate was used as a detector, and pointing accuracy was, for about half of the observation time, around 0.5 arc sec. The relationship between the shape of the flare and the structure of the photospheric magnetic field is discussed. A map of the electron temperature distribution derived from the intensity ratio of the Lyman continua at 880 A and 815 A showed a lower temperature in regions of higher activity. A very small geometrical thickness of 50–500 m in the C III emitting region of the flare was found. And the layer emitting the continuum in 1650 A is shown to be at a temperature of 5300 K in the flare and 4700 K in active regions.

Wind structure and variability in the middle atmosphere during the November 1980 Energy Budget Campaign

Between 6 November and 1 December 1980 a series of rocket observations were obtained from two sites in northern Scandinavia (~ 68°N) as part of the Energy Budget Campaign, revealing the presence of significant vertical and temporal changes in the wind structure. These changes coincided with different geomagnetic conditions, i.e. quiet and enhanced. This represents the largest amount of rocket data ever gathered from high latitudes over such a short interval of time. Prior to 16 November the meridional wind component above 60 km was found to be positive (southerly), while the magnitude of the zonal wind component increased with altitude. After 16 November the meridional component became negative (northerly) and the magnitude of the zonal wind component was noted to decrease with altitude. Time-sections of the perturbations of the zonal wind show the presence of vertically propagating waves, which suggest gravity wave activity. These waves increase in length from 1 km near 30 km to over 12 km near 80 km. The observational techniques employed at Andøya (~ 69°N), Norway, and Esrange (67.9°N), Sweden, consisted of chaff foil, instrumented rigid spheres, chemical trails, inflatable spheres and parachutes.

Input from station-oriented observations and its assimilation into the new formula for the International Reference Lower Ionosphere (IRLI)

In order to compare the station-oriented observations from a variety of experimental techniques, it is necessary to use standard and state-of-the art procedures for the methods of evaluation. While discussing the formulae used in the past for the calculation of mf/hf radio wave absorption and vlf/lf reflection coefficients, the use of the Sen-Wyller formula for the computation of A1 absorption at mf/hf and the use of generalised full wave theory for the calculation of vlf/lf reflection coefficients are recommended. For oblique incidence mf/hf (A3) absorption calculations, use of the generalised Booker quartic is recommended. The need to use a consistent and standard collision frequency model linked with the CIRA pressure model is recommended. While discussing the normalisation procedures used in the past for the global mapping of the D- and lower-E-region A1 absorption, the need to calculate the absorption (without normalisation) and then make a comparison with the IRI description is stressed. The use of the currently available rocket data, to model the peak parameters of the E-region, is discussed. More rocket observations to probe the E-region together with incoherent scatter data are needed to model the E-region peak parameters needed for incorporation into the new formula for the International Reference Lower Ionosphere (IRLI).

Rocket observation of the ultraviolet spectrum of comet Halley

An ultraviolet sounding rocket telescope/spectrograph experiment observed Comet Halley on 26 February 1986, 17 days after perihelion. From the long-slit spectra, the production rates of O, C, and CO are calculated. The derived water production rate is a lower limit of 5.0 × 10 29 s −1 and the volume mixing ratio of CO to H 2O is 21%. The predicted brightness distribution from a radial outflow model with H 2O and CO as parent molecules are in accordance with the measured spatial profiles of OI and CO emissions. The ratio of the production rates of CO to C is 2.7 which is consistent with the carbon source being the photodissociation of CO. However, the radial outflow model which best fits the CO data predicts significantly weaker CI emissions than was observed. A better fit to the carbon data is found when an inner coma source of C at a rate of 3% of the water production rate is included in the model.

中層大気中の慣性重力波に関する統計的研究

An analysis was made of the structure and behaviour of small-scale motions in the stratosphere and lower mesosphere with the aid of meteorological rocket observations over the period of six years from 1977 to 1982, covering the wide range of latitudes.By applying a filter to observed wind data with respect to height, wind fluctuations with characteristic vertical scales close to 10km are separated from large-scale components such as the mean field, planetary waves and tides.From the hodograph analysis it is found that at northern hemisphere stations most of horizontal wind vectors show the clockwise rotation with increasing height while they rotate anti-clockwise in the southern hemisphere. This strongly suggests that the wind fluctuations are due mainly to upward propagating inertia-gravity waves.On the basis of a simplified theory of inertia-gravity waves, the wave-frequency distribution is estimated statistically from the degree of elliptic polarization of holographs, and it is shown that the most predominant values of f/ω (f; the Coriolis parameter, ω; the intrinsic wave frequency) fall into a range of 0.2-0.4. Namely, the typical time scale of these waves is of the order of several hours in middle and high latitudes and of a day in low latitudes.Further discussions are made of the vertical profile of the wave energy density, and it is suggested, from the uniform decay of the wave amplitude with height that the wide spectra of horizontal phase velocities should be taken into account.

Recent Rocket Observations of the Ultraviolet Spectrum of the Zodiacal Light

AbstractObservations of the spectrum of the zodiacal light in the wavelength range 1800-3000 Å have been obtained in two recent sounding rocket experiments. The September 1979 observation was made close to the ecliptic plane at elongation angles of 20° and 28° and with a spectral resolution of 25 Å, while in April 1981 the elongation was 125° (inclination 60°), and the spectral resolution 50 Å. Both observations confirm the slight reddening in the ultraviolet reported previously and show the same dependence on elongation as in the visible. There appears to be some structure in the ultraviolet albedo of the dust grains near 2800 Å but the exact nature of this structure cannot be determined at the low spectral resolution of the present observations. Detailed descriptions of the two observations has been given by Cebula and Feldman (1982) and Tennyson (1983), respectively.

Rocket observations of the Orion reflection nebulosity in the range 130-200 nanometers and scattering properties of dust grains in the far-ultraviolet

view Abstract Citations (9) References (40) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Rocket observations of the Orion reflection nebulosity in the range 130-200 nanometers and scattering properties of dust grains in the far-ultraviolet. Onaka, T. ; Sawamura, M. ; Tanaka, W. ; Watanabe, T. ; Kodaira, K. Abstract Vacuum ultraviolet surface brightness maps of the southern part of the Orion region at the wavelengths 195.1, 179.6, 164.0, 148.4, and 132.8 nm were obtained by a rocket experiment. Large-scale bright nebulosity and a ridge structure in the western circumference of the Orion regions are clearly seen in these contour maps. Simple analysis shows that the observations can be explained by a front-dust-layer model, in which the diffuse light arises from the starlight scattered by dust grains in front of the stars, as well as by a back-dust-layer model, where dust grains behind the stars scatter the starlight to produce the diffuse nebulosity. A detailed discussion of the far-ultraviolet scattering properties of the dust grains in the observed region is included. Publication: The Astrophysical Journal Pub Date: December 1984 DOI: 10.1086/162696 Bibcode: 1984ApJ...287..359O Keywords: Interstellar Matter; Orion Nebula; Reflection Nebulae; Ultraviolet Astronomy; Astronomical Maps; Backscattering; Far Ultraviolet Radiation; Forward Scattering; Ridges; Spatial Distribution; Astrophysics full text sources ADS | data products SIMBAD (1)

Rocket observations of the ultraviolet airglow during morning twilight

The nitric oxide γ and δ bands, O II λ2470‐, O I λλ356‐ and 1304‐Å lines, and N2 Lyman‐Birge‐Hopfield and O2 Herzberg band emissions were observed during morning twilight between 90 and 246 km on September 24, 1979, with two rocket‐borne scanning monochromators viewing successively at 82° and 90° to the zenith near the sun‐earth‐rocket plane. The solar zenith angle was 110°. The relative intensitites of the two nitric oxide band systems suggest that the observed emission is primarily due to resonance fluorescence along the sunlit portion of the rocket line of sight, with the chemiluminescence contribution being greatly reduced from that observed during evening twilight. The densities at 200 km derived from the observed emission rates are 4×105 cm−3 for NO and 5×106 cm−3 for N(4S), consistent with recent odd nitrogen models which predict a much greater nighttime decrease of N(4S) than of NO. The atomic and ionic oxygen emissions are modeled in a self‐consistent way based on direct photoionization and photoelectron impact ionization. The atomic oxygen density near 100 km is derived from O2 Herzberg I band emission observed near the end of the flight.