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A sounding rocket measurement of the ultraviolet, atomic oxygen dayglow reveals an excess of emission compared to standard thermospheric model calculations at exospheric altitudes. We explore two explanations for this discrepancy: a breakdown of the radiative transfer model due to nonlocal thermal equilibrium (non-LTE) conditions above the exobase and a hot atomic oxygen geocorona. In particular, the effects of non-LTE on the 3P2, 1, 0 sublevel populations are modeled, and a hot O component in the upper thermosphere and lower exosphere is added to investigate the effects on the modeled emissions. For both cases, the data are reanalyzed and compared with the results using a standard LTE model. A hot O geocorona having a peak density of 10(exp 6)/cc at 550 km and a temperature of 4000 K is consistent with the data and appears to be the most reasonable explanation of the high-altitude enhanced emissions observed in the data.

The Berkeley extreme-ultraviolet airglow rocket spectrometer (BEARS) made spectroscopic measurements of far and extreme UV, atomic oxygen emissions from a Black Brandt XII (12.041 WT) sounding rocket launched from Wallops Island, Virginia, on September 30, 1988. BEARS' primary instrument, a near-normal Rowland mount spectrometer, measured several atomix oxygen and molecular nitrogen dayglow features at high spectral resolution (1.5 A): O I (989, 1027, 1304, and 1356 A); and N2 Lyman-Birge-Hopfield (4, 0) and (3, 0) bands at 1325 and 1354 A. The instrument collected over 800 s of data spanning altitudes of 150 - 963 km with look directions between 95 deg and 125 deg from zenith. We have analyzed the data using electrons and radiative transport models in a forward modeling approach. The model and data are generally in good agreement. However, there are some discrepancies, which are discussed in terms of remote sensing capabilities and improvements to the models.

The electron impact excitation cross section for the O I (1304 A) emission is enhanced in the terrestrial thermosphere owing to an optically thick cascade mechanism. Values for the contribution of the cascade have been calculated and deduced from measured 1304-A airglow emissions to between o and 200%. We have developed a model to calculate a large portion of the optically thick cascade contribution, including contributions from the radiative entrapment of the O I (1040, 1027, and 989 A) lines. High-resolution spectroscopic data from a sounding rocket experiment are analyzed using this model. The optically thick cascade contribution for the three lower lying states was evaluated to be 24.5% and compares well with recent calculations. The data, however, support a total contribution of 40%. The 15.5% difference is likely due to the contribution from higher Rydberg states.

[1] In January 2002 the SIERRA sounding rocket was launched from Alaska into active substorm expansion aurora. Direct measurements of the cold ionospheric population in darkness were made by the Thermal Electron Detector (TED), which was designed to measure thermal electrons that can carry auroral currents coupling the lower ionosphere and the magnetosphere. Measurement of thermal electrons must be accompanied by a careful study of electrostatic potentials forming near conducting bodies in a plasma. The TED instrument measurements show that a nonmonotonic potential barrier can form in the sheath around the attractively biased detector and prevent measurements of the core of the thermal electrons. The TED instrument design and response are discussed along with the current balance conditions which can lead to the formation of a potential barrier. A plasma distribution reconstruction technique enables key measurements of temperature, density, spacecraft potential, and an estimate of field-aligned current flow. Observed thermal electron core temperatures vary greatly, from ∼0.1 eV in the polar cap to ∼0.8 eV in auroral arcs. Outside active precipitation, the electron density agrees with an independent calculation based on measurements from the high-frequency (HF) wave receiver, verifying the method used for estimating the spacecraft potential. In the auroral regions the HF measurement of electron plasma density must be used to extract more accurate results for the spacecraft potential. The thermal electron data indicate that in the dark the nonnegligible auroral and secondary emission currents must be accounted for in order to understand the spacecraft potential and its impact on thermal electron measurements.

[1] Experiments were conducted during the NASA Equatorial Ionospheric Study (EQUIS) II sounding rocket campaign on Kwajalein Atoll to investigate the dynamics and stability of the postsunset equatorial F region ionosphere prior to the onset of equatorial spread F (ESF). Experiments took place on 7 and 15 August 2004, each composed of the launch of an instrumented and two chemical release sounding rockets. The instrumented rockets measured plasma number density, vector electric fields, and other parameters to an apogee of about 450 km. The chemical release rockets yielded lower thermospheric wind profile measurements. The Altair radar was used to monitor coherent and incoherent scatter in UHF and VHF bands. In both experiments, large-scale waves preceded the emergence of ESF depletions and irregularities. We propose that the large-scale waves were produced by a collisional shear instability. A three-dimensional electrodynamic model is constructed that can reproduce the shear flow observed by the rockets. On the basis of the model, we calculate the linear growth rate for the collisional shear instability and show that it can compete with the generalized Rayleigh Taylor instability. A scenario where the former generates the large-scale waves and initiates the latter is discussed.

[1] Investigation of Earth's mesosphere using sounding rockets equipped with a myriad of instruments has been a highly active field in the last 2 decades. This paper presents data from three separate instruments: an RF impedance probe, a DC fixed bias Langmuir probe, and an electric field probe, that were flown on a mesospheric sounding rocket flight investigating the presence of charged dust within and/or around a sporadic metal layer. The combined data set indicates a case of payload surface charging, the causes of which are investigated within this paper. A generic circuit model is developed to analyze payload charging and behavior of Langmuir-type instruments. The application of this model to the rocket payload indicates that the anomalous charging event was an outcome of triboelectrification of the payload surface from neutral dust particles present in the Earth's mesosphere. These results suggest caution in interpreting observations from the Langmuir class of instrumentation within dusty environments.

[1] The SIERRA sounding rocket launched 14 January 2002, northward from Poker Flat, Alaska, to an altitude of 735 km in active aurora. On the downleg, in the altitude range 500–700 km, the onboard high-frequency wave experiment detected structured whistler mode signals in the frequency range 100–1000 kHz, lasting nearly 200 s during which the rocket moved approximately 200 km downrange. The most prominent feature consisted of narrowband signals with frequency descending from 500 kHz to 250 kHz in about 0.5 s, with bandwidths ∼10 kHz, with frequency spacings ∼25 kHz, and with amplitudes in the range 10–400 μV/m. The structured whistler mode signals coincide with a region of Alfvenically accelerated electrons of the type often associated with the downward current region, poleward of the inverted-V electron structures usually associated with the upward current region. However, on short timescales there was no clear correlation between the whistler mode signals and the locally detected electron flux or density. Ray-tracing calculations indicate that concentrated sources of waves originating on the whistler mode resonance cone and moving upward through a model ionosphere, with speeds of 1000–5000 km/s, to rocket altitudes, exhibit the magnitude of dispersion of the observed structured whistler mode features. We evaluate the strengths and weaknesses of the hypothesis that these concentrated sources could be associated with phase space electron holes shedding electrostatic whistlers as they move upward along the field line at altitudes much higher than the rocket in the downward current region.

[1] Coherent backscatter from the auroral electrojet was observed by a 30 MHz imaging radar in Anchorage during the Joint Observations of Upper Latitude Electrodynamics (JOULE) campaign conducted from the Poker Flat Research Range in the spring of 2003. The observations were made at the same time that ionospheric electric fields and plasma number densities were measured in situ by instruments on sounding rockets. Neutral wind profiles were also measured during the campaign from triangulation of chemiluminescent trails from rocket releases. Aperture synthesis radar imaging techniques permit the sorting of the coherent backscatter into small azimuth and range bins and the determination of the scattering altitude. Individual Doppler spectra could thereby be unambiguously associated with in situ electric field measurements in the same small volume. We find that the Doppler shifts of the auroral echoes correspond to the ion acoustic speed times the cosine of the flow angle, where the former is predicted according to an empirical wave heating law. Type I echoes are only observed for very small flow angles regardless of the convection speed.

[1] We present data from a winter 2002 sounding rocket campaign for multiple observations of mesospheric charged dust. The campaign consisted of four identically instrumented payloads carrying detectors for charged mesospheric dust particles. The payloads reached an altitude of 100 km in the nighttime mesosphere and were flown from Poker Flat Research Range, Alaska, in conjunction with observations by the UAF sodium and iron resonance lidar system. Three of the four flights flew in sequence during the course of one night to study the temporal evolution of dust layers. Observations show good correlations between structure seen in the charged dust altitude profile, structure seen in the neutral metal layers observed by the lidars, and structure in the plasma density seen by the onboard Langmuir probes. The dust detector is sensitive to positively and negatively charged dust particles with ram energies of 1 to 11 eV for negatively and 3–11 eV for positively charged dust; that is, particles of approximately 5000 amu. The charged dust densities seen (estimated to be approximately 5 to 10 percent of the total dust density) are approximately 100 particles per cc, and the dust is negatively charged. Variations in the dust density of about 10% are seen in conjunction with structure in the plasma density and with the neutral metal layers. In this paper we present the details of the dust data and instrumentation; a companion paper explores the implications of the correlations seen between the dust and other mesospheric layers.

[1] We explore a mechanism by which density depletions associated with lower-hybrid cavities and similar structures are a direct consequence of ion trajectories resulting from transverse energization localized on scales comparable to the ion gyroradius. Specifically, a heating region localized to a flux tube having a diameter of the order of a few ambient thermal ion gyroradii will be depleted of ions because of heated-gyroradius-scale excursions of the ions away from the heating region. Cooler ions outside will have smaller average gyroradii and will be unable to compensate for the depletion inside the heating region. The outflux of energized ions from the heated region results in a density enhancement at its periphery. Motivated by space observations, we characterize density perturbations resulting from an idealized, cylindrically symmetric Gaussian temperature enhancement, using Monte Carlo simulations and an orbit-averaged density calculation. Our model generates density depletions of the order of 10% for a two-fold increase in Ti over the background value and 50% for a fifty-fold increase. In addition to density depletions the model predicts density-enhanced shoulders around cavity perimeters and shows how heated ion tails superimposed on cool ionospheric plasmas can be explained by hot, Maxwellian ions originating on nonlocal flux tubes. We present examples of shoulders observed by sounding rockets and by the Freja satellite. Finally, we use sounding rocket measurements to demonstrate that the distribution of cavity widths (or chord lengths) is relatively narrow (16 ± 10 m), with an average width that remains nearly unchanged even as plasma density varies over five orders of magnitude. This result is consistent with gyroradius being the key scaling parameter, although it does not rule out other scaling predictions that do not depend on plasma density.

[1] On 11 March 1998 the Langmuir Turbulence sounding rocket was launched through the Arecibo heater beam during an experiment to measure electric fields and plasma densities in the heater interaction region. In spite of a serious degradation of the Arecibo heater, the rocket data has provided evidence of Z mode waves and field aligned striations above the O mode reflection height. These observations give credence to the theory that Z mode wave interactions with field-aligned striations may be, in part, responsible for some of the features of the reflected HF spectrum observed in heating experiments. We also find strong low-frequency electric fields where the local plasma frequency matches an electron cyclotron harmonic. This suggests that electron Bernstein modes must be generated in the interaction process and can propagate to regions where they are severely damped.

[1] Gravity waves (GWs) are a ubiquitious dynamical feature of the polar summer mesopause region. During three summer campaigns, in 1991, 1993 and 1994, we launched seven sounding rockets from the north Norwegian island Andoya. Each of these payloads carried an ionization gauge capable of measuring the total atmospheric density at a high spatial resolution. From these measurements, temperature profiles were determined for altitudes between 70 and 110 km, with an altitude resolution of 200 m. The temperature profiles reveal significant rms variations that are as large as 6 K at 80 km, 10 K at 85 km, and even 20 K at 95 km. During three out of the seven launches a bright noctilucent cloud (NLC) was simultaneously detected by our ground-based lidar and by rocket-borne in situ experiments. During these flights, the NLC is located close to a local temperature minimum below the mesopause. We then estimated gravity wave parameters from accompanying falling sphere and chaff wind observations and found signatures that the wave periods during the NLC cases were on the order of 7–9 hours, with corresponding horizontal wavelengths of 600–1000 km. Motivated by these observations, we used a microphysical model of NLC generation and growth to study the interaction between GWs and NLC. Based on recently measured and modeled temperatures and water vapor mixing ratios, and our gravity wave parameter estimates, we find that the NLC layer indeed follows the motion of the cold phase of the wave by means of a complex interplay between ice crystal sedimentation, transport by the vertical wind, and simultaneous growth. It turns out that the history of individual particles significantly influences the observed properties of NLC. Furthermore, we find that GWs with periods longer than 6.5 hours amplify NLC while waves with shorter periods tend to destroy NLC. In addition, we can only find a correlation between local temperature minima and the location of the NLC provided that the wave periods are longer than ∼6 hours, which is consistent with our wave parameter estimates.

Electrons with energies up to 600 eV are observed with the retarding potential analyzer (RPA) instrument aboard the Several Compatible Experiments (SCEX) III sounding rocket. The electrons are concomitant with high-energy (2–6 keV) electron gun injections and also evidence themselves by luminosity observed with 3805 A and 3914 A photometers. Both the collected electron flux and luminosity measurements are strongly nonlinear with gun injection current. For a typical event, the electron distribution is similar to laboratory beam-plasma discharge (BPD) distributions reported by Sharp (1982) and when backed by HF electric field observations (Goerke et al., 1992; Llobet et al., 1985), the BPD mechanism becomes a most likely explanation. Strong turbulence theories of BPD predict a power law tail in the electron distribution, and we compare our spectral index with some previous observations.

The Ionospheric Focused Heating rocket was launched on May 30, 1992. The sounding rocket carried an instrument and chemical payload along a trajectory that crossed the intersection of the beams from the 430-MHz incoherent scatter radar and the 5.1-MHz high-power radio wave facility near Arecibo. The release of 30 kg of CF{sub 3}Br into the F region at 285 km altitude produced an ionospheric hole that acted like a convergent lens to focus the HF transmission. The power density inside the radio beam was raised by 12 dB immediately after the release. A wide range of new processes were recorded by in situ and ground-based instruments. Measurements by instruments flying through the modified ionosphere show small-scale microcavities (< 1 m) and downshifted electron plasma (Langmuir) waves inside the artificial cavity, electron density spikes at the edge of the cavity, and Langmuir waves coincident with ion gyroradius (4 m) cavities near the radio wave reflection altitude. The Arecibo incoherent scatter radar showed 20 dB or greater enhancements in ion acoustic and Langmuir wave turbulence after the 5.1-MHz radio beam was focused by the artificial lens. Enhancements in airglow from chemical reactions and, possibly, electron acceleration were recorded with optical instruments. Themore » Ionospheric Focused Heating experiment verified some of the preflight predictions and demonstrated the value of active experiments that combine high-power radio waves with chemical releases. 30 refs., 14 figs., 1 tab.« less

In June 1992 a NASA sponsored sounding rocket was flown through the Arecibo heater beam to study the structure of the heated volume. The rocket carried an instrument payload and traversed the 5.1-MHz reflection height at 268.5 km. Data from the plasma density probe are presented in this paper. The rocket passed through several regions of disturbed plasma both above and below the reflection level. In these regions, over 180 deep filamentary density depletions were detected. Measured perpendicular to the magnetic field, these depletions or filaments have a mean width at half maximum of 7 m which is roughly equal to twice the ion gyroradius (O + ) and a mean depletion depth of 6%. The ratio of parallel to perpendicular scale for these structures exceeds 20,000, and the spacing between the filaments is around 15 m. A power spectrum of the rocket data clearly shows the spectral content of the filaments and also reveals peaks at longer wavelengths which we interpret as the spacing between the bunches and between sets of filaments within a given bunch. We believe that previous scintillation and satellite measurements emphasized these longer wavelengths. The power spectrum measured by the rocket instrumentation falls off as k −4 for wavenumber k larger than 0.4/m and remains above the system noise for structure down to 1 m. It is clear that VHF backscatter from these structures can be explained by our data, as can many features of heater-related, field-aligned irregularities found in the literature.

Observations of electrons during a sounding rocket flight from Sondrestromfjord, Greenland, in 1985 showed numerous instances of electron time-of-flight dispersion, that is, a coherent structure in which fast electrons arrived before slow electrons. The instrumentation measured many pitch angles simultaneously with high time resolution, providing a detailed view of the temporal evolution of the electron signature at rocket altitudes which was indicative of an impulsive injection of electrons over a range of energies. A model utilizing an extended, quasi-static (static on a timescale of 1 s), parallel electric field was developed to investigate a possible mechanism for the injection of these electrons. The model is found to fit the data well only when a background is added which cannot be self-consistently generated by the model, although other parameters used in the model are in general agreement with previous reports. This leads to the conclusion that electron dispersion is more probably generated by a wave acceleration mechanism.

VHF radar data from the Summer 1990 Equatorial Spread F campaign on Kwajalein are presented. The Cornell 50 MHz portable radar interferometer (CUPRI) operated concurrently with the Altair UHF incoherent scatter radar throughout July and August and supported two sounding rocket flights on July 30 and August 2. This experiment provided the first opportunity to simultaneously diagnose equatorial spread F using the three prime experimental techniques: VHF/UHF coherent scatter, incoherent scatter, and in situ probe measurements of electric field and density fluctuations. The intensity of the coherent echoes observed was consistent with typical Jicamarca spread F observations, but chains of periodic, large-scale plasma upwellings were observed more often and for much longer durations on Kwajalein than have been seen over Peru. CUPRI also measured Doppler frequencies in one upwelling corresponding to 1200-m/s plasma drift velocities. This measurement agrees with recent observations of supersonic drift rates at the magnetic equator by spacecraft. Near the most active localized plasma upwellings, interferometer data reveal that the zonal drift rate of plasma irregularities can vary sharply in space, as one would expect for two-dimensional incompressible flow. We introduce a semiempirical model of the three-dimensional spectrum of F region irregularities that is consistent with the one-dimensional spectra of density fluctuations observed by sounding rockets and with the axial ratio of irregularities determined recently. Normalized to data from one of the rocket flights on Kwajalein, the model predicts the 3-m scattering cross-section measured by CUPRI to within a few decibels.

Sounding rocket data from the 1990 Combined Release and Radiation Effects Satellite (CRRES)/EQUIS equatorial spread F campaign on Kwajalein Atoll are presented. Two Terrier Malamute sounding rockets were launched into active spread F conditions on July 30 and August 2, respectively, and achieved apogee slightly below 500 km, just above the F peak. Plasma frequency probes aboard both rockets showed that the unstable nighttime F region is characterized by propagating steepened structures. Power density spectra for the structures typically exhibit two regions that obey k(exp -n) scaling, where n is approximately equal to 2 at wavelengths greater than 80-100 m and approximately equal to 5 at shorter wavelengths. These spectral indices are quiet variable, and the long-wavelength spectral index in particular seems to decrease with increasing amplitude of density fluctuations. The rocket payloads also measured vector electric fields in the plane perpendicular to B over wavelengths ranging from over 60 km to less than 6 m. Both vector components of the perpendicular electric field are proportional to delta n/n at wavelengths longer than 300 m but assume a Boltzmann relationship (with square of the absolute value of delta E approximately equal to (k(exp2))(square of the absolute value of (delta n/n)) at smaller scales. The perturbed zonal electric field, delta E(sub x), dominates the vertical field, delta E(sub z), at long wavelenghts, but the situation is reversed at smaller scales.

The Topaz3 auroral sounding rocket made the following observations concerning the transfer of precipitating auroral electron energy to transverse ion acceleration in the topside auroral zone. During the course of the flight, the precipitating electron beam was modified to varying degrees by interaction with VLF hiss, at times changing the beam into a field-aligned plateau. The electron distribution functions throughout the flight are classified according to the extent of this modification, and correspondences with ion acceleration events are sought. The hiss power during most of this rocket flight apparently exceeded the threshold for collapse into solitary structures. At the times of plateaued electron distributions, the collapse of these structures was limited by Landau damping through the ambient ions, resulting in a velocity-dependent acceleration of both protons and oxygen. This initial acceleration is sufficient to supply the number flux of upflowing ions observed at satellite altitudes. The bursty ion acceleration was anticorrelated, on 1-s or smaller timescales, with dispersive bursts of precipitating field-aligned electrons, although on longer timescales the bursty ions and the bursty electrons are correlated.

Electric field power spectra from two auroral sounding rocket flights show evidence of a distinct scale size regime for injection of energy into the auroral oval. The signature of this process is a broad plateau in the spectrum, with power law dependences at both shorter and longer scale sizes. We argue that the spectral properties at high k are dominated by processes occurring near the edges of inverted-V electron precipitation regions (auroral arcs). We see no compelling reason to conclude that a linear local plasma instability is occurring but rather, that nonlinear mixing and forward cascade yield the observed velocity field. The spectra of simultaneously observed density irregularities are quite different from those of the electric field, implying that the plasma density does not behave as a passive scalar in the auroral zone during active conditions. At low-k values we show that the rocket spectra are consistent with the power spectra of magnetospheric electric fields measured by the DE, AE-C, and Hilat stallites.

The critical ionization velocity (CIV) is an anomalous ionization mechanism first proposed by Alfven. Experiments have confirmed the existence of a critical velocity in laboratory experiments, but sounding rocket experiments have been ambiguous as to the existence of the critical velocity in the ionosphere. The purpose of this paper is to produce upper bound estimates of anomalous ion production in space-based experiments of the critical ionization velocity. The analysis relies on the results of implicit particle-in-cell simulations and a simple rate model to predict the number of ions produced as a neutral cloud traverses a point in space. The model assumes a point release of neutral gas in the ionosphere which is meant to represent a typical sounding rocket experiment. The results of the model suggest why strong evidence of CIV is not observed in space-based experiments. Space-based experiments require the anomalous ionization process to be initiated through seed ionization provided by charge exchange or other mechanisms. This seed ionization process is too slow in space experiments to ignite CIV. The results also indicate that some of the space based results can be accounted for by assuming a large barium-oxygen charge exchange cross section instead of invoking anomalous ionization mechanisms.

Wave and particle observations were made in the close vicinity of an argon plasma gun carned to over 600 km altitude on a sounding rocket. The gun was carned on a subpayload, separated from the main payload early in the flight. Twelve-second argon ion ejections were energized alternately with a peak energy of 100 or 200 eV. They produced waves, with multiple harmonics, in the range of ion cyclotron waves, 10 to 1000 Hz at rocket altitudes. Many of these waves could not be identified as corresponding to the cyclotron frequencies of any of the ions, argon or ambient, known to be present. In addition, the wave frequencies were observed to rise and fall and to change abruptly during a 12-s gun operation. The wave amplitudes, near a few hundred Hertz, were of the order of O. 1 V/m. Some of the waves may be ion-ion hybrid waves. Changes in ion populations were observed at the main payload and at the subpayload during gun operations. A gun-related, field-aligned, electron population also appeared.

The authors solve a linear numerical model of Alfven waves reflecting from the high-latitude ionosphere, both to better understanding the role of the ionosphere in the magnetosphere/ionosphere coupling process and to compare model results with in situ measurements. They use the model to compute the frequency-dependent amplitude and phase relations between the meridional electric and the zonal magnetic fields due to Alfven waves. These relations are compared with measurements taken by an auroral sounding rocket flow in the morningside oval and by the HILAT satellite traversing the oval at local noon. The sounding rocket's trajectory was mostly parallel to the auroral oval, and is measured enhanced fluctuating field energy in regions of electron precipitation. The rocket-measured phase data are in excellent agreement with the Alfven wave model, and the relation between the modeled and the measured by HILAT are related by the height-integrated Pedersen conductivity {Sigma}{sub p}, indicating that the measured field fluctuations were due mainly to structured field-aligned current systems. A reason for the relative lack of Alfven wave energy in the HILAT measurements could be the fact that the satellite traveled mostly perpendicular to the oval and therefore quickly traversed narrow regions of electron precipitation and associated wavemore » activity.« less

The paper reports data obtained from a sounding rocket flight which reached an apogee of 927 km and passed through several auroral arcs. Therma/superthermal ions were sampled by charged particle analyzers which allowed for a rapid (about 1 s) sampling of their distribution function. During portions of the flight when the rocket was not in an energetic auroral structure, the ion data are fit to a Maxwellian function which yields the plasma parameters. Throughout the middle portion of the flight, above 700-km altitude, ion distributions having a superthermal tail were measured. When the rocket was immersed in energetic auroral electron precipitation, two other ion distributions were observed. Transversely accelerated ions which represented bulk heating of the ambient population were observed continuously in these arcs. The characteristic perpendicular energy of the transversely bulk heated ions reached as high as 3 eV compared to typically less than 0.4 eV during nonauroral times. The observations are discussed in terms of some current theories of transverse ion energization.

The Echo 7 sounding rocket experiment injected electron beams on central tail field lines near L = 6.5. Numerous injections returned to the payload as 'conjugate echoes' after mirroring in the southern hemisphere. Field line lengths calculated from measured conjugate echo bounce times and energies are compared to predictions made by integrating electron trajectories through various magnetospheric models. Although Kp at launch was 3-, quiet time magnetic models best fit the echo measurements. Geosynchronous satellite magnetometer measurements near the Echo 7 field lines during the flight were best modeled by the Olson-Pfitzer Dynamic Model and the Tsyganenko-Usmanov model for Kp = 3. The discrepancy between the models that best fit the Echo 7 data and those that fit the satellite data was most likely due to uncertainties in the small-scale configuration of the magnetospheric models. The field line length measured by the conjugate echoes showed some temporal variation in the magnetic field, also indicated by the satellite magnetometers. This demonstrates the utility an Echo-style experiment could have in substorm studies.

Bispectral analysis has been applied to density irregularities at frequencies 5-30 Hz observed with a sounding rocket launched from Peru in March 1983. Unlike the power spectrum, the bispectrum contains statistical information about the phase relations between the Fourier components which make up the waveform. In the case of spread F data from 475 km the 5-30 Hz portion of the spectrum displays overall enhanced bicoherence relative to that of the background instrumental noise and to that expected due to statistical considerations, implying that the observed f exp -2.5 power law spectrum has a significant non-Gaussian component. This is consistent with previous qualitative analyses. The bicoherence has also been calculated for simulated equatorial spread F density irregularities in approximately the same wavelength regime, and the resulting bispectrum has some features in common with that of the rocket data. The implications of this analysis for equatorial spread F are discussed, and some future investigations are suggested.

Observations of the UV fluorescent emissions of the NO (1, 0) and (0, 1) gamma bands in the lower-thermospheric dayglow, made with a sounding rocket launched on March 7, 1989 from Poker Flat, Alaska, were analyzed. The resonant (1, 0) gamma band was found to be attenuated below an altitude of about 120 km. A self-absorption model based on Holstein transmission functions was developed for the resonant (1, 0) gamma band under varying conditions of slant column density and temperature and was applied for the conditions of the rocket flight. The results of the model agreed with the measured attenuation of the band, indicating the necessity of including self-absorption theory in the analysis of satellite and rocket limb data of NO.

The average wavelengths of VLF emissions in the auroral ionosphere were measured as a function of frequency using an orthogonal antenna technique. The measurements, made by an auroral sounding rocket, were sensitive to wavelengths between ∼5 m and ∼300 m for wave frequencies from 20 Hz to 10 kHz. The emissions just above the lower hybrid frequency had wavelengths of 12 m or less in many cases, increasing with increasing frequency. The measured wavelengths were such that the VLF emissions were resonant with electrons whose energies were a few hundred eV, whereas the inverted-V electrons had energies of ∼20 keV. Bursts of low-energy (

Data are presented on the evolution of electric field structures near the MAIMIK mother-daughter tethered rocket during active electron emissions from the rocket, which consisted of two separately instrumented payload sections which were detached in-flight. The results of the E field data analysis show that the temporal behavior of the fields was consistent with ion responses to the rapid charging of the active payload. A qualitative model of the interaction between the active payload and the ambient plasma background is developed to explain the electric field data, including the apparent causal relationship between the radial and tangential impulse components.

The tethered sounding rocket payload OEDIPUS A conducted bistatic propagation experiments on plasma waves in the auroral ionosphere. Synchronized sweeps of the frequency range 0-5 MHz by the 2-W transmitter high-frequency exciter (HEX) on the upper end of the tether and its associated receiver for exciter (REX) on the lower end have produced signatures of quasi-electrostatic waves guided along field-aligned depletions of ambient density. The propagation is in the slow Z mode, between the plasma frequency f{sub p} and the upper hybrid resonance frequency f{sub uhr} when f{sub p} is greater than the cyclotron frequency. The mode identification is based on payload measurements of f{sub p}. These waves have signal delays of about 1 ms. The delays are much greater than expected for free-space propagation over the transmitter-receiver separation distance which varies up to 960 m during the flight. The transmitted pulses typically appear inside a frequency bandwidth of about 100 kHz just above the plasma frequency, but occasionally occupy most of the available bandwidth, {approx equal}300 kHz, between f{sub p} and f{sub uhr}. The observed delays and the stretching by a factor of 3 of the transmitted 300-{mu}s pulses are accounted for with two-dimensional ray tracing using a completemore » electromagnetic solution of the hot plasma dispersion relation. Delayed Z mode pulses appear in about 20% of the ionograms. Given the weakness of the HEX transmitter and the abundance of examples obtained during the flight, guiding of natural Z mode emissions in the auroral ionosphere may be efficient and widespread.« less

Two recent sounding rocket experiments have yielded VLF wave data with spectral structures ordered by the hydrogen gyrofrequency. The spectral structures occur near and above the lower hybrid frequency in association with auroral hiss. These structures are observed within and near regions of auroral electron precipitation and transverse ion acceleration. They are accompanied by auroral hiss but are anticorrelated with spectral peaks at the lower hybrid frequency. They are typically found above 500 km altitude, have no measurable magnetic component, and are at least occasionally short wavelength. Because the spectral structures appear to be electrostatic, are ordered by the hydrogen gyrofrequency, and are short wavelength, the structures are interpreted as modes which connect the lower hybrid mode with the hydrogen Bernstein modes. A study of the plasma wave mode structure in the vicinity of the lower hybrid frequency is presented to substantiate this interpretation. These results imply that these waves are a common feature of the auroral zone ionsphere above 500 km altitude and exist any time that auroral hiss exists. The absence of previous satellite observations of this phenomenon can be explained by Doppler broadening.

Electron detectors on the Echo 7 active sounding rocket experiment measured 'conjugate echoes' resulting from artificial electron beam injections. Analysis of the drift motion of the electrons after a complete bounce leads to measurements of the magnetospheric convection electric field mapped to ionospheric altitudes. The magnetospheric field was highly variable, changing by tens of mV/m on time scales of as little as hundreds of millisec. While the smallest-scale magnetospheric field irregularities were mapped out by ionospheric conductivity, larger-scale features were enhanced by up to 50 mV/m in the ionosphere. The mismatch between magnetospheric and ionspheric convection fields indicates a violation of the equipotential field line condition. The parallel fields occurred in regions roughly 10 km across and probably supported a total potential drop of 10-100 V.

Results are presented on the solar EUV irradiance measurements in the range 30-100 nm obtained in a sounding rocket experiment launched from the White Sands Missile Range, New Mexico, on November 10, 1988. The observed solar EUV irradiance was found to be about 20 percent less than the solar EUV flux from a proxy model based on the daily 10.7-cm solar flux and its 81-day mean and the AE-E solar EUV data taken in the 1970s. The November 10 measurement of the solar EUV flux provides a good calibration reference spectrum for the solar EUV instruments on the San Marco satellite.

Accepted: 1989-11-09, 資料番号: SA1001632000

A newly developed stable and high quantum efficiency silicon photodiode was used to obtain an accurate measurement of the integrated absolute magnitude of the solar extreme UV photon flux in the spectral region between 50 and 800 A. The adjusted daily 10.7-cm solar radio flux and sunspot number were 168.4 and 121, respectively. The unattenuated absolute value of the solar EUV flux at 1 AU in the specified wavelength region was 6.81 x 10 to the 10th photons/sq cm per s. Based on a nominal probable error of 7 percent for National Institute of Standards and Technology detector efficiency measurements in the 50- to 500-A region (5 percent on longer wavelength measurements between 500 and 1216 A), and based on experimental errors associated with the present rocket instrumentation and analysis, a conservative total error estimate of about 14 percent is assigned to the absolute integral solar flux obtained.

Coordinated simultaneous measurements with the EISCAT incoherent scatter radar, Aureld-VIP sounding rocket, and Viking satellite are described. Background measurements from EISCAT provide us with the development of global plasma convection during the rocket night. The observed convection pattern is very distorted, with the eveningside reversal occurring at unusually low latitudes. On the morningside it withdraws back poleward from the measurement area. Viking particle measurements over the oval indicate a very complicated auroral topology with two sectors of boundary plasma sheet (BPS) and central plasma sheet (CPS) particles. The situation is interpreted as an intrusion of the evening side BPS into the morningside, which is also consistent with the convection pattern measured by EISCAT. Local measurements with the sounding rocket and radar indicate that the rocket flew in the northern part of the evening BPS area, approaching the “inner” transition region from BPS to CPS in its northward motion, thus confirming the existence of such a boundary.

Shear Alfven waves with amplitudes greater than 100 mV/m were observed on two recent sounding rocket flights. The largest waveforms are best described as a series of step functions, rather than as broadband noise or as single frequency waves. Complete two-dimensional E and B measurements at 4-ms time resolution were made, showing a downward propagation direction and implying insignificant reflection from the ionosphere at frequencies greater than 1 Hz. Intense, field-aligned, low-energy electron fluxes accompany the waves. Acceleration of these electrons by the Alfven waves is shown to be feasible. The waves in at least one case have a sufficently large ponderomotive potential to generate the observed density fluctuations of order one.

Two sounding rockets were used to simultaneously place two payloads on nearly the same magnetic field lines in the late-evening auroral zone. The dc electric field measurements obtained by the payloads imply a parallel potential of several kV below the higher payload, probably occurring between the two payloads. No possible resistive mechanism in observed in the 100 Hz-10 kKz band which could support the parallel field; this implies the existence of resistance-generating turbulence which are either at other frequencies, or of a type not measured by the probes, or localized parallel potentials not coincident with the payload trajectories.

A summary of auroral proton observations from 12 sounding rockets launched from Churchill Research Range is presented. Although these rockets were launched into different auroral conditions and at various local times, certain characteristics were observed in all flights. Energy spectra were peaked in the 5- to 10-keV energy intervals with typical intensities near 10$sup 5$ cm$sup -2$ s$sup -1$ sr$sup -1$ keV$sup -1$. Proton pitch angle distributions in the loss cone were isotropic at all energies less than 20 keV. At higher energies, distributions were either isotropic or anisotropic peaked near 90degree pitch angle. Temporal and spatial structure was observed in proton precipitation with typical time scales of the order of 100 equatorial gyroperiods and scale lengths of the order of 100 gyrodiameters. No obvious electron proton correlations were apparent in any of the data. Observations of interactions of the primary proton beam with the neutral atmosphere are presented. Beam spreading effects due to charge exchange interactions are demonstrated, and equilibrium fractions for protons in the atmosphere are measured and compared with relevant laboratory observations. The implication of these results concerning auroral proton source regions and precipitation mechanisms is discussed. (AIP)

On August 13, 1970, a sounding rocket launched from Wallops Island, Virginia, was used to successfully inject a controlled beam of energetic electrons into the trapping region of the earth's magnetosphere. The Aerobee 350 rocket carried a high-voltage electron gun, electron detectors, receivers to measure the electric field of waves generated by the experiment, and other apparatus to a peak altitude of 350 km. During a 10-min flight, more than 3000 16-ms-long 70-mA pulses of 35- to 43-keV electrons were injected into the magnetosphere with pitch angles within 25° of the local 90° mirror angle. The electrons, trapped in the geomagnetic field, bounced between the mirror point near the rocket and the southern conjugate point (−66° latitude, −82° longitude) while they were drifting eastward across field lines on a drift shell of constant McIlwain L parameter (2.56) under the gradient and curvature forces. Since Wallops Island conjugate mirror altitudes are at least 300 km lower than the injection altitudes, all returning electrons were backscattered from the atmosphere in the southern hemisphere. The rocket was launched eastward in an attempt to intercept the returning electrons, and for a 90-s interval about L apogee, electrons were detected returning from one, two, and in one case, three complete bounces to the southern hemisphere. The analyzed electron data agree well with echo patterns predicted from theoretical particle motion in models of the geomagnetic field combined with Monte Carlo studies of energy loss and diffusion in the conjugate point atmosphere. Observed bounce times, drift displacements, and cross L diffusion were in substantial agreement with theory. However, the returning flux was lower than predicted, and discrepancies between theory and experiment were observed at large diffusion distances. This experiment, Electron Echo 1, verified the concept of using controlled particle beams as magnetospheric probes, showing that such beams are sufficiently stable to be intercepted after bounces to the conjugate point and back.

Measurements of electron backscatter and photon fluxes at 3914 A excited by a 40-keV artificial electron beam were made on an ionospheric sounding rocket. Echo 3 launched from Fairbands, Alaska, on April 17, 1974. The backscattered electron fluxes were found to have a constant value independent of altitude, indicating no dependence on the atmospheric density and being several orders of magnitude higher than that predicted by Coulomb scattering. This result confirms measurements on the Echo 1 and 2 experiments. The origin of this anomalous scattering has not been identified. In contrast, photon emission from the ambient atmosphere excited by the beam at 3914 A varied directly with the change in the density of N$sub 2$ molecules. A rocket 'halo' of high-intensity backscattering and photon emission accompanied beam injections close to 90degree local magnetic pitch angle and was probably caused by beam scattering from the rocket.

A Black Brant VB sounding rocket was launched at 03h 56m 05s UT on August 17, 1970, into the expansion phase of a major magnetospheric substorm during which the perturbation magnetic field was in excess of 2000 γ at ground level. Measurements of the electric field component perpendicular to the earth's magnetic field made by double-probe detectors on board the rocket and by observation of the motion of two barium ion clouds released from the same rocket were in excellent agreement. The rocket remained within a region of intense particle precipitation where the field was 15°–45° south of geomagnetic west with a magnitude between 60 mV/m and 90 mV/m. The barium clouds drifted southeast into a region of weak aurora and smaller electric field. These measurements show that the electric field is not always smallest inside auroral arcs and that the poleward auroral expansion phase is not accompanied by poleward ionospheric plasma motion and suggest a divergence of the northward perpendicular ionospheric current and hence that a downward field-aligned current was present in the equatorward portion of the arc structure. During a portion of the flight the double-probe detectors also measured a parallel component of electric field between 10 and 24 mV/m which pointed downward toward the earth. The total electric field detected on board the rocket was deduced by two techniques: one technique which does not involve assumptions involving dc offsets of the detector but relies on the precessional motion of the rocket to separate E⊥ and E∥ and one high time resolution technique which involves an assumption that these offsets approach a constant value in the flight. The same basic conclusions were deduced from both techniques. When the possibility of current-driven anomalous resistivity due to ion acoustic waves is taken into account, the measurements are in agreement with a slow parallel motion of ambient plasma ions (

An auroral sounding rocket was launched from Fort Churchill at 0453 UT on April 24, 1968. At the time of the rocket flight, the Vela 3B satellite was passing through the magnetotail plasma sheet at very nearly the same magnetic local time. Electron spectra obtained from experiments on these vehicles are well described by central Maxwell-Boltzmann populations, with indications of a high-energy tail; the satellite spectra also suggest the presence of a low-energy tail. The higher-temperature spectra measured on the rocket may be derived from the satellite spectra by adiabatic compression.

An investigation is conducted concerning the conditions encountered during a Javelin sounding rocket experiment conducted on Apr. 3, 1970 at Fort Churchill, Canada. Evidence is presented that near the equatorward edge of the auroral arc an intense beam of cold plasma ions was flowing parallel to the earth's magnetic field. The beam was associated with intense narrow band electric field oscillations near the local ion gyrofrequency. The data support the hypothesis that intense electrostatic ion cyclotron waves were driven unstable by field-aligned currents.

Vector magnetic field measurements made during a sounding rocket flight in the polar cusp ionosphere show field fluctuations in the lower F-region which are interpreted as being caused by the payload's passage through a structured field aligned current system. The field aligned currents have a characteristic horizontal scale size of one kilometer. Analysis of one large field fluctuation gives a current density of 0.0001 amp/m sq.

The intensity of the He II 304-A radiation in the night sky was measured from a sounding rocket launched from White Sands Missile Range on June 9, 1972. The data obtained on this flight are compared with predictions of theoretical models of the He(+) altitude distribution within the plasmasphere. The observations are not consistent with an isothermal equilibrium model of the helium ion in the plasmasphere, confirming earlier results. The data are best fit by a diffussive equilibrium model of exospheric He(+) having a plasma temperature gradient of 0.5 K per km and a number density at 1600 km of 200,000 He(+) ions per cu cm. In this model the ion densities are calculated without allowance for thermal diffusion. A similar model that allows for thermal diffusion and that has a He(+) number density at 1600 km of 1500 per cu cm and a temperature gradient of 1.2 K per km yields a less satisfactory fit to the observations but is more consistent with in situ satellite observations.

A Nike Tomahawk sounding rocket was launched into a 400-gamma auroral substorm from Esrange, Kiruna, Sweden. The rocket instrumentation included a split Langmuir-probe plasma-velocity detector and a double-probe electric-field detector. Above 140-km altitude, the electric field deduced from the ion-flow velocity measurement and the electric field measured by the double probe agree to an accuracy within the uncertainties of the two measurements. The difference between the two measurements at altitudes below 140 km provides an in situ measurement of current density and conductivity. Alternatively, if values for the conductivity are assumed, the neutral-wind velocity can be deduced. The height-integrated current was 0.11 A/m flowing at an azimuth angle of 276 deg. The neutral winds were strong, exhibited substantial altitude variation in the east-west component, and were predominantly southward.

An auroral ion charge spectrometer was flown into a hydrogen aurora on a Javelin sounding rocket launched from Churchill, Manitoba. The instrument contained an electrostatic analyzer which selected particles with incident energy per unit charge up to 20 keV/charge and an 80-kV power supply which accelerated these ions onto an array of solid state detectors. Ions tentatively identified as H(+), He(+2), and O(+) were detected from 225 to 820 km in altitude. The experiment did not discriminate between H(+) and He(+), or between O(+), N(+), and C(+). Upper limits of highly charged heavy ion abundances have been set at 20% of the He(+2) and 0.15% of the H(+). It is concluded that both terrestrial and solar wind sources play significant roles in auroral ion precipitation.

Two rockets carrying electric field and low energy particle instrumentation were launched near noon at 80 deg magnetic latitude. One flight encountered polar cap conditions only while the other traversed part of the polar cusp. Although weak particle precipitation was measured on both flights, bursts of intense magnetosheath-type electron fluxes were detected on the latter. Strong electric fields such as would result from anti-sunward convection were observed during both flights. The measurements are compared with results obtained by other types of space craft and interpreted in the light of those data.

Two Nike-Apache payloads were launched into noctilucent cloud (NLC) displays from Esrange, Sweden in the summer of 1971 and two in the summer of 1973. A two-color photopolarimeter was part of the multiexperiment payload that included the Pandora collector of Dudley Observatory. The absolute brightness and degree of polarization are used to determine the size and number density of NLC particles. The Pandora collection size distribution and two arbitrary size distributions of ice, iron, and nickel are compared with the observations. The observed brightness and polarization suggests that the particles are principally less than 0.13-μm radius with number density of 106 particles/m3. The difference between the optical and the collection results suggests that either a large number of particles are undetected by collection or a significant number of the particles are the result of nucleation on complex ions.