Theory of short-scale field-aligned density striations due to ionospheric heating

NASA Technical Reports Server (NTRS)

Lee, M.-C.; Fejer, J. A.

1978-01-01

The theoretical saturation spectrum of parametrically excited Langmuir waves in a locally uniform ionosphere is shown by the present calculations to produce, by ohmic dissipation, short-scale field-aligned density striations. The spectrum of the calculated striations is not inconsistent with observations of field-aligned scatter of VHF and UHF waves in ionospheric modification experiments if local increases of the pump field due to focusing are invoked.

Simulations and observations of plasma depletion, ion composition, and airglow emissions in two auroral ionospheric depletion experiments

NASA Technical Reports Server (NTRS)

Yau, A. W.; Whalen, B. A.; Harris, F. R.; Gattinger, R. L.; Pongratz, M. B.

1985-01-01

Observations of plasma depletion, ion composition modification, and airglow emissions in the Waterhole experiments are presented. The detailed ion chemistry and airglow emission processes related to the ionospheric hole formation in the experiment are examined, and observations are compared with computer simulation results. The latter indicate that the overall depletion rates in different parts of the depletion region are governed by different parameters.

Modeling of N2 and O optical emissions for ionosphere HF powerful heating experiments

NASA Astrophysics Data System (ADS)

Sergienko, T.; Gustavsson, B.

Analyses of experiments of F region ionosphere modification by HF powerful radio waves show that optical observations are very useful tools for diagnosing of the interaction of the probing radio wave with the ionospheric plasma Hitherto the emissions usually measured in the heating experiment have been the 630 0 nm and the 557 7 nm lines of atomic oxygen Other emissions for instance O 844 8 nm and N2 427 8 nm have been measured episodically in only a few experiments although the very rich optical spectrum of molecular nitrogen potentially involves important information about ionospheric plasma in the heated region This study addresses the modeling of optical emissions from the O and the N2 triplet states first positive second positive Vegard-Kaplan infrared afterglow and Wu-Benesch band systems excited under a condition of the ionosphere heating experiment The auroral triplet state population distribution model was modified for the ionosphere heating conditions by using the different electron distribution functions suggested by Mishin et al 2000 2003 and Gustavsson at al 2004 2005 Modeling results are discussed from the point of view of efficiency of measurements of the N2 emissions in future experiments

Electromagnetic radiation by parametric decay of upper hybrid waves in ionospheric modification experiments

DOE Office of Scientific and Technical Information (OSTI.GOV)

Leyser, T.B.

1994-06-01

A nonlinear dispersion relation for the parametric decay of an electrostatic upper hybrid wave into an ordinary mode electromagnetic wave, propagating parallel to the ambient magnetic field, and an electrostatic low frequency wave, being either a lower hybrid wave or a high harmonic ion Bernstein wave, is derived. The coherent and resonant wave interaction is considered to take place in a weakly magnetized and collisionless Vlasov plasma. The instability growth rate is computed for parameter values typical of ionospheric modification experiments, in which a powerful high frequency electromagnetic pump wave is injected into the ionospheric F-region from ground-based transmitters. Themore » electromagnetic radiation which is excited by the decaying upper hybrid wave is found to be consistent with the prominent and commonly observed downshifted maximum (DM) emission in the spectrum of stimulated electromagnetic emission.« less

Effects of ionospheric modification on system performance

NASA Astrophysics Data System (ADS)

Ganguly, Suman

1989-12-01

Controlled ionospheric modification can be used for disrupting as well as facilitating communication and radar systems. After briefly describing the results achieved with the present day ionospheric modification facilities, a scenario is presented for the generation of strong and significant ionospheric modification. A few schemes are presented for the development of modern high power facilities using the state of the art technology and then the impact of such facilities on the system performance is described.

Generation of Artificial Acoustic-Gravity Waves and Traveling Ionospheric Disturbances in HF Heating Experiments

NASA Astrophysics Data System (ADS)

Pradipta, R.; Lee, M. C.; Cohen, J. A.; Watkins, B. J.

2015-10-01

We report the results of our ionospheric HF heating experiments to generate artificial acoustic-gravity waves (AGW) and traveling ionospheric disturbances (TID), which were conducted at the High-frequency Active Auroral Research Program facility in Gakona, Alaska. Based on the data from UHF radar, GPS total electron content, and ionosonde measurements, we found that artificial AGW/TID can be generated in ionospheric modification experiments by sinusoidally modulating the power envelope of the transmitted O-mode HF heater waves. In this case, the modulation frequency needs to be set below the characteristic Brunt-Vaisala frequency at the relevant altitudes. We avoided potential contamination from naturally-occurring AGW/TID of auroral origin by conducting the experiments during geomagnetically quiet time period. We determine that these artificial AGW/TID propagate away from the edge of the heated region with a horizontal speed of approximately 160 m/s.

High latitude artificial periodic irregularity observations with the upgraded EISCAT heating facility

NASA Astrophysics Data System (ADS)

Vierinen, Juha; Kero, Antti; Rietveld, Michael T.

2013-12-01

We present a recently developed ionospheric modification experiment that produces artificial periodic irregularities in the ionosphere and uses them to make observations of the spatiotemporal behaviour of the irregularities. In addition, the method can be used to measure Faraday rotation and vertical velocities. We also introduce a novel experiment that allows monitoring the formation of the irregularities during heating, in addition to observing their decay after heating. The first measurements indicate, contrary to existing theory, that the amplitude of the radar echoes from the periodic irregularities grows faster than they decay. We focus on the API effects in the D- and E-region of the ionosphere.

Optical Emissions Enhanced by O and X Mode Ionosphere HF Pumping: Similarities and Differences

NASA Astrophysics Data System (ADS)

Sergienko, T.; Brandstrom, U.; Gustavsson, B.; Blagoveshchenskaya, N. F.

2013-12-01

Strong enhancement of the optical emissions with excitation thresholds from 1.96 eV up to 18.75 eV have been observed during experiments of ionosphere modification by high power HF radio waves since the early 1970s. Up to now all these emissions were observed only during the interaction of the O-mode HF radio wave with the ionospheric plasma. On 19 October 2012, during an EISCAT heating experiment, strong optical emissions were observed by ALIS, in first time, for X-mode ionosphere pumping. While for O-mode heating the optical emission enhancements can be explained by the ionospheric electron heating and acceleration due to the nonlinear interaction of the powerful radio wave with ionosphere, the mechanism responsible for the emission enhancements during the X-mode heating is not known. In the experiment optical emissions have been measured in three different wave-lengths simultaneously from four ALIS stations. The emission intensity ratios as well as the characteristics of the spatial distribution of the enhanced optical emissions provide important information on the possible mechanisms of the radio wave - ionosphere interaction. In this report we present the results of comparison of the characteristics of the optical emissions caused by X-mode heating with the characteristics of the emissions enhanced by O-mode measured during same experiment.

Measurements of the ionospheric reaction to exhaust from dedicated burns of the space shuttle’s orbital maneuvering system engines over Kwajalein

NASA Astrophysics Data System (ADS)

Caton, R. G.; Groves, K. M.; Pedersen, T. R.; Hysell, D. L.; Carrano, C. S.; Bernhardt, P. A.; Tsunoda, R. T.; Coster, A. J.

2009-12-01

In a continuation of the Shuttle Ionospheric Modification with Pulsed Localized Exhaust (SIMPLEX) experiment, a series of Orbiting Maneuver Subsystem (OMS) engine burns from the space shuttle have been carried out over Kwajalein Atoll in the Republic of the Marshall Islands. Exhaust from the shuttle’s two OMS engines consists of CO, CO2, H2, H20, and N2, each of which interact with the background ionosphere (predominately O+) through charge exchange resulting in electron “holes.” Such interactions have been detected from the ground with radars, optical imagers, and GPS TEC measurements and from space with satellites such as the Communication/Navigation Outage Forecasting System (C/NOFS) in the Shuttle Exhaust Ion Turbulence Experiment (SEITE). In this talk, we present signatures of ionospheric modification resulting from OMS burns during recent shuttle missions observed in incoherent scatter returns on the ARPA Long-range Tracking And Instrumentation Radar (ALTAIR) and in optical data from an All-Sky Imager. GPS TEC measurements are investigated for evidence of depletions resulting from post-burn molecular recombination. Space Shuttle OMS Engine Burn

Recent Advances in Studies of Ionospheric Modification Using Rocket Exhaust (Invited)

NASA Astrophysics Data System (ADS)

Bernhardt, P. A.

2009-12-01

Rocket exhaust interacts with the ionosphere to produce a wide range of disturbances. A ten second burn of the Orbital Maneuver Subsystem (OMS) engines on the Space Shuttle deposits over 1 Giga Joule of energy into the upper atmosphere. The exhaust vapors travel at speeds between 4.7 and 10.7 km/s coupling momentum into the ions by both collisions and charge exchange. Long-lived plasma irregularities are formed by the artificial hypersonic “neutral wind” passing through the ionosphere. Charge exchange between the fast neutrals and the ambient ions yields high-speed ion beams that excite electro-static plasma waves. Ground based radar has been used to detect both field aligned irregularities and electrostatic turbulence driven by the Space Shuttle OMS exhaust. Molecular ions produced by the charge exchange with molecules in the rocket exhaust recombine with a time scale of 10 minutes leaving a residual plasma depression. This ionospheric “hole” fills in by ambipolar diffusion leaving a depleted magnetic flux tube. This large scale reduction in Pedersen conductivity can provide a seed for plasma interchange instabilities. For instance, a rocket firing on the bottom side of the ionosphere near the equator can trigger a Rayleigh-Taylor instability that is naturally seen as equatorial Spread-F. The Naval Research Laboratory has been exploring these phenomena with dedicated burns of the Space Shuttle OMS engines and exhaust releases from rockets. The Shuttle Ionospheric Modification with Pulsed Localized Exhaust (SIMPLEX) series of experiments uses ground radars to probe the ionosphere affected by dedicated burns of the Space Shuttle OMS engines. Radars located at Millstone Hill, Massachusetts; Arecibo, Puerto Rico; Jicamarca, Peru; Kwajalein, Marshall Island; and Alice Springs, Australia have participated in the SIMPLEX program. A companion program called Shuttle Exhaust Ionospheric Turbulence Experiment has or will use satellites to fly through the turbulence ionosphere produced by Space Shuttle Exhaust. This program is employing the Air Force Research Laboratory C/NOFS and the Canadian CASSIOPE/EPoP satellites to make in situ measurements of Space Shuttle exhaust effects. Finally, NRL is conducting the Charged Aerosol Release Experiment which employs a solid rocket motor to modify the ionosphere using supersonic particulate injection and dusty plasma formation. Both the theoretic basis for these experiments and as summary of the experimental results will be presented.

Modeling and design for a new ionospheric modification experiment

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sales, G.S.; Platt, I.G.; Haines, D.M.

1990-10-01

Plans are now underway to carry out new HF oblique ionospheric modification experiments with increased radiated power using a new high gain antenna system and a 1 MW transmitter. The output of this large transmitting system will approach 90 dBW. An important part of this program is to determine the existence of a threshold for non-linear effects by varying the transmitter output. For these experiments we are introducing a new ET probe system, a low power oblique sounder, to be used along the same propagation path as the high power disturbing transmitter. This concept was first used by soviet researchersmore » to insure that this diagnostic signal always passes through the modified region of the ionosphere. The HF probe system will use a low power (150 W) CW signal shifted by approximately 40 kHz from the frequency used by the high power system. The transmitter for the probe system will be at the same location as the high power transmitter while the probe receiver will be 2400 km down range. The probe receiving system uses multiple antennas to measure the the vertical and azimuthal angle of arrival as well the Doppler frequency shift of the arriving probe signal. The three antenna array will be in an L configuration to measure the phase differences between the antennas. At the midpath point a vertical sounder will provide the ionospheric information necessary for the frequency management of the experiment. Real-time signal processing will permit the site operators to evaluate the performance of the system and make adjustments during the experiment. A special ray tracing computer will be used to provide real-time frequencies and elevation beam steering during the experiment. A description of the system and the analysis used in the design of the experiment are presented.« less

Analysis of the backscatter spectrum in an ionospheric modification experiment

NASA Technical Reports Server (NTRS)

Kim, H.; Crawford, F. W.; Harker, K. J.

1976-01-01

The purpose of this study is to compare predictions of the backscatter spectrum, including effects of ionospheric inhomogeneity, with experimental observations of incoherent backscatter from an artificially heated region. Our calculations show that the strongest backscatter echo received is not from the reflection level but from a region some distance below (about 900-1100 m for an experiment carried out at Arecibo). By taking the standing wave pattern of the pump properly into account the present theory explains certain asymmetrical features of the upshifted and downshifted plasma lines in the backscatter spectrum.

Full-Wave Radio Characterization of Ionospheric Modification at HAARP

DTIC Science & Technology

2015-07-26

Full-Wave Radio Characterization of Ionospheric Modification at HAARP We have studied electrostatic and electromagnetic turbulence stimulated by...radio receivers at HAARP in Alaska, and ground-based radio receivers, incoherent scatter radars, and in-situ measurements from Canadian, ESA, and Polish...363255 San Juan, PR 00936 -3255 31-May-2015 ABSTRACT Final Report: Full-Wave Radio Characterization of Ionospheric Modification at HAARP Report Title We

Ground and Space-Based Measurement of Rocket Engine Burns in the Ionosphere

NASA Technical Reports Server (NTRS)

Bernhardt, P. A.; Ballenthin, J. O.; Baumgardner, J. L.; Bhatt, A.; Boyd, I. D.; Burt, J. M.; Caton, R. G.; Coster, A.; Erickson, P. J.; Huba, J. D.;

Remote sensing of ELF/VLF radiation induced in experiments on artificial modification of the ionosphere

NASA Astrophysics Data System (ADS)

Gavrilov, B. G.; Zetser, Yu. I.; Ryakhovskii, I. A.; Poklad, Yu. V.; Ermak, V. M.

2015-07-01

In 2012, remote measurements of electromagnetic signals in the ELF/VLF band were taken at different points in Russia during experiments on artificial ionospheric modification with the powerful HF wave at the EISCAT heating facility (Tromsø, Norway). The use of the new, highly sensitive magnetometric equipment allowed signals with an amplitude of a few femtoteslas to be recorded at a distance of up to 2000 km from the source. Analysis of the measurement results discovered substantial differences in the amplitude-phase characteristics of the signals, which were caused by a change in helio-geophysical conditions in the region of heating and along the signal passage route, and features of signal propagation, which are related to their mode of guided propagation, the directivity of the source, and angles of reception.

Basis of Ionospheric Modification by High-Frequency Waves

DTIC Science & Technology

2007-06-01

for conducting ionospheric heating experiments in Gakona, Alaska, as part of the High Frequency Active Auroral Research Program ( HAARP ) [5], is being...upgraded. The upgraded HAARP HF transmitting system will be a phased-array antenna of 180 elements. Each element is a cross dipole, which radiates a...supported by the High Frequency Active Auroral Research Program ( HAARP ), the Air Force Research Laboratory at Hanscom Air Force Base, MA, and by the Office

Analysis of the backscatter spectrum in an ionospheric modification experiment

NASA Technical Reports Server (NTRS)

Kim, H.; Crawford, F. W.; Harker, K. J.

1974-01-01

Predictions of the backscatter spectrum, including effects of ionospheric inhomogeneity, are compared with experimental observations of incoherent backscatter from an artificially heated region. Our calculations show that the strongest backscatter echo received is not from the reflection level, but from a region some distance below. Certain asymmetrical features are explained of the up-shifted and down-shifted plasma lines in the backscatter spectrum, and the several satellite peaks accompanying them.

Multiple-Station Observation of Frequency Dependence and Polarization Characteristics of ELF/VLF waves generated via Ionospheric Modification

NASA Astrophysics Data System (ADS)

Maxworth, A. S.; Golkowski, M.; Cohen, M.; Moore, R. C.

2014-12-01

Generation of Extremely Low Frequency (ELF) and Very Low Frequency (VLF) signals through ionospheric modification has been practiced for many years. Heating the lower ionosphere with high power HF waves allows for modulation of natural current systems. Our experiments were carried out at the High Frequency Active Auroral Research Program (HAARP) facility in Alaska, USA. In this experiment, the ionosphere was heated with a vertical amplitude modulating signal and the modulation frequency was changed sequentially within an array of 40 frequencies followed by a frequency ramp. The observed magnetic field amplitude and polarization of the generated ELF/VLF signals were analyzed for multiple sites and as a function of modulation frequency. Our three observation sites: Chistochina, Paxson and Paradise are located within 36km (azimuth 47.7°), 50.2km (azimuth -20°) and 99km (azimuth 80.3°) respectively. We show that the peak amplitudes observed as a function of frequency result from vertical resonance in the Earth-ionosphere waveguide and can be used to diagnose the D-region profile. Polarization analysis showed that out of the three sites Paxson shows the highest circularity in the magnetic field polarization, compared to Chistochina and Paradise which show highly linear polarizations. The experimental results were compared with a theoretical simulation model results and it was clear that in both cases, the modulated Hall current dominates the observed signals at Chistochina and Paradise sites and at Paxson there is an equal contribution from Hall and Pedersen currents. The Chistochina site shows the highest magnetic field amplitudes in both experimental and simulation environments. Depending upon the experimental and simulation observations at the three sites, a radiation pattern for the HAARP ionospheric heater can be mapped

Comparison of incoherent scatter radar observations of SIMPLEX electron density depletion with SAMI2 and SAMI3 model results

NASA Astrophysics Data System (ADS)

Bhatt, A.; Huba, J. D.; Bernhardt, P. A.; Erickson, P. J.

2010-12-01

The Space Shuttle's Orbital Maneuvering System (OMS) engines have been used for active ionospheric modification experiments employing ground based ionospheric radars as diagnostic tools. These experiments initiated by the Naval Research Laboratory in 1995 have been scheduled as the Shuttle Ionospheric Modification with Pulsed Localized Exhaust or SIMPLEX through the US Dept. of Defense's Space Test Program. During 2009, two SIMPLEX experiments with the shuttles STS-119 and STS-128 were viewed by the Millstone Hill 440 MHz radar in Westford, MA operated by the MIT Haystack Observatory. The objectives of these experiments were to observe local ion-acoustic turbulence and the ionospheric density irregularities created by the exhaust injection across the magnetic field that present a Bragg scattering target for the radar. The exhaust also creates a depletion in the background electron density at F-region altitudes that persists for a relatively long time and is readily detected by an incoherent scatter radar. The OMS engine burns release 10 kg/s of H2O, CO2, H2, and N2 molecules that charge exchange with ambient O+ ions at the F region heights, producing molecular ions and the electron density depletion due to the recombination with the ambient electrons. 2009 was a year of deep solar minimum that saw the background electron density values 19% lower than were expected during a solar minimum. (Emmert et al., GRL, 2010). We believe that the long recovery time from density depletion in SIMPLEX experiments of 2009 may have a root in the unique nature of the deep solar minimum. The density whole production and recovery will be modeled using NRL SAMI2 and SAMI3 model and the results will be discussed along with the observations using the incoherent scatter radar.

Thermospheric neutral density estimates from heater-induced ion up-flow at EISCAT

NASA Astrophysics Data System (ADS)

Kosch, Michael; Ogawa, Yasunobu; Yamazaki, Yosuke; Vickers, Hannah; Blagoveshchenskaya, Nataly

We exploit a recently-developed technique to estimate the upper thermospheric neutral density using measurements of ionospheric plasma parameters made by the EISCAT UHF radar during ionospheric modification experiments. Heating the electrons changes the balance between upward plasma pressure gradient and downward gravity, resulting in ion up-flow up to ~200 m/s. This field-aligned flow is retarded by collisions, which is directly related to the neutral density. Whilst the ion up-flow is consistent with the plasma pressure gradient, the estimated thermospheric neutral density depends on the assumed composition, which varies with altitude. Results in the topside ionosphere are presented.

New concepts in ionospheric modification. Final report, 15 April 1986-30 September 1987

DOE Office of Scientific and Technical Information (OSTI.GOV)

Banks, P.M.; Fraser-Smith, A.C.; Gilchrist, B.E.

1987-04-01

This report considers the ionospheric modification that can be produced by energetic charged-particle and photon beams, which are emitted from a platform or vehicle (spacecraft or rockets) located in the ionosphere. The various beams considered include (1) charged-particle beams composed of low-, moderate-, and high-energy electrons, (2) beams of ions and plasma, and (3) photon beams of soft x rays and extreme-ultraviolet radiation. Briefly considered, in addition to the beam topics, is the ionospheric modification produced by the release of neutral gas of high molecular weight from a rapidly moving vehicle such as the Space Shuttle Orbiter. When a rankingmore » is made in terms of the new information that may be obtained, the scale of the modification that may be produced, and the availability of beam sources, ionospheric modification by means of relativistic electron beams appears particularly promising. However, all the methods have their own distinctive features that could make their use desirable under particular circumstances. The modification produced by means of beams of soft x rays, for example, is not strongly dependent on the beam's direction relative to the earth's magnetic field, and thus modification can be produced in regions inaccessible to a charged-particle beam from the same vehicle.« less

Reexamining X-mode suppression and fine structure in artificial E region field-aligned plasma density irregularities

NASA Astrophysics Data System (ADS)

Miceli, R. J.; Hysell, D. L.; Munk, J.; McCarrick, M.; Huba, J. D.

2013-09-01

Artificial field-aligned plasma density irregularities (FAIs) were generated in the E region of the ionosphere above the High Frequency Active Auroral Research Program facility during campaigns in May and August of 2012 and observed using a 30 MHz coherent scatter radar imager in Homer, Alaska. The purpose of this ionospheric modification experiment was to measure the threshold pump power required to excite thermal parametric instabilities by O-mode heating and to investigate the suppression of the FAIs by simultaneous X-mode heating. We find that the threshold pump power for irregularity excitation was consistent with theoretical predictions and increased by approximately a factor of 2 when X-mode heating was present. A modified version of the Another Model of the Ionosphere (SAMI2) ionospheric model was used to simulate the threshold experiments and suggested that the increase was entirely due to enhanced D region absorption associated with X-mode heating. Additionally, a remarkable degree of fine structure possibly caused by natural gradient drift instability in the heater-modified volume was observed in experiments performed during geomagnetically active conditions.

In-situ Measurements of the Direction of Propagation of Pump Waves

NASA Astrophysics Data System (ADS)

James, H. G.; Bernhardt, P. A.; Leyser, T.; Siefring, C. L.

2017-12-01

In the course of an experiment to modify the ionosphere, the direction of pump wave propagation is affected by density gradients in the horizontal and vertical directions, fundamentally affecting wave-energy transport. Horizontal gradients on various scales may await a modification attempt as a preexisting state of the ionosphere and/or be changed by the deposition of heater radio-frequency energy. In the results from the Radio Receiver Instrument (RRI) in the enhanced Polar Outflow Probe (e-POP), we have recorded on the order of 100 flights over ionospheric heaters revealing a variety of processes that high-frequency pump waves experience in the ionosphere. E-POP flies on the Canadian satellite CASSIOPE in an elliptic (320 x 1400 km), highly-inclined (81°) orbit. High frequency measurements have been/are being made near SPEAR, HAARP, Sura, EISCAT Heating and Arecibo. Electromagnetic waves from ground-based heaters are detected by the two, orthogonal, 6-m dipoles on the RRI. The high input impedance of the RRI means that the dipoles act as voltage probes, from which the electric field of incoming waves can be simply computed. When combined with cold-magnetoplasma electric-field theory, the relationship of voltages on the two orthogonal dipoles is used to deduce the direction of arrival of an incoming wave in three dimensions. We illustrate the technique by its application to analysis of signals from different transmitters. These results show a variety of pump-wave propagation directions, indicating the complexity of density structure within which modification might take place. Such complexity illustrates the importance of three-dimensional models of density in the vicinity of modification.

A Diagnostic System for Studying Energy Partitioning and Assessing the Response of the Ionosphere during HAARP Modification Experiments

NASA Technical Reports Server (NTRS)

Djuth, Frank T.; Elder, John H.; Williams, Kenneth L.

1996-01-01

This research program focused on the construction of several key radio wave diagnostics in support of the HF Active Auroral Ionospheric Research Program (HAARP). Project activities led to the design, development, and fabrication of a variety of hardware units and to the development of several menu-driven software packages for data acquisition and analysis. The principal instrumentation includes an HF (28 MHz) radar system, a VHF (50 MHz) radar system, and a high-speed radar processor consisting of three separable processing units. The processor system supports the HF and VHF radars and is capable of acquiring very detailed data with large incoherent scatter radars. In addition, a tunable HF receiver system having high dynamic range was developed primarily for measurements of stimulated electromagnetic emissions (SEE). A separate processor unit was constructed for the SEE receiver. Finally, a large amount of support instrumentation was developed to accommodate complex field experiments. Overall, the HAARP diagnostics are powerful tools for studying diverse ionospheric modification phenomena. They are also flexible enough to support a host of other missions beyond the scope of HAARP. Many new research programs have been initiated by applying the HAARP diagnostics to studies of natural atmospheric processes.

The investigation of man-made modifications of the ionosphere. [effects of detonations and rocket exhaust

NASA Technical Reports Server (NTRS)

Bernhardt, P. A.; Darosa, A. V.; Price, K. M.

1980-01-01

Topics covered include: (1) the application of ionosphere modifications models to the simulation of results obtained when rocket-borne explosives were detonated in the ionosphere; (2) the problem of hypersonic vapor releases from orbiting vehicles; (3) measuring the electron content reduction resulting from the firing of a Centaur rocket in the ionosphere; and (4) the preliminary design of the critical frequency tracker which displays the value of electron concentration at the peak of the F 2 region, in real time.

Investigation of ionospheric disturbances and associated diagnostic techniques. Final report, 1 January 1992-31 December 1994

DOE Office of Scientific and Technical Information (OSTI.GOV)

Duncan, L.M.

1995-12-12

The objectives of this research and development program were to conduct simulation modeling of the generation and propagation of atmospheric acoustic signals associated with surface and subsurface ground disturbances; to construct an experimental measurement system for exploratory research studies of acoustic generated ionospheric disturbances; to model high power radio wave propagation through the ionosphere, including nonlinear wave plasma interaction effects; and to assist in the assessment of diagnostic systems for observation of ionospheric modification experiments using existing and planned high latitude high power RF transmitting facilities. A computer simulation of ionospheric response to ground launched acoustic pulses was constructed andmore » results compared to observational data associated with HF and incoherent scatter radar measurements of ionospheric effects produced by earthquakes and ground level explosions. These results were then utilized to help define the design, construct and test for an HF Doppler radar system. In addition, an assessment was conducted of ionospheric diagnostic instruments proposed for the Air Force/Navy High Frequency Active Auroral Research Program (HAARP).« less

Optical signature of an ionospheric hole

NASA Technical Reports Server (NTRS)

Mendillo, M.; Baumgardner, J.

1982-01-01

Simultaneous radio and optical diagnostics of a large, artificially-induced ionospheric modification were conducted during the June 1981 launch of a weather satellite. Intensified imaging and photometer observations at 6300 A, along the same ray path as VHF polarimeter measurements of the ionosphere's total electron content (TEC), were made while the rocket plume caused disturbances. A rapid TEC chemical depletion, on the order of -16.8 x 10 to the 12th el/sq cm, caused a burst of 6300 A radiation which expanded over 60 deg of the sky, with a peak intensity of almost 9 k R. Atmospheric diffusion and O(1D) quenching rate theoretical estimates were then tested, using the event as an active space plasma experiment.

Numerical simulation of the plasma thermal disturbances during ionospheric modification experiments at the SURA heating facility

NASA Astrophysics Data System (ADS)

Belov, Alexey; Huba, J. D.

indent=1cm We present the results of numerical simulation of the near-Earth plasma disturbances produced by resonant heating of the ionospheric F-region by high-power HF radio emission from the SURA facility. The computational model is based on the modified version of the SAMI2 code (release 1.00). The model input parameters are appropriated to the conditions of the SURA-DEMETER experiment. In this work, we study the spatial structure and temporal characteristics of stimulated large-scale disturbances of the electron number density and temperature. It is shown that the stimulated disturbances are observed throughout the ionosphere. Disturbances are recorded both in the region below the pump wave reflection level and in the outer ionosphere (up to 3000 km). At the DEMETER altitude, an increase in the ion number density is stipulated by the oxygen ions O (+) , whereas the number density of lighter H (+) ions decreases. A typical time of the formation of large-scale plasma density disturbances in the outer ionosphere is 2-3 min. After the heater is turned off, the disturbances relaxation time is approximately 30 min. The simulation results are important for planning future promising experiments on the formation of ionospheric artificial density ducts. This work was supported by the Russian Foundation for Basic Research (project No. 12-02-00747-a), and the Government of the Russian Federation (contract No. 14.B25.31.0008).

HF-enhanced 4278-Å airglow: evidence of accelerated ionosphere electrons?

NASA Astrophysics Data System (ADS)

Fallen, C. T.; Watkins, B. J.

2013-12-01

We report calculations from a one-dimensional physics-based self-consistent ionosphere model (SCIM) demonstrating that HF-heating of F-region electrons can produce 4278-Å airglow enhancements comparable in magnitude to those reported during ionosphere HF modification experiments at the High-frequency Active Auroral Research Program (HAARP) observatory in Alaska. These artificial 'blue-line' emissions, also observed at the EISCAT ionosphere heating facility in Norway, have been attributed to arise solely from additional production of N2+ ions through impact ionization of N2 molecules by HF-accelerated electrons. Each N2+ ion produced by impact ionization or photoionization has a probability of being created in the N2+(1N) excited state, resulting in a blue-line emission from the allowed transition to its ground state. The ionization potential of N2 exceeds 18 eV, so enhanced impact ionization of N2 implies that significant electron acceleration processes occur in the HF-modified ionosphere. Further, because of the fast N2+ emission time, measurements of 4278-Å intensity during ionosphere HF modification experiments at HAARP have also been used to estimate artificial ionization rates. To the best of our knowledge, all observations of HF-enhanced blue-line emissions have been made during twilight conditions when resonant scattering of sunlight by N2+ ions is a significant source of 4278-Å airglow. Our model calculations show that F-region electron heating by powerful O-mode HF waves transmitted from HAARP is sufficient to increase N2+ ion densities above the shadow height through temperature-enhanced ambipolar diffusion and temperature-suppressed ion recombination. Resonant scattering from the modified sunlit region can cause a 10-20 R increase in 4278-Å airglow intensity, comparable in magnitude to artificial emissions measured during ionosphere HF-modification experiments. This thermally-induced artificial 4278-Å aurora occurs independently of any artificial aurora maintained by HF-accelerated (non-thermal) electrons. The numerical results presented here do not necessarily rule out the presence of HF-accelerated electrons with energies exceeding 18 eV. However, vertical or field-aligned airglow intensity measurements made during twilight conditions do not provide definitive evidence of energetic HF-accelerated electrons. Consequently, artificial blue-line airglow measurements should not be used to estimate N2+ ionization rates without also accounting for temperature-dependent chemistry and diffusion. Future experiments that make simultaneous measurements of N2+ ion airglow emissions from both the first negative bands and the Meinel bands can potentially resolve the relative contributions of accelerated electron and resonant scattering mechanisms. Airglow emission rates from these bands are expected to be in strict proportion when the emissions result from electron impact ionization of N2 molecules. Side-view altitude-resolved 4278-Å airglow measurements may also indicate the presence of energetic HF-accelerated electrons if the blue-line emissions are determined to occur below the shadow height.

Attenuation of Scintillation of Discrete Cosmic Sources during Nonresonant HF Heating of the Upper Ionosphere

NASA Astrophysics Data System (ADS)

Bezrodny, V. G.; Watkins, B.; Charkina, O. V.; Yampolski, Y. M.

2014-03-01

The aim of the work is to experimentally investigate the response of scintillation spectra and indices of discrete cosmic sources (DCS) to modification of the ionospheric F-region by powerful electromagnetic fields with frequencies exceeding the Langmuir and upper hybrid ones. The results of a special experiment on the scintillations of radiation from DCS Cygnus A observed with using the 64-beam imaging riometer located near the Gakona village (Alaska, USA) are here presented. The ionosphere was artificially disturbed by powerful HAARP heater. Under the studied conditions of nonresonant heating of the ionospheric plasma, an earlier unknown effect of reducing the level of DCS scintillation was discovered. The theoretical interpretation has been given for the discovered effect, which using allowed the proposed technique of solving the inverse problem (recovery deviations of average electron density and temperature in the modified region from their unperturbed values).

Comparison of the effects induced by the ordinary (O-mode) and extraordinary (X-mode) polarized powerful HF radio waves in the high-latitude ionospheric F region

NASA Astrophysics Data System (ADS)

Blagoveshchenskaya, N. F.; Borisova, T. D.; Kalishin, A. S.; Kayatkin, V. N.; Yeoman, T. K.; Häggström, I.

2018-01-01

Using the results of coordinated experiments on the modification of the high-latitude ionosphere by powerful HF radio emission of the EISCAT/Heating facility, effects of the impact of powerful HF radio waves of the ordinary (O-mode) and extraordinary (X-mode) polarization on the high-latitude ionospheric F region have been compared. During the experiments, a powerful HF radio wave was emitted in the magnetic zenith direction at frequencies within the 4.5-7.9 MHz range. The effective power of the emission was 150-650 MW. The behavior and characteristics of small-scale artificial ionospheric irregularities (SAIIs) during O- and X-heating at low and high frequencies are considered in detail. A principal difference has been found in the development of the Langmuir and ion-acoustic turbulence (intensified by the heating of the plasma and ion-acoustic lines in the spectrum of the EISCAT radar of incoherent scatter of radio waves) in the O- and X-heating cycles after switching on the heating facility. It has been shown that, under the influence on the ionospheric plasma of a powerful HF radio wave of the X-polarization, intense spectral components in the spectrum of the narrow-band artificial ionospheric radio emission (ARI) were registered at distances on the order of 1200 km from the heating facility.

Ionospheric modification using relativistic electron beams

NASA Technical Reports Server (NTRS)

Banks, Peter M.; Fraser-Smith, Anthony C.; Gilchrist, B. E.

1990-01-01

The recent development of comparatively small electron linear accelerators (linacs) now makes possible a new class of ionospheric modification experiments using beams of relativistic electrons. These experiments can potentially provide much new information about the interactions of natural relativistic electrons with other particles in the upper atmosphere, and it may also make possible new forms of ionization structures extending down from the lower ionosphere into the largely un-ionized upper atmosphere. The consequences of firing a pulsed 1 A, 5 Mev electron beam downwards into the upper atmosphere are investigated. If a small pitch angle with respect to the ambient geomagnetic field is selected, the beam produces a narrow column of substantial ionization extending down from the source altitude to altitudes of approximately 40 to 45 km. This column is immediately polarized by the natural middle atmosphere fair weather electric field and an increasingly large potential difference is established between the column and the surrounding atmosphere. In the regions between 40 to 60 km, this potential can amount to many tens of kilovolts and the associated electric field can be greater than the field required for breakdown and discharge. Under these conditions, it may be possible to initiate lightning discharges along the initial ionization channel. Filamentation may also occur at the lower end to drive further currents in the partially ionized gases of the stratosphere. Such discharges would derive their energy from the earth-ionosphere electrical system and would be sustained until plasma depletion and/or electric field reduction brought the discharge under control. It is likely that this artificially-triggered lightning would produce measurable low-frequency radiation.

Analysis of the backscatter spectrum in an ionospheric modification experiment

NASA Technical Reports Server (NTRS)

Kim, H.

1973-01-01

Predictions of the backscatter spectrum are compared, including effects of ionospheric inhomogeneity with experimental observations of incoherent backscatter from an artificially heated region. Calculations show that the strongest backscatter echo received is not, in fact, from the reflection level, but from a region some distance below (about 0.5 km for an experiment carried out at Arecibo), where the pump wave from a HF transmitter approximately 100 kW) is below the threshold for parametric amplification. By taking the standing wave pattern of the pump into account, asymmetry is explained of the up-shifted and down-shifted plasma lines in the backscatter spectrum, and the several peaks typically observed in the region of the spectrum near the HF transmitter frequency.

Investigation of ELF/VLF waves created by a "beat-wave" HF ionospheric heating at high latitudes

NASA Astrophysics Data System (ADS)

Shumilov, Oleg; Tereshchenko, Evgeniy; Kasatkina, Elena; Gomonov, Alexandr

2015-04-01

The generation of extremely low frequency (ELF, 3-3000 Hz) and very low frequency (VLF, 3-30 kHz) electromagnetic waves by modulated ionospheric high frequency (HF, 2-30 MHz) heating is one of the main directions of ionospheric modification experiments. In this work, we present observations of ELF waves generated during a "beat-wave" heating experiments at the EISCAT heating facility. ELF waves were registered with the ELF receiver located at Lovozero (68 N, 35 E), 660 km east from the EISCAT Tromso heating facility (69.6 N, 19.2 E). Frequency shifts between the generated beat-wave and received ELF waves were detected in all sessions. It is shown that the amplitudes of ELF waves depend on the auroral electrojet current strength. Our results showing a strong dependence of ELF signal intensities on the substorm development seem to support the conclusion that electrojet currents may affect the BW generation of ELF/VLF waves.

Electromagnetic fluctuations generated in the boundary layer of laboratory-created ionospheric depletions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liu, Yu; Lei, Jiuhou, E-mail: leijh@ustc.edu.cn; Collaborative Innovation Center of Astronautical Science and Technology, Harbin 150001

Ionospheric depletions, produced by release of attachment chemicals into the ionosphere, were widely investigated and taken as a potential technique for the artificial modification of space weather. In this work, we reported the experimental evidence of spontaneously generated electromagnetic fluctuations in the boundary layer of laboratory-created ionospheric depletions. These depletions were produced by releasing attachment chemicals into the ambient plasmas. Electron density gradients and sheared flows arose in the boundary layer between the ambient and the negative ions plasmas. These generated electromagnetic fluctuations with fundamental frequency f{sub 0} = 70 kHz lie in the lower hybrid frequency range, and the mode propagates withmore » angles smaller than 90° (0.3π–0.4π) relative to the magnetic field. Our results revealed that these observed structures were most likely due to electromagnetic components of the electron-ion hybrid instability. This research demonstrates that electromagnetic fluctuations also can be excited during active release experiments, which should be considered as an essential ingredient in the boundary layer processes of ionospheric depletions.« less

Excitation of earth-ionosphere waveguide in the ELF and lower VLF bands by modulated ionospheric current. Technical report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Field, E.C.; Bloom, R.M.

1993-05-21

In this report the authors use the principal of reciprocity in conjunction with a full-wave propagation code to calculate ground-level fields excited by ionospheric currents modulated at frequencies between 50 and 100 Hz with HF heaters. Their results show the dependence on source orientation, altitude, and dimension and therefore pertain to experiments using the HIPAS or HAARP ionospheric heaters. In the end-fire mode, the waveguide excitation efficiency of an ELF HED in the ionosphere is up to 20 dB greater than for a ground-based antenna, provided its altitude does not exceed 80-to-90 km. The highest efficiency occurs for a sourcemore » altitude of around 70 km; if that altitude is raised to 100 km, the efficiency drops by about 20 dB in the day and 10 dB at night. That efficiency does not account for the greater conductivity modulation that might be achieved at altitudes greater than 70 km, however. The trade-off between the altitude dependencies of the excitation efficiency and maximum achievable modulation depends on the ERP of the HF heater, the optimum altitude increasing with increasing ERP. For HIPAS the best modulation altitude is around 70 km, whereas for HAARP there might be marginal value in modulating at attitudes as high as 100 Km. Ionospheric modification, Ionospheric currents, Ionospheric heating.« less

View of Soviet ionospheric modification research

DOE Office of Scientific and Technical Information (OSTI.GOV)

Duncan, L.M.; Showen, R.L.

1990-10-01

We have reviewed and provided a technical assessment of Soviet research of the past five to ten years in ionospheric modification by high-power radio waves. This review includes a comprehensive survey of Soviet published literature, conference proceedings, and direct discussions with the involved Soviet researchers. The current state of the art for Soviet research in this field is evaluated, identifying areas of potential breakthrough discoveries, and discussing implications of this work for emerging technologies and future applications. This assessment is divided into the categories of basic research, advanced research, and applications. Basic research is further subdivided into studies of themore » modified natural geophysical environment, nonlinear plasma physics, and polar geophysical studies. Advanced research topics include the generation of artificial ionization mirrors and high-power oblique propagation effects. A separate comparative assessment of Soviet theoretical work also is included in this analysis. Our evaluation of practical and potential applications of this research discusses the utility of ionospheric modification in creating disturbed radio wave propagation environments, and its role in current and future remote-sensing and telecommunications systems. This technical assessment does not include consideration of ionospheric modification by means other than high-power radio waves. The Soviet effort in ionospheric modification sustains theoretical and experimental research at activity levels considerably greater than that found in comparable programs in the West. Notable strengths of the Soviet program are its breadth of coverage, large numbers of scientific participation, theoretical creativity and insight, and its powerful radio wave transmitting facilities.« less

A Finite-Difference Time-Domain Model of Artificial Ionospheric Modification

NASA Astrophysics Data System (ADS)

Cannon, Patrick; Honary, Farideh; Borisov, Nikolay

Experiments in the artificial modification of the ionosphere via a radio frequency pump wave have observed a wide range of non-linear phenomena near the reflection height of an O-mode wave. These effects exhibit a strong aspect-angle dependence thought to be associated with the process by which, for a narrow range of off-vertical launch angles, the O-mode pump wave can propagate beyond the standard reflection height at X=1 as a Z-mode wave and excite additional plasma activity. A numerical model based on Finite-Difference Time-Domain method has been developed to simulate the interaction of the pump wave with an ionospheric plasma and investigate different non-linear processes involved in modification experiments. The effects on wave propagation due to plasma inhomogeneity and anisotropy are introduced through coupling of the Lorentz equation of motion for electrons and ions to Maxwell’s wave equations in the FDTD formulation, leading to a model that is capable of exciting a variety of plasma waves including Langmuir and upper-hybrid waves. Additionally, discretized equations describing the time-dependent evolution of the plasma fluid temperature and density are included in the FDTD update scheme. This model is used to calculate the aspect angle dependence and angular size of the radio window for which Z-mode excitation occurs, and the results compared favourably with both theoretical predictions and experimental observations. The simulation results are found to reproduce the angular dependence on electron density and temperature enhancement observed experimentally. The model is used to investigate the effect of different initial plasma density conditions on the evolution of non-linear effects, and demonstrates that the inclusion of features such as small field-aligned density perturbations can have a significant influence on wave propagation and the magnitude of temperature and density enhancements.

F region above Kauai - Measurement, model, modification

NASA Technical Reports Server (NTRS)

Johnson, C. Y.; Sjolander, G. W.; Oran, E. S.; Young, T. R.; Bernhardt, P. A.; Da Rosa, A. V.

1980-01-01

Results of the Lagopedo II experiment conducted from Kauai, Hawaii to investigate the ionospheric modification that occurs when rocket combustion products are introduced into the O(+)-rich F region are presented. The experiment involved the detonation of a chemical explosion in the F2 peak accompanied by rocket-borne measurements of ion composition and electron content in the vicinity of the explosion. The experimental data is found to be in good agreement with the predictions of a model of the nighttime ion densities in the midlatitude laminar ionosphere, with the exception of N2(+) densities before the explosion. H2O(+) and H3O(+) currents produced by considerable H2O outgassing from the rocket are used to determine a H3O(+)/H2O(+) dissociative recombination rate averaging 1.6 to 1.08, depending on model assumptions. At the time of the explosion, an ionic void 1 km in radius is observed, the boundary of which is characterized by a steep gradient in ionic densities. Evidence of variations in the concentrations of ambient ion species, new reactant species and ionic depletion by sweeping is also obtained.

Long-lasting upper D-region ionospheric modifications caused by intense +/- CG lightning discharges

NASA Astrophysics Data System (ADS)

Haldoupis, Christos

2013-04-01

In a recent Geophysical Research Letter we have presented observations from a single maritime storm showing that intense positive cloud-to-ground (+CG) lightning discharges during nighttime, which trigger both an elve and a sprite, are associated with long-lasting conductivity modifications in the upper D-region ionosphere. The ionospheric disturbances can be observed as perturbations in the amplitude and phase of VLF (very low frequency) signals propagating through or near the disturbed region. They are manifested as LOng Recovery early VLF Events (LOREs) which can last up to 20 - 30 minutes. The same ionospheric modifications may also produce abrupt step-like changes in VLF transmissions which offset signal levels for longer times (>30-60 min). Here we discuss these observations supplementing them with new evidence and some statistics. Among other things, the unpublished results show that very intense (currents > 250-300 kA) CG lightning discharges of either positive or negative polarity are always accompanied mainly by step-like LOREs. The evidence suggests that the electromagnetic pulse (EMP) of a very high peak current CG lightning stroke, which is likely able to produce an elve, produces by electron impact long lasting and spatially extended elevations in electron density at VLF ionospheric reflection heights in the upper D region ionosphere. The results identify a mechanism for the LORE VLF signatures and confirm predictions and postulations that elves may be accompanied by significant and long-lasting electron density perturbations in the upper D- lower E- region ionosphere.

Long-lasting D-region ionospheric modifications, caused by intense lightning in association with elve and sprite pairs

NASA Astrophysics Data System (ADS)

Haldoupis, Christos; Cohen, Morris; Cotts, Benjamin; Arnone, Enrico; Inan, Umran

2012-08-01

Observations show that intense +CG lightning discharges which trigger both an elve and a sprite are associated with long-lasting conductivity modifications in the upper D-region ionosphere. They are observed as strong perturbations in VLF signals propagating through the disturbed region, manifested as LOng Recovery Early VLF events (LORE), which can last up to 30 minutes. These same ionospheric modifications are also responsible for step-like changes, seen mostly in off-storm VLF transmissions, which offset signal levels even for longer times. The evidence suggests that when a very intense positive cloud to ground lightning stroke leads to an elve and a high altitude sprite, and possibly a sprite halo as well, there is production of long lasting elevations in electron density at VLF reflection heights that cause LOREs and severe effects on VLF propagation. The present results confirm past predictions and postulations that elves may be accompanied by long-lasting electron density perturbations in the lower ionosphere.

Effects of modification of the polar ionosphere with high-power short-wave extraordinary-mode HF waves produced by the spear heating facility

NASA Astrophysics Data System (ADS)

Borisova, T. D.; Blagoveshchenskaya, N. F.; S. Kalishin, A.; Oksavik, K.; Baddelley, L.; K. Yeoman, T.

2012-06-01

We present the results of modifying the F2 layer of the polar ionosphere experimentally with highpower HF extraordinary-mode waves. The experiments were performed in October 2010 using the short-wave SPEAR heating facility (Longyearbyen, Spitsbergen). To diagnose the effects of high-power HF waves by the aspect-scattering method in a network of diagnostic paths, we used the short-wave Doppler radar CUTLASS (Hankasalmi, Finland) and the incoherent scatter radar ESR (Longyearbyen, Spitsbergen). Excitation of small-scale artificial ionospheric irregularities was revealed, which were responsible for the aspect and backward scattering of the diagnostic signals. The measurements performed by the ESR incoherent scatter radar simultaneously with the heating demonstrated changes in the parameters of the ionospheric plasma, specifically, an increase in the electron density by 10-25 % and an increase in the electron temperature by 10-30 % at the altitudes of the F2 layer, as well as formation of sporadic ionization at altitudes of 140-180 km (below the F2 layer maximum). To explain the effects of ionosphere heating with HF extraordinary-mode waves, we propose a hypothesis of transformation of extraordinary electromagnetic waves to ordinary in the anisotropic, smoothly nonuniform ionosphere.

Active experiments in space plasmas; Symposium D4.1 of Commission D, COSPAR Scientific Assembly, 30th, Hamburg, Germany, July 11-21, 1994

NASA Technical Reports Server (NTRS)

Rietveld, M. T. (Editor)

1995-01-01

Papers from the conference are presented and cover the following topics: ion and electron beams; ionospheric modification; spacecraft interactions; chemical releases; and plasma waves. Auroras and plasma emissions are reported from electron beam injection experiments on the EXCEDE 3 rocket and APEX satellite respectively. The important parameters affecting the charging of spacecraft during the operation of electron guns is covered. The Active Magnetospheric Particle Acceleration Satellite (AMPAS) mission utilizing dual-payload tethered satellites and both up and downward directed electron beams is proposed to study the magnetosphere. Recent results and associated theories from the Sura, Arecibo and Troms ionospheric heating facitlites are presented. The effects of neutral gases on spacecraft charging are examined in a series of rocket flights. Many results from the Combined Release and Radiation Effects Satellite chemical release experiments are presented.

Radiotomographic imaging and GNSS remote sensing of the midlatitude ionosphere modified by powerful HF radiowaves.

NASA Astrophysics Data System (ADS)

Kunitsyn, V.; Andreeva, E. S.; Padokhin, A. M.; Vorontsov, A.; Frolov, V. L.; Komrakov, G.; Bernhardt, P. A.; Siefring, C. L.

2014-12-01

We present the results of the radiotomographic imaging and GNSS remote sensing of the artificial ionospheric disturbances obtained in the recent experiments on the modification of the midlatitude ionosphere by powerful HF radiowaves carried out at the Sura heating facility. The experiments were conducted using both O- and X- mode radiowaves, in daytime and nighttime conditions with various schemes of the radiation of the heating wave. Radio transmissions from the low- (Parus, e-POP on CASSIOPE) and high-orbital (GPS/GLONASS) navigational satellites received at the mobile network of receiving sites were used for the remote sensing of the heated area of the ionosphere. We study the variations in TEC caused by HF heating showing that the GNSS TEC spectra often contain frequency components corresponding to the modulation periods of the ERP of the heating wave. The manifestations of the heating-induced variations in TEC are most prominent in the area of magnetic zenith of the pumping wave. In this work we also present the radiotomographic reconstructions (including first time e-POP-SURA reconstructions) of the spatial structure of the disturbed area of the ionosphere corresponding to the directivity pattern of the heater as well as the spatial structure of the wave- like disturbances, which are possibly heating-induced AGWs, diverging from the heated area of the ionosphere. The spatial period of observed disturbances is 200-250 km and they are easily traced up to a distance of 700-800 km from the heated region, which is in good agreement with the modeling results.

Assessing the Suitability of the ClOud Reflection Algorithm (CORA) in Modelling the Evolution of an Artificial Plasma Cloud in the Ionosphere

NASA Astrophysics Data System (ADS)

Jackson-Booth, N.

2016-12-01

Artificial Ionospheric Modification (AIM) attempts to modify the ionosphere in order to alter the propagation environment. It can be achieved through injecting the ionosphere with aerosols, chemicals or radio signals. The effects of any such release can be detected through the deployment of sensors, including ground based high frequency (HF) sounders. During the Metal Oxide Space Clouds (MOSC) experiment (undertaken in April/May 2013 in the Kwajalein Atoll, part of the Marshall Islands) several oblique ionograms were recorded from a ground based HF system. These ionograms were collected over multiple geometries and allowed the effects on the HF propagation environment to be understood. These ionograms have subsequently been used in the ClOud Reflection Algorithm (CORA) to attempt to model the evolution of the cloud following release. This paper describes the latest validation results from CORA, both from testing against ionograms, but also other independent models of cloud evolution from MOSC. For all testing the various cloud models (including that generated by CORA) were incorporated into a background ionosphere through which a 3D numerical ray trace was run to produce synthetic ionograms that could be compared with the ionograms recorded during MOSC.

On the Accuracy of the Conjugation of High-Orbit Satellites with Small-Scale Regions in the Ionosphere

NASA Astrophysics Data System (ADS)

Safargaleev, V. V.; Safargaleeva, N. N.

2018-03-01

The degree of uncertainty that arises when mapping high-orbit satellites of the Cluster type into the ionosphere using three geomagnetic field models (T89, T98, and T01) has been estimated. Studies have shown that uncertainty is minimal in situations when a satellite in the daytime is above the equatorial plane of the magnetosphere at the distance of no more than 5 R E from the Earth's surface and is projected into the ionosphere of the northern hemisphere. In this case, the dimensions of the uncertainty region are about 50 km, and the arbitrariness of the choice of the model for projecting does not play a decisive role in organizing satellite support based on optical observations when studying such large-scale phenomena as, e.g., WTS, as well as heating experiments at the EISCAT heating facility for the artificial modification of the ionosphere and the generation of artificial fluctuations in the VLF band. In all other cases, the uncertainty in determining the position of the base of the field line on which the satellite is located is large, and additional information is required to correctly compare the satellite with the object in the ionosphere.

How and in Which way Space Weather Changed the Ionospheric Irregularities Occurrence During the St. Patricḱs Storm

NASA Astrophysics Data System (ADS)

Fagundes, P. R.; Barbosa, F. R. E., Sr.; Kavutarapu, V.; Fejer, B. G.; Pillat, V. G.; De Nardin, C. M.; Muella, M.

2017-12-01

During the solar cycle 24 there was a very intense geomagnetic storm, called St. Patricḱs Day storm and the effects of this storm on ionosphere has become a topic of extensive space weather investigation. The Dst during this storm reached -223 nT on March 17, 2015 at 23:00 UT. Special efforts have been devoted so far to investigate many aspects of the St. Patricḱs Day ionospheric storm such as the prompt penetration electric fields (PPEFs), GPS-TEC changes, electron density disturbances, plasma drift, O+ concentration modification, hemispherical asymmetry developments, equatorial ionization anomaly (EIA) modification, and ionospheric irregularities. Besides all these important studies, there are some essential aspects, which have not been addressed yet, related to the occurrence of ionospheric irregularities with different scale sizes. In this paper, we present and discuss the generation and suppression of ionospheric irregularities during March 2015, using the observations conducted in the Latin American Sector from 4 ionosondes (ESF) and 20 GPS-TEC stations (ROT phase fluctuation), which includes the St. Patricḱs Day geomagnetic storm period. Suppression of large-small scales ionospheric irregularities has occurred during the main and second night of the recovery phases. However, during the first night of recovery phase there was post-midnight ionospheric irregularities.

Multi Station Frequency Response and Polarization of ELF/VLF Signals Generated via Ionospheric Modification

NASA Astrophysics Data System (ADS)

Maxworth, Ashanthi; Golkowski, Mark; University of Colorado Denver Team

2013-10-01

ELF/VLF wave generation via HF modulated ionospheric heating has been practiced for many years as a unique way to generate waves in the ELF/VLF band (3 Hz - 30 kHz). This paper presents experimental results and associated theoretical modeling from work performed at the High Frequency Active Auroral Research Program (HAARP) facility in Alaska, USA. An experiment was designed to investigate the modulation frequency dependence of the generated ELF/VLF signal amplitudes and polarization at multiple sites at distances of 37 km, 50 km and 99 km from the facility. While no difference is observed for X mode versus O mode modulation of the heating wave, it is found that ELF/VLF amplitude and polarization as a function of modulated ELF/VLF frequency is different for each site. An ionospheric heating code is used to determine the primary current sources leading to the observations.

Thermal response of the F region ionosphere in artificial modification experiments by HF radio waves

NASA Technical Reports Server (NTRS)

Mantas, G. P.; Lahoz, C. H.; Carlson, H. C., Jr.

1981-01-01

The thermal response of the nighttime F region ionosphere to local heating by HF radio waves has been observed with the incoherent scatter radar at Arecibo, Puerto Rico. The observations consist of high-resolution space and time variation of the electron temperature as a high-power HF transmitter is switched on and off with a period 240 s. As soon as the HF transmitter is turned on, the electron temperature begins to rise rapidly in a narrow altitude region near 300 km, below the F2 layer peak. The electron temperature perturbation subsequently spreads over a broader altitude region. The observations are compared with the anticipated thermal response of the ionosphere based on numerical solutions of the coupled time-dependent heat conduction equations for the electron and composite ion gases and are found to be in good agreement over the entire altitude region covered by the observations.

On the Additional Absorption of Radio Emission from Discrete Cosmic Sources Under HF Modification of the Lower Ionosphere

NASA Astrophysics Data System (ADS)

Bezrodny, V. G.; Charkina, O. V.; Yampolski, Yu. M.

2015-12-01

The possibilities of modification of a weakly ionized plasma are investigated theoretically and experimentally within different electron density behavior models. The dependence of the additional absorption of radiation of discreet cosmic sources Cassiopeia A and Cygnus A in the artificially disturbed ionospheric D-region on the amplitude of heating signal during the special measuring campaigns of February and October 2008 has been analyzed. The ionosphere has been modified with using the world most powerful HAARP heater, Alaska, USA. The 64 beam riometer located in the immediate vicinity of the heater was used as the recording system.

Artificial ionospheric modification: The Metal Oxide Space Cloud experiment

NASA Astrophysics Data System (ADS)

Caton, Ronald G.; Pedersen, Todd R.; Groves, Keith M.; Hines, Jack; Cannon, Paul S.; Jackson-Booth, Natasha; Parris, Richard T.; Holmes, Jeffrey M.; Su, Yi-Jiun; Mishin, Evgeny V.; Roddy, Patrick A.; Viggiano, Albert A.; Shuman, Nicholas S.; Ard, Shaun G.; Bernhardt, Paul A.; Siefring, Carl L.; Retterer, John; Kudeki, Erhan; Reyes, Pablo M.

2017-05-01

Clouds of vaporized samarium (Sm) were released during sounding rocket flights from the Reagan Test Site, Kwajalein Atoll in May 2013 as part of the Metal Oxide Space Cloud (MOSC) experiment. A network of ground-based sensors observed the resulting clouds from five locations in the Republic of the Marshall Islands. Of primary interest was an examination of the extent to which a tailored radio frequency (RF) propagation environment could be generated through artificial ionospheric modification. The MOSC experiment consisted of launches near dusk on two separate evenings each releasing 6 kg of Sm vapor at altitudes near 170 km and 180 km. Localized plasma clouds were generated through a combination of photoionization and chemi-ionization (Sm + O → SmO+ + e-) processes producing signatures visible in optical sensors, incoherent scatter radar, and in high-frequency (HF) diagnostics. Here we present an overview of the experiment payloads, document the flight characteristics, and describe the experimental measurements conducted throughout the 2 week launch window. Multi-instrument analysis including incoherent scatter observations, HF soundings, RF beacon measurements, and optical data provided the opportunity for a comprehensive characterization of the physical, spectral, and plasma density composition of the artificial plasma clouds as a function of space and time. A series of companion papers submitted along with this experimental overview provide more detail on the individual elements for interested readers.

Sporadic E ionization layers observed with radar imaging and ionospheric modification

NASA Astrophysics Data System (ADS)

Hysell, D. L.; Munk, J.; McCarrick, M.

2014-10-01

Sporadic E ionization layers have been observed in the daytime subauroral ionospheric E layer by a 30 MHz radar in Alaska. The radar detects coherent backscatter from meter-scale field-aligned plasma density irregularities. The irregularities were generated by ionospheric modification—by the emission of strong HF electromagnetic waves directly beneath the layers—making the layers visible to the radar. Aperture-synthesis methods are used to generate imagery of the layers from the radar data. The layers are patchy, with patches organized along fronts spaced by tens of kilometers and propagating slowly toward the southwest. Similar, naturally occurring layers are commonly observed at middle latitudes at night in the absence of ionospheric modification. That the patchy layers can be found at high magnetic latitudes during the day argues that they are most likely produced through the interaction of the ionospheric layer with neutral atmospheric waves and instabilities. Attenuation of the radar echoes when the HF emission frequency exceeded the third harmonic of the electron gyrofrequency was observed and is discussed.

Two-Dimensional Vlasov Simulations of Fast Stochastic Electron Heating in Ionospheric Modification Experiments

NASA Astrophysics Data System (ADS)

Speirs, David Carruthers; Eliasson, Bengt; Daldorff, Lars K. S.

2017-10-01

Ionospheric heating experiments using high-frequency ordinary (O)-mode electromagnetic waves have shown the induced formation of magnetic field-aligned density striations in the ionospheric F region, in association with lower hybrid (LH) and upper hybrid (UH) turbulence. In recent experiments using high-power transmitters, the creation of new plasma regions and the formation of descending artificial ionospheric layers (DAILs) have been observed. These are attributed to suprathermal electrons ionizing the neutral gas, so that the O-mode reflection point and associated turbulence is moving to a progressively lower altitude. We present the results of two-dimensional (2-D) Vlasov simulations used to study the mode conversion of an O-mode pump wave to trapped UH waves in a small-scale density striation of circular cross section. Subsequent multiwave parametric decays lead to UH and LH turbulence and to the excitation of electron Bernstein (EB) waves. Large-amplitude EB waves result in rapid stochastic electron heating when the wave amplitude exceeds a threshold value. For typical experimental parameters, the electron temperature is observed to rise from 1,500 K to about 8,000 K in a fraction of a millisecond, much faster than Ohmic heating due to collisions which occurs on a timescale of an order of a second. This initial heating could then lead to further acceleration due to Langmuir turbulence near the critical layer. Stochastic electron heating therefore represents an important potential mechanism for the formation of DAILs.

Very low frequency radio signatures of transient luminous events above thunderstorms

NASA Astrophysics Data System (ADS)

Marshall, Robert Andrew

Lightning discharges emit intense optical and acoustic energy, in the form of lightning and thunder, respectively, but a large amount of energy is emitted as radio-frequency electromagnetic pulses (EMP). These pulses can be detected thousands of kilometers away, thanks to efficient propagation in the waveguide formed by the conducting Earth and the overlying ionosphere. In addition, intense discharges interact with the overlying ionosphere at 80-100 km altitude. The EMP-ionosphere interaction is directly observed in one manifestation as the bright transient optical emissions known as "elves", but in addition, the interaction can directly modify the free electron density in the nighttime lower ionosphere. Modifications of the ionospheric electron density can be detected via subionospheric Very Low Frequency (VLF) remote sensing. In this method, coherent signals from powerful VLF transmitters, built for submarine communication and operated by the Navy, are monitored and their amplitude and phase are tracked in time. The variations of these signais are used to sense ionospheric modifications through rapid changes in the received amplitude and/or phase when the transmitted signal propagates through an ionospheric perturbation. When these perturbations are caused by lightning, they are known as "Early VLF" perturbations, due to the negligible delay between the lightning discharge and the appearance of the VLF signal change, whereas lightning-induced electron precipitation (LEP) events have a delay of 1--2 seconds. In this work, correlations between VLF signatures and optical events are used to show that these Early VLF events may be the signature of ionospheric modification by in-cloud (IC) lightning discharges. While the more impressive cloud-to-ground (CG) lightning discharges are more commonly observed and better understood, they are outnumbered in occurrence 3:1 by IC discharges, whose effects may be relatively stronger in the overlying ionosphere. We use a 3D time-domain model of the lightning EMP-ionosphere interaction to calculate expected ionospheric density changes from IC discharges. We find that bursts of IC-EMPs can significantly modify the lower ionosphere, with both increases and decreases in electron density. We then use a frequency-domain model of the VLF transmitter signal propagation in the Earth-ionosphere waveguide to a receiver to show that these density changes are consistent with measurements. Our results demonstrate that these Early VLF events, which are ubiquitous in VLF data, are signatures of the effects of in-cloud lightning, and that they can be used to quantify the effects of IC lightning on the ionosphere during an intense thunderstorm.

UHF Radar observations at HAARP with HF pump frequencies near electron gyro-harmonics and associated ionospheric effects

NASA Astrophysics Data System (ADS)

Watkins, Brenton; Fallen, Christopher; Secan, James

Results for HF modification experiments at the HAARP facility in Alaska are presented for experiments with the HF pump frequency near third and fourth electron gyro-harmonics. A UHF diagnostic radar with range resolution of 600 m was used to determine time-dependent altitudes of scattering from plasma turbulence during heating experiments. Experiments were conducted with multiple HF frequencies stepped by 20 kHz above and below the gyro-harmonic values. During times of HF heating the HAARP facility has sufficient power to enhance large-scale ionospheric densities in the lower ionosphere (about 150-200 km altitude) and also in the topside ionosphere (above about 350 km). In the lower ionosphere, time-dependent decreases of the altitude of radar scatter result from electron density enhancements. The effects are substantially different even for relatively small frequency steps of 20 kHz. In all cases the time-varying altitude decrease of radar scatter stops about 5-10 km below the gyro-harmonic altitude that is frequency dependent; we infer that electron density enhancements stop at this altitude where the radar signals stop decreasing with altitude. Experiments with corresponding total electron content (TEC) data show that for HF interaction altitudes above about 170 km there is substantial topside electron density increases due to upward electron thermal conduction. For lower altitudes of HF interaction the majority of the thermal energy is transferred to the neutral gas and no significant topside density increases are observed. By selecting an appropriate HF frequency a little greater than the gyro-harmonic value we have demonstrated that the ionospheric response to HF heating is a self-oscillating mode where the HF interaction altitude moves up and down with a period of several minutes. If the interaction region is above about 170 km this also produces a continuously enhanced topside electron density and upward plasma flux. Experiments using an FM scan with the HF frequency increasing near the gyro-harmonic value were conducted. The FM scan rate was sufficiently slow that the electron density was approximately in an equilibrium state. For these experiments the altitude of the HF interaction follows a near straight line downward parallel to the altitude-dependent gyro-harmonic level.

Large-Scale Ionospheric Effects Related to Electron-Gyro Harmonics: What We Have Learned from HAARP.

NASA Astrophysics Data System (ADS)

Watkins, B. J.; Fallen, C. T.; Secan, J. A.

2014-12-01

The HAARP ionospheric modification facility has unique capabilities that enable a wide range of HF frequencies with transmit powers ranging from very low to very high values. We will review a range of experiment results that illustrate large-scale ionospheric effects when the HF frequencies used are close to electron gyro-harmoncs and we focus mainly on the 3rd and 4th harmonics. The data are primarily from the UHF diagnosticc radar and total electron content (TEC) observations through the heated topside ionosphere. Radar data for HF frequencies just above and just below gyro harmoncs show significant differences in radar scatter cross-section that suggest differing plasma processes, and this effect is HF power dependent with some effects only observable with full HF power. For the production of artificial ionization in the E-region when the HF frequency is near gyro-harmoncs the results differ significantly for relatively small (50 kHz) variations in the HF frequency. We show how slow FM scans in conjunction with gyro-harmonic effects are effective in producing artificial ionization in the lower ionosphere.In the topside ionosphere enhanced density and upward fluxes have been observed and these may act as effective ducts for the propagation of VLF waves upward into the magneosphere. Experimental techniques have been developed that may be used to continuously maintain these effects in the topside ionossphere.

High frequency based detection of TIDs in the Net-TIDE project: challenges and opportunities for long HF paths

NASA Astrophysics Data System (ADS)

Verhulst, Tobias

2016-07-01

Travelling Ionospheric Disturbances (TIDs) are the ionospheric signatures of atmospheric gravity waves. TIDs carry along information about their sources of excitations which may be either natural (energy input from the auroral region, earthquakes/tsunamis, hurricanes, solar terminator, and others) or artificial (ionospheric modification experiments, nuclear explosions, and other powerful blasts like industrial accidents). TIDs contribute to the energy and momentum exchange between different regions of the ionosphere, especially during geomagnetic storms. Their tracking is important because the TIDs affect all services that rely on predictable ionospheric radio wave propagation. Although a number of methods have been proposed to measure TID characteristics, none is able to operate in real time for monitoring purposes. In the framework of a new NATO Science for Peace and Security multi-year project (2014--2017) we are exploiting for the first time the European network of high precision ionospheric DPS4D sounders and the related software to directly identify TIDs over Europe and specify in real-time the gravity wave parameters based on measuring the variations of the angles-of-arrival and Doppler frequencies of ionospherically reflected HF radio signals. The project will run until 2017 and is expected to result in a pilot network of DPS4D ionospheric sounders in Europe, enhanced with a system to process the TID observations for real-time diagnostics and issue warnings for TIDs and the potential disturbance over the area. Based on these warnings the end-users can put in action specific mitigation techniques to protect their systems. The technical challenges of operating long distance ionospheric HF radio links for the detection of TIDs will be discussed.

Shear Alfven Wave Injection in the Magnetosphere by Ionospheric Modifications in the Absence of Electrojet Currents

NASA Astrophysics Data System (ADS)

Papadopoulos, K.; Eliasson, B.; Shao, X.; Labenski, J.; Chang, C.

2011-12-01

A new concept of generating ionospheric currents in the ULF/ELF range with modulated HF heating using ground-based transmitters even in the absence of electrojet currents is presented. The new concept relies on using HF heating of the F-region to modulate the electron temperature and has been given the name Ionospheric Current Drive (ICD). In ICD, the pressure gradient associated with anomalous or collisional F-region electron heating drives a local diamagnetic current that acts as an antenna to inject mainly Magneto-Sonic (MS) waves in the ionospheric plasma. The electric field associated with the MS wave drives Hall currents when it reaches the E region of the ionosphere. The Hall currents act as a secondary antenna that inject waves in the Earth-Ionosphere Waveguide (EIW) below and shear Alfven waves or EMIC waves upwards towards the conjugate regions. The paper presents: (i) Theoretical results using a cold Hall MHD model to study ICD and the generation of ULF/ELF waves by the modulation of the electron pressure at the F2-region with an intense HF electromagnetic wave. The model solves equations governing the dynamics of the shear Alfven and magnetosonic modes, of the damped modes in the diffusive Pedersen layer, and of the weakly damped helicon wave mode in the Hall-dominated E-region. The model incorporates realistic profile of the ionospheric conductivities and magnetic field configuration. We use the model to simulate propagation and dynamics of the low-frequency waves and their injection into the magnetosphere from the HAARP and Arecibo ionospheric heaters. (ii) Proof of principle experiments using the HAARP ionospheric heater in conjunction with measurements by the DEMETER satellite This work is supported by ONR MURI grant and DARPA BRIOCHE Program

Modification of planetary atmospheres by material from the rings

NASA Technical Reports Server (NTRS)

Atreya, S. K.

1984-01-01

The modification of the atmospheres and ionospheres of ringed planets by the injection of ionized and neutral material from the rings is discussed, on the basis of Pioneer and Voyager observations. It is shown that although no direct evidence exists for the injection of material from the rings into the atmosphere, such an interaction could account for the observed thermal structure and ionospheric properties of Jupiter, Saturn, Uranus, and the Jovian satellite Io.

Generation of Artificial Ionospheric Irregularities by the Modification of the Earth's Middle-Latitude Ionosphere by X-Mode Powerful HF Radio Waves

NASA Astrophysics Data System (ADS)

Frolov, Vladimir; Padokhin, Artem; Kunitsyn, Viacheslav; Akchurin, Adel; Bolotin, Ilya; Zykov, Evgeniy; Vertogradov, Gennadiy

Basing on experimental data obtained at the SURA heating facility by modification of the Earth’s middle-latitude ionosphere, we consider in the report some peculiarities of the generation of artificial plasma density irregularities when X-mode powerful waves (PW) are used for ionosphere pumping [1]. Experiments were carried out during 2008 - 2012 under quite ionospheric conditions (Sigma K_p = 10 - 30). Analysis of obtained experimental data has shown that: 1) In our measurements the generation of small-scale irregularities with l{_⊥} {≃} 10 - 20 m is not observed in contrast to analogous measurements conducted at the EISCAT-heater [2,3]. 2) The generation of irregularities with l{_⊥} {≃} 50 m - 3 km is mainly observed in evening and night hours. In these conditions their intensity is by 3 to 4 times below in comparison with the O-mode pumping. During day hours these irregularities are not detected due to both strong PW energy absorption in the lower ionosphere and forming a defocusing lens at altitudes of 130 - 150 km [4]. 3) The generation of irregularities with l{_⊥} {≥} 5 - 10 km is only observed in evening and night hours. In these conditions their intensity is by 10 times below in comparison with the O-mode pumping. 4) The generation of the irregularities with l{_⊥} {≥} 50 m is observed only when the PW reflects in the ionospheric F _{2} region. 5) Under day-time conditions the defocusing lens is forming at altitudes of about of 130 - 150 km when the ionosphere is pumping both X- and O- mode powerful waves [4]. Its horizontal size is determined by the HF beam. In our experiments [1] it was revealed that the stronger generation of irregularities with scale-lengths l{_⊥} {≃} 5 - 10 km is observed at the HF beam edge where the effective radiated power is of about 0.1 P _{max}. Such a “beam-edge” effect is also observed when the ionosphere is modified by O-mode PW. The enhancement of irregularity generation at the HF beam edge was considered in [5]. The work was supported by RFBR grants (## 12-05-00312, 13-02-12074, 13-02-12241, 14-05-31445, 14-05-00855, 14-05-10069), grant MK-2670.2014.5, and by the scientific program “Geophysics”. References: 1. Frolov et al. // Radiophys. Quant. Electron., Engl. Transl., 2013 (submitted for publication). 2. Blagovethshenskaya N.F., et al. // Geophys. Res. Lett., 2011. Vol. 38, L08802, doi:10.1029/2011GL046724. 3. Blagoveshchensraya N.F. et al. // J. Atmos. Sol.-Terr. Phys., 2013. Vol. 105-106, p. 231. 4. Boiko G.N. et al. // Radiophys. Quant. Electron., Engl. Transl., 1985. Vol. 28, No. 8, p. 960. 5. Kuo S., et al. // Geophys. Res. Lett., 2010. Vol. 37, L01101, doi:10.1029/2009GL041471.

Ionospheric chemical releases

NASA Technical Reports Server (NTRS)

Bernhardt, Paul A.; Scales, W. A.

1990-01-01

Ionospheric plasma density irregularities can be produced by chemical releases into the upper atmosphere. F-region plasma modification occurs by: (1) chemically enhancing the electron number density; (2) chemically reducing the electron population; or (3) physically convecting the plasma from one region to another. The three processes (production, loss, and transport) determine the effectiveness of ionospheric chemical releases in subtle and surprising ways. Initially, a chemical release produces a localized change in plasma density. Subsequent processes, however, can lead to enhanced transport in chemically modified regions. Ionospheric modifications by chemical releases excites artificial enhancements in airglow intensities by exothermic chemical reactions between the newly created plasma species. Numerical models were developed to describe the creation and evolution of large scale density irregularities and airglow clouds generated by artificial means. Experimental data compares favorably with theses models. It was found that chemical releases produce transient, large amplitude perturbations in electron density which can evolve into fine scale irregularities via nonlinear transport properties.

Features of the Electromagnetic and Plasma Disturbances Induced at the Altitudes of the Earth's Outer Ionosphere by Modification of the Ionospheric F 2 Region Using High-Power Radio Waves Radiated by the SURA Heating Facility

NASA Astrophysics Data System (ADS)

Frolov, V. L.; Rapoport, V. O.; Schorokhova, E. A.; Belov, A. S.; Parrot, M.; Rauch, J.-L.

2016-08-01

In this paper we systematize the results of studying the characteristics of the plasma-density ducts, which was conducted in 2005-2010 during the DEMETER-satellite operation. The ducts are formed at altitudes of about 700 km as a result of the ionospheric F 2 region modification by high-power high-frequency radio waves radiated by the midlatitude SURA heating facility. All the performed measurements are used as the basis for determining the formation conditions for such ducts, the duct characteristics are studied, and the opportunities for the duct influence on the ionosphere-magnetosphere coupling and propagation of radio waves of various frequency ranges are demonstrated. The results of numerical simulation of the formation of such ducts are presented.

Airglow during ionospheric modifications by the sura facility radiation. experimental results obtained in 2010

NASA Astrophysics Data System (ADS)

Grach, S. M.; Klimenko, V. V.; Shindin, A. V.; Nasyrov, I. A.; Sergeev, E. N.; A. Yashnov, V.; A. Pogorelko, N.

2012-06-01

We present the results of studying the structure and dynamics of the HF-heated volume above the Sura facility obtained in 2010 by measurements of ionospheric airglow in the red (λ = 630 nm) and green (λ = 557.7 nm) lines of atomic oxygen. Vertical sounding of the ionosphere (followed by modeling of the pump-wave propagation) and measurements of stimulated electromagnetic emission were used for additional diagnostics of ionospheric parameters and the processes occurring in the heated volume.

Response of mesospheric ozone to the heating of the lower ionosphere by high-power HF radio emission

NASA Astrophysics Data System (ADS)

Kulilov, Yu. Yu.; Frolov, V. L.; Grigor'ev, G. I.; Demkin, V. M.; Komrakov, G. P.; Krasilnokov, A. A.; Ryskin, V. G.

2013-01-01

We detected a decrease in the intensity of microwave radiation at the atmospheric ozone line at a frequency of 110836.04 MHz during ionospheric modification by high-power HF radiowaves radiated by the Sura Ionospheric Heating Facility. The obtained experimental data allowed us to hypothesize that this effect was caused by the fact that mesospheric ozone was affected by internal gravity waves generated in the E region of the ionosphere during its high-power HF radiowave heating.

Observations of HF backscatter decay rates from HAARP generated FAI

NASA Astrophysics Data System (ADS)

Bristow, William; Hysell, David

2016-07-01

Suitable experiments at the High-frequency Active Auroral Research Program (HAARP) facilities in Gakona, Alaska, create a region of ionospheric Field-Aligned Irregularities (FAI) that produces strong radar backscatter observed by the SuperDARN radar on Kodiak Island, Alaska. Creation of FAI in HF ionospheric modification experiments has been studied by a number of authors who have developed a rich theoretical background. The decay of the irregularities, however, has not been so widely studied yet it has the potential for providing estimates of the parameters of natural irregularity diffusion, which are difficult measure by other means. Hysell, et al. [1996] demonstrated using the decay of radar scatter above the Sura heating facility to estimate irregularity diffusion. A large database of radar backscatter from HAARP generated FAI has been collected over the years. Experiments often cycled the heater power on and off in a way that allowed estimates of the FAI decay rate. The database has been examined to extract decay time estimates and diffusion rates over a range of ionospheric conditions. This presentation will summarize the database and the estimated diffusion rates, and will discuss the potential for targeted experiments for aeronomy measurements. Hysell, D. L., M. C. Kelley, Y. M. Yampolski, V. S. Beley, A. V. Koloskov, P. V. Ponomarenko, and O. F. Tyrnov, HF radar observations of decaying artificial field aligned irregularities, J. Geophys. Res. , 101, 26,981, 1996.

Observations of HF backscatter decay rates from HAARP generated FAI

NASA Astrophysics Data System (ADS)

Bristow, W. A.; Hysell, D. L.

2016-12-01

Suitable experiments at the High-frequency Active Auroral Research Program (HAARP) facilities in Gakona, Alaska, create a region of ionospheric Field-Aligned Irregularities (FAI) that produces strong radar backscatter observed by the SuperDARN radar on Kodiak Island, Alaska. Creation of FAI in HF ionospheric modification experiments has been studied by a number of authors who have developed a rich theoretical background. The decay of the irregularities, however, has not been so widely studied yet it has the potential for providing estimates of the parameters of natural irregularity diffusion, which are difficult measure by other means. Hysell, et al. [1996] demonstrated using the decay of radar scatter above the Sura heating facility to estimate irregularity diffusion. A large database of radar backscatter from HAARP generated FAI has been collected over the years. Experiments often cycled the heater power on and off in a way that allowed estimates of the FAI decay rate. The database has been examined to extract decay time estimates and diffusion rates over a range of ionospheric conditions. This presentation will summarize the database and the estimated diffusion rates, and will discuss the potential for targeted experiments for aeronomy measurements. Hysell, D. L., M. C. Kelley, Y. M. Yampolski, V. S. Beley, A. V. Koloskov, P. V. Ponomarenko, and O. F. Tyrnov, HF radar observations of decaying artificial field aligned irregularities, J. Geophys. Res. , 101, 26,981, 1996.

Active experiments in space plasmas; Symposium D4.1 of Commission D, COSPAR Scientific Assembly, 30th, Hamburg, Germany, July 11-21, 1994

NASA Astrophysics Data System (ADS)

Rietveld, M. T.

1995-07-01

Papers from the conference are presented and cover the following topics: ion and electron beams; ionospheric modification; spacecraft interactions; chemical releases; and plasma waves. Auroras and plasma emissions are reported from electron beam injection experiments on the EXCEDE 3 rocket and APEX satellite respectively. The important parameters affecting the charging of spacecraft during the operation of electron guns is covered. The Active Magnetospheric Particle Acceleration Satellite (AMPAS) mission utilizing dual-payload tethered satellites and both up and downward directed electron beams is proposed to study the magnetosphere. Recent results and associated theories from the Sura, Arecibo and Troms ionospheric heating facitlites are presented. The effects of neutral gases on spacecraft charging are examined in a series of rocket flights. Many results from the Combined Release and Radiation Effects Satellite chemical release experiments are presented. For individual titles, see A95-83500 through A95-83535.

Early/fast VLF events produced by the quiescent heating of the lower ionosphere by thunderstorms

NASA Astrophysics Data System (ADS)

Kabirzadeh, R.; Marshall, R. A.; Inan, U. S.

2017-06-01

Large and easily distinguishable perturbations of the VLF transmitter signals due to interactions with thundercloud-driven ionospheric modifications have been observed and studied for about three decades. These events are called "early/fast VLF" or "early VLF" events due to their immediate detection (˜20 ms) after the causative lightning flash on the ground and the fast rise time of the perturbed signal. Despite many years of study, the physical mechanisms responsible for these perturbations are still under investigation. Modifications of the sustained heating level of the ionosphere due to a lightning flash has been previously proposed as the causative mechanism of early/fast VLF events. The perturbations predicted by this mechanism, however, have been much smaller than experimental observations of 0.2-1 dB or higher. In this study, by using an improved 3-D thundercloud electrostatic upward coupling model which uses a realistic geomagnetic field, we find that the sustained heating model can predict perturbations that are consistent with reported experimental observations. Modifications in the quiescent heating of the lower ionosphere by thundercloud fields by individual lightning flashes may thus account for some observations of early/fast VLF events.

IonRayTrace: An HF Propagation Model for Communications and Radar Applications

DTIC Science & Technology

2014-12-01

for modeling the impact of ionosphere variability on detection algorithms. Modification of IonRayTrace’s source code to include flexible gridding and...color denotes plasma frequency in MHz .................................................................. 6 4. Ionospheric absorption (dB) versus... Ionosphere for its environmental background [3]. IonRayTrace’s operation is summarized briefly in Section 3. However, the scope of this document is primarily

HF produced ionospheric electron density irregularities diagnosed by UHF radio star scintillations

NASA Technical Reports Server (NTRS)

Frey, A.; Gordon, W. E.

1982-01-01

Three observations of radio star intensity fluctuations at UHF are reported for HF ionospheric modification experiments carried out at the Arecibo Observatory. Two observations at 430 MHz and one at 1400 MHz suggest that the the thin phase screen theory is a good approximation to the observed power spectra. It is noted, however, that the theory has to be extended to include antenna filtering. This type of filtering is important for UHF radio star scintillations since the antenna usually has a narrow beamwidth. HF power densities of less than 37 microwatts/sq m incident on the ionosphere give rise to electron density irregularities larger than 13% of the ambient density (at 260 km) having scale sizes of approximately 510 m perpendicular to the geomagnetic field. The irregularities are found to form within 20-25 s after the HF power is turned on. The drift velocities of the irregularities can be estimated from the observed power spectra.

Ionospheric modification at twice the electron cyclotron frequency.

PubMed

Djuth, F T; Pedersen, T R; Gerken, E A; Bernhardt, P A; Selcher, C A; Bristow, W A; Kosch, M J

2005-04-01

In 2004, a new transmission band was added to the HAARP high-frequency ionospheric modification facility that encompasses the second electron cyclotron harmonic at altitudes between approximately 220 and 330 km. Initial observations indicate that greatly enhanced airglow occurs whenever the transmission frequency approximately matches the second electron cyclotron harmonic at the height of the upper hybrid resonance. This is the reverse of what happens at higher electron cyclotron harmonics. The measured optical emissions confirm the presence of accelerated electrons in the plasma.

Solitons and ionospheric modification

NASA Technical Reports Server (NTRS)

Sheerin, J. P.; Nicholson, D. R.; Payne, G. L.; Hansen, P. J.; Weatherall, J. C.; Goldman, M. V.

1982-01-01

The possibility of Langmuir soliton formation and collapse during ionospheric modification is investigated. Parameters characterizing former facilities, existing facilities, and planned facilities are considered, using a combination of analytical and numerical techniques. At a spatial location corresponding to the exact classical reflection point of the modifier wave, the Langmuir wave evolution is found to be dominated by modulational instability followed by soliton formation and three-dimensional collapse. The earth's magnetic field is found to affect the shape of the collapsing soliton. These results provide an alternative explanation for some recent observations.

Ionospheric Storm Effects and Equatorial Plasma Irregularities During the 17-18 March 2015 Event

NASA Technical Reports Server (NTRS)

Zhou, Yun-Liang; Luhr, Hermann; Xiong, Chao; Pfaff, Robert F.

2016-01-01

The intense magnetic storm on 17-18 March 2015 caused large disturbances of the ionosphere. Based on the plasma density (Ni) observations performed by the Swarm fleet of satellites, the Gravity Recovery and Climate Experiment mission, and the Communications/Navigation Outage Forecasting System satellite, we characterize the storm-related perturbations at low latitudes. All these satellites sampled the ionosphere in morning and evening time sectors where large modifications occurred. Modifications of plasma density are closely related to changes of the solar wind merging electric field (E (sub m)). We consider two mechanisms, prompt penetration electric field (PPEF) and disturbance dynamo electric field (DDEF), as the main cause for the Ni redistribution, but effects of meridional wind are also taken into account. At the start of the storm main phase, the PPEF is enhancing plasma density on the dayside and reducing it on the nightside. Later, DDEF takes over and causes the opposite reaction. Unexpectedly, there appears during the recovery phase a strong density enhancement in the morning/pre-noon sector and a severe Ni reduction in the afternoon/evening sector, and we suggest a combined effect of vertical plasma drift, and meridional wind is responsible for these ionospheric storm effects. Different from earlier studies about this storm, we also investigate the influence of storm dynamics on the initiation of equatorial plasma irregularities (EPIs). Shortly after the start of the storm main phase, EPIs appear in the post-sunset sector. As a response to a short-lived decline of E (sub m), EPI activity appears in the early morning sector. Following the second start of the main phase, EPIs are generated for a few hours in the late evening sector. However, for the rest of the storm main phase, no more EPIs are initiated for more than 12 hours. Only after the onset of recovery phase does EPI activity start again in the post-midnight sector, lasting more than 7 hours.This comprehensive view of ionospheric storm effects and plasma irregularities adds to our understanding of conditions that lead to ionospheric instabilities.

Ionospheric storm effects and equatorial plasma irregularities during the 17-18 March 2015 event

NASA Astrophysics Data System (ADS)

Zhou, Yun-Liang; Lühr, Hermann; Xiong, Chao; Pfaff, Robert F.

2016-09-01

The intense magnetic storm on 17-18 March 2015 caused large disturbances of the ionosphere. Based on the plasma density (Ni) observations performed by the Swarm fleet of satellites, the Gravity Recovery and Climate Experiment mission, and the Communications/Navigation Outage Forecasting System satellite, we characterize the storm-related perturbations at low latitudes. All these satellites sampled the ionosphere in morning and evening time sectors where large modifications occurred. Modifications of plasma density are closely related to changes of the solar wind merging electric field (Em). We consider two mechanisms, prompt penetration electric field (PPEF) and disturbance dynamo electric field (DDEF), as the main cause for the Ni redistribution, but effects of meridional wind are also taken into account. At the start of the storm main phase, the PPEF is enhancing plasma density on the dayside and reducing it on the nightside. Later, DDEF takes over and causes the opposite reaction. Unexpectedly, there appears during the recovery phase a strong density enhancement in the morning/prenoon sector and a severe Ni reduction in the afternoon/evening sector, and we suggest a combined effect of vertical plasma drift, and meridional wind is responsible for these ionospheric storm effects. Different from earlier studies about this storm, we also investigate the influence of storm dynamics on the initiation of equatorial plasma irregularities (EPIs). Shortly after the start of the storm main phase, EPIs appear in the postsunset sector. As a response to a short-lived decline of Em, EPI activity appears in the early morning sector. Following the second start of the main phase, EPIs are generated for a few hours in the late evening sector. However, for the rest of the storm main phase, no more EPIs are initiated for more than 12 h. Only after the onset of recovery phase does EPI activity start again in the postmidnight sector, lasting more than 7 h. This comprehensive view of ionospheric storm effects and plasma irregularities adds to our understanding of conditions that lead to ionospheric instabilities.

First observations of minority ion (H+) structuring in stimulated radiation during second electron gyroharmonic heating experiments

NASA Astrophysics Data System (ADS)

Bordikar, M. R.; Scales, W. A.; Samimi, A. R.; Bernhardt, P. A.; Brizcinski, S.; McCarrick, M. J.

2013-04-01

This work presents the first observations of unique narrowband emissions ordered near the hydrogen ion (H+) gyrofrequency (fcH) in the stimulated electromagnetic emission spectrum when the transmitter is tuned near the second electron gyroharmonic frequency (2fce) during ionospheric modification experiments. The frequency structuring of these newly discovered emission lines is quite unexpected since H+ is known to be a minor constituent in the interaction region which is near 160 km altitude. The spectral lines are typically shifted from the pump wave frequency by harmonics of a frequency about 10% less than fcH (≈ 800 Hz) and have a bandwidth of less than 50 Hz which is near the O+ gyrofrequency fcO. A theory is proposed to explain these emissions in terms of a parametric decay instability in a multi-ion species plasma due to possible proton precipitation associated with the disturbed conditions during the heating experiment. The observations can be explained by including several percent H+ ions into the background plasma. The implications are new possibilities for characterizing proton precipitation events during ionospheric heating experiments.

Estimating the electron energy distribution during ionospheric modification from spectrographic airglow measurements

NASA Astrophysics Data System (ADS)

Hysell, D. L.; Varney, R. H.; Vlasov, M. N.; Nossa, E.; Watkins, B.; Pedersen, T.; Huba, J. D.

2012-02-01

The electron energy distribution during an F region ionospheric modification experiment at the HAARP facility near Gakona, Alaska, is inferred from spectrographic airglow emission data. Emission lines at 630.0, 557.7, and 844.6 nm are considered along with the absence of detectable emissions at 427.8 nm. Estimating the electron energy distribution function from the airglow data is a problem in classical linear inverse theory. We describe an augmented version of the method of Backus and Gilbert which we use to invert the data. The method optimizes the model resolution, the precision of the mapping between the actual electron energy distribution and its estimate. Here, the method has also been augmented so as to limit the model prediction error. Model estimates of the suprathermal electron energy distribution versus energy and altitude are incorporated in the inverse problem formulation as representer functions. Our methodology indicates a heater-induced electron energy distribution with a broad peak near 5 eV that decreases approximately exponentially by 30 dB between 5-50 eV.

Modifications of the ionosphere prior to large earthquakes: report from the Ionosphere Precursor Study Group

NASA Astrophysics Data System (ADS)

Oyama, K.-I.; Devi, M.; Ryu, K.; Chen, C. H.; Liu, J. Y.; Liu, H.; Bankov, L.; Kodama, T.

2016-12-01

The current status of ionospheric precursor studies associated with large earthquakes (EQ) is summarized in this report. It is a joint endeavor of the "Ionosphere Precursor Study Task Group," which was formed with the support of the Mitsubishi Foundation in 2014-2015. The group promotes the study of ionosphere precursors (IP) to EQs and aims to prepare for a future EQ dedicated satellite constellation, which is essential to obtain the global morphology of IPs and hence demonstrate whether the ionosphere can be used for short-term EQ predictions. Following a review of the recent IP studies, the problems and specific research areas that emerged from the one-year project are described. Planned or launched satellite missions dedicated (or suitable) for EQ studies are also mentioned.

Experiments and theory on parametric instabilities excited in HF heating experiments at HAARP

NASA Astrophysics Data System (ADS)

Kuo, Spencer; Snyder, Arnold; Lee, M. C.

2014-06-01

Parametric instabilities excited by O-mode HF heater and the induced ionospheric modification were explored via HAARP digisonde operated in a fast mode. The impact of excited Langmuir waves and upper hybrid waves on the ionosphere are manifested by bumps in the virtual spread, which expand the ionogram echoes upward as much as 140 km and the downward range spread of the sounding echoes, which exceeds 50 km over a significant frequency range. The theory of parametric instabilities is presented. The theory identifies the ionogram bump located between the 3.2 MHz heater frequency and the upper hybrid resonance frequency and the bump below the upper hybrid resonance frequency to be associated with the Langmuir and upper hybrid instabilities, respectively. The Langmuir bump is located close to the upper hybrid resonance frequency, rather than to the heater frequency, consistent with the theory. Each bump in the virtual height spread of the ionogram is similar to the cusp occurring in daytime ionograms at the E-F2 layer transition, indicating that there is a small ledge in the density profile similar to E-F2 layer transitions. The experimental results also show that the strong impact of the upper hybrid instability on the ionosphere can suppress the Langmuir instability.

Experiments and theory on parametric instabilities excited in HF heating experiments at HAARP

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kuo, Spencer; Snyder, Arnold; Lee, M. C.

2014-06-15

Parametric instabilities excited by O-mode HF heater and the induced ionospheric modification were explored via HAARP digisonde operated in a fast mode. The impact of excited Langmuir waves and upper hybrid waves on the ionosphere are manifested by bumps in the virtual spread, which expand the ionogram echoes upward as much as 140 km and the downward range spread of the sounding echoes, which exceeds 50 km over a significant frequency range. The theory of parametric instabilities is presented. The theory identifies the ionogram bump located between the 3.2 MHz heater frequency and the upper hybrid resonance frequency and the bump below themore » upper hybrid resonance frequency to be associated with the Langmuir and upper hybrid instabilities, respectively. The Langmuir bump is located close to the upper hybrid resonance frequency, rather than to the heater frequency, consistent with the theory. Each bump in the virtual height spread of the ionogram is similar to the cusp occurring in daytime ionograms at the E-F2 layer transition, indicating that there is a small ledge in the density profile similar to E-F2 layer transitions. The experimental results also show that the strong impact of the upper hybrid instability on the ionosphere can suppress the Langmuir instability.« less

Electron Acceleration and Ionization Production in High-Power Heating Experiments at HAARP

NASA Astrophysics Data System (ADS)

Mishin, E. V.; Pedersen, T.

2012-12-01

Recent ionospheric modification experiments with the 3.6 MW transmitter at the High Frequency Active Auroral Research Program (HAARP) facility in Alaska led to discovery of artificial ionization descending from the nominal interaction altitude in the background F-region ionosphere by ~60-80 km. Artificial ionization production is indicated by significant 427.8 nm emissions from the 1st negative band of N2+ and the appearance of transmitter-induced bottomside traces in ionosonde data during the periods of most intense optical emissions. However, the exact mechanisms producing the artificial plasmas remain to be determined. Yet the only existing theoretical models explain the development of artificial plasma as an ionizing wavefront moving downward due to ionization by electrons accelerated by HF-excited strong Langmuir turbulence (SLT) generated near the plasma resonance, where the pump frequency matches the plasma frequency. However, the observations suggest also the significance of interactions with upper hybrid and electron Bernstein waves near multiples of the electron gyrofrequency. We describe recent observations and discuss suitable acceleration mechanisms.

Observations of enhanced ion line frequency spectrum during Arecibo ionospheric modification experiment

NASA Technical Reports Server (NTRS)

Hagfors, T.; Zamlutti, C. J.

1974-01-01

The Arecibo 430 MHz incoherent scatter radar (ISR) was used to monitor the effects of modifying the ionosphere by a high power HF transmitter feeding the 305 m reflector antenna. When in the ordinary magnetoionic mode parametric instabilities develop in the ionosphere near the reflection level. Manifestations of these instabilities are the strong enhancement of Langmuir oscillations in the direction of the ISR beam at a wavelength of 35 cm and the simultaneous much weaker enhancement of ion oscillations in that direction. The spectral analysis of the enhanced peak with a height resolution of 2.4 km shows that the ionic mode enhancement most often has a double humped frequency spectrum corresponding to up- and down-going ion acoustic waves. The shape of the frequency spectrum is interpreted in terms of a stable oscillation which is driven by a secondary electrostatic field caused by nonlinear interaction of Langmuir waves within a cone centered on the magnetic field and by the scattering of the pump field on stable Langmuir waves travelling along the direction of the ISR.

Ionospheric modification by radio waves: An overview and novel applications

NASA Astrophysics Data System (ADS)

Kosch, M. J.

2008-12-01

High-power high-frequency radio waves, when beamed into the Earth's ionosphere, can heat the plasma by particle collisions in the D-layer or generate wave-plasma resonances in the F-layer. These basic phenomena have been used in many research applications. In the D-layer, ionospheric currents can be modulated through conductance modification to produce artificial ULF and VLF waves, which propagate allowing magnetospheric research. In the mesopause, PMSE can be modified allowing dusty plasma research. In the F-layer, wave-plasma interactions generate a variety of artificially stimulated phenomena, such as (1) magnetic field-aligned plasma irregularities linked to anomalous radio wave absorption, (2) stimulated electromagnetic emissions linked to upper-hybrid resonance, (3) optical emissions linked to electron acceleration and collisions with neutrals, and (4) Langmuir turbulence linked to enhanced radar backscatter. These phenomena are reviewed. In addition, some novel applications of ionospheric heaters will be presented, including HF radar sounding of the magnetosphere, the production of E-region optical emissions, and measurements of D-region electron temperature for controlled PMSE research.

Ionospheric Correction of D-InSAR Using Split-Spectrum Technique and 3D Ionosphere Model in Deformation Monitoring

NASA Astrophysics Data System (ADS)

Chen, Y.; Guo, L.; Wu, J. J.; Chen, Q.; Song, S.

2014-12-01

In Differential Interferometric Synthetic Aperture Radar (D-InSAR) atmosphere effect including troposphere and ionosphere is one of the dominant sources of error in most interferograms, which greatly reduced the accuracy of deformation monitoring. In recent years tropospheric correction especially Zwd in InSAR data processing has ever got widely investigated and got efficiently suppressed. And thus we focused our study on ionospheric correction using two different methods, which are split-spectrum technique and Nequick model, one of the three dimensional electron density models. We processed Wenchuan ALOS PALSAR images, and compared InSAR surface deformation after ionospheric modification using the two approaches mentioned above with ground GPS subsidence observations to validate the effect of split-spectrum method and NeQuick model, further discussed the performance and feasibility of external data and InSAR itself during the study of the elimination of InSAR ionospheric effect.

Analysis of the Metal Oxide Space Clouds (MOSC) HF Propagation Environment

NASA Astrophysics Data System (ADS)

Jackson-Booth, N.; Selzer, L.

2015-12-01

Artificial Ionospheric Modification (AIM) attempts to modify the ionosphere in order to alter the high frequency (HF) propagation environment. It can be achieved through injections of aerosols, chemicals or radio (RF) signals into the ionosphere. The Metal Oxide Space Clouds (MOSC) experiment was undertaken in April/May 2013 to investigate chemical AIM. Two sounding rockets were launched from the Kwajalein Atoll (part of the Marshall Islands) and each released a cloud of vaporized samarium (Sm). The samarium created a localized plasma cloud, with increased electron density, which formed an additional ionospheric layer. The ionospheric effects were measured by a wide range of ground based instrumentation which included a network of high frequency (HF) sounders. Chirp transmissions were made from three atolls and received at five sites within the Marshall Islands. One of the receive sites consisted of an 18 antenna phased array, which was used for direction finding. The ionograms have shown that as well as generating a new layer the clouds created anomalous RF propagation paths, which interact with both the cloud and the F-layer, resulting in 'ghost traces'. To fully understand the propagation environment a 3D numerical ray trace has been undertaken, using a variety of background ionospheric and cloud models, to find the paths through the electron density grid for a given fan of elevation and azimuth firing angles. Synthetic ionograms were then produced using the ratio of ray path length to speed of light as an estimation of the delay between transmission and observation for a given frequency of radio wave. This paper reports on the latest analysis of the MOSC propagation environment, comparing theory with observations, to further understanding of AIM.

Ionospheric Behavior During the First Few Hours of Intense Geomagnetic Storms

NASA Technical Reports Server (NTRS)

Mannucci, Anthony J.; Crowley, Geoff; Tsurutani, Bruce; Fuller-Rowell, Tim

2006-01-01

The behavior of the ionosphere during the first few hours of intense geomagnetic storms is presented. The topics include: 1) TEC Modification; 2) JASON TEC (1336 km altitude); 3) Multiple Storms; 4) CHAMP (greater than 400 km) November 20, 2003; 5) November 20, 1PM LT, Ground; 6) Role of Modeling; and 7) Composition-related increase.

Variability of plasma-line enhancement in ionospheric modification experiments.

NASA Technical Reports Server (NTRS)

Fejer, J. A.

1972-01-01

A simple explanation for the variations of plasma-line intensity is suggested. The explanation is based on the fact that the plasma waves responsible for scattering the radar waves occur over a very limited range of heights. The explanation further makes use of the fact that the position of these height ranges of generation depends primarily on the gradient of the number density and to a lesser extent on the temperature and the orientation of the diagnostic radar beam.

A study of ionospheric grid modification technique for BDS/GPS receiver

NASA Astrophysics Data System (ADS)

Liu, Xuelin; Li, Meina; Zhang, Lei

2017-07-01

For the single-frequency GPS receiver, ionospheric delay is an important factor affecting the positioning performance. There are many kinds of ionospheric correction methods, common models are Bent model, IRI model, Klobuchar model, Ne Quick model and so on. The US Global Positioning System (GPS) uses the Klobuchar coefficients transmitted in the satellite signal to correct the ionospheric delay error for a single frequency GPS receiver, but this model can only reduce the ionospheric error of about 50% in the mid-latitudes. In the Beidou system, the accuracy of the correction delay is higher. Therefore, this paper proposes a method that using BD grid information to correct GPS ionospheric delay to improve the ionospheric delay for the BDS/GPS compatible positioning receiver. In this paper, the principle of ionospheric grid algorithm is introduced in detail, and the positioning accuracy of GPS system and BDS/GPS compatible positioning system is compared and analyzed by the real measured data. The results show that the method can effectively improve the positioning accuracy of the receiver in a more concise way.

Pluto-Charon solar wind interaction dynamics

NASA Astrophysics Data System (ADS)

Hale, J. P. M.; Paty, C. S.

2017-05-01

This work studies Charon's effects on the Pluto-solar wind interaction using a multifluid MHD model which simulates the interactions of Pluto and Charon with the solar wind as well as with each other. Specifically, it investigates the ionospheric dynamics of a two body system in which either one or both bodies possess an ionosphere. Configurations in which Charon is directly upstream and directly downstream of Pluto are considered. Depending on ionospheric and solar wind conditions, Charon could periodically pass into the solar wind flow upstream of Pluto. The results of this study demonstrate that in these circumstances Charon modifies the upstream flow, both in the case in which Charon possesses an ionosphere, and in the case in which Charon is without an ionosphere. This modification amounts to a change in the gross structure of the interaction region when Charon possesses an ionosphere but is more localized when Charon lacks an ionosphere. Furthermore, evidence is shown that supports Charon acting to partially shield Pluto from the solar wind when it is upstream of Pluto, resulting in a decrease in ionospheric loss by Pluto.

Atmosphere-Ionosphere Electrodynamic Coupling

NASA Astrophysics Data System (ADS)

Sorokin, V. M.; Chmyrev, V. M.

Numerous phenomena that occur in the mesosphere, ionosphere, and the magnetosphere of the Earth are caused by the sources located in the lower atmosphere and on the ground. We describe the effects produced by lightning activity and by ground-based transmitters operated in high frequency (HF) and very low frequency (VLF) ranges. Among these phenomena are the ionosphere heating and the formation of plasma density inhomogeneities, the excitation of gamma ray bursts and atmospheric emissions in different spectral bands, the generation of ULF/ELF/VLF electromagnetic waves and plasma turbulence in the ionosphere, the stimulation of radiation belt electron precipitations and the acceleration of ions in the upper ionosphere. The most interesting results of experimental and theoretical studies of these phenomena are discussed below. The ionosphere is subject to the action of the conductive electric current flowing in the atmosphere-ionosphere circuit. We present a physical model of DC electric field and current formation in this circuit. The key element of this model is an external current, which is formed with the occurrence of convective upward transport of charged aerosols and their gravitational sedimentation in the atmosphere. An increase in the level of atmospheric radioactivity results in the appearance of additional ionization and change of electrical conductivity. Variation of conductivity and external current in the lower atmosphere leads to perturbation of the electric current flowing in the global atmosphere-ionosphere circuit and to the associated DC electric field perturbation both on the Earth's surface and in the ionosphere. Description of these processes and some results of the electric field and current calculations are presented below. The seismic-induced electric field perturbations produce noticeable effects in the ionosphere by generating the electromagnetic field and plasma disturbances. We describe the generation mechanisms of such experimentally observed effects as excitation of plasma density inhomogeneities, field-aligned currents, and ULF/ELF emissions and the modification of electron and ion altitude profiles in the upper ionosphere. The electrodynamic model of the ionosphere modification under the influence of some natural and man-made processes in the atmosphere is also discussed. The model is based on the satellite and ground measurements of electromagnetic field and plasma perturbations and on the data on atmospheric radioactivity and soil gas injection into the atmosphere.

Recent Science Campaigns at HAARP

NASA Astrophysics Data System (ADS)

McCoy, R. P.; Bristow, W. A.; Fallen, C. T.

2017-12-01

Experiments in HF ionospheric heating using the High­frequency Active Auroral Research Program (HAARP) facilities have tremendous potential for informing our investigation of the Earth's upper atmosphere, ionosphere, and magnetosphere. They provide a unique opportunity for quantifying and modeling the multi­scale coupled processes that characterize the interactions between the plasma in near­Earth space, the Earth's magnetic field, and the neutral gasses of the atmosphere. Physical parameters of the region are often difficult to measure with ground­based instruments, and the measurements that are possible are often poorly resolved in range or time or unavailable outside narrow altitude regimes. HF ionospheric modification experiments allow us to measure ionospheric and thermospheric state parameters more systematically and over a broader range of conditions than would otherwise be possible. HAARP is the world's most powerful and most flexible HF transmitting facility, capable of generating 3.6 MW of RF power over a frequency range from about 2 MHz to about 10 MHz. The electronic phased array antenna provides the ability to direct the RF energy to a large region of the sky above Alaska. HAARP was constructed through a research program managed by the Air Force Research Laboratory (AFRL), and the Office of Naval Research (ONR). It was jointly funded by AFRL, ONR, and the Defense Advanced Projects Research Agency (DARPA). These agencies ended of their program of HAARP research in 2014, and donated the site equipment to the University of Alaska, Fairbanks (UAF), in the summer of 2015, who now operate the facility as an international observatory for radio plasma heating and subauroral physics. Since taking control of HAARP, UAF has carried out research campaigns in February 2017, and September 2017. The topics investigated in the campaigns included the physics of ionospheric irregularities (FAI), the stimulated electromagnetic emissions (SEE), generation of optical emissions from the heated region, and technological impacts of irregularities. This paper will give an overview of the status of the facility and will present preliminary results from the experiments carried out in the campaigns.

Electrodynamics of the Martian Ionosphere

NASA Astrophysics Data System (ADS)

Ledvina, S. A.; Brecht, S. H.

2017-12-01

The presence of the Martian crustal magnetic fields makes a significant modification to the interaction between the solar wind/IMF and the ionosphere of the planet. This paper presents the results of 3-D hybrid simulations of Martian solar wind interaction containing the Martian crustal fields., self-consistent ionospheric chemistry and planetary rotation. It has already been reported that the addition of the crustal fields and planetary rotation makes a significant modification of the ionospheric loss from Mars, Brecht et al., 2016. This paper focuses on two other aspects of the interaction, the electric fields and the current systems created by the solar wind interaction. The results of several simulations will be analyzed and compared. The electric fields around Mars due to its interaction with the solar wind will be examined. Special attention will be paid to the electric field constituents (∇ X B, ∇Pe, ηJ). Regions where the electric field is parallel to the magnetic field will be found and the implications of these regions will be discussed. Current systems for each ion species will be shown. Finally the effects on the electric fields and the current systems due to the rotation of Mars will be examined.

Parameterized study of the ionospheric modification associated with sun-aligned polar cap arcs

NASA Technical Reports Server (NTRS)

Crain, D. J.; Sojka, J. J.; Schunk, R. W.; Zhu, L.

1993-01-01

The local ionospheric modification that is due to a generalized steady state solar aligned (SA) arc structure is addressed. For a representative set of SA arc parameters which includes both convection and precipitation, emphasis is placed on the modification by SA polar cap arcs upon the F region electron density and the height integrated conductivity. At low fluxes and low characteristic energies, SA polar cap arcs have the most pronounced relative effect at F region altitudes in darkness for winter solar minimum conditions. The absolute enhancement in summer solar minimum and winter solar maximum is equivalent to that of winter solar minimum, but the higher ambient densities make the relative enhancement less. The TEC enhancement associated with an SA arc may be used to indicate the degree of plasma cross flow across the arc.

Feedback instability of the ionospheric resonant cavity

NASA Technical Reports Server (NTRS)

Lysak, Robert L.

1991-01-01

A model is developed that provides a theoretical basis for previous numerical results showing a feedback instability with frequencies characteristic of Alfven travel times within the region of the large increase of Alfven speed above the ionosphere. These results have been extended to arbitrary ionospheric conductivity by developing a numerical solution of the cavity dispersion relation that involves Bessel functions of complex order and argument. It is concluded that the large contrast between the magnetospheric and ionospheric Alfven speed leads to the formation of resonant cavity modes with frequencies ranging from 0.1 to 1 Hz. The presence of the cavity leads to a modification of the reflection characteristics of Alfven waves with frequencies that compare to the cavity's normal modes.

The theory of ionospheric focused heating

NASA Technical Reports Server (NTRS)

Bernhardt, P. A.; Duncan, L. M.

1987-01-01

Ionospheric modification by high power radio waves and by chemical releases are combined in a theoretical study of ionospheric focused heating. The release of materials which promote electron-ion recombination creates a hole in the bottomside ionosphere. The ionospheric hole focuses high power radio waves from a ground-based transmitter to give a 20 dB or greater enhancement in power density. The intense radio beam excites atomic oxygen by collisions with accelerated electrons. Airglow from the excited oxygen provides a visible trace of the focused beam. The large increase in the intensity of the radio beam stimulates new wave-plasma interactions. Numerical simulations show that the threshold for the two-plasmon decay instability is exceeded. The interaction of the pump electromagnetic wave with the backward plasmon produces a scattered electromagnetic wave at 3/2 the pump frequency. The scattered wave provides a unique signature of the two-plasmon decay process for ground-based detection.

ARL Support of NRL Rocket Experiments to Investigate Ionospheric Phenomena

DTIC Science & Technology

2010-08-31

reallocate the funds to support NRL’s ongoing efforts to develop an ionospheric tomography network in South America to support the C/NOFS satellite...of NRL Rocket Experiments to Investigate Ionospheric Phenomena 5a. CONTRACT NUMBER N00173-09-1-G036 5b. GRANT NUMBER N00173-09-1-G036 5c...1-G036 ARL Support of NRL Rocket Experiments to Investigate Ionospheric Phenomena BY DR. TREVOR W. GARNER APPLIED RESEARCH LABORATORIES THE

Heater-induced ionization inferred from spectrometric airglow measurements

NASA Astrophysics Data System (ADS)

Hysell, D. L.; Miceli, R. J.; Varney, R. H.; Schlatter, N.; Huba, J. D.

2013-12-01

Spectrographic airglow measurements were made during an ionospheric modification experiment at HAARP on March 12, 2013. Artificial airglow enhancements at 427.8, 557.7, 630.0, 777.4, and 844.6 nm were observed. On the basis of these emissions and using a methodology based on the method of Backus and Gilbert [1968, 1970], we estimate the suprathermal electron population and the subsequent equilibrium electron density profile, including contributions from electron impact ionization. We find that the airglow is consistent with significant induced ionization in view of the spatial intermittency of the airglow.

Ionospheric modification - An initial report on artificially created equatorial Spread F

NASA Technical Reports Server (NTRS)

Ossakow, S. L.; Zalesak, S. T.; Mcdonald, B. E.

1978-01-01

A numerical simulation code for investigating equatorial Spread F in the collisional Rayleigh-Taylor regime is utilized to follow the evolution of artificial plasma density depletions injected into the bottomside nighttime equatorial F region. The 70 km diameter hole rapidly rises and steepens, forming plasma density enhancements at altitudes below the rising hole. The distribution of enhancements and depletions is similar to natural equatorial Spread F phenomena, except it occurs on a much faster time scale. These predictions warrant carrying out artificial injection experiments in the nighttime equatorial F region.

High-resolution studies of the HF ionospheric modification interaction region

NASA Technical Reports Server (NTRS)

Duncan, L. M.; Sheerin, J. P.

1985-01-01

The use of the pulse edge analysis technique to explain ionospheric modifications caused by high-power HF radio waves is discussed. The technique, implemented at the Arecibo Observatory, uses long radar pulses and very rapid data sampling. A comparison of the pulse leading and trailing edge characteristics is obtained and the comparison is used to estimate the relative changes in the interaction region height and layer width; an example utilizing this technique is provided. Main plasma line overshoot and miniovershoot were studied from the pulse edge observations; the observations at various HF pulsings and radar resolutions are graphically presented. From the pulse edge data the development and the occurrence of main plasma line overshoot and miniovershoot are explained. The theories of soliton formation and collapse, wave ducting, profile modification, and parametric instabilities are examined as a means of explaining main plasma line overshoots and miniovershoots.

Magnetic zenith effect in the ionospheric modification by an X-mode HF heater wave

NASA Astrophysics Data System (ADS)

Blagoveshchenskaya, N. F.; Borisova, T. D.; Haggstrom, I.; Rietveld, M. T.; Yeoman, T. K.

2013-12-01

We report experimental results aimed at an investigation of the magnetic zenith effect in the high latitude ionosphere F region from ionospheric modification by powerful HF heater wave with X-polarization. The ionospheric modification was produced by the HF heating facility at Tromsø (Norway) using the phased array with a narrow beam with of 6 degrees. Effective radiated power was varied between 450 and 1000 MW. The HF pump wave radiated in different directions relative to the magnetic field from 90 degrees (vertical) to 78 degrees (magnetic zenith) at frequencies near or above the ordinary-mode critical frequency. The response of the ionosphere plasma to the HF pump wave impact was checked by the UHF incoherent scatter radar located in the immediate vicinity of the HF heater. UHF radar was probing the plasma parameters, such as electron density and temperature (Ne and Te), HF-induced plasma and ion lines in the altitude range from 90 to 600 km. It was running in a scanning mode when UHF radar look angles were changed from 74 to 90 degrees by 1 or 2 degree step. It was clearly demonstrated that the strongest heater-induced effects took place in the magnetic field-aligned direction when HF pointing was also to the magnetic zenith. It was found that strong Ne enhancement of up to 80 % along magnetic field (artificial density ducts) were excited only under HF pumping towards magnetic zenith. The width of the artificial ducts comes to only 2 degrees. The Ne increases were accompanied by the Te enhancements of up to about 50 %. Less pronounced Te increases were also observed in the directions of 84 and 90 degrees. Strong Ne enhancements can be accompanied by excitation of strong HF-induced plasma and ion lines. Thus experimental results obtained points to the strong magnetic zenith effect due to self-focusing powerful HF radio wave with X-mode polarization.

Low-Frequency Waves in HF Heating of the Ionosphere

NASA Astrophysics Data System (ADS)

Sharma, A. S.; Eliasson, B.; Milikh, G. M.; Najmi, A.; Papadopoulos, K.; Shao, X.; Vartanyan, A.

2016-02-01

Ionospheric heating experiments have enabled an exploration of the ionosphere as a large-scale natural laboratory for the study of many plasma processes. These experiments inject high-frequency (HF) radio waves using high-power transmitters and an array of ground- and space-based diagnostics. This chapter discusses the excitation and propagation of low-frequency waves in HF heating of the ionosphere. The theoretical aspects and the associated models and simulations, and the results from experiments, mostly from the HAARP facility, are presented together to provide a comprehensive interpretation of the relevant plasma processes. The chapter presents the plasma model of the ionosphere for describing the physical processes during HF heating, the numerical code, and the simulations of the excitation of low-frequency waves by HF heating. It then gives the simulations of the high-latitude ionosphere and mid-latitude ionosphere. The chapter also briefly discusses the role of kinetic processes associated with wave generation.

CRRES combined radiation and release effects satellite program

NASA Technical Reports Server (NTRS)

Giles, B. L. (Compiler); Mccook, M. A. (Compiler); Mccook, M. W. (Compiler); Miller, G. P. (Compiler)

1995-01-01

The various regions of the magnetosphere-ionosphere system are coupled by flows of charged particle beams and electromagnetic waves. This coupling gives rise to processes that affect both technical and non-technical aspects of life on Earth. The CRRES Program sponsored experiments which were designed to produce controlled and known input to the space environment and the effects were measured with arrays of diagnostic instruments. Large amounts of material were used to modify and perturb the environment in a controlled manner, and response to this was studied. The CRRES and PEGSAT satellites were dual-mission spacecraft with a NASA mission to perform active chemical-release experiments, grouped into categories of tracer, modification, and simulation experiments. Two sounding rocket chemical release campaigns completed the study.

Qualitative Investigation of the Earthquake Precuesors Prior to the March 14,2012 Earthquake in Japan

NASA Astrophysics Data System (ADS)

Raghuwanshi, Shailesh Kumar; Gwal, Ashok Kumar

Abstract: In this study we have used the Empirical Mode Decomposition (EMD) method in conjunction with the Cross Correlation analysis to analyze ionospheric foF2 parameter Japan earthquake with magnitude M = 6.9. The data are collected from Kokubunji (35.70N, 139.50E) and Yamakawa (31.20N, 130.60E) ionospheric stations. The EMD method was used for removing the geophysical noise from the foF2 data and then to calculate the correlation coefficient between them. It was found that the ionospheric foF2 parameter shows anomalous change few days before the earthquake. The results are in agreement with the theoretical model evidencing ionospheric modification prior to Japan earthquake in a certain area around the epicenter.

Arecibo - HF experiments in the E_region

NASA Astrophysics Data System (ADS)

Nossa, E.; Jain, K.; Sulzer, M. P.; Perillat, P.

2017-12-01

The new Arecibo Observatory - HF facility started operations in 2015. The HF facility is fully operational, acquiring consecutive days of data without unwanted interruptions. It has a maximum transmitted power of 600kW, with center frequencies at 5.125 MHz and 8.175 MHz. The 8.175 (5.125) MHz band frequency has a gain of 25.5 (22) dB and HPBW of 8.5 (13) degrees. The effects of the HF experiments in the ionosphere are being observed with the Arecibo incoherent scatter radar (ISR). The ISR has two beams that simultaneously could sense the modified region and the region outside of the affected volume. The ISR has height resolution of 300 m. and allows to observe from altitudes 95 km to the topside ionosphere. Observation of the E-region - HF experiments are sparse but possible at Arecibo. High ionization at a height 100 km are needed to modify the region artificially. This paper presents examples of E-region enhanced plasma lines (See Figure). Diagnostic of the layers is made using the ISR to estimate electron density, temperatures, ion drifts, among others. The data shows exceptional modifications of the ionosphere that range from creating artificial cavities and layers, induced irregularities, substantial variations in temperature profiles to enhanced ion and plasma densities.Previously, the HF experiments were performed to study specific effects in a narrow region. However, the extent of the data collected with the ISR during 2017 is revealing new features and different kind of forces that artificially modify extended regions of the ionosphere. This paper exhibits examples where the interaction between the E and F-region when HF experiments are evident. A theory of a correlation between the two layers due to different conductivities is explored to illustrate how the enhancement of irregularities is produced and maintained over time. Examples of strong artificially induced irregularities formed at F-region heights when Sporadic E-layer is present are shown to support the theory.The Figure shows an enhanced plasma line for the diurnal E-region. For this HF experiment, the plasma density increased from 3.6 MHz to 5.1MHz (which corresponds to the HF frequency). The vertical lines observed in the Figure are artifacts from the data, as well as the fake enhanced plasma lines at frequencies different than the HF frequency.

Nonlinear interaction of strong microwave beam with the ionosphere MINIX rocket experiment

NASA Astrophysics Data System (ADS)

Kaya, N.; Matsumoto, H.; Miyatake, S.; Kimura, I.; Nagatomo, M.

A rocket-borne experiment called 'MINIX' was carried out to investigate the nonlinear interaction of a strong microwave energy beam with the ionosphere. The MINIX stands for Microwave-Ionosphere Nonlinear Interaction eXperiment and was carried out on August 29, 1983. The objective of the MINIX is to study possible impacts of the SPS microwave energy beam on the ionosphere, such as the ohmic heating and plasma wave excitation. The experiment showed that the microwave with f = 2.45 GHz nonlinearly excites various electrostatic plasma waves, though no ohmic heating effects were detected.

HICO and RAIDS Experiment Payload - Remote Atmospheric and Ionospheric Detection System (RAIDS)

NASA Technical Reports Server (NTRS)

Budzien, Scott

2009-01-01

The HICO and RAIDS Experiment Payload - Remote Atmospheric and Ionospheric Detection System (HREP-RAIDS) experiment will provide atmospheric scientists with a complete description of the major constituents of the thermosphere (layer of the Earth's atmosphere) and ionosphere (uppermost layer of the Earth's atmosphere), global electron density profiles at altitudes between 100 - 350 kilometers.

The effect of a gamma ray flare on Schumann resonances

NASA Astrophysics Data System (ADS)

Nickolaenko, A. P.; Kudintseva, I. G.; Pechony, O.; Hayakawa, M.; Hobara, Y.; Tanaka, Y. T.

2012-09-01

We describe the ionospheric modification by the SGR 1806-20 gamma flare (27 December 2004) seen in the global electromagnetic (Schumann) resonance. The gamma rays lowered the ionosphere over the dayside of the globe and modified the Schumann resonance spectra. We present the extremely low frequency (ELF) data monitored at the Moshiri observatory, Japan (44.365° N, 142.24° E). Records are compared with the expected modifications, which facilitate detection of the simultaneous abrupt change in the dynamic resonance pattern of the experimental record. The gamma flare modified the current of the global electric circuit and thus caused the "parametric" ELF transient. Model results are compared with observations enabling evaluation of changes in the global electric circuit.

Ionospheric modifications in high frequency heating experiments

NASA Astrophysics Data System (ADS)

Kuo, Spencer P.

2015-01-01

Featured observations in high-frequency (HF) heating experiments conducted at Arecibo, EISCAT, and high frequency active auroral research program are discussed. These phenomena appearing in the F region of the ionosphere include high-frequency heater enhanced plasma lines, airglow enhancement, energetic electron flux, artificial ionization layers, artificial spread-F, ionization enhancement, artificial cusp, wideband absorption, short-scale (meters) density irregularities, and stimulated electromagnetic emissions, which were observed when the O-mode HF heater waves with frequencies below foF2 were applied. The implication and associated physical mechanism of each observation are discussed and explained. It is shown that these phenomena caused by the HF heating are all ascribed directly or indirectly to the excitation of parametric instabilities which instigate anomalous heating. Formulation and analysis of parametric instabilities are presented. The results show that oscillating two stream instability and parametric decay instability can be excited by the O-mode HF heater waves, transmitted from all three heating facilities, in the regions near the HF reflection height and near the upper hybrid resonance layer. The excited Langmuir waves, upper hybrid waves, ion acoustic waves, lower hybrid waves, and field-aligned density irregularities set off subsequent wave-wave and wave-electron interactions, giving rise to the observed phenomena.

Parametric excitation of very low frequency (VLF) electromagnetic whistler waves and interaction with energetic electrons in radiation belt

NASA Astrophysics Data System (ADS)

Sotnikov, V.; Kim, T.; Caplinger, J.; Main, D.; Mishin, E.; Gershenzon, N.; Genoni, T.; Paraschiv, I.; Rose, D.

2018-04-01

The concept of a parametric antenna in ionospheric plasma is analyzed. Such antennas are capable of exciting electromagnetic radiation fields, specifically the creation of whistler waves generated at the very low frequency (VLF) range, which are also capable of propagating large distances away from the source region. The mechanism of whistler wave generation is considered a parametric interaction of quasi-electrostatic whistler waves (also known as low oblique resonance (LOR) oscillations) excited by a conventional loop antenna. The interaction of LOR waves with quasi-neutral density perturbations in the near field of an antenna gives rise to electromagnetic whistler waves on combination frequencies. It is shown in this work that the amplitude of these waves can considerably exceed the amplitude of whistler waves directly excited by a loop. Additionally, particle-in-cell simulations, which demonstrate the excitation and spatial structure of VLF waves excited by a loop antenna, are presented. Possible applications including the wave-particle interactions to mitigate performance anomalies of low Earth orbit satellites, active space experiments, communication via VLF waves, and modification experiments in the ionosphere will be discussed.

Ionospheric Simulation System for Satellite Observations and Global Assimilative Modeling Experiments (ISOGAME)

NASA Technical Reports Server (NTRS)

Pi, Xiaoqing; Mannucci, Anthony J.; Verkhoglyadova, Olga P.; Stephens, Philip; Wilson, Brian D.; Akopian, Vardan; Komjathy, Attila; Lijima, Byron A.

2013-01-01

ISOGAME is designed and developed to assess quantitatively the impact of new observation systems on the capability of imaging and modeling the ionosphere. With ISOGAME, one can perform observation system simulation experiments (OSSEs). A typical OSSE using ISOGAME would involve: (1) simulating various ionospheric conditions on global scales; (2) simulating ionospheric measurements made from a constellation of low-Earth-orbiters (LEOs), particularly Global Navigation Satellite System (GNSS) radio occultation data, and from ground-based global GNSS networks; (3) conducting ionospheric data assimilation experiments with the Global Assimilative Ionospheric Model (GAIM); and (4) analyzing modeling results with visualization tools. ISOGAME can provide quantitative assessment of the accuracy of assimilative modeling with the interested observation system. Other observation systems besides those based on GNSS are also possible to analyze. The system is composed of a suite of software that combines the GAIM, including a 4D first-principles ionospheric model and data assimilation modules, an Internal Reference Ionosphere (IRI) model that has been developed by international ionospheric research communities, observation simulator, visualization software, and orbit design, simulation, and optimization software. The core GAIM model used in ISOGAME is based on the GAIM++ code (written in C++) that includes a new high-fidelity geomagnetic field representation (multi-dipole). New visualization tools and analysis algorithms for the OSSEs are now part of ISOGAME.

Soviet ionospheric modification research

DOE Office of Scientific and Technical Information (OSTI.GOV)

Duncan, L.M.; Carlson, H.C.; Djuth, F.T.

1988-07-01

Soviet published literature in ionospheric modification research by high-power radio waves is assessed, including an evaluation of its impact on and applications to future remote-sensing and telecommunications systems. This assessment is organized to place equal emphasis on basic research activities, designed to investigate both the natural geophysical environment and fundamental plasma physics; advanced research programs, such as those studying artificial ionization processes and oblique high-power radio propagation and practical system applications and operational limitations addressed by this research. The assessment indicates that the Soviet Union sustains high-quality theoretical and experimental research programs in ionospheric modification, with a breadth and levelmore » of effort greatly exceeding comparable Western programs. Soviet theoretical research tends to be analytical and intuitive, as compared to the Western emphasis on numerical simulation techniques. The Soviet experimental approach is less exploratory, designed principally to confirm theoretical predictions. Although limited by inferior diagnostic capabilities, Soviet experimental facilities are more numerous, operate on a more regular basis, and transmit radio wave powers exceeding those os Western facilities. Because of its broad scope of activity, the Soviet Union is better poised to quickly exploit new technologies and system applications as they are developed. This panel has identified several key areas of Soviet research activity and emerging technology that may offer long-term opportunities for remote-sensing and telecommunications advantages. However, we have found no results that suggest imminent breakthrough discoveries in these fields.« less

Radio Tomography of Ionospheric Structures (probably) due to Underground-Surface-Atmosphere-Ionosphere Coupling

NASA Astrophysics Data System (ADS)

Kunitsyn, V.; Nesterov, I.; Andreeva, E.; Rekenthaler, D. A.

2012-12-01

Ionospheric radio-tomography (RT) utilizes radio signals transmitted from the global navigational satellite systems (GNSS), including low-orbiting (LO) navigational systems such as Transit, Tsikada, etc., and high-orbiting (HO) navigational systems such as GPS, GLONASS, Galileo, Beidou, etc. The signals that are transmitted from the LO navigational satellites and recorded by ground receiving chains can be inverted for almost instantaneous (5-8 min) 2D snapshots of electron density. The data from the networks of ground receivers that record the signals of the HO satellites are suitable for implementing high-orbital RT (HORT), i.e. reconstructing the 4D distributions of the ionospheric electron density (one 3D image every 20-30 min). In the regions densely covered by the GNSS receivers, it is currently possible to get a time step of 2-4 min. The LORT and HORT approaches have a common methodical basis: in both these techniques, the integrals of electron density along the ray between the satellite and the receiver are measured, and then the tomographic procedures are applied to reconstruct the distributions of electron density. We present several examples of the experiments on the ionospheric RT, which are related to the Underground-Surface-Atmosphere-Ionosphere (USAI) coupling. In particular, we demonstrate examples of RT images of the ionosphere after industrial explosions, rocket launches, and modification of the ionosphere by high-power radio waves. We also show RT cross sections reflecting ionospheric disturbances caused by the earthquakes (EQ) and tsunami waves. In these cases, there is an evident cause-and-effect relationship. The perturbations are transferred between the geospheres predominantly by acoustic gravity waves (AGW), whose amplitudes increase with increasing height. As far as EQ are concerned, the cause of the USAI coupling mechanism is not obvious. It is clear, however, that the regular RT studies can promote the solution of this challenging problem. The single-point measurements (by ionosondes or by isolated receivers) are not amenable to unambiguous interpretation; based on these data, it is impossible to distinguish the contribution of USAI coupling from the ionospheric effects induced by the "ordinary" impacts (the Sun, the solar wind, geomagnetic perturbations, galactic cosmic rays, etc.). In order to localize sources of the ionospheric disturbances, the geophysicist needs information on the spatial structure and dynamics of the ionospheric perturbations. This information (2D-4D RT images) is optimally provided by RT methods. We present examples of the ionospheric disturbances caused by EQs as well as the ionospheric precursors of these EQs in the form of specific ionospheric irregularities: AGW- and soliton-like wave disturbances, which we identified using RT methods. Based on the results of the RT studies in the Alaska and Taiwan regions, we have detected several dozen AGW-related precursors of EQs. These data allow us to attempt to locate the source of these perturbations. We discuss the possibilities and prospects of further research aimed at identifying and analyzing precursors of EQs and establishing the mechanisms of USAI coupling. We are grateful to Northwest Research Associates, Inc., and Dr. L.-C.Tsai for providing raw RT data for Alaska and Taiwan.

47 CFR 27.64 - Protection from interference.

Code of Federal Regulations, 2010 CFR

2010-10-01

... is being caused, it may, after notice and an opportunity for a hearing, require modifications to any... provided against interference caused by tropospheric and ionospheric propagation of signals. ...

47 CFR 27.64 - Protection from interference.

Code of Federal Regulations, 2011 CFR

2011-10-01

... is being caused, it may, after notice and an opportunity for a hearing, require modifications to any... provided against interference caused by tropospheric and ionospheric propagation of signals. ...

47 CFR 27.64 - Protection from interference.

Code of Federal Regulations, 2012 CFR

2012-10-01

... is being caused, it may, after notice and an opportunity for a hearing, require modifications to any... provided against interference caused by tropospheric and ionospheric propagation of signals. ...

Study of thermospheric and ionospheric tidal responses to the 2009 stratospheric sudden warming by an assimilative atmosphere-ionosphere coupled TIME-GCM with FORMOSAT-3/COSMIC observations

NASA Astrophysics Data System (ADS)

Lin, Jia-Ting; Liu, Hanli; Liu, Jann-Yenq; Lin, Charles C. H.; Chen, Chia-Hung; Chang, Loren; Chen, Wei-Han

In this study, ionospheric peak densities obtained from radio occultation soundings of FORMOSAT-3/COSMIC are decomposed into their various constituent tidal components for studying the stratospheric sudden warming (SSW) effects on the tidal responses during the 2008/2009. The observations are further compared with the results from an atmosphere-ionosphere coupled model, TIME-GCM. The model assimilates MERRA 3D meteorological data between the lower-boundary (~30km) and 0.1h Pa (~62km) by a nudging method. The comparison shows general agreement in the major features of decrease of migrating tidal signatures (DW1, SW2 and TW3) in ionosphere around the growth phase of SSW, with phase/time shifts in the daily time of maximum around EIA and middle latitudes. Both the observation and simulation indicate a pronounced enhancement of the ionospheric SW2 signatures after the stratospheric temperature increase. The model suggest that the typical morning enhancement/afternoon reduction of electron density variation is mainly caused by modification of the ionospheric migrating tidal signatures. The model shows that the thermospheric SW2 tide variation is similar to ionosphere as well as the phase shift. These phases shift of migrating tides are highly related to the present of induced secondary planetary wave 1 in the E region.

Heater-induced ionization inferred from spectrometric airglow measurements

NASA Astrophysics Data System (ADS)

Hysell, D. L.; Miceli, R. J.; Kendall, E. A.; Schlatter, N. M.; Varney, R. H.; Watkins, B. J.; Pedersen, T. R.; Bernhardt, P. A.; Huba, J. D.

2014-03-01

Spectrographic airglow measurements were made during an ionospheric modification experiment at High Frequency Active Auroral Research Program on 12 March 2013. Artificial airglow enhancements at 427.8, 557.7, 630.0, 777.4, and 844.6 nm were observed. On the basis of these emissions and using a methodology based on the method of Backus and Gilbert (1968, 1970), we estimate the suprathermal electron population and the subsequent equilibrium electron density profile, including contributions from electron impact ionization. We find that the airglow is consistent with heater-induced ionization in view of the spatial intermittency of the airglow.

Ionospheric tomography using Faraday rotation of Automatic Dependent Surveillance Broadcast (UHF) signals Ionospheric Measurement From ADS-B Signals

NASA Astrophysics Data System (ADS)

Cushley, Alex Clay

The proposed launch of a CubeSat carrying the first space-borne ADS-B receiver by RMCC will create a unique opportunity to study the modification of radio waves following propagation through the ionosphere as the signals propagate from the transmitting aircraft to the passive satellite receiver(s). Experimental work is described which successfully demonstrated that ADS-B data can be used to reconstruct two-dimensional electron density maps of the ionosphere using techniques from computerized tomography. Ray-tracing techniques are used to determine the characteristics of individual waves, including the wave path and the state of polarization at the satellite receiver. The modelled Faraday rotation is determined and converted to TEC along the ray-paths. The resulting TEC is used as input for CIT using ART. This study concentrated on meso-scale structures 100--1000 km in horizontal extent. The primary scientific interest of this thesis was to show the feasibility of a new method to image the ionosphere and obtain a better understanding of magneto-ionic wave propagation. Keywords: Automatic Dependent Surveillance-Broadcast (ADS-B), Faraday rotation, electromagnetic (EM) waves, radio frequency (RF) propagation, ionosphere (auroral, irregularities, instruments and techniques), electron density profile, total electron content (TEC), computer ionospheric tomography (CIT), algebraic reconstruction technique (ART).

Modification of the ionosphere near the terminator due to the passage of a strong tropical cyclone through the large Island

NASA Astrophysics Data System (ADS)

Belyaev, G.; Boychev, B.; Kostin, V.; Trushkina, E.; Ovcharenko, O.

2015-03-01

Earlier by the authors according to the Intercosmos Bulgaria-1300 and Cosmos-1809 satellite data it's been shown that the ionosphere is modified above the tropical cyclones (TC). Local perturbations of the plasma density, the appearance of the electric fields and the development of ELF-VLF zone of turbulence were observed. These effects were due to the injection of up stream of neutral particles from TC. In this paper the data of the Cosmos-1809 satellite when tropical cyclone Harry (1989) passed through the island of New Caledonia was examined. Influence of evening and morning terminators on the structure of the ionosphere from TC was discussed. It is detected: 1 - the appearance of latitude belt (up to 5000km) of structured perturbations in the night ionosphere; 2 - simulation in the illuminated ionosphere of periodic oscillation of the electric field with a scale ~ 400 km, passing beyond plasma pause. Model for the formation above TC in the lower ionosphere vertical submerged jet that injects neutral particles of different varieties into the upper ionosphere on ballistic trajectories was proposed. Changing of the ionization of neutral particles near the terminator and the deviation of the jet under the interaction of the TC with the island are confirmed in the proposed model.

Interharmonic modulation products as a means to quantify nonlinear D-region interactions

NASA Astrophysics Data System (ADS)

Moore, Robert

Experimental observations performed during dual beam ionospheric HF heating experiments at the High frequency Active Auroral Research Program (HAARP) HF transmitter in Gakona, Alaska are used to quantify the relative importance of specific nonlinear interactions that occur within the D region ionosphere. During these experiments, HAARP broadcast two amplitude modulated HF beams whose center frequencies were separated by less than 20 kHz. One beam was sinusoidally modulated at 500 Hz while the second beam was sinusoidally modulated using a 1-7 kHz linear frequency-time chirp. ELF/VLF observations performed at two different locations (3 and 98 km from HAARP) provide clear evidence of strong interactions between all field components of the two HF beams in the form of low and high order interharmonic modulation products. From a theoretical standpoint, the observed interharmonic modulation products could be produced by several different nonlinearities. The two primary nonlinearities take the form of wave-medium interactions (i.e., cross modulation), wherein the ionospheric conductivity modulation produced by one signal crosses onto the other signal via collision frequency modification, and wave-wave interactions, wherein the conduction current associated with one wave mixes with the electric field of the other wave to produce electron temperature oscillations. We are able to separate and quantify these two different nonlinearities, and we conclude that the wave-wave interactions dominate the wave-medium interactions by a factor of two. These results are of great importance for the modeling of transioinospheric radio wave propagation, in that both the wave-wave and the wave-medium interactions could be responsible for a significant amount of anomalous absorption.

Conference Proceedings on Ionospheric Modification and Its Potential to Enhance or Degrade the Performance of Military Systems Held in Bergen, Norway on 28-31 May 1990 (La Modification de l’Ionosphere et son Potentiel d’Amelioration ou de Degradation des Performances des Systemes Militaires)

DTIC Science & Technology

1990-05-31

hbeter at Arecibo. shbing teperral evolution of spotita diattlrbutio. (Barrnhardt at al, 1988). ftAStdA LOC WEf SP2CTh 5VF £NHAIJCRV DOWIr FUTO C...astt tubsim. Ahmy, Phpe. Iubidt. 31,73(1669) (1631 LM.Dsgtyue, R.SJqduv. Ojieolmv, V.DA-dhap, mad Vlmhuhebm, O"fm.4ai msAl Lmwmm telbahaci leo J1.h P...aestual gas devaity drop rapid" as the beam expands, When the neutral dentsity Is low, so bIto a robability of knsazanin. Them, If CV bn to occur. It

Advanced Ionospheric Sensing using GROUP-C and LITES aboard the ISS

NASA Astrophysics Data System (ADS)

Budzien, S. A.; Stephan, A. W.; Chakrabarti, S.; Finn, S. C.; Cook, T.; Powell, S. P.; O'Hanlon, B.; Bishop, R. L.

2015-12-01

The GPS Radio Occultation and Ultraviolet Photometer Co-located (GROUP-C) and Limb-imaging Ionospheric and Thermospheric Extreme-ultraviolet Spectrograph (LITES) experiments are manifested for flight aboard the International Space Station (ISS) in 2016 as part of the Space Test Program Houston #5 payload. The two experiments provide technical development and risk-reduction for future DoD space weather sensors suitable for ionospheric specification, space situational awareness, and data products for global ionosphere assimilative models. In addition, the combined instrument complement of these two experiments offers a unique opportunity to study structures of the nighttime ionosphere. GROUP-C includes an advanced GPS receiver providing ionospheric electron density profiles and scintillation measurements and a high-sensitivity far-ultraviolet photometer measuring horizontal ionospheric gradients. LITES is an imaging spectrograph that spans 60-140 nm and will obtain high-cadence limb profiles of the ionosphere and thermosphere from 150-350 km altitude. In the nighttime ionosphere, recombination of O+ and electrons produces optically thin emissions at 91.1 and 135.6 nm that can be used to tomographically reconstruct the two-dimensional plasma distribution in the orbital plane below ISS altitudes. Ionospheric irregularities, such as plasma bubbles and blobs, are transient features of the low and middle latitude ionosphere with important implications for operational systems. Irregularity structures have been studied primarily using ground-based systems, though some spaced-based remote and in-situ sensing has been performed. An ionospheric observatory aboard the ISS would provide new capability to study low- and mid-latitude ionospheric structures on a global scale. By combining for the first time high-sensitivity in-track photometry, vertical ionospheric airglow spectrographic imagery, and recent advancements in UV tomography, high-fidelity tomographic reconstruction of nighttime structures can be performed from the ISS. We discuss the tomographic approach, simulated reconstructions, and value added by including complementary ground-based observations. Acknowledgements: This work is supported by NRL Work Unit 76-1C09-05.

47 CFR 27.64 - Protection from interference.

Code of Federal Regulations, 2014 CFR

2014-10-01

... is being caused, it may, after notice and an opportunity for a hearing, require modifications to any... provided against interference caused by tropospheric and ionospheric propagation of signals. (d) Harmful...

47 CFR 27.64 - Protection from interference.

Code of Federal Regulations, 2013 CFR

2013-10-01

... is being caused, it may, after notice and an opportunity for a hearing, require modifications to any... provided against interference caused by tropospheric and ionospheric propagation of signals. (d) Harmful...

The Combined Radio Interferometry and COSMIC Experiment in Tomography (CRICKET) Campaign

NASA Astrophysics Data System (ADS)

Dymond, Kenneth; Coker, Clayton; Bernhardt, Paul; Cohen, Aaron; Crane, Patrick; Kassim, Namir; Lazio, Joseph; Weiler, Kurt; Watts, Christopher; Rickard, Lee J.; Taylor, Greg; Schinzel, Frank; Philstrom, Ylva; Close, Sigrid; Colestock, Patrick; Myers, Steve; Datta, Abirhup

We report on the Combined Radio Interferometry and COSMIC Experiment in Tomography Campaign (CRICKET) held on September 15 and 17, 2007. The experiment used the Constellation Observing System for Meteorology, Ionosphere, and Climate (COSMIC also known as FORMOSAT-3) in conjunction with the Very Large Array radio telescope, located near Socorro, NM, to study the ionosphere from the global scale down to the regional scale. Each COSMIC satellite includes three instruments capable of measuring the ionosphere: the Tiny Ionospheric Photometer (TIP), a UV radiometer; the GPS Occultation experiment (GOX), a dual-frequency GPS occultation receiver; and the Tri-band Beacon (TBB), a three frequency coherently radiating radio beacon. These three instruments have been demonstrated to be a powerful means for characterizing the global-scale ionosphere. The VLA when deployed at its largest extent and while operating at 73.8 MHz is incredibly sensitive to relative total electron content variations of the regional ionosphere over about a 30-100 km diameter area. In this work, we concentrate on the first set of observations on September 15, 2007 at approximately 0830 UT. We have successfully married these heterogeneous data sets, using a tomographic data fusion approach, to produce a consistent ionospheric specification from the global scale down to the regional scale.

Early Results from the RAIDS Experiment on the ISS

NASA Astrophysics Data System (ADS)

Budzien, S. A.; Bishop, R. L.; Stephan, A. W.; Christensen, A. B.; Hecht, J. H.; Straus, P. R.

2009-12-01

The Remote Atmospheric and Ionospheric Detection System (RAIDS) is a suite of three photometers, three spectrometers, and two spectrographs which span the wavelength range 55-874 nm and remotely sense the thermosphere and ionosphere by scanning and imaging the limb. RAIDS was scheduled to fly to the Japanese Experiment Module—Exposed Facility (JEM-EF) aboard the International Space Station (ISS) in September 2009. RAIDS along with a companion hyperspectral imaging experiment will serve as the first US payload on the JEM-EF. The scientific objectives of the new RAIDS experiment are to study the temperature of the lower thermosphere (100-200 km), to measure composition and chemistry of the lower thermosphere and ionosphere, and to measure the initial source of OII 83.4 nm emission. RAIDS will provide valuable data useful for exploring tidal effects in the thermosphere and ionosphere system, validating dayside ionospheric remote sensing methods, and studying local time variations in important chemical and thermal processes. Early observational results from the RAIDS experiment will be presented. The RAIDS sensor suite performs multispectral limb scanning from the open end of the HICO-RAIDS Experiment Payload aboard the ISS.

HISCAT: A proposed new scatter facility in Northern Scandinavia

NASA Technical Reports Server (NTRS)

Bostrom, R.; Thide, B.

1986-01-01

It is proposed that a new versatile ionospheric and atmospheric scatter radar be constructed in northern Scandavia through a multinational collaborative effort. The new facility tentatively named HISCAT (High frequency, High power, High latitude, Heating and Ionospheric Scatter facility), should be used for scientific investigations of: the physics of the neutral (middle) atmosphere; fundamental plasma phenomena, natural or artificially induced in the ionosphere; electrodynamic conditions at high altitudes above the auroral region and in the polar cap ionosphere; plasma waves in the solar atmosphere. The system should thus be able to operate as a mesosphere-stratosphere-troposphere (MST) radar, a so-called ionospheric modification facility, incoherent-scatter radar, coherent-scatter radar, and solar radar. Basically, the new facility should be a device that can operate simultaneously on several frequencies in the frequency range 5 to 50 MHz not covered by other instruments. It should comprise: powerful transmitters, capable of delivering a total average power of several megawatts; an advanced phased antenna array of high gain forming one or two steerable and well collimated beams; and an advanced data collection and analysis system.

47 CFR 22.352 - Protection from interference.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 1934, as amended, (47 U.S.C. 303(f), 316), require modifications to any Public Mobile station as... interference caused by tropospheric and ionospheric propagation of signals. (6) Facilities for which the...

47 CFR 22.352 - Protection from interference.

Code of Federal Regulations, 2011 CFR

2011-10-01

... 1934, as amended, (47 U.S.C. 303(f), 316), require modifications to any Public Mobile station as... interference caused by tropospheric and ionospheric propagation of signals. (6) Facilities for which the...

47 CFR 22.352 - Protection from interference.

Code of Federal Regulations, 2013 CFR

2013-10-01

... 1934, as amended, (47 U.S.C. 303(f), 316), require modifications to any Public Mobile station as... interference caused by tropospheric and ionospheric propagation of signals. (6) Facilities for which the...

47 CFR 22.352 - Protection from interference.

Code of Federal Regulations, 2014 CFR

2014-10-01

... 1934, as amended, (47 U.S.C. 303(f), 316), require modifications to any Public Mobile station as... interference caused by tropospheric and ionospheric propagation of signals. (6) Facilities for which the...

47 CFR 22.352 - Protection from interference.

Code of Federal Regulations, 2012 CFR

2012-10-01

... 1934, as amended, (47 U.S.C. 303(f), 316), require modifications to any Public Mobile station as... interference caused by tropospheric and ionospheric propagation of signals. (6) Facilities for which the...

SAMI2 model results for the quiet time low latitude ionosphere over India

NASA Astrophysics Data System (ADS)

Rao, S. S.; Sharma, Shweta; Pandey, R.

2018-04-01

Efficacy of SAMI2 model for the Indian low latitude region around 75°E longitudes has been tested for different levels of solar flux. With a slight modification of the plasma drift velocity the SAMI2 model has been successful in reproducing quiet time ionospheric low latitude features like Equatorial Ionization Anomaly. We have also showed the formation of electron hole in the topside equatorial ionosphere in the Indian sector. Simulation results show the formation of electron hole in the altitude range 800-2500 km over the magnetic equator. Indian zone results reveal marked differences with regard to the time of occurrence, seasonal appearances and strength of the electron hole vis-a-vis those reported for the American equatorial region.

Electron density modification in ionospheric E layer by inserting fine dust particles

DOE Office of Scientific and Technical Information (OSTI.GOV)

Misra, Shikha, E-mail: shikhamish@gmail.com; Mishra, S. K.

2015-02-15

In this paper, we have developed the kinetics of E-region ionospheric plasma comprising of fine dust grains and shown that the electron density in E-layer can purposely be reduced/enhanced up to desired level by inserting fine dust particles of appropriate physical/material properties; this may certainly be promising for preferred rf-signal processing through these layers. The analytical formulation is based on average charge theory and includes the number and energy balance of the plasma constituents along with charge balance over dust particles. The effect of varying number density, work function, and photo-efficiency of dust particles on ionospheric plasma density at differentmore » altitude in E-layer has been critically examined and presented graphically.« less

LITES and GROUP-C Mission Update: Ionosphere and Thermosphere Sensing from the ISS

NASA Astrophysics Data System (ADS)

Stephan, A. W.; Budzien, S. A.; Chakrabarti, S.; Hysell, D. L.; Powell, S. P.; Finn, S. C.; Cook, T.; Bishop, R. L.

2016-12-01

The Limb-imaging Ionospheric and Thermospheric Extreme-ultraviolet Spectrograph (LITES) and GPS Radio Occultation and Ultraviolet Photometer Co-located (GROUP-C) experiments are scheduled for launch to the International Space Station (ISS) in November 2016 as part of the Space Test Program Houston #5 payload (STP-H5). The two experiments provide technical development and risk-reduction for future space weather sensors suitable for ionospheric specification, space situational awareness, and data products for global ionosphere assimilative models. The combined instrument suite of these experiments offers a unique capability to study spatial and temporal variability of the thermosphere and ionosphere using multi-sensor and tomographic approaches. LITES is an imaging spectrograph that spans 60-140 nm and continuously acquires limb profiles of the ionosphere and thermosphere from 150-350 km altitude. GROUP-C includes a high-sensitivity far-ultraviolet photometer measuring horizontal ionospheric gradients and an advanced GPS receiver providing ionospheric electron density profiles and scintillation measurements. High-cadence limb images and nadir photometry from GROUP-C/LITES are combined to tomographically reconstruct high-fidelity two-dimensional volume emission rates within the ISS orbital plane. The GPS occultation receiver provides independent measurements to calibrate and validate advanced daytime ionospheric algorithms and nighttime tomography. The vantage from the ISS on the lower portion of the thermosphere and ionosphere will yield measurements complementary to the NASA GOLD and ICON missions which are expected to fly during the STP-H5 mission. We present a mission status update and available early orbit observations, and the opportunities for using these new data to help address questions regarding the complex and dynamic features of the low and middle latitude ionosphere-thermosphere system that have important implications for operational systems.

Active experiments in the ionosphere and geomagnetic field variations

NASA Astrophysics Data System (ADS)

Sivokon, V. P.; Cherneva, N. V.; Khomutov, S. Y.; Serovetnikov, A. S.

2014-11-01

Variations of ionospheric-magnetospheric relation energy, as one of the possible outer climatology factors, may be traced on the basis of analysis of natural geophysical phenomena such as ionosphere artificial radio radiation and magnetic storms. Experiments on active impact on the ionosphere have been carried out for quite a long time in Russia as well. The most modern heating stand is located in Alaska; it has been used within the HAARP Program. The possibility of this stand to affect geophysical fields, in particular, the geomagnetic field is of interest.

Sub-Ionospheric Measurements of the Ocean, Atmosphere, and Ionosphere from the CARINA Satellites

NASA Astrophysics Data System (ADS)

Bernhardt, P. A.; Montgomery, J. A., Jr.; Siefring, C. L.; Gatling, G.

2016-12-01

New satellites designed to fly between 150 and 250 km has been constructed to study a wide range of geophysical topics extending from the ocean to the topside ionosphere. The key features of the CARINA satellites are (1) the ability of sustain long duration (60 day) orbits below the F-Layer ionosphere, (2) download large quantities of data (10 GBytes) per pass over a ground station, and (3) a heritage instrument payload comprised of an Electric Field Instrument (EFI) with full range measurements from 3 to 13 MHz, a Ram Langmuir Probe (RLP) the measures ion density from 102 to 106 cm-3 with 10 kHz sample rate, an Orbiting GPS Receiver (OGR) providing overhead total electron content and satellite position and the Wake Retro Reflectors (WRR) that use laser ranging for precise orbit determination. Each letter in "CARINA" represents one of the science objectives. "Coastal" ocean wave remote sensing of the sea surface wave height spectrum derived from HF surface wave scatter to the satellite. Assimilation ionospheric models are supported by Global measurements of GPS total electron count (TEC) and in situ plasma density for updating data driven ionospheric models (GAIM, IDA3D, etc.). Radio wave propagation and interactions determine the impact of the bottomside ionosphere on HF ray trajectories, the effects of ionospheric irregularities that yield UHF/L-band scintillations and ionospheric modifications by high power HF waves. Ionospheric structures such are sporadic-E and intermediate layers, traveling ionospheric disturbances (TID's) and large scale bottomside fluctuations in the F-layer are directly measured by CARINA sensors. Neutral drag is studied along the orbit through reentry modeling of drag coefficients and neutral density model updates. Finally, Atmospherics and lightning knowledge is acquired through studies of lightning EM pulses and their impact on ionosphere. Two CARINA satellites separated by 2000 km flying above 50 degree inclination represents the baseline mission.

First incoherent scatter radar observations of radio wave pumping in the ionosphere around the second electron gyroharmonic

NASA Astrophysics Data System (ADS)

Kosch, Michael; Bristow, Bill; Gustavsson, Bjorn; Heinselman, Craig; Hughes, John; Isham, Brett; Mutiso, Charles; Nielsen, Kim; Pedersen, Todd; Wang, Weiyuan; Wong, Alfred

We report results from a unique experiment performed at the HIPAS ionospheric modification facility in Alaska. High power radio waves at 2.85 MHz, which corresponds to the second electron gyroharmonic at 240 km altitude, were transmitted into the nighttime ionosphere. Diagnostics included optical equipment at HIPAS and HAARP, 288 km to the south-east, the PFISR radar at Poker Flat, 32 km to the north-west, and the Kodiak SuperDARN radar, 856 km to the south-west. Camera observations of the stimulated optical emissions at 557.7 nm (O1S, threshold 4.2 eV) and 630 nm (O1D, threshold 2 eV) were made, allowing tomographic reconstruction of the volume emission. The first observations of pump-induced 732 nm (O+, threshold 18.6 eV) emissions are reported. Kodiak radar backscatter, which is a proxy for upper-hybrid resonance, shows strong production of striations without a minimum on the second gyroharmonic, confirming previous results. PFISR analysis shows clear evidence of electron temperature enhancements, consistent with previous EISCAT results, maximizing when the pump frequency matches the second gyroharmonic and when double resonance occurs, i.e. the upper-hybrid resonance frequency matches the second gyroharmonic. This is consistent with the optical observations. From the above data, we are able to infer the efficiency of different groups of electron-accelerating mechanisms.

Charge exchange contamination of CRIT-II barium CIV experiment. [critical ionization velocity in ionosphere

NASA Technical Reports Server (NTRS)

Swenson, G. R.; Mende, S. B.; Meyerott, R. E.; Rairden, R. L.

1991-01-01

Experiments have been recently performed which attempted to confirm critical ionization velocity (CIV) ionization by deploying chemicals at high velocity in the ionosphere. Specifically, the CRIT-II rocket performed a barium release in the ionosphere, where observations of Ba(+) resonant emissions following the release are believed to have resulted from the CIV process. Calculations are presented which suggest a significant fraction (if not all) of the Ba(+) observed likely resulted from charge exchange with the thermosphere ions and not through CIV processes. The results presented here are pertinent to other CIV experiments performed in the ionosphere. It is recommended that laboratory measurements should be made of the charge exchange cross section between O(+) and Ba as well as other metal vapors used in CIV experiments.

Artificial excitation of ELF waves with frequency of Schumann resonance

NASA Astrophysics Data System (ADS)

Streltsov, A. V.; Guido, T.; Tulegenov, B.; Labenski, J.; Chang, C.-L.

2014-11-01

We report results from the experiment aimed at the artificial excitation of extremely low-frequency (ELF) electromagnetic waves with frequencies corresponding to the frequency of Schumann resonance. Electromagnetic waves with these frequencies can form a standing pattern inside the spherical cavity formed by the surface of the Earth and the ionosphere. In the experiment the ELF waves were excited by heating the ionosphere with X-mode HF electromagnetic waves generated at the High Frequency Active Auroral Research Program (HAARP) facility in Alaska. The experiment demonstrates that heating of the ionosphere can excite relatively large-amplitude electromagnetic waves with frequencies in the range 7.8-8.0 Hz when the ionosphere has a strong F layer, the frequency of the HF radiation is in the range 3.20-4.57 MHz, and the electric field greater than 5 mV/m is present in the ionosphere.

Exploiting artificial intelligence for in-situ analysis of high-resolution radio emission measurements on a CubeSat

NASA Astrophysics Data System (ADS)

Isham, Brett; Bergman, Jan; Krause, Linda; Rincon-Charris, Amilcar; Bruhn, Fredrik; Funk, Peter; Stramkals, Arturs

2016-07-01

CubeSat missions are intentionally constrained by the limitations of their small platform. Mission payloads designed for low volume, mass, and power, may however be disproportionally limited by available telemetry allocations. In many cases, it is the data delivered to the ground which determines the value of the mission. However, transmitting more data does not necessarily guarantee high value, since the value also depends on data quality. By exploiting fast on-board computing and efficient artificial intelligence (AI) algorithms for analysis and data selection, the usage of the telemetry link can be optimized and value added to the mission. This concept is being implemented on the Puerto Rico CubeSat, which will make measurements of ambient ionospheric radio waves and ion irregularities and turbulence. Principle project goals include providing aerospace and systems engineering experiences to students. Science objectives include the study of natural space plasma processes to aid in better understanding of space weather and the Sun to Earth connection, and in-situ diagnostics of ionospheric modification experiments using high-power ground-based radio transmitters. We hope that this project might point the way to the productive use of AI in space and other remote, low-data-bandwidth environments.

Investigation of ionospheric precursors related to deep and intermediate earthquakes based on spectral and statistical analysis

NASA Astrophysics Data System (ADS)

Oikonomou, Christina; Haralambous, Haris; Muslim, Buldan

2017-01-01

Ionospheric TEC (Total Electron Content) variations prior to the deep (≈600 km) earthquake doublet close to magnetic equator in Peru (M = 7.6) and to the intermediate (≈200 km) earthquake in Afghanistan (M = 7.5) during 2015 were investigated using measurements from Global Navigation Satellite System (GNSS) network with the aim to detect possible ionospheric precursors of these events. For this we applied both statistical and spectral analysis. Ionospheric anomalies related to both earthquakes were observed few hours and few days prior to the earthquakes during daytime localized mainly near the epicenter. These were large-scale positive TEC anomalies and small-scale TEC oscillations with periods of 20 min and duration around 2-4 h appearing at the same local time each day. Several days prior to the earthquake in Peru a significant phenomenon was observed during afternoon time related to the modification of the Equatorial Ionization Anomaly (EIA) structure. During nighttime, however, it was not possible to identify any ionospheric earthquake precursor due to the concurrence of various phenomena, such as Equatorial Plasma Bubbles and pre- and post-midnight TEC peaks prior to Peru earthquake, and solar terminator transition prior to both earthquakes which could induce resembling ionospheric anomalies.

Complex analysis of the ionospheric response to operation of ``Progress'' cargo spacecraft according to the data of GNSS receivers in Baikal region

NASA Astrophysics Data System (ADS)

Ishin, Artem; Voeykov, Sergey; Perevalova, Natalia; Khakhinov, Vitaliy

2017-12-01

As a part of the Plasma-Progress and Radar-Progress space experiments conducted from 2006 to 2014, effects of the Progress spacecraft engines on the ionosphere have been studied using data from Global Navigation Satellite System (GNSS) receivers. 72 experiments have been carried out. All these experiments were based on data from the International GNSS Service (IGS) to record ionospheric plasma irregularities caused by engine operation. 35 experiments used data from the ISTP SB RAS network SibNet. The analysis of the spatio-temporal structure of total electron content (TEC) variations has shown that the problem of identifying the TEC response to engine operation is complicated by a number of factors: 1) the engine effect on ionospheric plasma is strongly localized in space and has a relatively low intensity; 2) a small number of satellite-receiver radio rays due to the limited number of GNSS stations, particularly before 2013; 3) a potential TEC response is masked with background ionospheric disturbances of various intensities. However, TEC responses are identified with certainty when a satellite-receiver radio ray crosses a disturbed region within minutes after the impact. TEC responses have been registered in 7 experiments (10 % of cases). The amplitude of ionospheric response (0.3-0.16 TECU) exceeded the background TEC variations (~0.25 TECU) several times. The TEC data indicate that the ionospheric irregularity lifetime is from 4 to 10 minutes. According to the estimates we made, the transverse size of irregularities is from 12 to 30 km.

Real-time estimation of ionospheric delay using GPS measurements

NASA Astrophysics Data System (ADS)

Lin, Lao-Sheng

1997-12-01

When radio waves such as the GPS signals propagate through the ionosphere, they experience an extra time delay. The ionospheric delay can be eliminated (to the first order) through a linear combination of L1 and L2 observations from dual-frequency GPS receivers. Taking advantage of this dispersive principle, one or more dual- frequency GPS receivers can be used to determine a model of the ionospheric delay across a region of interest and, if implemented in real-time, can support single-frequency GPS positioning and navigation applications. The research objectives of this thesis were: (1) to develop algorithms to obtain accurate absolute Total Electron Content (TEC) estimates from dual-frequency GPS observables, and (2) to develop an algorithm to improve the accuracy of real-time ionosphere modelling. In order to fulfil these objectives, four algorithms have been proposed in this thesis. A 'multi-day multipath template technique' is proposed to mitigate the pseudo-range multipath effects at static GPS reference stations. This technique is based on the assumption that the multipath disturbance at a static station will be constant if the physical environment remains unchanged from day to day. The multipath template, either single-day or multi-day, can be generated from the previous days' GPS data. A 'real-time failure detection and repair algorithm' is proposed to detect and repair the GPS carrier phase 'failures', such as the occurrence of cycle slips. The proposed algorithm uses two procedures: (1) application of a statistical test on the state difference estimated from robust and conventional Kalman filters in order to detect and identify the carrier phase failure, and (2) application of a Kalman filter algorithm to repair the 'identified carrier phase failure'. A 'L1/L2 differential delay estimation algorithm' is proposed to estimate GPS satellite transmitter and receiver L1/L2 differential delays. This algorithm, based on the single-site modelling technique, is able to estimate the sum of the satellite and receiver L1/L2 differential delay for each tracked GPS satellite. A 'UNSW grid-based algorithm' is proposed to improve the accuracy of real-time ionosphere modelling. The proposed algorithm is similar to the conventional grid-based algorithm. However, two modifications were made to the algorithm: (1) an 'exponential function' is adopted as the weighting function, and (2) the 'grid-based ionosphere model' estimated from the previous day is used to predict the ionospheric delay ratios between the grid point and reference points. (Abstract shortened by UMI.)

Positioning performance of the NTCM model driven by GPS Klobuchar model parameters

NASA Astrophysics Data System (ADS)

Hoque, Mohammed Mainul; Jakowski, Norbert; Berdermann, Jens

2018-03-01

Users of the Global Positioning System (GPS) utilize the Ionospheric Correction Algorithm (ICA) also known as Klobuchar model for correcting ionospheric signal delay or range error. Recently, we developed an ionosphere correction algorithm called NTCM-Klobpar model for single frequency GNSS applications. The model is driven by a parameter computed from GPS Klobuchar model and consecutively can be used instead of the GPS Klobuchar model for ionospheric corrections. In the presented work we compare the positioning solutions obtained using NTCM-Klobpar with those using the Klobuchar model. Our investigation using worldwide ground GPS data from a quiet and a perturbed ionospheric and geomagnetic activity period of 17 days each shows that the 24-hour prediction performance of the NTCM-Klobpar is better than the GPS Klobuchar model in global average. The root mean squared deviation of the 3D position errors are found to be about 0.24 and 0.45 m less for the NTCM-Klobpar compared to the GPS Klobuchar model during quiet and perturbed condition, respectively. The presented algorithm has the potential to continuously improve the accuracy of GPS single frequency mass market devices with only little software modification.

Assimilative modeling of low latitude ionosphere

NASA Technical Reports Server (NTRS)

Pi, Xiaoqing; Wang, Chunining; Hajj, George A.; Rosen, I. Gary; Wilson, Brian D.; Mannucci, Anthony J.

2004-01-01

In this paper we present an observation system simulation experiment for modeling low-latitude ionosphere using a 3-dimensional (3-D) global assimilative ionospheric model (GAIM). The experiment is conducted to test the effectiveness of GAIM with a 4-D variational approach (4DVAR) in estimation of the ExB drift and thermospheric wind in the magnetic meridional planes simultaneously for all longitude or local time sectors. The operational Global Positioning System (GPS) satellites and the ground-based global GPS receiver network of the International GPS Service are used in the experiment as the data assimilation source. 'The optimization of the ionospheric state (electron density) modeling is performed through a nonlinear least-squares minimization process that adjusts the dynamical forces to reduce the difference between the modeled and observed slant total electron content in the entire modeled region. The present experiment for multiple force estimations reinforces our previous assessment made through single driver estimations conducted for the ExB drift only.

First Ionospheric Results From the MAVEN Radio Occultation Science Experiment (ROSE)

NASA Astrophysics Data System (ADS)

Withers, Paul; Felici, M.; Mendillo, M.; Moore, L.; Narvaez, C.; Vogt, M. F.; Jakosky, B. M.

2018-05-01

Radio occultation observations of the ionosphere of Mars can span the full vertical extent of the ionosphere, in contrast to in situ measurements that rarely sample the main region of the ionosphere. However, most existing radio occultation electron density profiles from Mars were acquired without clear context for the solar forcing or magnetospheric conditions, which presents challenges for the interpretation of these profiles. Here we present 48 ionospheric electron density profiles acquired by the Mars Atmosphere and Volatile EvolutioN mission (MAVEN) Radio Occultation Science Experiment (ROSE) from 5 July 2016 to 27 June 2017 at solar zenith angles of 54° to 101°. Latitude coverage is excellent, and comprehensive context for the interpretation of these profiles is provided by other MAVEN instruments. The profiles show a 9-km increase in ionospheric peak altitude in January 2017 that is associated with a lower atmospheric dust storm, variations in electron densities in the M1 layer that cannot be explained by variations in the solar soft X-ray flux, and topside electron densities that are larger in strongly magnetized regions than in weakly magnetized regions. MAVEN Radio Occultation Science Experiment electron density profiles are publicly available on the NASA Planetary Data System.

Nonlinear plasma experiments in geospace with gigawatts of RF power at HAARP

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sheerin, J. P., E-mail: jsheerin@emich.edu; Cohen, Morris B., E-mail: mcohen@gatech.edu

2015-12-10

The ionosphere is the ionized uppermost layer of our atmosphere (from 70 – 500 km altitude) where free electron densities yield peak critical frequencies in the HF (3 – 30 MHz) range. The ionosphere thus provides a quiescent plasma target, stable on timescales of minutes, for a whole host of active plasma experiments. High power RF experiments on ionospheric plasma conducted in the U.S. have been reported since 1970. The largest HF transmitter built to date is the HAARP phased-array HF transmitter near Gakona, Alaska which can deliver up to 3.6 Gigawatts (ERP) of CW RF power in the range of 2.8more » – 10 MHz to the ionosphere with microsecond pointing, power modulation, and frequency agility. With an ionospheric background thermal energy in the range of only 0.1 eV, this amount of power gives access to the highest regimes of the nonlinearity (RF intensity to thermal pressure) ratio. HAARP’s unique features have enabled the conduct of a number of unique nonlinear plasma experiments in the interaction region of overdense ionospheric plasma including generation of artificial aurorae, artificial ionization layers, VLF wave-particle interactions in the magnetosphere, parametric instabilities, stimulated electromagnetic emissions (SEE), strong Langmuir turbulence (SLT) and suprathermal electron acceleration. Diagnostics include the Modular UHF Ionospheric Radar (MUIR) sited at HAARP, the SuperDARN-Kodiak HF radar, spacecraft radio beacons, HF receivers to record stimulated electromagnetic emissions (SEE) and telescopes and cameras for optical emissions. We report on short timescale ponderomotive overshoot effects, artificial field-aligned irregularities (AFAI), the aspect angle dependence of the intensity of the HF-enhanced plasma line, and production of suprathermal electrons. One of the primary missions of HAARP, has been the generation of ELF (300 – 3000 Hz) and VLF (3 – 30 kHz) radio waves which are guided to global distances in the Earth-ionosphere waveguide. We review recent efforts to improve the efficiency of the generation ELF/VLF and develop alternative mechanisms that do not require a natural ionospheric current. Applications include the controlled study of ionospheric irregularities affecting spacecraft communication and navigation systems.« less

Nonlinear plasma experiments in geospace with gigawatts of RF power at HAARP

NASA Astrophysics Data System (ADS)

Sheerin, J. P.; Cohen, Morris B.

2015-12-01

The ionosphere is the ionized uppermost layer of our atmosphere (from 70 - 500 km altitude) where free electron densities yield peak critical frequencies in the HF (3 - 30 MHz) range. The ionosphere thus provides a quiescent plasma target, stable on timescales of minutes, for a whole host of active plasma experiments. High power RF experiments on ionospheric plasma conducted in the U.S. have been reported since 1970. The largest HF transmitter built to date is the HAARP phased-array HF transmitter near Gakona, Alaska which can deliver up to 3.6 Gigawatts (ERP) of CW RF power in the range of 2.8 - 10 MHz to the ionosphere with microsecond pointing, power modulation, and frequency agility. With an ionospheric background thermal energy in the range of only 0.1 eV, this amount of power gives access to the highest regimes of the nonlinearity (RF intensity to thermal pressure) ratio. HAARP's unique features have enabled the conduct of a number of unique nonlinear plasma experiments in the interaction region of overdense ionospheric plasma including generation of artificial aurorae, artificial ionization layers, VLF wave-particle interactions in the magnetosphere, parametric instabilities, stimulated electromagnetic emissions (SEE), strong Langmuir turbulence (SLT) and suprathermal electron acceleration. Diagnostics include the Modular UHF Ionospheric Radar (MUIR) sited at HAARP, the SuperDARN-Kodiak HF radar, spacecraft radio beacons, HF receivers to record stimulated electromagnetic emissions (SEE) and telescopes and cameras for optical emissions. We report on short timescale ponderomotive overshoot effects, artificial field-aligned irregularities (AFAI), the aspect angle dependence of the intensity of the HF-enhanced plasma line, and production of suprathermal electrons. One of the primary missions of HAARP, has been the generation of ELF (300 - 3000 Hz) and VLF (3 - 30 kHz) radio waves which are guided to global distances in the Earth-ionosphere waveguide. We review recent efforts to improve the efficiency of the generation ELF/VLF and develop alternative mechanisms that do not require a natural ionospheric current. Applications include the controlled study of ionospheric irregularities affecting spacecraft communication and navigation systems.

A survey of ELF and VLF research on lightning-ionosphere interactions and causative discharges

NASA Astrophysics Data System (ADS)

Inan, U. S.; Cummer, S. A.; Marshall, R. A.

2010-06-01

Extremely low frequency (ELF) and very low frequency (VLF) observations have formed the cornerstone of measurement and interpretation of effects of lightning discharges on the overlying upper atmospheric regions, as well as near-Earth space. ELF (0.3-3 kHz) and VLF (3-30 kHz) wave energy released by lightning discharges is often the agent of modification of the lower ionospheric medium that results in the conductivity changes and the excitation of optical emissions that constitute transient luminous events (TLEs). In addition, the resultant ionospheric changes are best (and often uniquely) observable as perturbations of subionospherically propagating VLF signals. In fact, some of the earliest evidence for direct disturbances of the lower ionosphere in association with lightning discharges was obtained in the course of the study of such VLF perturbations. Measurements of the detailed ELF and VLF waveforms of parent lightning discharges that produce TLEs and terrestrial gamma ray flashes (TGFs) have also been very fruitful, often revealing properties of such discharges that maximize ionospheric effects, such as generation of intense electromagnetic pulses (EMPs) or removal of large quantities of charge. In this paper, we provide a review of the development of ELF and VLF measurements, both from a historical point of view and from the point of view of their relationship to optical and other observations of ionospheric effects of lightning discharges.

A Medium-Scale Traveling Ionospheric Disturbance Observed from the Ground and from Space

NASA Astrophysics Data System (ADS)

Watts, C.; Dymond, K. F.; Coker, C.; Budzien, S.; Bernhardt, P.; Kassim, N.; Lazio, J.; Cohen, A.; Weiler, K.; Crane, P.; Clarke, T.; Rickard, L. J.; Taylor, G. B.; Schinzel, F.; Philstrom, Y.; Kuniyoshi, M.; Close, S.; Colestock, P.; Myers, S.; Datta, A.

2008-12-01

We report the first optical observations from space of a Medium-scale Traveling Ionospheric Disturbance (MSTID) of the Traveling Wave Packet type. The observations were made during the Combined Radio Interferometry and COSMIC Experiment in Tomography Campaign (CRICKET) held on September 15, 2007 at ~0830 UT. The experiment used a Constellation Observing System for Meteorology, Ionosphere, and Climate (COSMIC also known as FORMOSAT-3) satellite in conjunction with the Very Large Array (VLA) radio telescope, located near Socorro, NM, to study the ionosphere from the global scale down to the regional scale while the TIDs propagated through it. The COSMIC/FORMOSAT-3 satellite measured the ionosphere both horizontally and with altitude while the VLA measured the directions and speed of the TIDs. Our observations provide new information on this poorly understood class of TID

Medium-scale traveling ionospheric disturbances by three-dimensional ionospheric GPS tomography

NASA Astrophysics Data System (ADS)

Chen, C. H.; Saito, A.; Lin, C. H.; Yamamoto, M.; Suzuki, S.; Seemala, G. K.

2016-02-01

In this study, we develop a three-dimensional ionospheric tomography with the ground-based global position system (GPS) total electron content observations. Because of the geometric limitation of GPS observation path, it is difficult to solve the ill-posed inverse problem for the ionospheric electron density. Different from methods given by pervious studies, we consider an algorithm combining the least-square method with a constraint condition, in which the gradient of electron density tends to be smooth in the horizontal direction and steep in the vicinity of the ionospheric F2 peak. This algorithm is designed to be independent of any ionospheric or plasmaspheric electron density models as the initial condition. An observation system simulation experiment method is applied to evaluate the performance of the GPS ionospheric tomography in detecting ionospheric electron density perturbation at the scale size of around 200 km in wavelength, such as the medium-scale traveling ionospheric disturbances.

Multi-instrumental Analysis of the Ionospheric Density Response to Geomagnetic Disturbances

NASA Astrophysics Data System (ADS)

Zakharenkova, I.; Astafyeva, E.

2014-12-01

Measurements provided by Low Earth Orbit (LEO) satellite missions have already proved to be very efficient in investigations of global redistribution of ionospheric plasma and thermosphere mass density during such phenomena as geomagnetic storms. LEO satellites have various instruments for research of the ionosphere response to the space weather events like GPS receiver for precise orbit determination (POD), total electron content estimation and radio occultation, altimeter, planar Langmuir probe, topside sounder, special detectors for particle fluxes, magnetometer etc. In this paper, we present results of joint analysis of LEO satellite data, in particular CHAMP, DMSP, JASON, as well as data provided by ground-based networks of GPS receivers and ionosonde stations for global ionospheric response to the geomagnetic disturbances. We use in-situ plasma density data from CHAMP and DMSP satellites, along with data of GPS receiver onboard CHAMP-satellite and ground-based GPS-receivers to study occurrence and global distribution of ionospheric irregularities during the main phase of the storm. Using CHAMP GPS measurements, we created maps of GPS phase fluctuation activity and found two specific zones of the most intense irregularities - first is the region of the auroral oval at high latitudes of both hemispheres, the second one is the low-latitudes/equatorial region between Africa and South America. The interhemispheric asymmetry of the ionospheric irregularities intensity and occurrence in polar region is discussed. Analysis of the topside TEC, derived from CHAMP onboard GPS POD antenna, indicate the significant redistribution of the topside ionospheric plasma density in the equatorial, middle and high-latitude ionosphere during main and recovery phases of geomagnetic storm. Multi-instrumental data allow to analyze in detail the complex modification and dynamics of the upper atmosphere in different altitudinal, spatial and temporal scales.

A study of the Ionospheric electron density profile with FORMOSAT-3/COSMIC observation data

NASA Astrophysics Data System (ADS)

Chou, Min-Yang; Tsai, Ho-Fang; Lin, Chi-Yen; Lee, I.-Te; Lin, Charles; Liu, Jann-Yenq

2015-04-01

The GPS Occultation Experiment payload onboard FORMOSAT-3/COSMIC microsatellite constellation is capable of scanning the ionospheric structure by the radio occultation (RO) technique to retrieve precise electron density profiles since 2006. Due to the success of FORMOSAT-3/COSMIC, the follow-on mission, FORMOSAT-7/COSMIC-2, is to launch 12 microsatellites in 2016 and 2018, respectively, with　the Global Navigation Satellite Systems (GNSS) RO instrument onboard for tracking GPS, Galileo and/or GLONASS satellite signals and to provide more than 8,000 RO soundings per day globally. An overview of the validation of the FORMOSAT-3/COSMIC ionospheric profiling is given by means of the traditional Abel transform through bending angle and total electron content (TEC), while the ionospheric data assimilation is also applied, based on the Gauss-Markov Kalman filter with the International Reference Ionosphere model (IRI-2007) and global ionosphere map (GIM) as background model, to assimilate TEC observations from FORMOSAT-3/COSMIC. The results shows comparison of electron density profiles from Abel inversion and data assimilation. Furthermore, an observing system simulation experiment is also applied to determine the impact of FORMOSAT-7/COSMIC-2 on ionospheric weather monitoring, which reveals an opportunity on advanced study of small spatial and temporal variations in the ionosphere.

Kinesonde observations of ionosphere modification by intense electromagnetic fields from Platteville, Colorado.

NASA Technical Reports Server (NTRS)

Wright, J. W.

1973-01-01

Observations by the Kinesonde (a multifrequency, spaced antenna, digitized complex-amplitude radio sounding system) of ionospheric responses to excitation by the high-power transmitter at Platteville, Colo., are described. Increases of echo scintillation rate and intensity at frequencies reflected near and far from the excitation level are shown. Significant onset delays of these responses suggest disturbance propagation velocities of a few kilometers per second. Calculated echolocations show a time-dependent development toward the excitation region, again with a delayed response. Comments are offered regarding the relative utility of ionogram and Kinesonde observations for study of these phenomena.

Artificial Excitation of Schumann Resonance with HAARP

NASA Astrophysics Data System (ADS)

Streltsov, A. V.; Chang, C. L.

2014-12-01

We report results from the experiment aimed at the artificial excitation of extremely-low-frequency (ELF) electromagnetic waves with frequencies corresponding to the frequency of Schumann resonance (typically, 7.5 - 8.0 Hz frequency range). Electromagnetic waves with these frequencies can form a standing pattern inside the spherical cavity formed by the surface of the earth and the ionosphere. In the experiment the ELF waves were excited by heating the ionosphere with X-mode HF electromagnetic waves generated by the High Frequency Active Auroral Research Program (HAARP) facility in Alaska. The experiment demonstrates that heating of the ionosphere can excite relatively large-amplitude electromagnetic waves with frequencies in the range of the Schumann resonance, when the ionosphere has a strong F-layer and an electric field greater than 5 mV/m is present in the E-region.

Space Plasma Exploration by Active Radar (SPEAR induced modifications of the high latitude (78°N) ionosphere observed by both coherent and incoherent radars (Invited)

NASA Astrophysics Data System (ADS)

Baddeley, L. J.; Haggstrom, I.; Wright, D. M.; Isham, B.; Gallop, P.

2010-12-01

The SPEAR (Space Plasma Exploration by Active Radar) system, which is the newest operational heating facility, is located on Svalbard at 78°N (75° CGM) latitude and, as such, is the highest latitudinally located heating system. The unique geomagnetic location of SPEAR also allows it to be inside the Polar Cap at all local times. It is co-located with several facilities, including the EISCAT Incoherent Scatter Radar. The system is also inside the fields of view of several SuperDARN Coherent Scatter Radars. An overview of the SPEAR system, specific operating modes, as well as data from new, currently undergoing and planned experiments conducted in 2010 will be presented and discussed. Procedures for any future collaborative experiments will also be presented.

Ionospheric Results with Sounding Rockets and the Explorer VIII Satellite (1960 )

NASA Technical Reports Server (NTRS)

Bourdeau, R. E.

1961-01-01

A review is made of ionospheric data reported since the IGY from rocket and satellite-borne ionospheric experiments. These include rocket results on electron density (RF impedance probe), D-region conductivity (Gerdien condenser), and electron temperature (Langmuir probe). Also included are data in the 1000 kilometer region on ion concentration (ion current monitor) and electron temperature from the Explorer VIII Satellite (1960 xi). The review includes suggestions for second generation experiments and combinations thereof particularly suited for small sounding rockets.

Adding Spatially Correlated Noise to a Median Ionosphere

NASA Astrophysics Data System (ADS)

Holmes, J. M.; Egert, A. R.; Dao, E. V.; Colman, J. J.; Parris, R. T.

2017-12-01

We describe a process for adding spatially correlated noise to a background ionospheric model, in this case the International Reference Ionosphere (IRI). Monthly median models do a good job describing bulk features of the ionosphere in a median sense. It is well known that the ionosphere almost never actually looks like its median. For the purposes of constructing an Operational System Simulation Experiment, it may be desirable to construct an ionosphere more similar to a particular instant, hour, or day than to the monthly median. We will examine selected data from the Global Ionosphere Radio Observatory (GIRO) database and estimate the amount of variance captured by the IRI model. We will then examine spatial and temporal correlations within the residuals. This analysis will be used to construct a temporal-spatial gridded ionosphere that represents a particular instantiation of those statistics.

Sounding rocket/ground-based observation campaign to study Medium-Scale Traveling Ionospheric Disturbances (MSTID)

NASA Astrophysics Data System (ADS)

Yamamoto, Mamoru; Otsuka, Yuichi; Abe, Takumi; Yokoyama, Tatsuhiro; Bernhardt, Paul; Watanabe, Shigeto; Yamamoto, Masa-yuki; Larsen, Miguel; Saito, Akinori; Pfaff, Robert; Ishisaka, Keigo

2012-07-01

An observation campaign is under preparation. It is to launch sounding rockets S-520-27 and S-310-42 from Uchinoura Space Center of JAXA, while ground-based instruments measure waves in the ionosphere. The main purpose of the study is to reveal seeding mechanism of Medium-Scale Traveling Ionospheric Disturbances (MSTID). The MSTID is enhanced in the summer nighttime of the mid-latitude ionosphere. The MSTID is not only a simple reflection of atmospheric waves to the ionosphere, but includes complicated processes including the electromagnetic coupling of the F- and E-regions, and inter-hemisphere coupling of the ionosphere. We will measure ionospheric parameters such as electron density and electric fields together with neutral winds in the E- and F-regions. TMA and Lithium release experiment will be conducted with S-310-42 and S-520-27 rockets, respectively. The observation campaign is planned in summer 2012 or 2013. In the presentation we will overview characteristics of MSTID, and show plan and current status of the project. We also touch results from the sounding rocket S-520-26 that was launched on January 12, 2012. We will show results of the rocket-ground dual-band beacon experiment.

Geophysical Remote Sensing Using the HF Pumped Stimulated Brillouin Scatter (SBS) Emission Lines Produced by HAARP

NASA Astrophysics Data System (ADS)

Bernhardt, P. A.; Selcher, C. A.

2009-12-01

An ordinary or extraordinary mode electromagnetic wave can decay into a low frequency electrostatic wave and a scattered electromagnetic wave by a process called stimulated Brillouin scatter (SBS). The low frequency wave can be either an ion acoustic wave (IA) or an electrostatic ion cyclotron (EIC) wave. The first detection ion acoustic waves by this process during ionospheric modification with high power radio waves was reported by Norin et al. (2009) using the HAARP transmitter in Alaska. The first detection of the electrostatic ion cyclotron waves is reported here using HAARP during the March 2009 campaign. Subsequent experiments have provided additional verification of the SBS process and quantitative interpretation of the scattered wave frequency offsets to yield measurements of the electron temperatures in the heated ionosphere by Bernhardt et al. (2009). Using the SBS technique to generate ion acoustic waves, electron temperatures between 3000 and 4000 K were measured over the HAARP facility. The matching conditions for decay of the high frequency pump wave show that in addition to the production of an ion-acoustic wave, an electrostatic ion cyclotron wave can produced by the generalized SBS processes only if the pump waves makes a large angle with the magnetic field. When the EIC mode is produced, it is seen as a narrow of stimulated electromagnetic emissions at the ion cyclotron frequency. Occasionally, multiple lines are seen and analyzed to yield the relative abundance of oxygen, and molecular ions in the lower ionosphere. This ion mass spectrometer interpretation of the SBS data is new to the field of ionosphere remote sensing. In addition, based on the matching condition theory, the first profiles of the scattered wave amplitude are produced using the stimulated Brillouin scatter (SBS) matching conditions. These profiles are consistent with maximum ionospheric interactions at the upper-hybrid resonance height and at a region just below the plasma resonance altitude where the pump wave electric fields reach their maximum values. All of these measurements of the HF modified ionosphere are made possible at HAARP because of (1) the recently increased transmitter power to 3.6 MW into the large antenna array and (2) the new digital receiver diagnostics that allow up to 100 dB dynamic range in the stimulated electromagnetic emission measurements. Paul A. Bernhardt, Craig A. Selcher, Robert H. Lehmberg, Serafin Rodriguez, Joe Thomason, Mike McCarrick, Gordon Frazer, Determination of the Electron Temperature in the Modified Ionosphere over HAARP Using the HF Pumped Stimulated Brillouin Scatter (SBS) Emission Lines, Annales Geophysicae, in press, 2009. Norin, L., Leyser, T. B., Nordblad, E., Thidé, B., and McCarrick, M., Unprecedentedly strong and narrow electromagnetic emissions stimulated by high-frequency radio waves in the ionosphere, Phys. Rev. Lett., 102, 065003, 2009.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Argo, P.E.; DeLapp, D.; Sutherland, C.D.

TRACKER is an extension of a three-dimensional Hamiltonian raytrace code developed some thirty years ago by R. Michael Jones. Subsequent modifications to this code, which is commonly called the {open_quotes}Jones Code,{close_quotes} were documented by Jones and Stephensen (1975). TRACKER incorporates an interactive user`s interface, modern differential equation integrators, graphical outputs, homing algorithms, and the Ionospheric Conductivity and Electron Density (ICED) ionosphere. TRACKER predicts the three-dimensional paths of radio waves through model ionospheres by numerically integrating Hamilton`s equations, which are a differential expression of Fermat`s principle of least time. By using continuous models, the Hamiltonian method avoids false caustics and discontinuousmore » raypath properties often encountered in other raytracing methods. In addition to computing the raypath, TRACKER also calculates the group path (or pulse travel time), the phase path, the geometrical (or {open_quotes}real{close_quotes}) pathlength, and the Doppler shift (if the time variation of the ionosphere is explicitly included). Computational speed can be traded for accuracy by specifying the maximum allowable integration error per step in the integration. Only geometrical optics are included in the main raytrace code; no partial reflections or diffraction effects are taken into account. In addition, TRACKER does not lend itself to statistical descriptions of propagation -- it requires a deterministic model of the ionosphere.« less

Application of small-size antennas for estimation of angles of arrival of HF signals scattered by ionospheric irregularities

NASA Astrophysics Data System (ADS)

Guo, Qiang; Galushko, Volodymyr G.; Zalizovski, Andriy V.; Kashcheyev, Sergiy B.; Zheng, Yu

2018-05-01

A modification of the Doppler Interferometry Technique is suggested to enable estimating angles of arrival of comparatively broadband HF signals scattered by random irregularities of the ionospheric plasma with the use of small-size weakly directional antennas. The technique is based on the measurements of cross-spectra phases of the probe radiation recorded at least in three spatially separated points. The developed algorithm has been used to investigate the angular and frequency-time characteristics of HF signals propagating at frequencies above the maximum usable one (MUF) for the direct radio path Moscow-Kharkiv. The received signal spectra show presence of three families of spatial components attributed, respectively, to scattering by plasma irregularities near the middle point of the radio path, ground backscatter signals and scattering of the sounding signals by the intense plasma turbulence associated with auroral activations. It has been shown that the regions responsible for the formation of the third family components are located well inside the auroral oval. The drift velocity and direction of the auroral ionosphere plasma have been determined. The obtained estimates are consistent with the classical conception of the ionospheric plasma convection at high latitudes and do not contradict the results of investigations of the auroral ionosphere dynamics using the SuperDARN network.

Ionospheric Remote Sensing using GPS Radio Occultation and Ultraviolet Photometry aboard the ISS

NASA Astrophysics Data System (ADS)

Budzien, S. A.; Powell, S. P.; O'Hanlon, B.; Humphreys, T.; Bishop, R. L.; Stephan, A. W.; Gross, J.; Chakrabarti, S.

2017-12-01

The GPS Radio Occultation and Ultraviolet Photometer Co-located (GROUP-C) experiment launched to the International Space Station (ISS) on February 19, 2017 as part of the Space Test Program Houston #5 payload (STP-H5). After early orbit testing, GROUP-C began routine science operations in late April. GROUP-C includes a high-sensitivity far-ultraviolet photometer measuring horizontal nighttime ionospheric gradients and an advanced software-defined GPS receiver providing ionospheric electron density profiles, scintillation measurements, and lower atmosphere profiles. GROUP-C and a companion experiment, the Limb-Imaging Ionospheric and Thermospheric Extreme-Ultraviolet Spectrograph (LITES), offer a unique capability to study spatial and temporal variability of the thermosphere and ionosphere using multi-sensor approaches, including ionospheric tomography. Data are collected continuously across low- and mid-latitudes as the ISS orbit precesses through all local times every 60 days. The GROUP-C GPS sensor routinely collects dual-frequency GPS occultations, makes targeted raw signal captures of GPS and Galileo occultations, and includes multiple antennas to characterize multipath in the ISS environment. The UV photometer measures the 135.6 nm ionospheric recombination airglow emision along the nightside orbital track. We present the first analysis of ionospheric observations, discuss the challenges and opportunities of remote sensing from the ISS platform, and explore how these new data help address questions regarding the complex and dynamic features of the low and middle latitude ionosphere-thermosphere relevant to the upcoming GOLD and ICON missions.

Application of GPS Technologies to study Pre-earthquake processes. A review and future prospects

NASA Astrophysics Data System (ADS)

Pulinets, S. A.; Liu, J. Y. G.; Ouzounov, D.; Hernandez-Pajares, M.; Hattori, K.; Krankowski, A.; Zakharenkova, I.; Cherniak, I.

2016-12-01

We present the progress reached by the GPS TEC technologies in study of pre-seismic anomalies in the ionosphere appearing few days before the strong earthquakes. Starting from the first case studies such as 17 August 1999 M7.6 Izmit earthquake in Turkey the technology has been developed and converted into the global near real-time monitoring of seismo-ionospheric effects which is used now in the multiparameter nowcast and forecast of the strong earthquakes. Development of the techniques of the seismo-ionospheric anomalies identification was carried out in parallel with the development of the physical mechanism explaining these anomalies generation. It was established that the seismo-ionospheric anomalies have a self-similarity property, are dependent on the local time and are persistent at least for 4 hours, deviation from undisturbed level could be both positive and negative depending on the leading time (in days) to the moment of impending earthquake and from longitude of anomaly in relation to the epicenter longitude. Low latitude and near equatorial earthquakes demonstrate the magnetically conjugated effect, while the middle and high latitude earthquakes demonstrate the single anomaly over the earthquake preparation zone. From the anomalies morphology the physical mechanism was derived within the framework of the more complex Lithosphere-Atmosphere-Ionosphere-Magnetosphere Coupling concept. In addition to the multifactor analysis of the GPS TEC time series the GIM MAP technology was applied also clearly showing the seismo-ionospheric anomalies locality and their spatial size correspondence to the Dobrovolsky determination of the earthquake preparation zone radius. Application of ionospheric tomography techniques permitted to study not only the total electron content variations but also the modification of the vertical distribution of electron concentration in the ionosphere before earthquakes. The statistical check of the ionospheric precursors passed the Molchan diagram criteria, the most severe criteria used in seismology for precursor's verification.

Initial Results of HamSCI Ham Radio 21 August 2017 Eclipse Ionospheric Experiments

NASA Astrophysics Data System (ADS)

Frissell, N. A.; Gerrard, A. J.; Vega, J. S.; Katz, J. D.; West, M. L.; Gunning, S. W.; Moses, M. L.; Miller, E. S.; Erickson, P. J.; Huba, J.; Silver, H. W.; Ceglia, F.; Smith, P.; Williams, R.; Shovkoplyas, A.; Earle, G. D.; Gerzoff, R.; Gladstone, P.; Reyer, S. E.; Ackermann, J. R.; Bern, D.; Rose, S. W.

2017-12-01

On 21 August 2017, a total solar eclipse will cause the shadow of the moon to traverse the United States from Oregon to South Carolina in just over 90 minutes. The sudden absence of sunlight due to the eclipse, especially solar UV and x-rays, provides an impulse function to the upper atmosphere that modifies the neutral dynamics, plasma concentrations, and related properties. Despite more than 60 years of research, questions remain regarding eclipse-induced ionospheric impacts. Ham radio operators' advanced technical skills and inherent interest in ionospheric science make the amateur radio community ideal for contributing to and and participating in large-scale ionospheric sounding experiments. We present initial results from three amateur radio experiments designed to study the 2017 total solar eclipse: the Solar Eclipse QSO Party (SEQP), the HF Wideband Recording Experiment, and the Eclipse Frequency Measurement Test (FMT). These experiments are coordinated by HamSCI, the Ham Radio Science Citizen Investigation, a citizen science organization that connects the amateur radio community to the professional space science research community for mutual benefit.

Engineering aspect of the Microwave Ionosphere Nonlinear Interaction Experiment (MINIX) with a sounding rocket

NASA Astrophysics Data System (ADS)

Nagatomo, M.; Kaya, N.; Matsumoto, H.

1984-10-01

One type of problem arising in connection with an evaluation of the feasibility of the Solar Power Satellite (SPS) and the definition of suitable SPS designs is related to environmental issues. Questions exist, for instance, regarding the interaction between microwave power and the upper atmosphere. The present investigation is concerned with the Microwave Ionosphere Nonlinear Interaction Experiment (MINIX), which is a space plasma experiment originally devoted to the research of space plasma physics. MINIX is eventually to observe possible effects of a strong microwave field in the ionospheric environment. The scientific requirements of the MINIX are discussed, taking into account functional and experimental conditions. Attention is also given to rocket characteristics, experimental design, the payload, the inflight experiment configuration, and details concerning the conduction of the experiment.

Radio Sounding of the Martian and Venusian Ionospheres

NASA Astrophysics Data System (ADS)

Paetzold, M.; Haeusler, B.; Bird, M. K.; Peter, K.; Tellmann, S.; Tyler, G. L.; Withers, P.

2011-12-01

The Mars Express Radio Science Experiment MaRS and the radio science experiment Vera on Venus Express sound the ionospheres of Mars and Venus, respectively, at two frequencies in the microwave band and cover altitudes from the base of the ionosphere at 80 km (100 km at Venus) to the ionopause at altitudes between 300 km and 600 km. In general, both ionospheres consists of a lower layer M1 (V1 at Venus) at about 110 km (115 km), and the main layer M2 (V2) at about 135 km (145 km) altitude, both formed mainly by solar radiation at X-ray and EUV, respectively. The specific derivation and interpretation of the vertical electron density profiles at two radio frequencies from radio sounding is demonstrated in detail. Cases of quiet and disturbed ionospheric electron density profiles and cases of potential misinterpretations are presented. The behavior of the peak densities and peak altitudes of both ionospheres as a function of solar zenith angle and phase of the solar cycle as seen with Mars Express and Venus Express will be compared with past observations, models and conclusions.

Effects of large-scale irregularities of the ionosphere in the propagation of decametric radio waves

NASA Astrophysics Data System (ADS)

Kerblai, T. S.; Kovalevskaia, E. M.

1985-12-01

A numerical experiment is used to study the simultaneous influence of regular space-time gradients and large-scale traveling ionospheric disturbances (TIDs) as manifested in the angular and Doppler characteristics of decametric-wave propagation. Conditions typical for middle latitudes are chosen as the ionospheric models: conditions under which large-scale TIDs in the F2-layer evolve on the background of winter or equinox structures of the ionosphere. Certain conclusions on the character of TID effects for various states of the background ionosphere are drawn which can be used to interpret experimental results.

Rocket studies of the lower ionosphere

NASA Technical Reports Server (NTRS)

Bowhill, Sidney A.

1990-01-01

The earth's ionosphere in the altitude range of 50 to 200 km was investigated by rocket-borne sensors, supplemented by ground-based measurement. The rocket payloads included mass spectrometers, energetic particle detectors, Langmuir probes and radio propagation experiments. Where possible, rocket flights were included in studies of specific phenomena, and the availability of data from other experiments greatly increased the significance of the results. The principal ionospheric phenomena studied were: winter anomaly in radiowave absorption, ozone and molecular oxygen densities, mid-latitude sporadic-E layers, energetic particle precipitation at middle and low latitudes, ionospheric instabilities and turbulence, and solar eclipse effects in the D and E regions. This document lists personnel who worked on the project, and provides a bibliography of resultant publications.

Abnormal Circulation Changes in the Winter Stratosphere, Detected Through Variations of D Region Ionospheric Absorption

NASA Technical Reports Server (NTRS)

Delamorena, B. A.

1984-01-01

A method to detect stratospheric warmings using ionospheric absorption records obtained by an Absorption Meter (method A3) is introduced. The activity of the stratospheric circulation and the D region ionospheric absorption as well as other atmospheric parameters during the winter anomaly experience an abnormal variation. A simultaneity was found in the beginning of abnormal variation in the mentioned parameters, using the absorption records for detecting the initiation of the stratospheric warming. Results of this scientific experience of forecasting in the El Arenosillo Range, are presented.

CARINA Satellite Mission to Investigate the Upper Atmosphere below the F-Layer Ionosphere

NASA Astrophysics Data System (ADS)

Siefring, C. L.; Bernhardt, P. A.; Briczinski, S. J., Jr.; Huba, J.; Montgomery, J. A., Jr.

2017-12-01

A new satellite design permits broad science measurements from the ocean to the ionosphere by flying below the F-Layer. The satellite called CARINA for Coastal-Ocean, Assimilation, Radio, Ionosphere, Neutral-Drag, and Atmospherics. The unique system capabilities are long duration orbits below the ionosphere and a HF receiver to measure broadband signals. The CARINA science products include recording the ocean surface properties, data for assimilation into global ionosphere models, radio wave propagation measurements, in-situ observations of ionospheric structures, validating neutral drag models and theory, and broadband atmospheric lightning characterization. CARINA will also measure nonlinear wave-generation using ionospheric modification sites in Alaska, Norway, Puerto Rico, and Russia and collaborate with geophysics HF radars (such as Super-DARN) for system calibration. CARINA is a linear 6-U CubeSat with a long antenna extended in the wake direction. The CARINA science mission is supported by three instruments. First, the Electric Field Instrument (EFI) is a radio receiver covering the 2 to 18 MHz range. The receiver can capture both narrow and wide bandwidths for up to 10 minutes. EFI is designed to provide HF signal strength and phase, radar Doppler shift and group delay, and electron plasma density from photoelectron excited plasma waves. Second a Ram Langmuir Probe (RLP) measures high-resolution ion currents at a 10 kHz rate. These measurements yield electron and ion density at the spacecraft. Finally, the Orbiting GPS Receiver (OGR) provides dual frequency GPS position with ionosphere correction. OGR also measures total electron content above the spacecraft and L-Band scintillations. CARINA will be the lowest satellite in orbit at 250 km altitude, <0.01 eccentricity, and up to 4-month lifetime. The design supports unique capabilities with broad applications to the geosciences. Remote sensing of the ocean will sample the HF signals scattered from the rough sea surface to measure the wave height spectrum over large areas. CARINA will provide an enhanced understanding of HF system limiting phenomena such as travelling ionospheric disturbances, field aligned irregularities, sporadic-E and bottomside ionosphere structures.This work supported by the Naval Research Laboratory Base Program.

Filtering Drifter Trajectories Sampled at Submesoscale Resolution

DTIC Science & Technology

2015-05-11

bution. The modification allows PE variances to change in time through parameterization (10) with the cutoff scale 1.56 10 ms , corresponding to the...more sophisticated real-time ionosphere correction algo- rithms. We consider this study to be an attempt at improving the quality of the drifter data

Doppler measurements of the ionosphere on the occasion of the Apollo-Soyuz test project. Part 1: Computer simulation of ionospheric-induced Doppler shifts

NASA Technical Reports Server (NTRS)

Grossi, M. D.; Gay, R. H.

1975-01-01

A computer simulation of the ionospheric experiment of the Apollo-Soyuz Test Project (ASTP) was performed. ASTP is the first example of USA/USSR cooperation in space and is scheduled for summer 1975. The experiment consists of performing dual-frequency Doppler measurements (at 162 and 324 MHz) between the Apollo Command Service Module (CSM) and the ASTP Docking Module (DM), both orbiting at 221-km height and at a relative distance of 300 km. The computer simulation showed that, with the Doppler measurement resolution of approximately 3 mHz provided by the instrumentation (in 10-sec integration time), ionospheric-induced Doppler shifts will be measurable accurately at all times, with some rare exceptions occurring when the radio path crosses regions of minimum ionospheric density. The computer simulation evaluated the ability of the experiment to measure changes of columnar electron content between CSM and DM (from which horizontal gradients of electron density at 221-km height can be obtained) and to measure variations in DM-to-ground columnar content (from which an averaged columnar content and the electron density at the DM can be deduced, under some simplifying assumptions).

Active experiments in geospace plasmas with gigawatts of RF power at HAARP

NASA Astrophysics Data System (ADS)

Sheerin, James

2016-07-01

The ionosphere provides a relatively quiescent plasma target, stable on timescales of minutes, for a whole host of active plasma experiments. The largest HF transmitter built to date is the HAARP phased-array HF transmitter near Gakona, Alaska which can deliver up to 3.6 Gigawatts (ERP) of CW RF power in the range of 2.8 - 10 MHz to the ionosphere with millisecond pointing, power modulation, and frequency agility. With an ionospheric background thermal energy in the range of only 0.1 eV, this amount of power gives access to the highest regimes of the nonlinearity (RF intensity to thermal pressure) ratio. HAARP's unique features have enabled the conduct of a number of nonlinear plasma experiments in the inter¬action region of overdense ionospheric plasma including generation of artificial aurorae, artificial ionization layers, VLF wave-particle interactions in the magnetosphere, parametric instabilities, stimulated electromagnetic emissions (SEE), strong Langmuir turbulence (SLT) and suprathermal electron acceleration. Diagnostics include the Modular UHF Ionospheric Radar (MUIR) sited at HAARP, the SuperDARN-Kodiak HF radar, spacecraft radio beacons, HF receivers to record stimulated electromagnetic emissions (SEE) and optics for optical emissions. We report on short timescale ponderomotive overshoot effects, artificial field-aligned irregularities (AFAI), the aspect angle dependence of the intensity of the HF-enhanced plasma line, and production of suprathermal electrons. Applications are made to the controlled study of fundamental nonlinear plasma processes of relevance to laboratory plasmas, ionospheric irregularities affecting spacecraft communication and navigation systems, artificial ionization mirrors, wave-particle interactions in the magnetosphere, active global magnetospheric experiments, and many more.

The CERTO Beacon on CASSIOPE/e-POP and Experiments Using High-Power HF Ionospheric Heaters

NASA Astrophysics Data System (ADS)

Siefring, Carl L.; Bernhardt, Paul A.; James, H. Gordon; Parris, Richard Todd

2015-06-01

A new Coherent Electromagnetic Radio Tomography (CERTO) beacon is on the CASSIOPE satellite and part of the enhanced-Polar Outflow Probe (e-POP) suite of scientific instruments. CERTO signals can be used to measure ionospheric Total Electron Content (TEC) and radio scintillations along propagation paths between CERTO and receivers. The combination of CERTO and the array of e-POP in-situ diagnostics form a powerful tool for studying ionospheric plasma processes that have not been previously possible. Of note, the combination CERTO and the Radio Receiver Instrument (RRI), a modern digital receiver, which measures between 10 Hz to 18 MHz in selectable bands allows for innovative High Frequency (HF) radio propagation experiments. The use of high-power HF ionospheric heating facilities for such experiments further allows for repeatable studies of a number of important plasma processes. The new CERTO beacon transmits un-modulated, phase-coherent waves at 150, 400, and 1067 MHz with either right-hand-circular or linear polarization and TEC is measured using either differential phase and/or Faraday rotation. With a linear array of CERTO receivers, TEC data can be used for tomographic imaging of the ionosphere yielding two-dimensional maps of the plasma below the satellite orbit. In addition, the three CERTO frequencies cover a wide range for determination of radio scintillation effects caused by diffraction from propagation through ionospheric irregularities. We will describe the CERTO beacon and several potential innovative experiments using HF heating facilities in conjunction with CERTO, the RRI and other e-POP instruments.

Artificial Ionization and UHF Radar Response Associated with HF Frequencies near Electron Gyro-Harmonics (Invited)

NASA Astrophysics Data System (ADS)

Watkins, B. J.; Fallen, C. T.; Secan, J. A.

2013-12-01

We present new results from O-mode ionospheric heating experiments at the HAARP facility in Alaska to demonstrate that the magnitude of artificial ionization production is critically dependent on the choice of HF frequency near gyro-harmonics. For O-mode heating in the lower F-region ionosphere, typically about 200 km altitude, artificial ionization enhancements are observed in the lower ionosphere (about 150 - 220 km) and also in the topside ionosphere above about 500 km. Lower ionosphere density enhancements are inferred from HF-enhanced ion and plasma-line signals observed with UHF radar. Upper ionospheric density enhancements have been observed with TEC (total electron content) experiments by monitoring satellite radio beacons where signal paths traverse the HF-modified ionosphere. Both density enhancements and corresponding upward plasma fluxes have also been observed in the upper ionosphere via in-situ satellite observations. The data presented focus mainly on observations near the third and fourth gyro-harmonics. The specific values of the height-dependent gyro-harmonics have been computed from a magnetic model of the field line through the HF heated volume. Experiments with several closely spaced HF frequencies around the gyro-harmonic frequency region show that the magnitude of the lower-ionosphere artificial ionization production maximizes for HF frequencies about 1.0 - 1.5 MHz above the gyro-harmonic frequency. The response is progressively larger as the HF frequency is increased in the frequency region near the gyro-harmonics. For HF frequencies that are initially greater than the gyro-harmonic value the UHF radar scattering cross-section is relatively small, and non-existent or very weak signals are observed; as the signal returns drop in altitude due to density enhancements the HF interaction region passes through lower altitudes where the HF frequency is less than the gyro-harmonic value, for these conditions the radar scattering cross-section is significantly increased and strong signals persist while the high-power HF is present . Simultaneous observations of topside TEC measurements and lower-ionosphere UHF radar observations suggest there is an optimum altitude region to heat the lower F-region in order to produce topside ionosphere density enhancements. The observations are dependent on HF power levels and we show several examples where heating results are only observed for the high-power levels attainable with the HAARP facility.

Assessment of Ionospheric Gradient Impacts on Ground-Based Augmentation System (GBAS) Data in Guangdong Province, China

PubMed Central

Wang, Zhipeng; Wang, Shujing; Zhu, Yanbo; Xin, Pumin

2017-01-01

Ionospheric delay is one of the largest and most variable sources of error for Ground-Based Augmentation System (GBAS) users because inospheric activity is unpredictable. Under normal conditions, GBAS eliminates ionospheric delays, but during extreme ionospheric storms, GBAS users and GBAS ground facilities may experience different ionospheric delays, leading to considerable differential errors and threatening the safety of users. Therefore, ionospheric monitoring and assessment are important parts of GBAS integrity monitoring. To study the effects of the ionosphere on the GBAS of Guangdong Province, China, GPS data collected from 65 reference stations were processed using the improved “Simple Truth” algorithm. In addition, the ionospheric characteristics of Guangdong Province were calculated and an ionospheric threat model was established. Finally, we evaluated the influence of the standard deviation and maximum ionospheric gradient on GBAS. The results show that, under normal ionospheric conditions, the vertical protection level of GBAS was increased by 0.8 m for the largest over bound σvig (sigma of vertical ionospheric gradient), and in the case of the maximum ionospheric gradient conditions, the differential correction error may reach 5 m. From an airworthiness perspective, when the satellite is at a low elevation, this interference does not cause airworthiness risks, but when the satellite is at a high elevation, this interference can cause airworthiness risks. PMID:29019953

Assessment of Ionospheric Gradient Impacts on Ground-Based Augmentation System (GBAS) Data in Guangdong Province, China.

PubMed

Wang, Zhipeng; Wang, Shujing; Zhu, Yanbo; Xin, Pumin

2017-10-11

Ionospheric delay is one of the largest and most variable sources of error for Ground-Based Augmentation System (GBAS) users because inospheric activity is unpredictable. Under normal conditions, GBAS eliminates ionospheric delays, but during extreme ionospheric storms, GBAS users and GBAS ground facilities may experience different ionospheric delays, leading to considerable differential errors and threatening the safety of users. Therefore, ionospheric monitoring and assessment are important parts of GBAS integrity monitoring. To study the effects of the ionosphere on the GBAS of Guangdong Province, China, GPS data collected from 65 reference stations were processed using the improved "Simple Truth" algorithm. In addition, the ionospheric characteristics of Guangdong Province were calculated and an ionospheric threat model was established. Finally, we evaluated the influence of the standard deviation and maximum ionospheric gradient on GBAS. The results show that, under normal ionospheric conditions, the vertical protection level of GBAS was increased by 0.8 m for the largest over bound σ v i g (sigma of vertical ionospheric gradient), and in the case of the maximum ionospheric gradient conditions, the differential correction error may reach 5 m. From an airworthiness perspective, when the satellite is at a low elevation, this interference does not cause airworthiness risks, but when the satellite is at a high elevation, this interference can cause airworthiness risks.

Low Latitude Ionospheric Effects on Radiowave Propagation

DTIC Science & Technology

1998-06-01

was used. Active earth-based observation equipment includes coherent and non-coherent scatter radars, and vertical and oblique incidence sounders...ionospheric monitoring during this experiment consisted of an oblique sounder, apparatus to measure time-of-flight of transionospheric signals, and an...is configured to monitor the ionosphere directly overhead in the vertical incidence configuration, or with an obliquely -launched antenna elevation

Stimulated Brillouin scatter and stimulated ion Bernstein scatter during electron gyroharmonic heating experiments

NASA Astrophysics Data System (ADS)

Fu, H.; Scales, W. A.; Bernhardt, P. A.; Samimi, A.; Mahmoudian, A.; Briczinski, S. J.; McCarrick, M. J.

2013-09-01

Results of secondary radiation, Stimulated Electromagnetic Emission (SEE), produced during ionospheric modification experiments using ground-based high-power radio waves are reported. These results obtained at the High Frequency Active Auroral Research Program (HAARP) facility specifically considered the generation of Magnetized Stimulated Brillouin Scatter (MSBS) and Stimulated Ion Bernstein Scatter (SIBS) lines in the SEE spectrum when the transmitter frequency is near harmonics of the electron gyrofrequency. The heater antenna beam angle effect was investigated on MSBS in detail and shows a new spectral line postulated to be generated near the upper hybrid resonance region due to ion acoustic wave interaction. Frequency sweeping experiments near the electron gyroharmonics show for the first time the transition from MSBS to SIBS lines as the heater pump frequency approaches the gyroharmonic. Significantly far from the gyroharmonic, MSBS lines dominate, while close to the gyroharmonic, SIBS lines strengthen while MSBS lines weaken. New possibilities for diagnostic information are discussed in light of these new observations.

Ionospheric ion temperature forecasting in multiples of 27 days

NASA Astrophysics Data System (ADS)

Sojka, Jan J.; Schunk, Robert W.; Nicolls, Michael J.

2014-03-01

The ionospheric variability found at auroral locations is usually assumed to be unpredictable. The magnetosphere, which drives this ionospheric variability via storms and substorms, is at best only qualitatively describable. In this study we demonstrate that over a 3 year period, ionospheric variability observed from Poker Flat, Alaska, has, in fact, a high degree of long-term predictability. The observations used in this study are (a) the solar wind high speed stream velocity measured by the NASA Advanced Composition Explorer satellite, used to define the corotating interaction region (CIR), and (b) the ion temperature at 300 km altitude measured by the National Science Foundation Poker Flat Incoherent Scatter Radar over Poker Flat, Alaska. After determining a seasonal and diurnal climatology for the ion temperature, we show that the residual ion temperature heating events occur synchronously with CIR-geospace interactions. Furthermore, we demonstrate examples of ion temperature forecasting at 27, 54, and 81 days. A rudimentary operational forecasting scenario is described for forecasting recurrence 27 days ahead for the CIR-generated geomagnetic storms. These forecasts apply specifically to satellite tracking operations (thermospheric drag) and emergency HF-radio communications (ionospheric modifications) in the polar regions. The forecast is based on present-day solar and solar wind observations that can be used to uniquely identify the coronal hole and its CIR. From this CIR epoch, a 27 day forecast is then made.

Opportunities investigating the thermosphere/ionosphere system by low Earth orbiting satellite missions (Invited)

NASA Astrophysics Data System (ADS)

Stolle, C.; Park, J.; Luhr, H.

2013-12-01

New opportunities for investigating the thermosphere/ionosphere interactions arise from in situ measurements on board low Earth orbiting satellites. Ten years of successful operation of the CHAMP satellite mission at a unique orbit altitude of about 400 km revealed many interesting features of the coupling between the thermosphere and ionosphere and the different atmospheric layers. Examples are the investigations of signatures of stratospheric warming events that are known to change significantly the dynamics of the equatorial ionosphere. It was shown that these modifications are due to an enhancement of lunar tidal effects, e.g. reflected in the thermospheric zonal wind, in the equatorial electroje or in the eastward electric field. Another topic concerns the energy deposit in the F-region though cooling of the thermal electron gas caused by elastic and inelastic processes (Schunk and Nagy, 2009). We find that a significant deposition is present during day at mid latitudes. At low latitudes the energy flux remain important until midnight. Observed heating rates depend on the satellite altitudes, but they are globally available from the CHAMP data. Further enhanced investigations are expected from ESA's three-satellite Swarm mission with a launch planned in 2014. The mission will provide observations of electron density, electron and ion temperature, ion drift and the electric field together with neutral density and winds. High-precision magnetic field observations will allow monitoring ionospheric currents.

Assessing ionospheric activity by long time series of GNSS signals: the search of possible connection with seismicity

NASA Astrophysics Data System (ADS)

Galeandro, Angelo; Mancini, Francesco; De Giglio, Michaela; Barbarella, Maurizio

2014-05-01

The modifications of some atmospheric physical properties prior to a high magnitude earthquake were recently debated in the frame of the Lithosphere-Atmosphere-Ionosphere (LAI) Coupling model. Among this variety of phenomena, the ionization of air at the ionospheric levels due to leaking of gases from earth crust through the analysis of long time series of GNSS (Global Navigation Satellite System) signals was investigated in this work. Several authors used the dispersive properties of the ionospheric strata towards the GNSS signals to detect possible ionospheric anomalies over areas affected by earthquakes and some evidences were encountered. However, the spatial scale and temporal domains over which such disturbances come into evidence is still a controversial item. Furthermore, the correspondence by chance between ionospheric disturbances and relevant seismic activity is even more difficult to model whenever the reference time period and spatial extent of investigation are confined. Problems could also arise from phenomena due to solar activity (now at culmination within the 11 years-long solar cycle) because such global effects could reduce the ability to detect disturbances at regional or local spatial scale. In this work, two case studies were investigated. The first one focuses on the M = 6.3 earthquake occurred on April 6, 2009, close to the city of L'Aquila (Abruzzo, Italy). The second concerns the M = 5.9 earthquake occurred on May 20, 2012, between the cities of Ferrara and Modena (Emilia Romagna, Italy). To investigate possible connections between the ionospheric activity and seismicity for such events, a five-year (2008-2012) long series of high resolution ionospheric maps was used. These maps were produced by authors from GNSS data collected by permanent stations uniformly distributed around the epicenters and allowed to assess the ionospheric activity through the analysis of the TEC (Total Electron Content). To avoid the influence of solar activity, only nighttime hours were considered. Moreover, to de?ne the temporal domain of potential ionospheric disturbances and separate local from global effects, results from local observations were compared with regional TEC series. The whole analysis shows episodes where anomalies in the ionospheric activity were detected in the vicinity of the mentioned shocks. However, their statistical significance and the temporal correlation with seismic activity are still controversial.

Unprecedentedly Strong and Narrow Electromagnetic Emissions Stimulated by High-Frequency Radio Waves in the Ionosphere

DOE Office of Scientific and Technical Information (OSTI.GOV)

Norin, L.; Leyser, T. B.; Nordblad, E.

2009-02-13

Experimental results of secondary electromagnetic radiation, stimulated by high-frequency radio waves irradiating the ionosphere, are reported. We have observed emission peaks, shifted in frequency up to a few tens of Hertz from radio waves transmitted at several megahertz. These emission peaks are by far the strongest spectral features of secondary radiation that have been reported. The emissions are attributed to stimulated Brillouin scattering, long predicted but hitherto never unambiguously identified in high-frequency ionospheric interaction experiments. The experiments were performed at the High-Frequency Active Auroral Research Program (HAARP), Alaska, USA.

Unprecedentedly strong and narrow electromagnetic emissions stimulated by high-frequency radio waves in the ionosphere.

PubMed

Norin, L; Leyser, T B; Nordblad, E; Thidé, B; McCarrick, M

2009-02-13

Experimental results of secondary electromagnetic radiation, stimulated by high-frequency radio waves irradiating the ionosphere, are reported. We have observed emission peaks, shifted in frequency up to a few tens of Hertz from radio waves transmitted at several megahertz. These emission peaks are by far the strongest spectral features of secondary radiation that have been reported. The emissions are attributed to stimulated Brillouin scattering, long predicted but hitherto never unambiguously identified in high-frequency ionospheric interaction experiments. The experiments were performed at the High-Frequency Active Auroral Research Program (HAARP), Alaska, USA.

Integrated Verification Experiment data collected as part of the Los Alamos National Laboratory`s Source Region Program. Appendix D: Ionospheric measurements for IVEs

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fitzgerald, T.J.; Carlos, R.C.; Argo, P.E.

As part of the integrated verification experiment (IVE), we deployed a network of hf ionospheric sounders to detect the effects of acoustic waves generated by surface ground motion following underground nuclear tests at the Nevada Test Site. The network sampled up to four geographic locations in the ionosphere from almost directly overhead of the surface ground zero out to a horizontal range of 60 km. We present sample results for four of the IVEs: Misty Echo, Texarkana, Mineral Quarry, and Bexar.

INSPIRE - Premission. [Interactive NASA Space Physics Ionosphere Radio Experiment

NASA Technical Reports Server (NTRS)

Taylor, William W. L.; Mideke, Michael; Pine, William E.; Ericson, James D.

1992-01-01

The Interactive NASA Space Physics Ionosphere Radio Experiment (INSPIRE) designed to assist in a Space Experiments with Particle Accelerators (SEPAC) project is discussed. INSPIRE is aimed at recording data from a large number of receivers on the ground to determine the exact propagation paths and absorption of radio waves at frequencies between 50 Hz and 7 kHz. It is indicated how to participate in the experiment that will involve high school classes, colleges, and amateur radio operators.

A Mid-Latitude Skywave Propagation Experiment: Overview and Results

NASA Astrophysics Data System (ADS)

Munton, D. C.; Calfas, R. S.; Gaussiran, T., II; Rainwater, D.; Flesichmann, A. M.; Schofield, J. R.

2016-12-01

We will describe a mid-latitude HF skywave propagation experiment conducted during 19-27 January, 2014. There were two primary goals to the experiment. First, we wanted to build an understanding of the impact that medium scale traveling ionospheric disturbances have on the angles of arrival of the HF signals. The second goal was to provide a diverse data set that could serve as a baseline for propagation model development and evaluation. We structured individual tests during the experiment to increase the knowledge of temporal and spatial length scales of various ionospheric features. The experiment was conducted during both day and night periods and spanned a wide range of ionospheric states. We conducted the experiment at White Sands Missile Range, New Mexico and in the surrounding area. As part of the experiment, we deployed a number of active HF transmitters, and an array of dipole antennas to provide angle of arrival measurements. We also deployed a smaller array of more novel compact electro-magnetic vector sensors (EMVSs). Other instrumentation specific to the remote sensing of the ionosphere included digisondes, GNSS receivers, beacon satellite receivers, and optical instruments. We will provide a complete description of the experiment configuration and the data products.Finally, we will provide a discussion of experimental results, focusing on ionospheric conditions during the angle-of-arrival determinations, and the impact ionospheric disturbances can have on these measurements. We use the angle-of-arrival determinations to estimate TID properties, including velocity and direction.This research is based upon work supported in part by the Office of the Director of National Intelligence (ODNI), Intelligence Advanced Research Projects Activity (IARPA), via US Navy Contract N00024-07-D-6200. The views and conclusions contained herein are those of the authors and should not be interpreted as necessarily representing the official policies or endorsements, either expressed or implied, of ODNI, IARPA, US Navy, or the U.S. Government. The U.S. Government is authorized to reproduce and distribute reprints for Governmental purposes notwithstanding any copyright annotation thereon.

Role of the ''fountain effect'' in the equatorial ionosphere in the prolonged retention of radioactive products of the ''Starfish'' explosion at F-region altitudes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bolyunova, A.D.

1975-01-01

The effect of prolonged retention of radioactive products (fission fragments) following the ''Starfish'' thermonuclear explosion at F-region altitudes of the ionosphere of lower and middle latitudes discovered on the Kosmos 3, Kosmos 5, and Kosmos 6 satellites is analyzed from the point of view of concepts concerning ion transport processes in the equatorial ionosphere. A qualitative explanation for this phenomenon based on the ''fountain effect'' in the equatorial ionosphere is proposed which is in satisfactory agreement with experiment.

Time series of GNSS-derived ionospheric maps to detect anomalies as possible precursors of high magnitude earthquakes

NASA Astrophysics Data System (ADS)

Barbarella, M.; De Giglio, M.; Galeandro, A.; Mancini, F.

2012-04-01

The modification of some atmospheric physical properties prior to a high magnitude earthquake has been recently debated within the Lithosphere-Atmosphere-Ionosphere (LAI) Coupling model. Among this variety of phenomena the ionization of air at the higher level of the atmosphere, called ionosphere, is investigated in this work. Such a ionization occurrences could be caused by possible leaking of gases from earth crust and their presence was detected around the time of high magnitude earthquakes by several authors. However, the spatial scale and temporal domain over which such a disturbances come into evidence is still a controversial item. Even thought the ionospheric activity could be investigated by different methodologies (satellite or terrestrial measurements), we selected the production of ionospheric maps by the analysis of GNSS (Global Navigation Satellite Data) data as possible way to detect anomalies prior of a seismic event over a wide area around the epicentre. It is well known that, in the GNSS sciences, the ionospheric activity could be probed by the analysis of refraction phenomena occurred on the dual frequency signals along the satellite to receiver path. The analysis of refraction phenomena affecting data acquired by the GNSS permanent trackers is able to produce daily to hourly maps representing the spatial distribution of the ionospheric Total Electron Content (TEC) as an index of the ionization degree in the upper atmosphere. The presence of large ionospheric anomalies could be therefore interpreted in the LAI Coupling model like a precursor signal of a strong earthquake, especially when the appearance of other different precursors (thermal anomalies and/or gas fluxes) could be detected. In this work, a six-month long series of ionospheric maps produced from GNSS data collected by a network of 49 GPS permanent stations distributed within an area around the city of L'Aquila (Abruzzi, Italy), where an earthquake (M = 6.3) occurred on April 6, 2009, were investigated. Basically, the proposed methodology is able to perform a time series analysis of the TEC maps and, eventually, define the spatial and temporal domains of ionospheric disturbances. This goal was achieved by a time series analysis of the spatial dataset able to compare a local pattern of ionospheric activity with its historical mean value and detect areas where the TEC content exhibits anomalous values. This data processing shows some 1 to 2 days long anomalies about 20 days before of the seismic event (confirming also results provided in recent studies by means of ionospheric soundings).

First results of registering ionospheric disturbances obtained with SibNet network of GNSS receivers in active space experiments

NASA Astrophysics Data System (ADS)

Ishin, Artem; Perevalova, Natalia; Voeykov, Sergey; Khakhinov, Vitaliy

2017-12-01

Global and regional networks of GNSS receivers have been successfully used for geophysical research for many years; the number of continuous GNSS stations in the world is steadily growing. The article presents the first results of the use of a new regional network of GNSS stations (SibNet) in active space experiments. The Institute of Solar-Terrestrial Physics of Siberian Branch of Russian Academy of Sciences (ISTP SB RAS) has established this network in the South Baikal region. We describe in detail SibNet, characteristics of receivers in use, parameters of antennas and methods of their installation. We also present the general structure of observation site and the plot of coverage of the receiver operating zone at 50-55° latitudes by radio paths. It is shown that the selected location of receivers allows us to detect ionospheric irregularities of various scales. The purpose of the active space experiments was to reveal and record parameters of the ionospheric irregu larities caused by effects from jet streams of Progress cargo spacecraft. The mapping technique enabled us to identify weak, vertically localized ionospheric irregularities and associate them with the Progress spacecraft engine impact. Thus, it has been shown that SibNet deployed in the Southern Baikal region is an effective instrument for monitoring ionospheric conditions.

Ion energization in Ganymede's magnetosphere: Using multifluid simulations to interpret ion energy spectrograms

NASA Astrophysics Data System (ADS)

Paty, C.; Paterson, W.; Winglee, R.

2008-06-01

We investigate the ion population and energy distribution within Ganymede's magnetosphere by examining Ganymede's ionospheric outflow as a source of heavy (O+) and light (H+) ions and the Jovian magnetospheric plasma as an external source of heavy ions. We develop a method for examining the energy distributions of each ion species in a three-dimensional multifluid simulation in a way directly comparable to the observations of the Plasma Experiment on the Galileo spacecraft. This is used to provide new insight to the existing controversy over the composition of Ganymede's observed ionospheric outflow, and enables further examination of the energetic signatures of the ion population trapped within Ganymede's magnetosphere. The model-predicted ionospheric outflow is consistent with the in situ ion energy spectrograms observed by the Galileo Plasma Experiment at closest approach, and requires that both ionospheric H+ and O+ are present in the population of ions exiting Ganymede's ionosphere over the polar cap. The outward flux of ionospheric ions was calculated to be ~1026 ions/cm2/s, which is in agreement with independently calculated sputtering rates of Ganymede's icy surface. The modeled spectrograms define characteristic energy signatures and populations for various regions of Ganymede's magnetosphere, which illustrate the major sources of ions trapped within the magnetosphere are Ganymede's ionospheric O+ and H+. The fact that very little plasma was observed inside Ganymede's magnetosphere during the G8 flyby is attributed to the region being shadowed from the sun for ~60 h, which may indicate the importance of photoionization for sustaining Ganymede's ionospheric plasma source.

Spatial Structure of Large-Scale Plasma Density Perturbations HF-Induced in the Ionospheric F 2 Region

NASA Astrophysics Data System (ADS)

Frolov, V. L.; Komrakov, G. P.; Glukhov, Ya. V.; Andreeva, E. S.; Kunitsyn, V. E.; Kurbatov, G. A.

2016-07-01

We consider the experimental results obtained by studying the large-scale structure of the HF-disturbed ionospheric region. The experiments were performed using the SURA heating facility. The disturbed ionospheric region was sounded by signals radiated by GPS navigation satellite beacons as well as by signals of low-orbit satellites (radio tomography). The results of the experiments show that large-scale plasma density perturbations induced at altitudes higher than the F2 layer maximum can contribute significantly to the measured variations of the total electron density and can, with a certain arrangement of the reception points, be measured by the GPS sounding method.

Near real-time PPP-based monitoring of the ionosphere using dual-frequency GPS/BDS/Galileo data

NASA Astrophysics Data System (ADS)

Liu, Zhinmin; Li, Yangyang; Li, Fei; Guo, Jinyun

2018-03-01

Ionosphere delay is very important to GNSS observations, since it is one of the main error sources which have to be mitigated even eliminated in order to determine reliable and precise positions. The ionosphere is a dispersive medium to radio signal, so the value of the group delay or phase advance of GNSS radio signal depends on the signal frequency. Ground-based GNSS stations have been used for ionosphere monitoring and modeling for a long time. In this paper we will introduce a novel approach suitable for single-receiver operation based on the precise point positioning (PPP) technique. One of the main characteristic is that only carrier-phase observations are used to avoid particular effects of pseudorange observations. The technique consists of introducing ionosphere ambiguity parameters obtained from PPP filter into the geometry-free combination of observations to estimate ionospheric delays. Observational data from stations that are capable of tracking the GPS/BDS/GALILEO from the International GNSS Service (IGS) Multi-GNSS Experiments (MGEX) network are processed. For the purpose of performance validation, ionospheric delays series derived from the novel approach are compared with the global ionospheric map (GIM) from Ionospheric Associate Analysis Centers (IAACs). The results are encouraging and offer potential solutions to the near real-time ionosphere monitoring.

Power-Stepped HF Cross-Modulation Experiments: Simulations and Experimental Observations

NASA Astrophysics Data System (ADS)

Greene, S.; Moore, R. C.

2014-12-01

High frequency (HF) cross modulation experiments are a well established means for probing the HF-modified characteristics of the D-region ionosphere. The interaction between the heating wave and the probing pulse depends on the ambient and modified conditions of the D-region ionosphere. Cross-modulation observations are employed as a measure of the HF-modified refractive index. We employ an optimized version of Fejer's method that we developed during previous experiments. Experiments were performed in March 2013 at the High Frequency Active Auroral Research Program (HAARP) observatory in Gakona, Alaska. During these experiments, the power of the HF heating signal incrementally increased in order to determine the dependence of cross-modulation on HF power. We found that a simple power law relationship does not hold at high power levels, similar to previous ELF/VLF wave generation experiments. In this paper, we critically compare these experimental observations with the predictions of a numerical ionospheric HF heating model and demonstrate close agreement.

Controlled Studies of Whistler Wave Interactions with Energetic Particles in Radiation Belts

DTIC Science & Technology

2009-07-01

the IGRF geomagnetic field and PIM ionosphere /plasmasphere models . Those simulations demonstrate that on this particular evening 28.5 kHz whistler...a simplified slab model of ionospheric plasmas, we can compute the transmission coefficient and, subsequently, estimate that -15% of the incident...with inner radiation belts as well as the ionospheric effects caused by precipitated energetic electrons. The whistler waves used in our experiments

A medium-scale traveling ionospheric disturbance observed from the ground and from space

NASA Astrophysics Data System (ADS)

Dymond, K. F.; Watts, C.; Coker, C.; Budzien, S. A.; Bernhardt, P. A.; Kassim, N.; Lazio, T. J.; Weiler, K.; Crane, P. C.; Ray, P. S.; Cohen, A.; Clarke, T.; Rickard, L. J.; Taylor, G. B.; Schinzel, F.; Pihlstrom, Y.; Kuniyoshi, M.; Close, S.; Colestock, P.; Myers, S.; Datta, A.

2011-10-01

We report ultraviolet optical observations from space of a Medium-Scale Traveling Ionospheric Disturbance (MSTID) made during the Combined Radio Interferometry and COSMIC Experiment in Tomography Campaign (CRICKET) held on September 15, 2007 at ˜8:30 UT. The experiment used a Constellation Observing System for Meteorology, Ionosphere, and Climate (COSMIC also known as FORMOSAT-3) satellite in conjunction with the Very Large Array (VLA) radio telescope, located near Socorro, NM, to study the ionosphere from the global scale down to the regional scale while the TIDs propagated through it. The COSMIC/FORMOSAT-3 satellite measured the F region electron density both horizontally and with altitude while the VLA measured the directions and speeds of the TIDs. These observations provide new information on this poorly understood class of TID and demonstrate the possibility of studying MSTIDs using space-based optical instruments.

Occultation Experiment: Results of the First Direct Measurement of Mars's Atmosphere and Ionosphere.

PubMed

Kliore, A; Cain, D L; Levy, G S; Eshleman, V R; Fjeldbo, G; Drake, F D

1965-09-10

Changes in the frequency, phase, and amplitude of the Mariner IV radio signal, caused by passage through the atmosphere and ionosphere of Mars, were observed immediately before and after occultation by the planet. Preliminary analysis of these effects has yielded estimates of the refractivity and density of the atmosphere near the surface, the scale height in the atmosphere, and the electron density profile of the Martian ionosphere. The atmospheric density, temperature, and scale height are lower than previously predicted, as are the maximum density, temperature, scale height, and altitude of the ionosphere.

Full-Scale Numerical Modeling of Turbulent Processes in the Earth's Ionosphere

DOE Office of Scientific and Technical Information (OSTI.GOV)

Eliasson, B.; Stenflo, L.; Department of Physics, Linkoeping University, SE-581 83 Linkoeping

2008-10-15

We present a full-scale simulation study of ionospheric turbulence by means of a generalized Zakharov model based on the separation of variables into high-frequency and slow time scales. The model includes realistic length scales of the ionospheric profile and of the electromagnetic and electrostatic fields, and uses ionospheric plasma parameters relevant for high-latitude radio facilities such as Eiscat and HAARP. A nested grid numerical method has been developed to resolve the different length-scales, while avoiding severe restrictions on the time step. The simulation demonstrates the parametric decay of the ordinary mode into Langmuir and ion-acoustic waves, followed by a Langmuirmore » wave collapse and short-scale caviton formation, as observed in ionospheric heating experiments.« less

Influence of heating experiments on parameters of Schumann resonances

NASA Astrophysics Data System (ADS)

Agranat, Irina; Sivokon, Vladimir

2017-10-01

Recently the significant increase in intensity of researches in the field of the fissile impact on geophysical processes in various environments is noted. Special attention is paid to a research of impact on an ionosphere of a potent short-wave radio emission of heating stands. Today experiments on change of an ionosphere are made generally at stands HAARP, EISCAT in Tromse (Norway). Within the Russian campaign (Tomsk) EISCAT/heating (AARI_HFOX) made from October 19 to October 30, 2016 experiments on impact on an ionosphere F-layer by the radiation potent HF. For assessment of impact of these experiments on geophysical processes mathematical methods carried out the analysis of change of the parameters of the Schumann resonances received on the basis of data from the station of constant observation of the Schumann resonances in the city of Tomsk, the Tomsk State University (Russia).

Beating HF waves to generate VLF waves in the ionosphere

NASA Astrophysics Data System (ADS)

Kuo, Spencer; Snyder, Arnold; Kossey, Paul; Chang, Chia-Lie; Labenski, John

2012-03-01

Beat-wave generation of very low frequency (VLF) waves by two HF heaters in the ionosphere is formulated theoretically and demonstrated experimentally. The heater-induced differential thermal pressure force and ponderomotive force, which dominate separately in the D and F regions of the ionosphere, drive an electron current for the VLF emission. A comparison, applying appropriate ionospheric parameters shows that the ponderomotive force dominates in beat-wave generation of VLF waves. Three experiments, one in the nighttime in the absence of D and E layers and two in the daytime in the presence of D and E layers, were performed. X mode HF heaters of slightly different frequencies were transmitted at CW full power. VLF waves at 10 frequencies ranging from 3.5 to 21.5 kHz were generated. The frequency dependencies of the daytime and nighttime radiation intensities are quite similar, but the nighttime radiation is much stronger than the daytime one at the same radiation frequency. The intensity ratio is as large as 9 dB at 11.5 kHz. An experiment directly comparing VLF waves generated by the beat-wave approach and by the amplitude modulation (AM) approach was also conducted. The results rule out the likely contribution of the AM mechanism acting on the electrojet and indicate that beat-wave in the VLF range prefers to be generated in the F region of the ionosphere through the ponderomotive nonlinearity, consistent with the theory. In the nighttime experiment, the ionosphere was underdense to the HF heaters, suggesting a likely setting for effective beat-wave generation of VLF waves by the HF heaters.

Ionospheric Tomography Using Faraday Rotation of Automatic Dependant Surveillance Broadcast UHF Signals

NASA Astrophysics Data System (ADS)

Cushley, A. C.

2013-12-01

The proposed launch of a satellite carrying the first space-borne ADS-B receiver by the Royal Military College of Canada (RMCC) will create a unique opportunity to study the modification of the 1090 MHz radio waves following propagation through the ionosphere from the transmitting aircraft to the passive satellite receiver(s). Experimental work successfully demonstrated that ADS-B data can be used to reconstruct two dimensional (2D) electron density maps of the ionosphere using computerized tomography (CT). The goal of this work is to evaluate the feasibility of CT reconstruction. The data is modelled using Ray-tracing techniques. This allows us to determine the characteristics of individual waves, including the wave path and the state of polarization at the satellite receiver. The modelled Faraday rotation (FR) is determined and converted to total electron content (TEC) along the ray-paths. The resulting TEC is used as input for computerized ionospheric tomography (CIT) using algebraic reconstruction technique (ART). This study concentrated on meso-scale structures 100-1000 km in horizontal extent. The primary scientific interest of this thesis was to show the feasibility of a new method to image the ionosphere and obtain a better understanding of magneto-ionic wave propagation. Multiple feature input electron density profile to ray-tracing program. Top: reconstructed relative electron density map of ray-trace input (Fig. 1) using TEC measurements and line-of-sight path. Bottom: reconstructed electron density map of ray-trace input using quiet background a priori estimate.

Electrodynamics of ionospheric weather over low latitudes

NASA Astrophysics Data System (ADS)

Abdu, Mangalathayil Ali

2016-12-01

The dynamic state of the ionosphere at low latitudes is largely controlled by electric fields originating from dynamo actions by atmospheric waves propagating from below and the solar wind-magnetosphere interaction from above. These electric fields cause structuring of the ionosphere in wide ranging spatial and temporal scales that impact on space-based communication and navigation systems constituting an important segment of our technology-based day-to-day lives. The largest of the ionosphere structures, the equatorial ionization anomaly, with global maximum of plasma densities can cause propagation delays on the GNSS signals. The sunset electrodynamics is responsible for the generation of plasma bubble wide spectrum irregularities that can cause scintillation or even disruptions of satellite communication/navigation signals. Driven basically by upward propagating tides, these electric fields can suffer significant modulations from perturbation winds due to gravity waves, planetary/Kelvin waves, and non-migrating tides, as recent observational and modeling results have demonstrated. The changing state of the plasma distribution arising from these highly variable electric fields constitutes an important component of the ionospheric weather disturbances. Another, often dominating, component arises from solar disturbances when coronal mass ejection (CME) interaction with the earth's magnetosphere results in energy transport to low latitudes in the form of storm time prompt penetration electric fields and thermospheric disturbance winds. As a result, drastic modifications can occur in the form of layer restructuring (Es-, F3 layers etc.), large total electron content (TEC) enhancements, equatorial ionization anomaly (EIA) latitudinal expansion/contraction, anomalous polarization electric fields/vertical drifts, enhanced growth/suppression of plasma structuring, etc. A brief review of our current understanding of the ionospheric weather variations and the electrodynamic processes underlying them and some outstanding questions will be presented in this paper.

Global Assimilative Ionospheric Model

DTIC Science & Technology

2002-09-30

CHAMP) and Satelite de Aplicaciones Cientificas-C (SAC-C), as well as from the Ionospheric Occultation Experiment (IOX) instrument developed by...strong interest in future collaborative research. TRANSITIONS Our project is still in its initial stage. No software has been transitioned to

Rocket observations of electron-density irregularities in the equatorial ionosphere below 200 km

NASA Technical Reports Server (NTRS)

Klaus, D. E.; Smith, L. G.

1978-01-01

Nike Apache rockets carring instrumentation to measure electron density and its fine structure in the equatorial ionosphere were launched from Chilca, Peru in May and June 1975. The fine structure experiment and the data reduction system are described. Results obtained from this system are presented and compared with those obtained by VHF radar and from other rocket studies. A description of the equatorial ionosphere and its features is also presented.

Ionosphere monitoring and forecast activities within the IAG working group "Ionosphere Prediction"

NASA Astrophysics Data System (ADS)

Hoque, Mainul; Garcia-Rigo, Alberto; Erdogan, Eren; Cueto Santamaría, Marta; Jakowski, Norbert; Berdermann, Jens; Hernandez-Pajares, Manuel; Schmidt, Michael; Wilken, Volker

2017-04-01

Ionospheric disturbances can affect technologies in space and on Earth disrupting satellite and airline operations, communications networks, navigation systems. As the world becomes ever more dependent on these technologies, ionospheric disturbances as part of space weather pose an increasing risk to the economic vitality and national security. Therefore, having the knowledge of ionospheric state in advance during space weather events is becoming more and more important. To promote scientific cooperation we recently formed a Working Group (WG) called "Ionosphere Predictions" within the International Association of Geodesy (IAG) under Sub-Commission 4.3 "Atmosphere Remote Sensing" of the Commission 4 "Positioning and Applications". The general objective of the WG is to promote the development of ionosphere prediction algorithm/models based on the dependence of ionospheric characteristics on solar and magnetic conditions combining data from different sensors to improve the spatial and temporal resolution and sensitivity taking advantage of different sounding geometries and latency. Our presented work enables the possibility to compare total electron content (TEC) prediction approaches/results from different centers contributing to this WG such as German Aerospace Center (DLR), Universitat Politècnica de Catalunya (UPC), Technische Universität München (TUM) and GMV. DLR developed a model-assisted TEC forecast algorithm taking benefit from actual trends of the TEC behavior at each grid point. Since during perturbations, characterized by large TEC fluctuations or ionization fronts, this approach may fail, the trend information is merged with the current background model which provides a stable climatological TEC behavior. The presented solution is a first step to regularly provide forecasted TEC services via SWACI/IMPC by DLR. UPC forecast model is based on applying linear regression to a temporal window of TEC maps in the Discrete Cosine Transform (DCT) domain. Performance tests are being conducted at the moment in order to improve UPC predicted products for 1-, 2-days ahead. In addition, UPC is working to enable short-term predictions based on UPC real-time GIMs (labelled URTG) and implementing an improved prediction approach. TUM developed a forecast method based on a time series analysis of TEC products which are either B-spline coefficients estimated by a Kalman filter or TEC grid maps derived from the B-spline coefficients. The forecast method uses a Fourier series expansion to extract the trend functions from the estimated TEC product. Then the trend functions are carried out to provide predicted TEC products. The forecast algorithm developed by GMV is based on the ionospheric delay estimation from previous epochs using GNSS data and the main dependence of ionospheric delays on solar and magnetic conditions. Since the ionospheric behavior is highly dependent on the region of the Earth, different region-based algorithmic modifications have been implemented in GMV's magicSBAS ionospheric algorithms to be able to estimate and forecast ionospheric delays worldwide. Different TEC prediction approaches outlined here will certainly help to learn about forecasting ionospheric ionization.

Performance of ionospheric maps in support of long baseline GNSS kinematic positioning at low latitudes

NASA Astrophysics Data System (ADS)

Park, J.; Sreeja, V.; Aquino, M.; Cesaroni, C.; Spogli, L.; Dodson, A.; De Franceschi, G.

2016-05-01

Ionospheric scintillation occurs mainly at high and low latitude regions of the Earth and may impose serious degradation on GNSS (Global Navigation Satellite System) functionality. The Brazilian territory sits on one of the most affected areas of the globe, where the ionosphere behaves very unpredictably, with strong scintillation frequently occurring in the local postsunset hours. The correlation between scintillation occurrence and sharp variations in the ionospheric total electron content (TEC) in Brazil is demonstrated in Spogli et al. (2013). The compounded effect of these associated ionospheric disturbances on long baseline GNSS kinematic positioning is studied in this paper, in particular when ionospheric maps are used to aid the positioning solution. The experiments have been conducted using data from GNSS reference stations in Brazil. The use of a regional TEC map generated under the CALIBRA (Countering GNSS high-Accuracy applications Limitations due to Ionospheric disturbances in BRAzil) project, referred to as CALIBRA TEC map (CTM), was compared to the use of the Global Ionosphere Map (GIM), provided by the International GNSS Service (IGS). Results show that the use of the CTM greatly improves the kinematic positioning solution as compared with that using the GIM, especially under disturbed ionospheric conditions. Additionally, different hypotheses were tested regarding the precision of the TEC values obtained from ionospheric maps, and its effect on the long baseline kinematic solution evaluated. Finally, this study compares two interpolation methods for ionospheric maps, namely, the Inverse Distance Weight and the Natural Neighbor.

Radio Observations of the Ionosphere From an Imaging Array and a CubeSat

NASA Astrophysics Data System (ADS)

Isham, B.; Gustavsson, B.; Bullett, T. W.; Bergman, J. E. S.; Rincón-Charris, A.; Bruhn, F.; Funk, P.

2017-12-01

The ionosphere is a source of many radio emissions in the various low-frequency, medium-frequency, and high-frequency bands (0 to 30 MHz). In addition to natural radio emissions, artificial emissions can be stimulated using high-power radiowave ionospheric modification facilities. Two complementary projects are underway for the purpose of improving our knowledge of the processes of radio emissions from the ionosphere. One project is the Aguadilla radio array, located in northwestern Puerto Rico. The Aguadilla array is intended to produce 2 to 25 MHz radio images of the ionosphere, as well as to perform bistatic radar imaging of the ionosphere over Puerto Rico. The array will consist of multiple antenna elements, each of which is a single active (electromagnetically short) crossed electric dipole. The elements are arranged within a roughly 200 by 300-meter core array, in a semi-random pattern providing an optimal distribution of baseline vectors, with 6-meter minimum spacing to eliminate spacial aliasing. In addition, several elements are arranged in a partial ring around the central core, providing a roughly four times expanded region in u-v space for improved image resolution and quality. Phase is maintained via cabled connections to a central location. A remote array is also being developed, in which phase is maintained between elements by through the use of GPS-disciplined rubidium clocks. The other project involves the GimmeRF radio instrument, designed for 0.3 to 30 MHz vector observation of the radio electric field, and planned for launch in 2020 on a CubeSat. The data rate that can be sustained by GimmeRF far exceeds any available communication strategy. By exploiting fast on-board computing and efficient artificial intelligence (AI) algorithms for analysis and data selection, the usage of the telemetry link can be optimized and value added to the mission. Radio images recorded by the radio array from below the ionosphere can be directly compared with the radio data received by GimmeRF in the topside ionosphere, with the goal of better understanding the geometry and therefore the mechanisms of the radio emission processes.

Experimentally investigate ionospheric depletion chemicals in artificially created ionosphere

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liu Yu; Cao Jinxiang; Wang Jian

2012-09-15

A new approach for investigating ionosphere chemical depletion in the laboratory is introduced. Air glow discharge plasma closely resembling the ionosphere in both composition and chemical reactions is used as the artificially created ionosphere. The ionospheric depletion experiment is accomplished by releasing chemicals such as SF{sub 6}, CCl{sub 2}F{sub 2}, and CO{sub 2} into the model discharge. The evolution of the electron density is investigated by varying the plasma pressure and input power. It is found that the negative ion (SF{sub 6}{sup -}, CCl{sub 2}F{sub 2}{sup -}) intermediary species provide larger reduction of the electron density than the positive ionmore » (CO{sub 2}{sup +}) intermediary species. The negative ion intermediary species are also more efficient in producing ionospheric holes because of their fast reaction rates. Airglow enhancement attributed to SF{sub 6} and CO{sub 2} releases agrees well with the published data. Compared to the traditional methods, the new scheme is simpler to use, both in the release of chemicals and in the electron density measurements. It is therefore more efficient for investigating the release of chemicals in the ionosphere.« less

Interpretation of the electric fields measured in an ionospheric critical ionization velocity experiment

NASA Technical Reports Server (NTRS)

Brenning, N.; Faelthammar, C.-G.; Marklund, G.; Haerendel, G.; Kelley, M. C.; Pfaff, R.

1991-01-01

The quasi-dc electric fields measured in the CRIT I ionospheric release experiment are studied. In the experiment, two identical barium shaped charges were fired toward a main payload, and three-dimensional measurements of the electric field inside the streams were made. The relevance of proposed mechanisms for electron heating in the critical ionization velocity (CIV) mechanism is addressed. It is concluded that both the 'homogeneous' and the 'ionizing front' models probably are valid, but in different parts of the streams. It is also possible that electrons are directly accelerated by a magnetic field-aligned component of the electric field. The coupling between the ambient ionosphere and the ionized barium stream is more complicated that is usually assumed in CIV theories, with strong magnetic-field-aligned electric fields and probably current limitation as important processes.

Pre-launch simulation experiment of microwave-ionosphere nonlinear interaction rocket experiment in the space plasma chamber

NASA Astrophysics Data System (ADS)

Kaya, N.; Tsutsui, M.; Matsumoto, H.; Kimura, I.

1980-09-01

A pre-flight test experiment of a microwave-ionosphere nonlinear interaction rocket experiment (MINIX) has been carried out in a space plasma simulation chamber. Though the first rocket experiment ended up in failure because of a high voltage trouble, interesting results are observed in the pre-flight experiment. A significant microwave heating of plasma up to 300% temperature increase is observed. Strong excitations of plasma waves by the transmitted microwaves in the VLF and HF range are observed as well. These microwave effects may have to be taken into account in solar power satellite projects in the future.

Artificial Aurora and Ionospheric Heating by HAARP

NASA Astrophysics Data System (ADS)

Hadavandkhani, S.; Nikouravan, Bijan; Ghazimaghrebi, F.

2016-08-01

A recent experiment was achieved at HAARP to study the scaling of the ionospherically generated ELF signal with power transmitted from the high frequency (HF) array. The results were in excellent agreement with computer simulations. The outcomes approving that the ELF power increases with the square of the incident HF power. This paper present a review on the situation of the ionized particles in Ionospheric layer when stimulated by artificial an ELF and VLF external high energy radio waves.

Achievements of ATS-6 beacon experiment over Indian sub-continent

NASA Technical Reports Server (NTRS)

Deshpande, M. R.; Rastogi, R. G.; Vats, H. O.; Sethia, G.; Chandra, H.; Davies, K.; Grubb, R. N.; Jones, J. E.

1978-01-01

The repositioning of the ATS-6 satellite at 34 deg E enabled the scientific community of India to use the satellite's radio beacon for ionospheric studies. Two scientific projects were undertaken. The objective of the first project was to map ionospheric electron content, range rate errors, traveling ionospheric phenomena, solar flare effect, and magnetic phenomena. The second project was aimed at studying geophysical phenomena associated with the equatorial electrojet. The principal results of these studies are described.

Radar investigation of barium releases over Arecibo Observatory, Puerto Rico

NASA Technical Reports Server (NTRS)

Djuth, Frank T.

1995-01-01

The NASA Combined Release and Radiation Effects Satellite (CRRES) El Coqui rocket campaign was successfully carried out in Puerto Rico during the period 18 May through 12 July 1992. This report describes five chemical release experiments in the upper ionosphere supported by Geospace Research, Inc. during the El Coqui campaign. Additional spin-off science is also discussed. The El Coqui releases are designated AA-1 (rocket 36-082), AA-2 (rocket 36-081), AA-3b (rocket 36-064), AA-4 (rocket 36-065), and AA-7 (rocket 36-083). Particular attention is paid to releases AA-2 and AA-4. These two experiments involved the illumination of ionospheric release regions with powerful high-frequency (HF) radio waves transmitted from the Arecibo HF facility. In the AA-2 experiment, microinstabilities excited by the HF wave in a Ba(+) plasma were examined. This release yielded a smooth plasma cloud that helped clarify several fundamental issues regarding the physics of wave plasma instabilities. During AA-2 extremely strong HF-induced Langmuir turbulence was detected with the Arecibo 430 MHz radar. CF3Br was released in the AA-4 study to create an ionospheric hole that focused the HF beam. This experiment successfully explored wave-plasma coupling in an O(+) ionosphere under conditions of very high HF electric field strengths.

ELF/VLF Wave Generation and Scattering from Modulated Heating of the Ionosphere at Arecibo Observatory

NASA Astrophysics Data System (ADS)

Maxworth, A. S.; Golkowski, M.; McCormick, J.; Cohen, M.; Hosseini, P.; Bittle, J.

2017-12-01

The recently completed ionospheric heater at Arecibo Observatory is used for modulated HF (5 or 8 MHz) heating of the ionosphere, to generate ELF/VLF (3 Hz - 30 kHz) waves. Observation of ramp and tone signals at frequencies from hundreds of Hz to several kHz at multiple receivers confirms the ability of the heater to modulate D region currents and create an ELF/VLF antenna in the ionosphere. Observed ELF/VLF signal amplitudes are lower than for similar experiments performed at high latitudes at the HAARP and Tromso facilities, for a variety of reasons including the reduced natural currents at mid latitudes, and the lower HF power of the Arecibo heater. The heating of the overhead ionosphere is also observed to change the Earth-ionosphere waveguide propagation characteristics as is evident from simultaneous observations of lightning induced sferics and VLF transmitter signals that propagate under the heated region. The active heating of the ionosphere modifies the reflection of incident VLF (3-30 kHz) waves. We present initial observations of HF heating of the D-region and resulting ELF/VLF wave generation.

Radio stimulation and diagnostics of space plasmas

NASA Technical Reports Server (NTRS)

Lee, Min-Chang

1993-01-01

We have investigated the small-scale topside ionospheric plasma structures first observed at Millstone Hill, Massachusetts with the 440 MHz incoherent scatter radar. These small-scale obliquely propagating plasma modes occurring in the vicinity of the midlatitude ionospheric trough, have large radar cross-sections and narrow spectral widths. They have, until recently, been dismissed solely as hard target contamination of the incoherent scatter radar. The geophysical conditions associated with the ionospheric trough, such as the field-aligned current activity and steep plasma density gradients, suggest that these recently discovered small-scale topside ionospheric plasmas may also appear in the auroral and polar ionosphere. In fact, this speculation has been corroborated by the preliminary experiments and data analyses at Tromso, Norway and Sondrestromfjord, Greenland. The primary research results are highlighted. Described in Section 3 are the experiments conducted at Arecibo, Puerto Rico in the past summer for simulating the geophysical conditions of generating these topside ionospheric plasma structures. Recommendation for the future research is finally given. Attached as the appendix of this report are several chapters which present the detailed results of research in the concerned topside ionospheric clutter. Highlights of the research results include: (1) causes of the enhanced radar backscatter (ERB) phenomenon; (2) occurrence of the ERB phenomenon; (3) altitudes of the ERB phenomenon; (4) strength of the ERB returns; (5) range of altitudes of the ERB returns; (6) occurrence frequency of the ERB phenomenon; (7) Doppler effect of the ERB phenomenon; (8) persistency of the ERB; and (9) distinction between ERB phenomenon and space object signatures.

Radio stimulation and diagnostics of space plasmas

NASA Astrophysics Data System (ADS)

Lee, Min-Chang

1993-02-01

We have investigated the small-scale topside ionospheric plasma structures first observed at Millstone Hill, Massachusetts with the 440 MHz incoherent scatter radar. These small-scale obliquely propagating plasma modes occurring in the vicinity of the midlatitude ionospheric trough, have large radar cross-sections and narrow spectral widths. They have, until recently, been dismissed solely as hard target contamination of the incoherent scatter radar. The geophysical conditions associated with the ionospheric trough, such as the field-aligned current activity and steep plasma density gradients, suggest that these recently discovered small-scale topside ionospheric plasmas may also appear in the auroral and polar ionosphere. In fact, this speculation has been corroborated by the preliminary experiments and data analyses at Tromso, Norway and Sondrestromfjord, Greenland. The primary research results are highlighted. Described in Section 3 are the experiments conducted at Arecibo, Puerto Rico in the past summer for simulating the geophysical conditions of generating these topside ionospheric plasma structures. Recommendation for the future research is finally given. Attached as the appendix of this report are several chapters which present the detailed results of research in the concerned topside ionospheric clutter. Highlights of the research results include: (1) causes of the enhanced radar backscatter (ERB) phenomenon; (2) occurrence of the ERB phenomenon; (3) altitudes of the ERB phenomenon; (4) strength of the ERB returns; (5) range of altitudes of the ERB returns; (6) occurrence frequency of the ERB phenomenon; (7) Doppler effect of the ERB phenomenon; (8) persistency of the ERB; and (9) distinction between ERB phenomenon and space object signatures.

Future Operations of HAARP with the UAF's Geophysical Institute

NASA Astrophysics Data System (ADS)

McCoy, R. P.

2015-12-01

The High frequency Active Aurora Research Program (HAARP) in Gakona Alaska is the world's premier facility for active experimentation in the ionosphere and upper atmosphere. The ionosphere affects communication, navigation, radar and a variety of other systems depending on, or affected by, radio propagation through this region. The primary component of HAARP, the Ionospheric Research Instrument (IRI), is a phased array of 180 HF antennas spread across 33 acres and capable of radiating 3.6 MW into the upper atmosphere and ionosphere. The array is fed by five 2500 kW generators, each driven by a 3600 hp diesel engine (4 + 1 spare). Transmit frequencies are selectable in the range 2.8 to 10 MHz and complex configurations of rapidly slewed single or multiple beams are possible. HAARP was owned by the Air Force Research Laboratory (AFRL/RV) in Albuquerque, NM but recently was transferred to the Geophysical Institute of the University of Alaska Fairbanks (UAF/GI). The transfer of ownership of the facility is being implemented in stages involving a Cooperative Research and Development Agreement (CRADA) and an Educational Partnership Agreement (EPA) which are complete, and future agreements to transfer ownership of the facility land. The UAF/GI plans to operate the facility for continued ionospheric and upper atmospheric experimentation in a pay-per-use model. In their 2013 "Decadal Survey in Solar and Space Physics" the National Research Council (NRC) made the recommendation to "Fully realize the potential of ionospheric modification…" and in their 2013 Workshop Report: "Opportunities for High-Power, High-Frequency Transmitters to Advance Ionospheric/Thermospheric Research" the NRC outlined the broad range of future ionospheric, thermospheric and magnetospheric experiments that could be performed with HAARP. HAARP is contains a variety of RF and optical ionospheric diagnostic instruments to measure the effects of the heater in real time. The UAF/GI encourages the scientific community to plan experiments at HAARP and bring their remote sensing instruments to HAARP for extended or permanent operation. The power and flexibility of HAARP and its unique location in the subarctic will help secure the future of this facility as the foremost laboratory for active experimentation in the ionosphere and upper atmosphere.

Layer structure of the Venus daytime ionosphere from Venera-15,-16 radio occultation

NASA Astrophysics Data System (ADS)

Gavrik, Anatoly

Up to now more than five hundred radio occultation experiments had been carried out by different missions to research physical properties of the Venus ionosphere. The purpose of this report is to show new properties of the Venus daytime ionosphere reanalyzing Venera-15,-16 dual-frequency occultation data. The high coherence and stability of radio signals of Venera- 15,-16 at wave lengths 32 cm and 8 cm, along with the fact, that the refractive amplification at 32 cm in the ionosphere exceeds by factor 6 the refractive amplification at 13 cm used by others researches, have allowed to perform analysis of radiophysical parameters in the Venus ionosphere more accurate. Progress in the radiovision theory and up-to-date digital processing techniques have provided an opportunity to discover unknown layered structure of the Venus daytime ionosphere. We offer the new technique of the data analysis that allows us to separate influence of noise, ionosphere and atmosphere on the radio occultation results. We point out that significant gradient variations in the vertical distribution of the electron density are observed in the region of maximum electron density of the daytime ionosphere at altitudes of 150-175 km. That testifies layered structure of this part of the Venus ionosphere. The results of data analysis reveal the regular existence of the ionospheric layers in the bottom daytime ionosphere at altitudes from 80 up to 115 km. The bottom border of the ionosphere part can vary in the range of 80-100 km, and gradients of the electron density show strong variability. We detect the wave structure in the top atmosphere and in the bottom ionosphere at altitudes from 60 up to 115 km as well. It is difficult to obtain correct electron density in the region, where we have detected the new ionospheric layers. Relative errors of the electron density are greater than 100% at altitudes between 80 and 120 km. The bottom part of the ionosphere is more variable, than overlying area of the main maximum of the daytime ionosphere. It is difficult to explain such layered structures of the Venus daytime ionosphere by means of existing model of the photochemical equilibrium.

Ionospheric manifestations of acoustic-gravity waves under quiet and disturbed conditions

NASA Astrophysics Data System (ADS)

Barabash, Vladimir; Chernogor, Leonid; Panasenko, Sergii; Domnin, Igor

2014-05-01

We present the observation results of wave disturbances in the ionosphere, which are known to be manifestations of atmospheric acoustic-gravity waves (AGWs). The observations have been conducted under quiet and naturally or artificially disturbed conditions by ionosonde and incoherent scatter radar located near Kharkiv, Ukraine. Wave disturbance parameters under quiet conditions were obtained and analysed during geophysical periods including vernal and autumn equinoxes as well as summer and winter solstices. The prevailing oscillation in ionospheric F2- layer had the period of 140 - 200 min and relative amplitude of 0.1 - 0.2. The duration of this oscillation changed from 5 - 7 to 24 hours, depending on a season. The amplitude of fluctuations with other periods was noticeably smaller. The time intervals at which the intensity of incoherent scatter signals varied quasi-periodically in the altitude range from 150 to 300 km were detected. The parameters of these variations were estimated using statistical analysis and bandpass filtering. The periods of wave processes were shown to be of 30 - 120 min, there durations did not exceed of 2 - 6 periods and relative amplitudes usually ranged from 0.03 to 0.15. The phase of oscillations was detected to propagate downwards. The vertical phase velocity of travelling ionospheric disturbances (TIDs) was estimated to be in the range from 50 to 200 m/s and increased with altitude. The observations of the partial solar eclipse on January, 4, 2011 near Kharkiv were used to study the ionospheric parameters in naturally disturbed conditions. The F2-layer critical frequency dropped by a factor of 2.1. The time delay of these variations with respect to the main magnitude of the solar disk obscuration was equal to about 16 minutes. The virtual height of signal reflection near the maximum of the F2-layer ionization increased by 70 km, and the height of the model parabolic layer increased by 10 km. Some decrease in electron density and growth of quasi-periodic variations with periods of about 30 and 60 min were detected at all observable heights during this solar eclipse. The diagnostics of wave processes has been performed during ionospheric modification experiments with EISCAT heater. This heater is at a distance of about 2400 km from Kharkiv incoherent scatter radar. We have detected the TIDs over Kharkiv with periods of 40 - 80 min. The duration of these disturbances has not exceeded 120 - 180 min. The relative amplitudes of the TIDs in electron density ranged from 0.05 to 0.15 and those in electron and ion temperatures were about 0.02 - 0.05. The possible mechanisms for the generation of AGWs and TIDs by high power HF radio waves are sharp thermal gradients at the edge of the heated region and modulation of the ionospheric current systems by periodic high power radio transmission.

Design and construction of Keda Space Plasma Experiment (KSPEX) for the investigation of the boundary layer processes of ionospheric depletions.

PubMed

Liu, Yu; Zhang, Zhongkai; Lei, Jiuhou; Cao, Jinxiang; Yu, Pengcheng; Zhang, Xiao; Xu, Liang; Zhao, Yaodong

2016-09-01

In this work, the design and construction of the Keda Space Plasma EXperiment (KSPEX), which aims to study the boundary layer processes of ionospheric depletions, are described in detail. The device is composed of three stainless-steel sections: two source chambers at both ends and an experimental chamber in the center. KSPEX is a steady state experimental device, in which hot filament arrays are used to produce plasmas in the two sources. A Macor-mesh design is adopted to adjust the plasma density and potential difference between the two plasmas, which creates a boundary layer with a controllable electron density gradient and inhomogeneous radial electric field. In addition, attachment chemicals can be released into the plasmas through a tailor-made needle valve which leads to the generation of negative ions plasmas. Ionospheric depletions can be modeled and simulated using KSPEX, and many micro-physical processes of the formation and evolution of an ionospheric depletion can be experimentally studied.

Spatial Characteristics of the 630-nm Artificial Ionospheric Airglow Generation Region During the Sura Facility Pumping

NASA Astrophysics Data System (ADS)

Shindin, A. V.; Klimenko, V. V.; Kogogin, D. A.; Beletsky, A. B.; Grach, S. M.; Nasyrov, I. A.; Sergeev, E. N.

2018-05-01

We describe the method and the results of modeling and retrieval of the spatial distribution of excited oxygen atoms in the HF-pumped ionospheric region based on two-station records of artificial airglow in the red line (λ = 630 nm). The HF ionospheric pumping was provided by the Sura facility. The red-line records of the night-sky portraits were obtained at two reception points—directly at the heating facility and 170 km east of it. The results were compared with the vertical ionospheric sounding data. It was found that in the course of the experiments the airglow region was about 250 km high and did not depend on the altitude of the pump-wave resonance. The characteristic size of the region was 35 km, and the shape of the distribution isosurfaces was well described by oblique spheroids or a drop-shaped form. The average value of the maximum concentration of excited atoms during the experiment was about 1000 cm-3.

Overview of our current understanding of the Titan ionosphere

NASA Astrophysics Data System (ADS)

Cravens, Thomas

An ionosphere was first detected on Titan in 1980 by the Voyager 1 radio occultation experi-ment and the first in situ measurements were made in 2004 by the Cassini spacecraft, although many theoretical studies were carried out prior to the Cassini mission. Earth and Titan are similar in that molecular nitrogen is the major neutral atmospheric species but these bodies differ in that the next most abundant species at Earth is molecular oxygen and at Titan is methane. As a consequence, the chemistry in the upper atmosphere and ionosphere is quite different for the two bodies. Titan's upper atmosphere and ionosphere strongly interact with Saturn's magnetospheric plasma. Magnetic fields were observed in Titan's ionosphere by the Cassini magnetometer and are induced as a consequence of this interaction, which affects the flow and distribution of plasma. Energetic electrons and ions from Saturn's magnetosphere precipitate into the upper atmosphere, acting as both heat and ionization sources. However, on the dayside, absorption of solar extreme ultraviolet radiation is thought to be the dominant source of ionization and energy. The electron temperatures measured in the ionosphere by the Cassini Langmuir probe (RPWS/LP) are about 1000 K, greatly exceeding the neutral temper-ature (about 150 K). The ion and neutral mass spectrometer (INMS) onboard Cassini detected a large number of ion species with mass numbers up to 100 Daltons and the energetic plasma spectrometer (CAPS) detected both negative and positive ion species at even higher mass num-bers. Primary ionization processes create N2+, N+, CH4+, CH3+, and other ion species, but a complex ion-neutral chemistry, involving methane and other hydrocarbon and nitriles species (acetylene, ethylene, ethane, hydrogen cyanide, benzene,. . . .), convert these initial species into numerous other species including CH5+, C2H5+, HCNH+, C3H5+, CH2NH2+, C6H7+. As in most ionospheres, chemistry dominates the ionospheric structure at lower altitudes but trans-port is more important at higher altitudes. Just at at Venus during higher dynamics pressure solar wind conditions, the magnetic field plays a key role in the ionospheric dynamics at Titan but neutral winds also contribute to the flow of plasma. This talk will provide an overview of observations of Titan's ionosphere and will also review the physical and chemical processes operating in this ionosphere.

Radio science electron density profiles of lunar ionosphere based on the service module of circumlunar return and reentry spacecraft

NASA Astrophysics Data System (ADS)

Wang, M.; Han, S.; Ping, J.; Tang, G.; Zhang, Q.

2017-09-01

The existence of lunar ionosphere has been under debate for a long time. Radio occultation experiments had been performed by both Luna 19/22 and SELENE missions and electron column density of lunar ionosphere was provided. The Apollo 14 mission also acquired the electron density with in situ measurements. But the results of these missions don't well-matched. In order to explore the lunar ionosphere, radio occultation with the service module of Chinese circumlunar return and reentry spacecraft has been performing. One coherent S-band and X-band radio signals were recorded by China deep space stations, and local correlation was adopted to compute carrier phases of both signals. Based on the above work, the electron density profiles of lunar ionosphere was obtained and analyzed.

The First Results About Earthquake Study with FORMOSAT-3/COSMIC

NASA Astrophysics Data System (ADS)

Liu, J. Y.; Oyama, K.; Jhuang, H. K.; Istep, M.; Hsiao, C. C.; Wang, Y. H.

2007-12-01

To improve the global weather prediction and space weather monitoring, six microsatellites termed the Formosa Satellite 3 - Constellation Observing System for Meteorology, Ionosphere, and Climate (FORMOSAT-3/COSMIC) were launched into a circular low-Earth orbit (LEO) from Vandenberg Air Force Base, California, at 0140 UTC on 15 April 2006. Each microsatellite of the joint Taiwan-US satellite constellation mission has a GPS occultation experiment (GOX) payload to operate the atmospheric and ionospheric radio occultation, a tiny ionospheric photometer (TIP) to observe the nighttime ionospheric airglow OI 135.6 nm emission, and a tri-band beacon (TBB) to tomographically estimate fine structures of ionospheric electron density on the satellite-to-receiver plane. While the GOX daily observes about 2500 vertical electron density profiles up to the satellite altitude, the TIP provides accurate horizontal gradients of nighttime electron density. In this study, anomalies in the ionospheric electron density structure and dynamics concurrently observed by FORMOSAT-3/COSMIC and co-located ground- based GPS receivers before recent large earthquakes are presented and discussed.

GBAS Ionospheric Anomaly Monitoring Based on a Two-Step Approach

PubMed Central

Zhao, Lin; Yang, Fuxin; Li, Liang; Ding, Jicheng; Zhao, Yuxin

2016-01-01

As one significant component of space environmental weather, the ionosphere has to be monitored using Global Positioning System (GPS) receivers for the Ground-Based Augmentation System (GBAS). This is because an ionospheric anomaly can pose a potential threat for GBAS to support safety-critical services. The traditional code-carrier divergence (CCD) methods, which have been widely used to detect the variants of the ionospheric gradient for GBAS, adopt a linear time-invariant low-pass filter to suppress the effect of high frequency noise on the detection of the ionospheric anomaly. However, there is a counterbalance between response time and estimation accuracy due to the fixed time constants. In order to release the limitation, a two-step approach (TSA) is proposed by integrating the cascaded linear time-invariant low-pass filters with the adaptive Kalman filter to detect the ionospheric gradient anomaly. The performance of the proposed method is tested by using simulated and real-world data, respectively. The simulation results show that the TSA can detect ionospheric gradient anomalies quickly, even when the noise is severer. Compared to the traditional CCD methods, the experiments from real-world GPS data indicate that the average estimation accuracy of the ionospheric gradient improves by more than 31.3%, and the average response time to the ionospheric gradient at a rate of 0.018 m/s improves by more than 59.3%, which demonstrates the ability of TSA to detect a small ionospheric gradient more rapidly. PMID:27240367

Ionospheric footprint of magnetosheathlike particle precipitation observed by an incoherent scatter radar

NASA Technical Reports Server (NTRS)

Watermann, Jurgen; Lummerzheim, Dirk; De La Beaujardiere, Odile; Newell, Patrick T.; Rich, Frederic J.

1994-01-01

We have examined Sondrestrom incoherent scatter radar observations of ionospheric plasma density and temperature distributions and measurements of F region ion drifts that were made during a prenoon pass of the Defense Meteorological Satellite Program (DMSP)-F7 satellite through the radar field of view. The spacecraft traversed a region of intense electron precipitation with a characteristic energy below approximately 200 eV. Particles with such low characteristic energies are believed to be directly or indirectly of magnetosheath origin. The precipitation region had a width about 2 deg invariant latitude and covered the low-latitude boundary layer (LLBL), the cusp, and the equatorward section of the plasma mantle (PM). The corotating radar observed a patch of enhanced electron density and elevated electron temperature in the F2 region between about 10.5 and 12 magnetic local time in the same invariant latitude range where DMSP-F7 detected the soft-electron flux. The ion drift pattern, also obtained by radar, shows that it is unlikely that the plasma patch was produced by solar radiation and advected into the radar field of view. We suggest that the radar observed modifications of the ionospheric plasma distribution, which resulted from direct entry of magnetosheath electrons into the magnetosphere and down to ionospheric altitudes. Model calculations of the ionospheric response to the observed electron precipitation support our interpretation. The spectral characteristics of the electron flux in the LLBL, cusp, and equatorward section of the PM were in this case too similar to allow to distinguish between them by using incoherent scatter radar measurements only.

An Analysis of the Second Project High Water Data

NASA Technical Reports Server (NTRS)

Woodbridge, David D.; Lasater, James A.; Fultz, Bennett M.; Clark, Richard E.; Wylie, Nancy

1963-01-01

Early in 1962 NASA established "Project High Water" to investigate the sudden release of large quantities of water into the upper atmosphere. The primary objectives of these experiments were to obtain information on the behavior of liquids released in the ionosphere and the localized effects on the ionosphere produced by the injection of large quantities of water. The data obtained in the two (2) Project High Water experiments have yielded an extensive amount of information concerning the complex phenomena associated with the sudden release of liquids in the Ionosphere. The detailed analysis of data obtained during the second Project High Water experiment (i.e., the third Saturn I vehicle test or SA-3) presented in this report demonstrates that the objectives of the Project High Water were achieved. In addition, the Project High Water has provided essential information relevant to a number of problems vital to manned explorations of space.

Space-Based Solar Power Conversion and Delivery Systems Study. Volume 3: Microwave Power Transmission Studies

NASA Technical Reports Server (NTRS)

1977-01-01

The Microwave Fower Beam Ionosphere effects and critical interfaces between th Microwave Power Transmission System (MPTS) and the Satellite were studied as part of the NASA/MSFC continuing research on the feasibility of power transmission from geosynchronous orbit. Theoretical predications of ionospheric modifications produced by the direct interaction of the MPTS on the earth's upper atmosphere are used to determine their impact on the performance of the Microwave Power Beam and Pilot Beam System as well as on other RF systems effected by the ionosphere. A technology program to quantitatively define these interactions is developed. Critical interface areas between the MPTS and the satellite which could have a major impact on cost and performance of the power system are idenfified and analyzed. The areas selected include: use of either a 20 kV versus 40 kV Amplitron, thermal blockage effects of Amplitron heat radiation by the satellite structure, effect of dielectric carry-through structure on power beam, and effect of material sublimation on performance of the Amplitron in Geosynchronous Orbit.

Ionospheric scintillation detection based on GPS observations, a case study over Iran

NASA Astrophysics Data System (ADS)

Sobhkhiz Miandehi, Sahar; Alizadeh Elizei, M. Mahdi; Schuh, Harald

2017-04-01

Global Positioning System (GPS) which is used extensively for various purposes such as navigation, surveying, remote sensing and telecommunication, is strongly affected by the earth's upper atmosphere, the ionosphere. Ionosphere is a highly variable region with complex physical characteristics in which the density of free electrons are large enough to have considerable effects on signals' propagation travelling through this dispersive medium. As GPS signals travel through the ionosphere, they may experience rapid amplitude fluctuations or unexpected phase changes. This is referred to as ionospheric scintillation. Ionospheric scintillation which is caused by small scale irregularities in the electron density, is one of the dominant propagation disturbances at radio frequency signals. These irregularities severely affect the accuracy and reliability of GPS measurements. Therefore it is necessary to investigate ionospheric scintillation and its effects on GPS observations. The focus of this paper is to detect ionospheric scintillations over Iran's region, during different periods of solar activity and to investigate these effects on GPS observations in more detail. Furthermore the effects of these irregularities on regional modeling of ionosphere over Iran is also investigated. The results show that effectiveness of this phenomenon depends on geographic location, local time and global geomagnetic storm index (kp index). The required data for this investigation are ground based measurements of permanent GPS stations over Iran, established by the National Cartographic Center of Iran (NCC).

AMPS data management requirements study. [user manuals (computer programs)/display devices - computerized simulation/experimentation/ionosphere

NASA Technical Reports Server (NTRS)

1975-01-01

A data simulation is presented for instruments and associated control and display functions required to perform controlled active experiments of the atmosphere. A comprehensive user's guide is given for the data requirements and software developed for the following experiments: (1) electromagnetic wave transmission; (2) passive observation of ambient plasmas; (3) ionospheric measurements with a subsatellite; (4) electron accelerator beam measurements; and (5) measurement of acoustic gravity waves in the sodium layer using lasers. A complete description of each experiment is given.

VHF Scintillation in an Artificially Heated Ionosphere

NASA Astrophysics Data System (ADS)

Suszcynsky, D. M.; Layne, J.; Light, M. E.; Pigue, M. J.; Rivera, L.

2017-12-01

As part of an ongoing project to characterize very-high-frequency (VHF) radio wave propagation through structured ionospheres, Los Alamos National Laboratory has been conducting a set of experiments to measure the scintillation effects of VHF transmissions under a variety of ionospheric conditions. Previous work (see 2015 Fall AGU poster by D. Suszcynsky et al.) measured the S4 index and ionospheric coherence bandwidth in the 32 - 44 MHz frequency range under naturally scintillated conditions in the equatorial region at Kwajalein Atoll during three separate campaigns centered on the 2014 and 2015 equinoxes. In this paper, we will present preliminary results from the February and September, 2017 High Altitude Auroral Research Project (HAARP) Experimental Campaigns where we are attempting to make these measurements under more controlled conditions using the HAARP ionospheric heater in a twisted-beam mode. Two types of measurements are made by transmitting VHF signals through the heated ionospheric volume to the Radio Frequency Propagation (RFProp) satellite experiment. The S4 scintillation index is determined by measuring the power fluctuations of a 135-MHz continuous wave signal and the ionospheric coherence bandwidth is simultaneously determined by measuring the delay spread of a frequency-modulated continuous wave (FMCW) signal in the 130 - 140 MHz frequency range. Additionally, a spatial Fourier transform of the CW time series is used to calculate the irregularity spectral density function. Finally, the temporal evolution of the time series is used to characterize spread-Doppler clutter effects arising from preferential ray paths to the satellite due to refraction off of isolated density irregularities. All results are compared to theory and scaled for comparison to the 32 - 44 MHz Kwajalein measurements.

Sounding rocket/ground-based observation campaign to study Medium-Scale Traveling Ionospheric Disturbances (MSTID)

NASA Astrophysics Data System (ADS)

Yamamoto, M.; Yokoyama, T.; Saito, A.; Otsuka, Y.; Yamamoto, M.; Abe, T.; Watanabe, S.; Ishisaka, K.; Saito, S.; Larsen, M.; Pfaff, R. F.; Bernhardt, P. A.

2012-12-01

An observation campaign is under preparation. It is to launch sounding rockets S-520-27 and S-310-42 from Uchinoura Space Center of JAXA while ground-based instruments measure waves in the ionosphere. It is scheduled in July/August 2013. The main purpose of the experiment is to reveal generation mechanism of Medium-Scale Traveling Ionospheric Disturbance (MSTID). The MSTID is the ionospheric wave with 1-2 hour periodicity, 100-200 km horizontal wavelength, and southwestward propagation. It is enhanced in the summer nighttime of the mid-latitude ionosphere. The MSTID is not only a simple atmospheric-wave modulation of the ionosphere, but shows similarity to characteristics of the Perkins instability. A problem is that growth rate of the Perkins instability is too small to explain the phenomena. We now hypothesize a generation mechanism that electromagnetic coupling of the F- and E-regions help rapid growth of the MSTID especially at its initial stage. In the observation campaign, we will use the sounding rocket S-520-27 for in-situ measurement of ionospheric parameters, i.e., electron density and electric fields. Wind velocity measurements in both F- and E-regions are very important as well. For the F-region winds, we will conduct Lithium-release experiment under the full-moon condition. This is a big technical challenge. Another rocket S-310-42 will be used for the E-region wind measurement with the TMA release. On the ground, we will use GEONET (Japanese vast GPS receiver network) to monitor horizontal distribution of GPS-TEC on the realtime bases. In the presentation we will show MSTID characteristics and the proposed generation mechanism, and discuss plan and current status of the project.

Formation of artificial plasma disturbances in the lower ionosphere

NASA Astrophysics Data System (ADS)

Bakhmet'eva, N. V.; Frolov, V. L.; Vyakhirev, V. D.; Kalinina, E. E.; Bolotin, I. A.; Akchurin, A. D.; Zykov, E. Yu.

2012-06-01

We present the results of experiments on sounding the disturbed ionospheric region produced by the high-power RF radiation of the "Sura" heating facility, which were performed simultaneously at two observation points. One point is located on the territory of the heating facility the other, and the other, at the observatory of Kazan State University (the "Observatory" point) in 170 km to the East from the facility. The experiments were aimed at studying the mechanism of formation of artificial disturbances in the lower ionosphere in the case of reflection of a high-power wave in the F region and determining the parameters of the signals of backscattering from artificial electron density irregularities which are formed as a result of ionospheric perturbations. The ionosphere was modified by a high-power RF O-mode wave, which was emitted by the transmitters of the "Sura" facility, in sessions several seconds or minutes long. The disturbed region was sounded using the vertical-sounding technique at the "Vasil'sursk" laboratory by the partial-reflection facility at a frequency of 2.95 MHz, and by the modified ionospheric station "Tsiklon" at ten frequencies ranged from 2 to 6.5 MHz at the "Observatory" point. At the same time, vertical-sounding ionograms were recorded in the usual regime. At the reception points, simultaneous changes in the amplitudes of the vertical-sounding signals and the aspect backscattering signals were recorded. These records correlate with the periods of operation of the heating facility. The characteristics and dynamics of the signals are discussed.

Equatorial ionospheric absorption during half a solar cycle (1964-1970)

NASA Technical Reports Server (NTRS)

Gnanalingam, S.

1972-01-01

An extensive series of vertical incidence absorption measurements made at an equatorial station is analyzed in detail for a better understanding of the lower ionosphere. A quantitive empirical relationship is derived between absorption and 1 to 8 A solar flux for moderate levels of solar activity. It is shown that the threshold flux for D region modification, at a solar zenith angle of 10 deg, is approximately 0.0005 erg/sq/cm/sec. Attention is drawn to the incidence of days of high absorption even in the absence of solar X-ray activity. Available evidence points to variability of the order of 10 to 40% in the intensity of the solar Lyman alpha radiation as the most likely cause of these unusual, though infrequent, enhancements in absorption.

A comparison of solar wind and ionospheric ion acoustic waves

NASA Technical Reports Server (NTRS)

Kintner, P. M.; Kelley, M. C.

1980-01-01

Ion acoustic waves produced during the Trigger experiment are compared to ion acoustic waves observed in the solar wind. After normalizing to the Debye length the spectra are nearly identical, although the ionospheric wave relative energy density is 100 times larger than the solar wind case.

Changes in the lower ionosphere during the eclipse--a preliminary report of the Canadian Programme: (1) introduction.

PubMed

Belrose, J S; McNamara, A G; Hall, J E

1970-06-20

Ground-based radio investigations and four rocket launches were carried out in Canada to study the effect of the eclipse on the solar radiation and electron densities in the lower ionosphere (below about 150 km). The following four articles describe the experiment.

Modeling ionospheric pre-reversal enhancement and plasma bubble growth rate using data assimilation

NASA Astrophysics Data System (ADS)

Rajesh, P. K.; Lin, C. C. H.; Chen, C. H.; Matsuo, T.

2017-12-01

We report that assimilating total electron content (TEC) into a coupled thermosphere-ionosphere model by using the ensemble Kalman filter results in improved specification and forecast of eastward pre-reversal enhancement (PRE) electric field (E-field). Through data assimilation, the ionospheric plasma density, thermospheric winds, temperature and compositions are adjusted simultaneously. The improvement of dusk-side PRE E-field over the prior state is achieved primarily by intensification of eastward neutral wind. The improved E-field promotes a stronger plasma fountain and deepens the equatorial trough. As a result, the horizontal gradients of Pedersen conductivity and eastward wind are increased due to greater zonal electron density gradient and smaller ion drag at dusk, respectively. Such modifications provide preferable conditions and obtain a strengthened PRE magnitude closer to the observation. The adjustment of PRE E-field is enabled through self-consistent thermosphere and ionosphere coupling processes captured in the model. The assimilative outputs are further utilized to calculate the flux tube integrated Rayleigh-Taylor instability growth rate during March 2015 for investigation of global plasma bubble occurrence. Significant improvements in the calculated growth rates could be achieved because of the improved update of zonal electric field in the data assimilation forecast. The results suggest that realistic estimate or prediction of plasma bubble occurrence could be feasible by taking advantage of the data assimilation approach adopted in this work.

The plasma environment, charge state, and currents of Saturn's C and D rings

NASA Technical Reports Server (NTRS)

Wilson, G. R.

1991-01-01

The charge state and associated currents of Saturn's C an D rings are studied by modeling the flow of ionospheric plasma from the mid- to low-latitude ionosphere to the vicinity of the rings. It is found that the plasma density near the C and D rings, at a given radial location, will experience a one to two order of magnitude diurnal variation. The surface charge density (SCD) of these rings can show significant radial and azimuthal variations due mainly to variation in the plasma density. The SCD also depends on structural features of the rings such as thickness and the nature of the particle size distribution. The associated azimuthal currents carried by these rings also show large diurnal variations resulting in field-aligned currents which close in the ionosphere. The resulting ionospheric electric field will probably not produce a significant amount of plasma convection in the topside ionosphere and inner plasmasphere.

The Ionosphere's Pocket Litter: Exploiting Crowd-Sourced Observations

NASA Astrophysics Data System (ADS)

Miller, E. S.; Frissell, N. A.; Kaeppler, S. R.; Demajistre, R.; Knuth, A. A.

2015-12-01

One of the biggest challenges faced in developing and testing our understanding of the ionosphere is acquiring data that characterizes the latitudinal and longitudinal variability of the ionosphere. While there are extensive networks of ground sites that sample the vertical distribution, we have rather poor coverage over the oceans and in parts of the southern hemisphere. Our ability to validate the ionospheric models is limited by the lack of point measurements and those measurements that essentially constitute characterization of horizontal gradients. In this talk, we discuss and demonstrate the use of various types of crowd-sourced information that enables us to extend our coverage over these regions. We will discuss new sources of these data, concepts for new experiments and the use of these data in assimilative models. We note that there are new, low cost options for obtaining data that broaden the participation beyond the aeronomy/ionospheric community.

Comparisons of ionospheric electron density distributions reconstructed by GPS computerized tomography, backscatter ionograms, and vertical ionograms

NASA Astrophysics Data System (ADS)

Zhou, Chen; Lei, Yong; Li, Bofeng; An, Jiachun; Zhu, Peng; Jiang, Chunhua; Zhao, Zhengyu; Zhang, Yuannong; Ni, Binbin; Wang, Zemin; Zhou, Xuhua

2015-12-01

Global Positioning System (GPS) computerized ionosphere tomography (CIT) and ionospheric sky wave ground backscatter radar are both capable of measuring the large-scale, two-dimensional (2-D) distributions of ionospheric electron density (IED). Here we report the spatial and temporal electron density results obtained by GPS CIT and backscatter ionogram (BSI) inversion for three individual experiments. Both the GPS CIT and BSI inversion techniques demonstrate the capability and the consistency of reconstructing large-scale IED distributions. To validate the results, electron density profiles obtained from GPS CIT and BSI inversion are quantitatively compared to the vertical ionosonde data, which clearly manifests that both methods output accurate information of ionopsheric electron density and thereby provide reliable approaches to ionospheric soundings. Our study can improve current understanding of the capability and insufficiency of these two methods on the large-scale IED reconstruction.

Ionospheric Research Using Digital Ionosondes.

DTIC Science & Technology

1983-07-01

HEIGHT ANALYSIS, ARTIST 96 7.0 CHEMICAL RELEASE EXPERIMENTS AT NATAL 105 8.0 IONOSPHERIC HEATING EXPERIMENTS AT ARECIBO 114 9.0 DIGISONDE 128...Jan 82 20:30 to 12 AST 89 67 Thule 82-022 92 68 Integrated Height Characteristic Thule 82-022 93 69 ARTIST Ionogram Print 103 70 Automatic Profiles...Where Manual and Automatic Scalings Fall Within Indicated Limits 97 6a ARTIST Initialization 99 6b ARTIST Initialization 100 6c ARTIST Output 101 N

Macroscopic time and altitude distribution of plasma turbulence induced in ionospheric modification experiments

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rose, H.; Dubois, D.; Russell, D.

1996-03-01

This is the final report of a three-year Laboratory-Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). This research concentrated on the time dependence of the heater, induced-turbulence, and electron-density profiles excited in the ionosphere by a powerful radio-frequency heater wave. The macroscopic density is driven by the ponderomotive pressure and the density self-consistently determines the heater propagation. For typical parameters of the current Arecibo heater, a dramatic quasi-periodic behavior was found. For about 50 ms after turn-on of the heater wave, the turbulence is concentrated at the first standing-wave maximum of the heater near reflectionmore » altitude. From 50--100 ms the standing-wave pattern drops by about 1--2 km in altitude and the quasi-periodicity reappears at the higher altitudes with a period of roughly 50 ms. This behavior is due to the half-wavelength density depletion grating that is set up by the ponderomotive pressure at the maxima of the heater standing-wave pattern. Once the grating is established the heater can no longer propagate to higher altitudes. The grating is then unsupported by the heater at these altitudes and decays, allowing the heater to propagate again and initiate another cycle. For stronger heater powers, corresponding to the Arecibo upgrade and the HAARP heater now under construction, the effects are much more dramatic.« less

Radar investigation of barium releases over Arecibo Observatory, Puerto Rico. Final report, 12 August 1991-30 June 1994

DOE Office of Scientific and Technical Information (OSTI.GOV)

Djuth, F.T.

1995-07-01

The NASA Combined Release and Radiation Effects Satellite (CRRES) El Coqui rocket campaign was successfully carried out in Puerto Rico during the period 18 May through 12 July 1992. This report describes five chemical release experiments in the upper ionosphere supported by Geospace Research, Inc. during the El Coqui campaign. Additional spin-off science is also discussed. The El Coqui releases are designated AA-1 (rocket 36-082), AA-2 (rocket 36-081), AA-3b (rocket 36-064), AA-4 (rocket 36-065), and AA-7 (rocket 36-083). Particular attention is paid to releases AA-2 and AA-4. These two experiments involved the illumination of ionospheric release regions with powerful high-frequencymore » (HF) radio waves transmitted from the Arecibo HF facility. In the AA-2 experiment, microinstabilities excited by the HF wave in a Ba(+) plasma were examined. This release yielded a smooth plasma cloud that helped clarify several fundamental issues regarding the physics of wave plasma instabilities. During AA-2 extremely strong HF-induced Langmuir turbulence was detected with the Arecibo 430 MHz radar. CF3Br was released in the AA-4 study to create an ionospheric hole that focused the HF beam. This experiment successfully explored wave-plasma coupling in an O(+) ionosphere under conditions of very high HF electric field strengths.« less

Recent Advances in Narrowband Stimulated Electromagnetic Emission NSEE Investigations at HAARP and EISCAT

NASA Astrophysics Data System (ADS)

Scales, Wayne

2016-07-01

Investigation of stimulated radiation, commonly known as Stimulated Electromagnetic Emissions (SEE), produced by the interaction of high-power, High Frequency HF radiowaves with the ionospheric plasma has been a vibrant area of research since the early 1980's. Substantial diagnostic information about ionospheric plasma characteristics, dynamics, and turbulence can be obtained from the frequency spectrum of the stimulated radiation. During the past several decades, so-called wideband SEE (WSEE) which exists in a frequency band of ±100 KHz or so of the transmit wave frequency (which is several MHz) has been investigated relatively thoroughly. Upgrades both in transmitter power and diagnostic receiver frequency sensitivity at major ionosphere interaction facilities (i.e. HAARP and EISCAT) have allowed new breakthroughs in the ability to study a plethora of processes associated with the ionospheric plasma during these active experiments. A primary advance is in observations of so-called narrowband SEE (NSEE) which exists roughly within ±1 kHz of the transmit wave frequency. NSEE investigation has opened the door for a potentially powerful tool for aeronomy investigations as well. An overview of several important new results associated with NSEE are discussed in this presentation, including observations, theory, computational modeling, as well as implications to new diagnostics of space plasma physics occurring during ionospheric interaction experiments.

Rocket radio measurement of electron density in the nighttime ionosphere

NASA Technical Reports Server (NTRS)

Gilchrist, B. E.; Smith, L. G.

1979-01-01

One experimental technique based on the Faraday rotation effect of radio waves is presented for measuring electron density in the nighttime ionosphere at midlatitudes. High frequency linearly-polarized radio signals were transmitted to a linearly-polarized receiving system located in a spinning rocket moving through the ionosphere. Faraday rotation was observed in the reference plane of the rocket as a change in frequency of the detected receiver output. The frequency change was measured and the information was used to obtain electron density data. System performance was evaluated and some sources of error were identified. The data obtained was useful in calibrating a Langmuir probe experiment for electron density values of 100/cu cm and greater. Data from two rocket flights are presented to illustrate the experiment.

POD and PPP with multi-frequency processing

NASA Astrophysics Data System (ADS)

Roldán, Pedro; Navarro, Pedro; Rodríguez, Daniel; Rodríguez, Irma

2017-04-01

Precise Orbit Determination (POD) and Precise Point Positioning (PPP) are methods for estimating the orbits and clocks of GNSS satellites and the precise positions and clocks of user receivers. These methods are traditionally based on processing the ionosphere-free combination. With this combination, the delay introduced in the signal when passing through the ionosphere is removed, taking advantage of the dependency of this delay with the square of the frequency. It is also possible to process the individual frequencies, but in this case it is needed to properly model the ionospheric delay. This modelling is usually very challenging, as the electron content in the ionosphere experiences important temporal and spatial variations. These two options define the two main kinds of processing: the dual-frequency ionosphere-free processing, typically used in the POD and in certain applications of PPP, and the single-frequency processing with estimation or modelisation of the ionosphere, mostly used in the PPP processing. In magicGNSS, a software tool developed by GMV for POD and PPP, a hybrid approach has been implemented. This approach combines observations from any number of individual frequencies and any number of ionosphere-free combinations of these frequencies. In such a way, the observations of ionosphere-free combination allow a better estimation of positions and orbits, while the inclusion of observations from individual frequencies allows to estimate the ionospheric delay and to reduce the noise of the solution. It is also possible to include other kind of combinations, such as geometry-free combination, instead of processing individual frequencies. The joint processing of all the frequencies for all the constellations requires both the estimation or modelisation of ionospheric delay and the estimation of inter-frequency biases. The ionospheric delay can be estimated from the single-frequency or dual-frequency geometry-free observations, but it is also possible to use a-priori information based on ionospheric models, on external estimations and on the expected behavior of the ionosphere. The inter-frequency biases appear because the delay of the signal inside the transmitter and the receiver strongly depends on its frequency. However, it is possible to include constraints in the estimator regarding these delays, assuming small variations over time. By using different types of combinations, all the available information from GNSS systems can be included in the processing. This is especially interesting for the case of Galileo satellites, which transmit in several frequencies, and the GPS IIF satellites, which transmit in L5 in addition to the traditional L1 and L2. Several experiments have been performed, to assess the improvement on performance of POD and PPP when using all the constellations and all the available frequencies for each constellation. This paper describes the new approach of multi-frequency processing, including the estimation of biases and ionospheric delays impacting on GNSS observations, and presents the results of the performed experimentation activities to assess the benefits in POD and PPP algorithms.

Early results of the ionospheric experiment of the Apollo-Soyuz Test Project

NASA Technical Reports Server (NTRS)

Grossi, M. D.; Gay, R. H.

1976-01-01

A description is presented of a spacecraft-to-spacecraft Doppler-tracking experiment which was performed by the Smithsonian Astrophysical Observatory on the occasion of the Apollo-Soyuz Test Project (ASTP). The experiment involved the measurement of the relative velocity between the ASTP docking module and the Apollo command service module by a Doppler-tracking method. The objectives of the ionospheric experiment include the measurement of the time changes of the columnar electron content between the two spacecraft. The obtained data can provide a basis for the determination of the horizontal gradients of electron density at the height of 220 km.

Experimental Verification of Ocean Bounced GPS Signals and Analysis of their Application to Ionospheric Corrections for Satellite Altimetry

NASA Technical Reports Server (NTRS)

Axelrad, P.; Cox, A. E.; Crumpton, K. S.

1997-01-01

An algorithm is presented which uses observations of Global Positioning System (GPS) signals reflected from the ocean surface and acquired by a GPS receiver onboard an altimetric satellite to compute the ionospheric delay present in the altimeter measurement. This eliminates the requirement for a dual frequency altimeter for many Earth observing missions. A ground-based experiment is described which confirms the presence of these ocean-bounced signals and demonstrates the potential for altimeter ionospheric correction at the centimeter level.

Ionospheric range-rate effects in satellite-to-satellite tracking

NASA Technical Reports Server (NTRS)

Lipofsky, J. R.; Bent, R. B.; Llewellyn, S. K.; Schmid, P. E.

1977-01-01

Investigation of ionospheric range and range-rate corrections in satellite-to-satellite tracking were investigated. Major problems were cited and the magnitude of errors that have to be considered for communications between satellites and related experiments was defined. The results point to the need of using a sophisticated modeling approach incorporating daily solar data, and where possible actual ionospheric measurements as update information, as a simple median model cannot possibly account for the complex interaction of the many variables. The findings provide a basis from which the residual errors can be estimated after ionospheric modeling is incorporated in the reduction. Simulations were performed for satellites at various heights: Apollo, Geos, and Nimbus tracked by ATS-6; and in two different geometric configurations: coplanar and perpendicular orbits.

Zonal drift velocities of the ionospheric plasma bubbles over brazilian region using oi630nm airglow digital images

NASA Astrophysics Data System (ADS)

Arruda, D. C. S.; Sobral, J. H. A.; Abdu, M. A.; Castilho, V. M.; Takahashi, H.

The zonal drift velocities of the ionospheric plasma bubbles over the Brazilian region are analyzed in this study that is based on OI630nm airglow digital images. These digital images were obtained by an all-sky imager system between October 1998 and August 2000, at Cachoeira Paulista (22.5°S, 45°W), a low latitude region. In this period, 138 nights of OI 630 nm airglow experiments were carried out of which 30 nights detected the ionospheric plasma bubbles. These 30 nights correspond to magnetically quiet days (ΣK_P<24+) and were grouped according approximately to their season. KEY WORDS: Imager System, Ionospheric Plasma Bubbles, Zonal drift velocities, OI630nm.

Effects of 27-day averaged tidal forcing on the thermosphere-ionosphere as examined by the TIEGCM

NASA Astrophysics Data System (ADS)

Maute, A. I.; Forbes, J. M.; Hagan, M. E.

2016-12-01

The variability of the ionosphere and thermosphere is influenced by solar and geomagnetic forcing and by lower atmosphere coupling. During the last solar minimum low- and mid-latitude ionospheric observations have shown strong longitudinal signals which are associated with upward propagating tides. Progress has been made in explaining observed ionospheric and thermospheric variations by investigating possible coupling mechanisms e.g., wind dynamo, propagation of tides into the upper thermosphere, global circulation changes, and compositional effects. To fully understand the vertical coupling a comprehensive set of simultaneous measurements of key quantities is missing. The Ionospheric Connection (ICON) explorer will provide such a data set and the data interpretation will be supported by numerical modeling to investigate the lower to upper atmosphere coupling. Due to ICON's orbit, 27 days of measurements are needed to cover all longitudes and local times and to be able to derive tidal components. In this presentation we employ the Thermosphere Ionosphere Electrodynamics General Circulation Model (TIEGCM) to evaluate the influence of the 27-day processing window on the ionosphere and thermosphere state. Specifically, we compare TIEGCM simulations that are forced at its 97 km lower boundary by daily tidal fields from 2009 MERRA-forced TIME-GCM output [Häusler et al., 2015], and by the corresponding 27-day mean tidal fields. Apart from the expected reduced day-to-day variability when using 27-day averaged tidal forcing, the simulations indicate net NmF2 changes at low latitudes, which vary with season. First results indicate that compositional effects may influence the Nmf2 modifications. We will quantify the effect of using a 27-day averaged diurnal tidal forcing versus daily ones on the equatorial vertical drift, low and mid-latitude NmF2 and hmF2, global circulation, and composition. The possible causes for the simulated changes will be examined. The result of this study will be important for the comparison of the ICON observations with the accompanying ICON-TIEGCM simulations and guide the model-data interpretation.

Earth's magnetic field effect on MUF calculation and consequences for hmF2 trend estimates

NASA Astrophysics Data System (ADS)

Elias, Ana G.; Zossi, Bruno S.; Yiğit, Erdal; Saavedra, Zenon; de Haro Barbas, Blas F.

2017-10-01

Knowledge of the state of the upper atmosphere, and in particular of the ionosphere, is essential in several applications such as systems used in radio frequency communications, satellite positioning and navigation. In general, these systems depend on the state and evolution of the ionosphere. In all applications involving the ionosphere an essential task is to determine the path and modifications of ray propagation through the ionospheric plasma. The ionospheric refractive index and the maximum usable frequency (MUF) that can be received over a given distance are some key parameters that are crucial for such technological applications. However, currently the representation of these parameters are in general simplified, neglecting the effects of Earth's magnetic field. The value of M(3000)F2, related to the MUF that can be received over 3000 km is routinely scaled from ionograms using a technique which also neglects the geomagnetic field effects assuming a standard simplified propagation model. M(3000)F2 is expected to be affected by a systematic trend linked to the secular variations of Earth's magnetic field. On the other hand, among the upper atmospheric effects expected from increasing greenhouse gases concentration is the lowering of the F2-layer peak density height, hmF2. This ionospheric parameter is usually estimated using the M(3000)F2 factor, so it would also carry this ;systematic trend;. In this study, the geomagnetic field effect on MUF estimations is analyzed as well as its impact on hmF2 long-term trend estimations. We find that M(3000)F2 increases when the geomagnetic field is included in its calculation, and hence hmF2, estimated using existing methods involving no magnetic field for M(3000)F2 scaling, would present a weak but steady trend linked to these variations which would increase or compensate the few kilometers decrease ( 2 km per decade) expected from greenhouse gases effect.

Ionospheric Simulation System for Satellite Observations and Global Assimilative Model Experiments - ISOGAME

NASA Technical Reports Server (NTRS)

Pi, Xiaoqing; Mannucci, Anthony J.; Verkhoglyadova, Olga; Stephens, Philip; Iijima, Bryron A.

2013-01-01

Modeling and imaging the Earth's ionosphere as well as understanding its structures, inhomogeneities, and disturbances is a key part of NASA's Heliophysics Directorate science roadmap. This invention provides a design tool for scientific missions focused on the ionosphere. It is a scientifically important and technologically challenging task to assess the impact of a new observation system quantitatively on our capability of imaging and modeling the ionosphere. This question is often raised whenever a new satellite system is proposed, a new type of data is emerging, or a new modeling technique is developed. The proposed constellation would be part of a new observation system with more low-Earth orbiters tracking more radio occultation signals broadcast by Global Navigation Satellite System (GNSS) than those offered by the current GPS and COSMIC observation system. A simulation system was developed to fulfill this task. The system is composed of a suite of software that combines the Global Assimilative Ionospheric Model (GAIM) including first-principles and empirical ionospheric models, a multiple- dipole geomagnetic field model, data assimilation modules, observation simulator, visualization software, and orbit design, simulation, and optimization software.

Modeling Amateur Radio Soundings of the Ionospheric Response to the 2017 Great American Eclipse

NASA Astrophysics Data System (ADS)

Frissell, N. A.; Katz, J. D.; Gunning, S. W.; Vega, J. S.; Gerrard, A. J.; Earle, G. D.; Moses, M. L.; West, M. L.; Huba, J. D.; Erickson, P. J.; Miller, E. S.; Gerzoff, R. B.; Liles, W.; Silver, H. W.

2018-05-01

On 21 August 2017, a total solar eclipse traversed the continental United States and caused large-scale changes in ionospheric densities. These were detected as changes in medium- and high-frequency radio propagation by the Solar Eclipse QSO Party citizen science experiment organized by the Ham Radio Science Citizen Investigation (hamsci.org). This is the first eclipse-ionospheric study to make use of measurements from a citizen-operated, global-scale HF propagation network and develop tools for comparison to a physics-based model ionosphere. Eclipse effects were observed ±0.3 hr on 1.8 MHz, ±0.75 hr on 3.5 and 7 MHz, and ±1 hr on 14 MHz and are consistent with eclipse-induced ionospheric densities. Observations were simulated using the PHaRLAP raytracing toolkit in conjunction with the eclipsed SAMI3 ionospheric model. Model results suggest 1.8, 3.5, and 7 MHz refracted at h≥125 km altitude with elevation angles θ≥22°, while 14 MHz signals refracted at h < 125 km with elevation angles θ < 10°.

Influence of Solar Irradiance on Polar Ionospheric Convection

NASA Astrophysics Data System (ADS)

Burrell, A. G.; Yeoman, T. K.; Stephen, M.; Lester, M.

2016-12-01

Plasma convection over the poles shows the result of direct interactions between the terrestrial atmosphere, magnetosphere, and the sun. The paths that the ionospheric plasma takes in the polar cap form a variety of patterns, which have been shown to depend strongly on the direction of the Interplanetary Magnetic Field (IMF) and the reconnection rate. While the IMF and level of geomagnetic activity clearly alter the plasma convection patterns, the influence of changing solar irradiance is also important. The solar irradiance and magnetospheric particle precipitation regulate the rate of plasma production, and thus the ionospheric conductivity. Previous work has demonstrated how season alters the convection patterns observed over the poles, demonstrating the importance that solar photoionisation has on plasma convection. This study investigates the role of solar photoionisation on convection more directly, using measurements of ionospheric convection made by the Super Dual Auroral Radar Network (SuperDARN) and solar irradiance observations made by the Solar EUV Experiment (SEE) to explore the influence of the solar cycle on ionospheric convection, and the implications this may have on magnetosphere-ionosphere coupling.

Preliminary investigation of Faraday rotation effects and description of polarization measurements on the AFGL high latitude meteor scatter test bed

NASA Astrophysics Data System (ADS)

Ostergaard, Jens C.

1989-01-01

The background, methodology and preliminary results of an investigation of Faraday rotation effects on the Meteor Scatter High Latitude Test Bed in Greenland are presented. A short review of polarization theory for radio waves, presenting basic properties and changes when reflected from the surface of the earth or propagated through the ionosphere is included. Material published by other workers is presented to give the background for the current interest in Faraday rotation on meteor scatter links. Propagation losses for meteor scatter paths originate from spatial spreading of RF energy, scattering losses at the meteor trail, ionospheric absorption and polarization mismatch at the receiving antenna. That part of the polarization mismatch generated by the ionosphere, the Faraday rotation, is described and evaluated. A method to compute the Faraday rotation is presented and results obtained for the AFGL MSHL Test Bed are given. An experiment, including the measurement of signal strength and polarization throughout the lifetime of the individual meteor scatter return is needed to fully assess the combined affects of absorption and depolarization during both quiet and disturbed ionospheric conditions. The measurement accuracy to be expected from a proposed experiment is evaluated. A few examples of meteor scatter returns obtained with a prototype experiment in Greenland are shown and discussed.

Plasma waves produced by the xenon ion beam experiment on the Porcupine sounding rocket

NASA Technical Reports Server (NTRS)

Kintner, P. M.; Kelley, M.

1982-01-01

The production of electrostatic ion cyclotron waves by a perpendicular ion beam in the F-region ionosphere is described. The ion beam experiment was part of the Porcupine program and produced electrostatic hydrogen cyclotron waves just above harmonics of the hydrogen cyclotron frequency. The plasma process may be thought of as a magnetized background ionosphere through which an unmagnetized beam is flowing. The dispersion equation for this hypothesis is constructed and solved. Preliminary solutions agree well with the observed plasma waves.

Analysis of satellite data on energetic particles of ionospheric origin

NASA Technical Reports Server (NTRS)

Sharp, R. D.; Johnson, R. G.; Shelley, E. G.

1976-01-01

The principal result of this program has been the completion of a detailed statistical study of the properties of precipitating O(+) and H(+) ions during two principal magnetic storms. The results of the analysis of selected data of ion mass spectrometer experiment on satellites are given with emphasis on the morphology of the O(+) ions of ionospheric origin with energies in the 0.7 les than or equal to E less than or equal to 12 keV range that were discovered with this experiment.

Dayside Magnetosphere-Ionosphere Coupling and Prompt Response of Low-Latitude/Equatorial Ionosphere

NASA Astrophysics Data System (ADS)

Tu, J.; Song, P.

2017-12-01

We use a newly developed numerical simulation model of the ionosphere/thermosphere to investigate magnetosphere-ionosphere coupling and response of the low-latitude/equatorial ionosphere. The simulation model adapts an inductive-dynamic approach (including self-consistent solutions of Faraday's law and retaining inertia terms in ion momentum equations), that is, based on magnetic field B and plasma velocity v (B-v paradigm), in contrast to the conventional modeling based on electric field E and current j (E-j paradigm). The most distinct feature of this model is that the magnetic field in the ionosphere is not constant but self-consistently varies, e.g., with currents, in time. The model solves self-consistently time-dependent continuity, momentum, and energy equations for multiple species of ions and neutrals including photochemistry, and Maxwell's equations. The governing equations solved in the model are a set of multifluid-collisional-Hall MHD equations which are one of unique features of our ionosphere/thermosphere model. With such an inductive-dynamic approach, all possible MHD wave modes, each of which may refract and reflect depending on the local conditions, are retained in the solutions so that the dynamic coupling between the magnetosphere and ionosphere and among different regions of the ionosphere can be self-consistently investigated. In this presentation, we show that the disturbances propagate in the Alfven speed from the magnetosphere along the magnetic field lines down to the ionosphere/thermosphere and that they experience a mode conversion to compressional mode MHD waves (particularly fast mode) in the ionosphere. Because the fast modes can propagate perpendicular to the field, they propagate from the dayside high-latitude to the nightside as compressional waves and to the dayside low-latitude/equatorial ionosphere as rarefaction waves. The apparent prompt response of the low-latitude/equatorial ionosphere, manifesting as the sudden increase of the upward flow around the equator and global antisunward convection, is the result of such coupling of the high-latitude and the low-latitude/equatorial ionosphere, and the requirement of the flow continuity, instead of mechanisms such as the penetration electric field.

A new unequal-weighted triple-frequency first order ionosphere correction algorithm and its application in COMPASS

NASA Astrophysics Data System (ADS)

Liu, WenXiang; Mou, WeiHua; Wang, FeiXue

2012-03-01

As the introduction of triple-frequency signals in GNSS, the multi-frequency ionosphere correction technology has been fast developing. References indicate that the triple-frequency second order ionosphere correction is worse than the dual-frequency first order ionosphere correction because of the larger noise amplification factor. On the assumption that the variances of three frequency pseudoranges were equal, other references presented the triple-frequency first order ionosphere correction, which proved worse or better than the dual-frequency first order correction in different situations. In practice, the PN code rate, carrier-to-noise ratio, parameters of DLL and multipath effect of each frequency are not the same, so three frequency pseudorange variances are unequal. Under this consideration, a new unequal-weighted triple-frequency first order ionosphere correction algorithm, which minimizes the variance of the pseudorange ionosphere-free combination, is proposed in this paper. It is found that conventional dual-frequency first-order correction algorithms and the equal-weighted triple-frequency first order correction algorithm are special cases of the new algorithm. A new pseudorange variance estimation method based on the three carrier combination is also introduced. Theoretical analysis shows that the new algorithm is optimal. The experiment with COMPASS G3 satellite observations demonstrates that the ionosphere-free pseudorange combination variance of the new algorithm is smaller than traditional multi-frequency correction algorithms.

Preliminary theoretical acoustic and rf sounding calculations for MILL RACE

DOE Office of Scientific and Technical Information (OSTI.GOV)

Warshaw, S.I.; Dubois, P.F.

1981-11-02

As participant in DOE/ISA's Ionospheric Monitoring Program, LLNL has the responsibility of providing theoretical understanding and calculational support for experimental activities carried out by Los Alamos National Laboratory in using ionospheric sounders to remotely detect violent atmospheric phenomena. We have developed a system of interconnected computer codes which simulate the entire range of atmospheric and ionospheric processes involved in this remote detection procedure. We are able to model the acoustic pulse shape from an atmospheric explosion, the subsequent nonlinear transport of this energy to all parts of the immediate atmosphere including the ionosphere, and the propagation of high-frequency ratio wavesmore » through the acoustically perturbed ionosphere. Los Alamos' coverage of DNA's MILL RACE event provided an excellent opportunity to assess the credibility of the calculational system to correctly predict how ionospheric sounders would respond to a surface-based chemical explosion. In this experiment, 600 tons of high explosive were detonated at White Sands Missile Range at 12:35:40 local time on 16 September 1981. Vertical incidence rf phase sounders and bistatic oblique incidence rf sounders fielded by Los Alamos and SRI International throughout New Mexico and southern Colorado detected the ionospheric perturbation that ensued. A brief account of preliminary calculations of the acoustic disturbance and the predicted ionospheric sounder signatures for MILL RACE is presented. (WHK)« less

New Concepts in Ionospheric Modification

DTIC Science & Technology

1987-04-01

lasers, Phys. Fluids, 26, 1688-1692, 1986. Welford, W.T., and R. Winston , The Optics of Nonimaging Concentrators , 200 pp., Academic, New York, 1978...tantalum target/reflector assembly. We now use the following relationship, which follows from the conservation of optical 6tendue [ Welford and Winston ...of existing data obtained during thruster firings on STS-3 and Spacelab-2. (’orisiderable optical and plasma data are immediately available for study

Nonlinear wave fronts and ionospheric irregularities observed by HF sounding over a powerful acoustic source

NASA Astrophysics Data System (ADS)

Blanc, Elisabeth; Rickel, Dwight

1989-06-01

Different wave fronts affected by significant nonlinearities have been observed in the ionosphere by a pulsed HF sounding experiment at a distance of 38 km from the source point of a 4800-kg ammonium nitrate and fuel oil (ANFO) explosion on the ground. These wave fronts are revealed by partial reflections of the radio sounding waves. A small-scale irregular structure has been generated by a first wave front at the level of a sporadic E layer which characterized the ionosphere at the time of the experiment. The time scale of these fluctuations is about 1 to 2 s; its lifetime is about 2 min. Similar irregularities were also observed at the level of a second wave front in the F region. This structure appears also as diffusion on a continuous wave sounding at horizontal distances of the order of 200 km from the source. In contrast, a third front unaffected by irregularities may originate from the lowest layers of the ionosphere or from a supersonic wave front propagating at the base of the thermosphere. The origin of these structures is discussed.

INSPIRE Project (IoNospheric Sounding for Pre-seismic anomalies Identification REsearch): Main Results and Future Prospects

NASA Astrophysics Data System (ADS)

Pulinets, S. A.; Andrzej, K.; Hernandez-Pajares, M.; Cherniak, I.; Zakharenkova, I.; Rothkaehl, H.; Davidenko, D.

2017-12-01

The INSPIRE project is dedicated to the study of physical processes and their effects in ionosphere which could be determined as earthquake precursors together with detailed description of the methodology of ionospheric pre-seismic anomalies definition. It was initiated by ESA and carried out by international consortium. The physical mechanisms of the ionospheric pre-seismic anomalies generation from ground to the ionosphere altitudes were formulated within framework of the Lithosphere-Atmosphere-Ionosphere-Magnetosphere Coupling (LAIMC) model (Pulinets et al., 2015). The general algorithm for the identification of the ionospheric precursors was formalized which also takes into account the external Space Weather factors able to generate the false alarms. Importance of the special stable pattern called the "precursor mask" was highlighted which is based on self-similarity of pre-seismic ionospheric variations. The role of expert decision in pre-seismic anomalies interpretation for generation of seismic warning is important as well. The algorithm performance of the LAIMC seismo-ionospheric effect detection module has been demonstrated using the L'Aquila 2009 earthquake as a case study. The results of INSPIRE project have demonstrated that the ionospheric anomalies registered before the strong earthquakes could be used as reliable precursors. The detailed classification of the pre-seismic anomalies was presented in different regions of the ionosphere and signatures of the pre-seismic anomalies as detected by ground and satellite based instruments were described what clarified methodology of the precursor's identification from ionospheric multi-instrumental measurements. Configuration for the dedicated multi-observation experiment and satellite payload was proposed for the future implementation of the INSPIRE project results. In this regard the multi-instrument set can be divided by two groups: space equipment and ground-based support, which could be used for real-time monitoring. Together with scientific and technical tasks the set of political, logistic and administrative problems (including certification of approaches by seismological community, juridical procedures by the governmental authorities) should be resolved for the real earthquake forecast effectuation.

Power-Stepped HF Cross Modulation Experiments at HAARP

NASA Astrophysics Data System (ADS)

Greene, S.; Moore, R. C.; Langston, J. S.

2013-12-01

High frequency (HF) cross modulation experiments are a well established means for probing the HF-modified characteristics of the D-region ionosphere. In this paper, we apply experimental observations of HF cross-modulation to the related problem of ELF/VLF wave generation. HF cross-modulation measurements are used to evaluate the efficiency of ionospheric conductivity modulation during power-stepped modulated HF heating experiments. The results are compared to previously published dependencies of ELF/VLF wave amplitude on HF peak power. The experiments were performed during the March 2013 campaign at the High Frequency Active Auroral Research Program (HAARP) Observatory. HAARP was operated in a dual-beam transmission format: the first beam heated the ionosphere using sinusoidal amplitude modulation while the second beam broadcast a series of low-power probe pulses. The peak power of the modulating beam was incremented in 1-dB steps. We compare the minimum and maximum cross-modulation effect and the amplitude of the resulting cross-modulation waveform to the expected power-law dependence of ELF/VLF wave amplitude on HF power.

Attribution of ionospheric vertical plasma drift perturbations to large-scale waves and the dependence on solar activity (Invited)

NASA Astrophysics Data System (ADS)

Liu, H.; Richmond, A. D.

2013-12-01

In this study we quantify the contribution of individual large-scale waves to ionospheric electrodynamics, and examine the dependence of the ionospheric perturbations on solar activity. We focus on migrating diurnal tide (DW1) plus mean winds, migrating semidiurnal tide (SW2), quasi-stationary planetary wave 1 (QSPW1), and nonmigrating semidiurnal westward wave 1 (SW1) under northern winter conditions, when QSPW1 and SW1 are climatologically strong. From TIME-GCM simulations under solar minimum conditions, we calculate equatorial vertical ExB drifts due to mean winds and DW1, SW2, SW1 and QSPW1. In particular, wind components of both SW2 and SW1 become large at mid to high latitudes in the E-region, and kernel functions obtained from numerical experiments reveal that they can significantly affect the equatorial ion drift, likely through modulating the E-region wind dynamo. The most evident changes of total ionospheric vertical drift when solar activity is increased are seen around dawn and dusk, reflecting the more dominant role of large F-region Pedersen conductivity and of the F-region dynamo under high solar activity. Therefore, the lower atmosphere driving of the ionospheric variability is more evident under solar minimum conditions, not only because variability is more identifiable in a quieter background, but also because the E-region wind dynamo is more significant. These numerical experiments also demonstrate that the amplitudes, phases and latitudinal and vertical structures of large-scale waves are important in quantifying the ionospheric responses.

Impact of active geomagnetic conditions on stimulated radiation during ionospheric second electron gyroharmonic heating

NASA Astrophysics Data System (ADS)

Bordikar, M. R.; Scales, W. A.; Mahmoudian, A.; Kim, H.; Bernhardt, P. A.; Redmon, R.; Samimi, A. R.; Brizcinski, S.; McCarrick, M. J.

2014-01-01

Recently, narrowband emissions ordered near the H+ (proton) gyrofrequency (fcH) were reported in the stimulated electromagnetic emission (SEE) spectrum during active geomagnetic conditions. This work presents new observations and theoretical analysis of these recently discovered emissions. These emission lines are observed in the stimulated electromagnetic emission (SEE) spectrum when the transmitter is tuned near the second electron gyroharmonic frequency (2fce) during recent ionospheric modification experiments at the High Frequency Active Auroral Research (HAARP) facility near Gakona, Alaska. The spectral lines are typically shifted below and above the pump wave frequency by harmonics of a frequency roughly 10% less than fcH (≈ 800 Hz) with a narrow emission bandwidth less than the O+ gyrofrequency (≈ 50 Hz). However, new observations and analysis of emission lines ordered by a frequency approximately 10% greater than fcH are presented here for the first time as well. The interaction altitude for the heating for all the observations is in the range of 160 km up to 200 km. As described previously, proton precipitation due to active geomagnetic conditions is considered as the reason for the presence of H+ ions known to be a minor background constituent in this altitude region. DMSP satellite observations over HAARP during the heating experiments and ground-based magnetometer and riometer data validate active geomagnetic conditions. The theory of parametric decay instability in multi-ion component plasma including H+ ions as a minority species described in previous work is expanded in light of simultaneously observed preexisting SEE features to interpret the newly reported observations. Impact of active geomagnetic conditions on the SEE spectrum as a diagnostic tool for proton precipitation event characterization is discussed.

Artificial plasma cusp generated by upper hybrid instabilities in HF heating experiments at HAARP

NASA Astrophysics Data System (ADS)

Kuo, Spencer; Snyder, Arnold

2013-05-01

High Frequency Active Auroral Research Program digisonde was operated in a fast mode to record ionospheric modifications by the HF heating wave. With the O mode heater of 3.2 MHz turned on for 2 min, significant virtual height spread was observed in the heater off ionograms, acquired beginning the moment the heater turned off. Moreover, there is a noticeable bump in the virtual height spread of the ionogram trace that appears next to the plasma frequency (~ 2.88 MHz) of the upper hybrid resonance layer of the HF heating wave. The enhanced spread and the bump disappear in the subsequent heater off ionograms recorded 1 min later. The height distribution of the ionosphere in the spread situation indicates that both electron density and temperature increases exceed 10% over a large altitude region (> 30 km) from below to above the upper hybrid resonance layer. This "mini cusp" (bump) is similar to the cusp occurring in daytime ionograms at the F1-F2 layer transition, indicating that there is a small ledge in the density profile reminiscent of F1-F2 layer transitions. Two parametric processes exciting upper hybrid waves as the sidebands by the HF heating waves are studied. Field-aligned purely growing mode and lower hybrid wave are the respective decay modes. The excited upper hybrid and lower hybrid waves introduce the anomalous electron heating which results in the ionization enhancement and localized density ledge. The large-scale density irregularities formed in the heat flow, together with the density irregularities formed through the parametric instability, give rise to the enhanced virtual height spread. The results of upper hybrid instability analysis are also applied to explain the descending feature in the development of the artificial ionization layers observed in electron cyclotron harmonic resonance heating experiments.

The Giotto radio-science experiment

NASA Technical Reports Server (NTRS)

Edenhofer, P.; Bird, M. K.; Buschert, H.; Esposito, P. B.; Porsche, H.; Volland, H.

1986-01-01

The scientific objectives of the Giotto Radio Science Experiment (GRE) are to determine the columnar electron content of Comet Halley/s ionosphere and the cometary mass fluence from atmospheric drag by using the radio signals from Giotto during the Halley encounter. The radio science data (S and X-band Doppler and range measurements) will be collected at NASA/s deep-space 64 m tracking antenna at Tidbinbilla near Canberra, in Australia. In order to separate the effects of the terrestrial ionosphere and the interplanetary plasma, S-band Doppler measurements will also be taken at Tidbinbilla along the line-of-sight of Japan/s cometary probe Sakigake during the Giotto-Halley Encounter. The measurements of cometary electron content and mass fluence will be inverted to derive the spatial distribution of the electron and mass (dust and gas) density within Halley/s coma. The GRE is the only experiment on Giotto capable of measuring the low-energy (10 eV) electron bulk population of Halley/s ionosphere and the total cometary mass flow impacting upon the spacecraft.

The character of drift spreading of artificial plasma clouds in the middle-latitude ionosphere

NASA Astrophysics Data System (ADS)

Blaunstein, N.

1996-02-01

Nonlinear equations describing the evolution of plasma clouds with real initial sizes, along and across the geomagnetic field B, which drift in the ionosphere in the presence of an ambient electric field and a neutral wind have been solved and analysed. An ionospheric model close to the real conditions of the middle-latitude ionosphere is introduced, taking into account the altitude dependence of the transport coefficients and background ionospheric plasma. The striation of the initial plasma cloud into a cluster of plasmoids, stretched along the field B, is obtained. The process of dispersive splitting of the initial plasma cloud can be understood in terms of gradient drift instability (GDI) as a most probable striation mechanism. The dependence of the characteristic time of dispersive splitting on the value of the ambient electric field, the initial plasma disturbance in the cloud and its initial sizes was investigated. The stretching criterion, necessary for the plasma cloud's striation is obtained. The possibility of the drift stabilization effect arising from azimuthal drift velocity shear, obtained by Drake et al. [1988], is examined for various parameters of the barium cloud and the background ionospheric conditions. A comparison with experimental data on the evolution of barium clouds in rocket experiments at the height of the lower ionosphere is made.

Control of the Earth's electric field intensity through solar wind modulation of galactic cosmic radiation: Support for a proposed atmospheric electrical sun-weather mechanism

NASA Technical Reports Server (NTRS)

Markson, R.

1980-01-01

The ionospheric potential and galactic cosmic radiation, found to be inversely correlated with the solar wind velocity are examined as being germane to weather modification. Since the ionospheric potential is proportional to the fair weather electric field intensity and cosmic radiation is the dominant source of atmospheric ionization, it is concluded that the Earth's overall electric field varies in phase with atmospheric ionization and that the latter is modulated by the solar wind. A proposed mechanism, in which solar control of ionizing radiation influences atmospheric electrification and thus possibly cloud physical processes is discussed. An experimental approach to critically test the proposed mechanism through comparison of the temporal variation of the Earth's electric field with conditions in the interplanetary medium is outlined.

Venus ionosphere: photochemical and thermal diffusion control of ion composition.

PubMed

Bauer, S J; Donahue, T M; Hartle, R E; Taylor, H A

1979-07-06

The major photochemical sources and sinks for ten of the ions measured by the ion mass spectrometer on the Pioneer Venus bus and orbiter spacecraft that are consistent with the neutral gas composition measured on the same spacecraft have been identified. The neutral gas temperature (Tn) as a function of solar zenith angle (chi) derived from measured ion distributions in photochemical equilibrium is given by Tn (K) = 323 cos(1/5)chi. Above 200 kilometers, the altitude behavior of ions is generally controlled by plasma diffusion, with important modifications for minor ions due to thermal diffusion resulting from the observed gradients of plasma temperatures. The dayside equilibrium distributions of ions are sometimes perturbed by plasma convection, while lateral transport of ions from the dayside seems to be a major source of the nightside ionosphere.

Upper Hybrid Effects in Artificial Ionization

NASA Astrophysics Data System (ADS)

Papadopoulos, K.; Eliasson, B. E.

2014-12-01

A most fascinating result of recent ionospheric experiments has been the discovery of artificial ionization by Pedersen et al. (GRL, 37, L02106, 2010). The Artificial Ionospheric Layers (AIL) were the result of F-region O-mode HF irradiation using the HAARP ionospheric heater operating at 3.6 MW power. As demonstrated by Eliasson et al. (JGR, 117, A10321, 2012) the physics controlling the observed phenomenon and its threshold can be summarized as: " Collisional ionization due to high energy (~ 20 eV) electron tails generated by the interaction of strong Langmuir turbulence with plasma heated at the upper hybrid resonance and transported at the reflection height". The objective of the current presentation is to explore the role of the upper hybrid heating in the formation of AIL and its implications to future experiments involving HF heaters operating in middle and equatorial latitudes.

Testing electrostatic equilibrium in the ionosphere by detailed comparison of ground magnetic deflection and incoherent scatter radar.

NASA Astrophysics Data System (ADS)

Cosgrove, R. B.; Schultz, A.; Imamura, N.

2016-12-01

Although electrostatic equilibrium is always assumed in the ionosphere, there is no good theoretical or experimental justification for the assumption. In fact, recent theoretical investigations suggest that the electrostatic assumption may be grossly in error. If true, many commonly used modeling methods are placed in doubt. For example, the accepted method for calculating ionospheric conductance??field line integration??may be invalid. In this talk we briefly outline the theoretical research that places the electrostatic assumption in doubt, and then describe how comparison of ground magnetic field data with incoherent scatter radar (ISR) data can be used to test the electrostatic assumption in the ionosphere. We describe a recent experiment conducted for the purpose, where an array of magnetometers was temporalily installed under the Poker Flat AMISR.

The Role of Ionospheric Conductivity in the Response of the Magnetosphere and Ionosphere to Changes in the Earth's Magnetic Field

NASA Astrophysics Data System (ADS)

Cnossen, I.; Wiltberger, M. J.; Richmond, A. D.; Ouellette, J.

2014-12-01

The strength and orientation of the Earth's magnetic field play an important role in the magnetosphere-ionosphere-thermosphere system. This is demonstrated in a set of idealized experiments with the Coupled Magnetosphere-Ionosphere-Thermosphere model using a dipolar magnetic field. A decrease of the dipole moment (M) causes an increase in ionospheric conductance. This increase in conductance results in enhanced field-aligned currents (FACs), which change the shape of the magnetosphere, and causes a deviation from theoretical scaling relations of the stand-off distance, the size of the polar cap, and the cross-polar cap potential with M. The orientation of the Earth's magnetic field determines how the angle μ between the geomagnetic dipole axis and the geocentric solar magnetospheric (GSM) z-axis varies with season and universal time (UT). The angle μ can affect solar wind-magnetosphere-ionosphere coupling in two distinct ways: via variations in ionospheric conductivity over the polar caps or via a change in the coupling efficiency between the solar wind and magnetosphere as a result of changes in geometry. Simulations in which the ionospheric conductivity was either kept fixed or allowed to vary realistically demonstrated that variations in ionospheric conductance are responsible for ~10-30% of the variations in the cross-polar cap potential associated with variations in μ for southward interplanetary magnetic field (IMF). The remainder was mostly due to variations in the magnetic reconnection rate, which were associated with variations in the length of the section of the separator line along which relatively strong reconnection occurs.

Broadband Ionospheric Scintillation Measurements from Space

NASA Astrophysics Data System (ADS)

Suszcynsky, D. M.; Light, M. E.; Pigue, M. J.

2014-12-01

The U.S. Department of Energy's Radio Frequency Propagation (RFProp) experiment consists of a satellite-based radio receiver suite to study various aspects of trans-ionospheric signal propagation and detection in four frequency bands, 2 - 55 MHz, 125 - 175 MHz, 365 - 415 MHz and 825 - 1100 MHz. In this paper, we present an overview of the RFProp on-orbit research and analysis effort with particular focus on an equatorial scintillation experiment called ESCINT. The 3-year ESCINT project is designed to characterize equatorial ionospheric scintillation in the upper HF and lower VHF portions of the radio spectrum (20 - 150 MHz). Both a 40 MHz continuous wave (CW) signal and 30 - 42 MHz swept frequency signal are transmitted to the satellite receiver suite from the Reagan Test Site at Kwajalein Atoll in the Marshall Islands (8.7° N, 167.7° E) in four separate campaigns centered on the 2014 and 2015 equinoxes. Results from the first campaign conducted from April 22 - May 15, 2014 will be presented including (a) coherence bandwidth measurements over a full range of transmission frequencies and scintillation activity levels, (b) spread-Doppler clutter effects arising from preferential ray paths to the satellite due to refraction off of isolated density irregularities, and (c) supporting ray-trace simulations. The broadband nature of the measurements is found to offer unique insight into both the structure of ionospheric irregularities and their impact on HF/VHF trans-ionospheric radio wave propagation.

Pressure Balance at Mars and Solar Wind Interaction with the Martian Atmosphere

NASA Technical Reports Server (NTRS)

Krymskii, A. M.; Ness, N. F.; Crider, D. H.; Breus, T. K.; Acuna, M. H.; Hinson, D.

2003-01-01

The strongest crustal fields are located in certain regions in the Southern hemisphere. In the Northern hemisphere, the crustal fields are rather weak and usually do not prevent direct interaction between the SW and the Martian ionosphere/atmosphere. Exceptions occur in the isolated mini-magnetospheres formed by the crustal anomalies. Electron density profiles of the ionosphere of Mars derived from radio occultation data obtained by the Radio Science Mars Global Surveyor (MGS) experiment have been compared with the crustal magnetic fields measured by the MGS Magnetometer/Electron Reflectometer (MAG/ER) experiment. A study of 523 electron density profiles obtained at latitudes from +67 deg. to +77 deg. has been conducted. The effective scale-height of the electron density for two altitude ranges, 145-165 km and 165-185 km, and the effective scale-height of the neutral atmosphere density in the vicinity of the ionization peak have been derived for each of the profiles studied. For the regions outside of the potential mini-magnetospheres, the thermal pressure of the ionospheric plasma for the altitude range 145-185 km has been estimated. In the high latitude ionosphere at Mars, the total pressure at altitudes 160 and 180 km has been mapped. The solar wind interaction with the ionosphere of Mars and origin of the sharp drop of the electron density at the altitudes 200-210 km will be discussed.

Study of midlatitude ionospheric irregularities and E- and F-region coupling based on rocket and radar observations from Japan

NASA Astrophysics Data System (ADS)

Yamamoto, M.

2015-12-01

We have been studying ionspheric irregularities in mid-latitude region by using radars, sounding rockets, etc. The mid-latitude ionosphere was considered much stable than those in the equatorial or polar region in the past, but our studies for years have revealed that there are much active variabilities. We found variety of wave-like structures that are specific in the mid-latitudes. One of the phenomena is quasi-periodic echoes (QP echoes) first observed by the MU radar that reflects horizontal plasma-density structures associated to sporadic-E layers. Another phenomenon is medium-scale traveling ionospheric disturbance (MSTID) in the F-region. In the generation mechanism we think that Ionospheric E- and F-region coupling process is important. In this presentation, we will discuss nature of mid-latitude ionosphere based on our observations; the MU radar, sounding rocket campaigns of SEEK-1/2, and recent MSTID rocket experiment from JAXA Uchinoura Space Center in July 2013.

Analysis of ELF Radio Atmospherics Radiated by Rocket-Triggered Lightning

NASA Astrophysics Data System (ADS)

Dupree, N. A.; Moore, R. C.; Pilkey, J. T.; Uman, M. A.; Jordan, D. M.; Caicedo, J. A.; Hare, B.; Ngin, T. K.

2014-12-01

Experimental observations of ELF radio atmospherics produced by rocket-triggered lightning flashes are used to analyze Earth-ionosphere waveguide excitation and propagation characteristics. Rocket-triggered lightning experiments are performed at the International Center for Lightning Research and Testing (ICLRT) located at Camp Blanding, Florida. Long-distance ELF observations are performed in California, Greenland, and Antarctica. The lightning current waveforms directly measured at the base of the lightning channel (at the ICLRT) along with pertinent Lightning Mapping Array (LMA) data are used together with the Long Wavelength Propagation Capability (LWPC) code to predict the radio atmospheric (sferic) waveform observed at the receiver locations under various ionospheric conditions. We identify fitted exponential electron density profiles that accurately describe the observed propagation delays, phase delays, and signal amplitudes. The ability to infer ionospheric characteristics using distant ELF observations greatly enhances ionospheric remote sensing capabilities, especially in regard to interpreting observations of transient luminous events (TLEs) and other ionospheric effects associated with lightning.

Regional application of multi-layer artificial neural networks in 3-D ionosphere tomography

NASA Astrophysics Data System (ADS)

Ghaffari Razin, Mir Reza; Voosoghi, Behzad

2016-08-01

Tomography is a very cost-effective method to study physical properties of the ionosphere. In this paper, residual minimization training neural network (RMTNN) is used in voxel-based tomography to reconstruct of 3-D ionosphere electron density with high spatial resolution. For numerical experiments, observations collected at 37 GPS stations from Iranian permanent GPS network (IPGN) are used. A smoothed TEC approach was used for absolute STEC recovery. To improve the vertical resolution, empirical orthogonal functions (EOFs) obtained from international reference ionosphere 2012 (IRI-2012) used as object function in training neural network. Ionosonde observations is used for validate reliability of the proposed method. Minimum relative error for RMTNN is 1.64% and maximum relative error is 15.61%. Also root mean square error (RMSE) of 0.17 × 1011 (electrons/m3) is computed for RMTNN which is less than RMSE of IRI2012. The results show that RMTNN has higher accuracy and compiles speed than other ionosphere reconstruction methods.

Artificial ionosphere layers for pumping-wave frequencies near the fourth electron gyroharmonic in experiments at the HAARP facility

NASA Astrophysics Data System (ADS)

Grach, S. M.; Sergeev, E. N.; Shindin, A. V.; Mishin, E. V.; Watkins, B.

2014-02-01

In this paper we consider the action (in the magnetic-zenith direction) of powerful high frequency (HF) radiation of ordinary polarization on the ionosphere F region. We deal with frequencies f 0 > 4 f ce ( f ce is the electron cyclotron frequency) of 1.7 GW equivalent radiated power. This action results in the appearance in the ionosphere of an artificial ionization layer. The layer descends with respect to the basic (unperturbed) layer at a rate of ˜500 m s-1 down to the altitude, where f 0 ≈ 4 f ce .

Global variations in Magnetosphere-Ionosphere system due to Sudden Impulses under different IMF By conditions

NASA Astrophysics Data System (ADS)

Ozturk, D. S.; Zou, S.; Slavin, J. A.; Ridley, A. J.

2016-12-01

A sudden impulse (SI) event is a rapid increase in solar wind dynamic pressure, which compresses the Earth's magnetosphere from the dayside and travels towards the Earth's tail. During the SI events, compression front reconfigures the Magnetosphere-Ionosphere (MI) current systems. This compression launches fast magnetosonic waves that carry the SI through magnetosphere and Alfven waves that enhance the field-aligned currents (FACs) at high-latitudes. FAC systems can be measured by Active Magnetosphere and Polar Electrodynamics Response Experiment (AMPERE). The propagation front also creates travelling convection vortices (TCVs) in the ionosphere that map to the equatorial flank regions of the Earth's magnetosphere. The TCVs then move from dayside to the nightside ionosphere. To understand these SI-driven disturbances globally, we use the University of Michigan Space Weather Modeling Framework (SWMF) with Global Magnetosphere (GM), Inner Magnetosphere (IM) and Ionosphere (IE) modules. We study the changes in the FAC systems, which link ionospheric and magnetospheric propagating disturbances under different IMF By conditions and trace the ionospheric disturbances to magnetospheric system to better understand the connection between two systems. As shown by previous studies, IMF By can cause asymmetries in the magnetic perturbations measured by the ground magnetometers. By using model results we determine the global latitudinal and longitudinal dependencies of the SI signatures on the ground. We also use the SWMF results to drive the Global Ionosphere Thermosphere Model (GITM) to reveal how the Ionosphere-Thermosphere system is affected by the SI propagation. Comparisons are carried out between the IE model output and high latitude convection patterns from Super Dual Auroral Radar Network (SuperDARN) measurements and SuperMAG ground magnetic field perturbations. In closing we have modeled the field-aligned currents, ionospheric convection patterns, temperature and density profiles to explore the global coupling of the ionosphere to magnetosphere during SI events with different By orientation.

Investigations into the Properties, Conditions, and Effects of the Ionosphere.

DTIC Science & Technology

1988-01-15

Innovative Approaches to Direct Measurement of N e 28 ]- J FEASIBILITY OF RADIO BLACKOUT MITIGATION IN THE BRAKING PHASE 28 OF AOTV OPERATIONS 1. Brief...Cell could be tested under simulated flight conditions in the SAIC plasma laboratory facility. AJ. FEASIBILITY OF RADIO BLACKOUT MITIGATION IN THE...enable calculation of chemical modification techniques ,. on phenomena of radio blackout during re-entry of orbiting spacecraft . * ,1. Brief

A Campaign to Study Equatorial Ionospheric Phenomena over Guam

NASA Astrophysics Data System (ADS)

Habash Krause, L.; Balthazor, R.; Dearborn, M.; Enloe, L.; Lawrence, T.; McHarg, M.; Petrash, D.; Reinisch, B. W.; Stuart, T.

2007-05-01

With the development of a series of ground-based and space-based experiments, the United States Air Force Academy (USAFA) is in the process of planning a campaign to investigate the relationship between equatorial ionospheric plasma dynamics and a variety of space weather effects, including: 1) ionospheric plasma turbulence in the F region, and 2) scintillation of radio signals at low latitudes. A Digisonde Portable Sounder DPS-4 will operate from the island of Guam (with a magnetic latitude of 5.6° N) and will provide measurements of ionospheric total electron content (TEC), vertical drifts of the bulk ionospheric plasma, and electron density profiles. Additionally, a dual-frequency GPS TEC/scintillation monitor will be located along the Guam magnetic meridian at a magnetic latitude of approximately 15° N. In campaign mode, we will combine these ground-based observations with those collected from space during USAFA's FalconSAT-3 and FalconSAT-5 low-earth orbit satellite missions, the first of which is scheduled to be active over a period of several months beginning in the 2007 calendar year. The satellite experiments are designed to characterize in situ irregularities in plasma density, and include measurements of bulk ion density and temperature, minority-to- majority ion mixing ratios, small scale (10 cm to 1 m) plasma turbulence, and ion distribution spectra in energy with sufficient resolution for observations of non-thermalized distributions that may be associated with velocity- space instabilities. Specific targets of investigation include: a) a comparison of plasma turbulence observed on- orbit with spread F on ionograms as measured with the Digisonde, b) a correlation between the vertical lifting of the ionospheric layer over Guam and the onset of radio scintillation activity along the Guam meridian at 15° N magnetic latitude, and c) a correlation between on-orbit turbulence and ionospheric scintillation at 15° N magnetic latitude. These relationships may provide further clues into understanding the trigger mechanisms responsible for instigating disturbances in the ionospheric plasma, thus resulting in a turbulent radio propagation medium that may cause outages of radio based communication and navigation systems.

The INAF/IAPS Plasma Chamber for ionospheric simulation experiment

NASA Astrophysics Data System (ADS)

Diego, Piero

2016-04-01

The plasma chamber is particularly suitable to perform studies for the following applications: - plasma compatibility and functional tests on payloads envisioned to operate in the ionosphere (e.g. sensors onboard satellites, exposed to the external plasma environment); - calibration/testing of plasma diagnostic sensors; - characterization and compatibility tests on components for space applications (e.g. optical elements, harness, satellite paints, photo-voltaic cells, etc.); - experiments on satellite charging in a space plasma environment; - tests on active experiments which use ion, electron or plasma sources (ion thrusters, hollow cathodes, field effect emitters, plasma contactors, etc.); - possible studies relevant to fundamental space plasma physics. The facility consists of a large volume vacuum tank (a cylinder of length 4.5 m and diameter 1.7 m) equipped with a Kaufman type plasma source, operating with Argon gas, capable to generate a plasma beam with parameters (i.e. density and electron temperature) close to the values encountered in the ionosphere at F layer altitudes. The plasma beam (A+ ions and electrons) is accelerated into the chamber at a velocity that reproduces the relative motion between an orbiting satellite and the ionosphere (≈ 8 km/s). This feature, in particular, allows laboratory simulations of the actual compression and depletion phenomena which take place in the ram and wake regions around satellites moving through the ionosphere. The reproduced plasma environment is monitored using Langmuir Probes (LP) and Retarding Potential Analyzers (RPA). These sensors can be automatically moved within the experimental space using a sled mechanism. Such a feature allows the acquisition of the plasma parameters all around the space payload installed into the chamber for testing. The facility is currently in use to test the payloads of CSES satellite (Chinese Seismic Electromagnetic Satellite) devoted to plasma parameters and electric field measurements in a polar orbit at 500 km altitude.

Longitudinal Ionospheric Variability Observed by LITES on the ISS

NASA Astrophysics Data System (ADS)

Stephan, A. W.; Finn, S. C.; Cook, T.; Geddes, G.; Chakrabarti, S.; Budzien, S. A.

2017-12-01

The Limb-Imaging Ionospheric and Thermospheric Extreme-Ultraviolet Spectrograph (LITES) is an imaging spectrograph designed to measure altitude profiles (150-350 km) of extreme- and far-ultraviolet airglow emissions that originate from photochemical processes in the ionosphere and thermosphere. During the daytime, LITES observes the bright O+ 83.4 nm emission from which the ionospheric profile can be inferred. At night, recombination emissions at 91.1 and 135.6 nm provide a direct measure of the electron content along the line of sight. LITES was launched and installed on the International Space Station (ISS) in late February 2017 where it has been operating along with the highly complementary GPS Radio Occultation and Ultraviolet Photometry - Colocated (GROUP-C) experiment. We will present some of the first observations from LITES in April 2017 that show longitudinal patterns in ionospheric density and the daily variability in those patterns. LITES vertical imaging from a vantage point near 410 km enables a particularly unique perspective on the altitude of the ionospheric peak density at night that can complement and inform other ground- and space-based measurements, and track the longitude-altitude variability that is reflective of changes in equatorial electrodynamics.

Compensation of the Ionospheric Effects on SAR Interferogram Based on Range Split-Spectrum and Azimuth Offset Methods - a Case Study of Yushu Earthquake

NASA Astrophysics Data System (ADS)

He, Y. F.; Zhu, W.; Zhang, Q.; Zhang, W. T.

2018-04-01

InSAR technique can measure the surface deformation with the accuracy of centimeter-level or even millimeter and therefore has been widely used in the deformation monitoring associated with earthquakes, volcanoes, and other geologic process. However, ionospheric irregularities can lead to the wavy fringes in the low frequency SAR interferograms, which disturb the actual information of geophysical processes and thus put severe limitations on ground deformations measurements. In this paper, an application of two common methods, the range split-spectrum and azimuth offset methods are exploited to estimate the contributions of the ionosphere, with the aim to correct ionospheric effects in interferograms. Based on the theoretical analysis and experiment, a performance analysis is conducted to evaluate the efficiency of these two methods. The result indicates that both methods can mitigate the ionospheric effect in SAR interferograms and the range split-spectrum method is more precise than the other one. However, it is also found that the range split-spectrum is easily contaminated by the noise, and the achievable accuracy of the azimuth offset method is limited by the ambiguous integral constant, especially with the strong azimuth variations induced by the ionosphere disturbance.

Low-latitude Ionospheric Research using the CIRCE Mission

NASA Astrophysics Data System (ADS)

Dymond, K.; Nicholas, A. C.; Budzien, S. A.; Stephan, A. W.

2016-12-01

The Coordinated Ionospheric Reconstruction Cubesat Experiment (CIRCE) is a dual-satellite mission consisting of two 6U CubeSats actively maintaining a lead-follow configuration in the same orbit with a launch planned for the 2018-2019 time frame. These nano-satellites will each feature two 1U ultraviolet photometers, observing the 135.6 nm emission of atomic oxygen at nighttime. The primary objective is to characterize the two-dimensional distribution of electrons in the Equatorial Ionization Anomaly (EIA). The methodology used to reconstruct the nighttime ionosphere employs continuous UV photometry from four distinct viewing angles in combination with an additional data source, such as in situ plasma density measurements or a wide-band beacon data, with advanced image space reconstruction algorithm tomography techniques. The COSMIC/FORMOSAT-3 (CF3) constellation featured six Tiny Ionospheric Photometers, a compact UV sensor design which served as the pathfinder for the CIRCE instruments. The TIP instruments on the CF3 satellites demonstrated detection of ionospheric bubbles before they had penetrated the peak of the F-region ionosphere. We present our mission concept, simulations illustrating the imaging capability of the sensor suite, and a range of science questions addressable using such a system.

Integrated Verification Experiment data collected as part of the Los Alamos National Laboratory's Source Region Program

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fitzgerald, T.J.; Carlos, R.C.; Argo, P.E.

As part of the integrated verification experiment (IVE), we deployed a network of hf ionospheric sounders to detect the effects of acoustic waves generated by surface ground motion following underground nuclear tests at the Nevada Test Site. The network sampled up to four geographic locations in the ionosphere from almost directly overhead of the surface ground zero out to a horizontal range of 60 km. We present sample results for four of the IVEs: Misty Echo, Texarkana, Mineral Quarry, and Bexar.

Plasma Density and Electro-Magnetic Field Perturbations Hf-Induced in the Outer Ionosphere: Review of Experimental Results

NASA Astrophysics Data System (ADS)

Frolov, Vladimir; Rauch, Jean-Louis; Parrot, Michel; Rapoport, Victor; Shorokhova, Elena

In the report we consider features of plasma density and electro-magnetic field perturbations induced in the Earth’s outer ionosphere by modification of F _{2} region by O-mode powerful HF radio waves radiated by the SURA heating facility. Experiments presented were carried out in 2005 - 2010. Plasma density perturbations were detected at altitudes of about of 700 km by instruments onboard the French DEMETER satellite when it intersected the disturbed magnetic flux tube. The formation of artificial HF-induced plasma density ducts in the outer ionosphere is a central discovery, which was made during the SURA-DEMETER experiments [1,2]. Analysis of experimental data available makes it possible to formulate ducts features and point out the conditions under which the formation of such ducts takes place. 1. Under night conditions ducts are characterized by the increased plasma density in the range from 20% to 80% relatively to its background value. As this takes place, the excess in the plasma ion component is due to O (+) ions dominating at altitudes of about 700 km, whereas the densities of lower mass H (+) and He ({+) } ions typically decrease by a percentage amount that is much more the relative increase in the density of O (+) ions. The duct formation was never observed under daytime conditions. According to [3] the HF-induced ducts were observed by ionosphere pumping in morning and evening hours but in these cases their intensity was no more than a few percentages. 2. The size of the ducts along the satellite orbits is of about 80 - 100 km. It is a reason why such ducts can be observed only if the minimal distance between the satellite and the center of the heated flux tube is less than 50 km. 3. The formation of ducts is observed only if the effective radiated power is more than 40 MW. For the SURA facility, to heat the ionosphere at higher efficiency due to the “magnetic-zenith effect”, the HF beam is often inclined by 12 - 16(°) southward. 4. The pump wave frequency should be no less than 0.5 - 0.7 MHz below the F _{2} layer critical frequency f _{0F2}. In the opposed case the penetration of the radiated power behind the F _{2} ionospheric layer can take place [4]. 5. Strong variations of the electron temperature are observed inside the ducts, at the same time the ion temperature is unchanged. 6. A feature of the ducts is the presence of strong electro-magnetic field fluctuations in a frequency range from a few Hz to tens of kHz [1,5]. 7. It was revealed that the formation of the ducts in the outer ionosphere can stimulate the precipitation of energetic electrons with E ≥ 100 keV from the Earth’s radiation belts [6]. The work was supported by RFBR grants (## 12-05-00312, 13-02-12074, 13-02-12241) and by the scientific program “Geophysics”. References: 1. Rapoport V.O., V.L. Frolov, G.P. Komrakov, et al. // Radiophysics and Quantum Electronics, 2007. Vol. 50(8), p. 645. 2. Frolov V.L., V.O. Rapoport, G.P. Komrakov, et. al. // JETP Letters, 2008. Vol. 88, No. 12, p. 790. 3. Frolov V.L., I.A. Bolotin, V.O. Rapoport, et. al. // XXIV All-Russian conference “Radio Wave Propagation”. Irkutsk, 2014 (submitted for publication). 4. Frolov V.L., N.A. Mityakov, E.A. Shorokhova, M. Parrot. // Radiophysics and Quantum Electronics, 2013. Vol. 56(6), p. 325. 5. Rapoport V.O., V.L. Frolov, S.V. Polyakov, et al. // J. Geophys. Res., 2010. Vol. 115, A10322, doi:10.1029/2010JA015484. 6. Markov G.A., A.S. Belov, V.L. Frolov, et al. // JETPh, 2010. Vol. 138, No. 6(12), p. 1037.

L-Band Ionosphere Scintillations Observed by A GNSS Receiver Array at HAARP

NASA Astrophysics Data System (ADS)

Morton, Y.; Pelgrum, W.; van Graas, F.

2011-12-01

As we enter a new solar maximum period, GNSS receivers, especially the ones operating in high latitude and equatorial regions, are facing an increasing threat from ionosphere scintillations. The increased solar activities, however, also offer a great opportunity to collect scintillation data to gain better understandings of scintillation effects on GNSS signals. During the past decade, many GPS receivers have been deployed around the globe to monitor ionosphere scintillations. Most of these GPS receivers are commercial receivers whose tracking mechanisms are not designed to operate under ionosphere scintillation. When strong scintillations occur, these receivers will either generate erroneous outputs or completely lose lock. Even when the scintillation is mild, the tracking loop outputs are not true representation of the signal parameters due the tracking loop transfer function. High quality, unprocessed GNSS receiver front end raw IF samples collected during ionosphere scintillations are necessary to produce realistic scintillation signal parameter estimations. In this presentation, we will update our effort in establishing a unique GNSS receiver array at HAARP, Alaska to collect GPS and GLONASS satellite signals at various stages of the GNSS receiver processing. Signal strength, carrier phase, and relative TEC measurements generated by the receiver array as well as additional on-site diagnostic instrumentation measurements obtained from two active heating experiment campaigns conducted in 2011 will be presented. Additionally, we will also highlight and contrast the artificial heating experiment results with observations of natural scintillation events captured by our receivers using an automatic event trigger mechanism during the past year. These interesting results demonstrate the feasibility and effectiveness of our experimental data collection system in providing insightful details of ionosphere responses to active perturbations and natural disturbances.

Cross-terminator ion flow in the ionospheres of Mars and Venus

NASA Astrophysics Data System (ADS)

Fraenz, Markus; Dubinin, Eduard; Angsmann, Anne; Nielsen, Erling; Woch, Joachim; Barabash, Stas; Lundin, Rickard; Fedorov, A.

The upper ionospheres of Mars and Venus are permeated by the magnetic fields induced by the solar wind. It is a long-standing question wether these fields can put the dense ionospheric plasma into motion. If so, the cross-terminator flow of the upper ionosphere could explain a significant part of the ion escape from the planets atmospheres. But it has been technically very challenging to measure the ion flow at energies below 20eV. The only such measurements have been made by the ORPA instrument of the Pioneer Venus Orbiter reporting speeds of 1-5km/s for O+ ions at Venus above 300km altitude at the terminator (Knudsen et al, GRL 1982). At Venus the flow has been explained by the pressure gradient force between dayside and nightside. It can explain the ion supply to the nightside ionosphere. At Mars comparable measurements have never been made. We here report on new measurements of the cross-terminator ion flow at Mars by the ASPERA 3 experiment onboard Mars Express with support from the MARSIS radar experiment which confirm O+ flow speeds of around 6km/s with fluxes of 1.2 ∗ 109 /cm2 s. We also discuss the complicated influence of the spacecraft potential on low energy measurements. At Mars the nightside ionosphere is much weaker than on Venus and the escape velocity only 5km/s. This means that the observed flow leads to escape from the planet. We discuss the implication of these new observation on the total ion escape and possible extensions of the analysis to dayside observations which might allow us to infer the flow structure imposed by the induced magnetic field. We then discuss the observational situation at Venus where the ASPERA-4 instrument allows similar measurements.

ULF Generation by Modulated Ionospheric Heating

NASA Astrophysics Data System (ADS)

Chang, C.; Labenski, J.; Wallace, T.; Papadopoulos, K.

2013-12-01

Modulated ionospheric heating experiments designed to generate ULF waves using the HAARP heater have been conducted since 2007. Artificial ULF waves in the Pc1 frequency range were observed from space and by ground induction magnetometers located in the vicinity of the heater as well as at long distances. Two distinct generation mechanisms of artificial ULF waves were identified. The first was electroject modulation under geomagnetically disturbed conditions. The second was pressure modulation in the E and F regions of the ionosphere under quiet conditions. Ground detections of ULF waves near the heater included both Shear Alfven waves and Magnetosonic waves generated by electrojet and/or pressure modulations. Distant ULF detections involved Magnetosonic wave propagation in the Alfvenic duct with pressure modulation as the most likely source. Summary of our observations and theoretical interpretations will be presented at the meeting. We would like to acknowledge the support provided by the staff at the HAARP facility during our ULF experiments.

H.F. emission related to the Li+ ion beam injected into ionosphere - ``PLAZMA'' rocket experiment

NASA Astrophysics Data System (ADS)

Klos, Z.; Zbyszynski, Z.; Agafonov, U. F.; Managadze, G. G.; Mayorov, A. D.

1993-10-01

The H.F. emission generated by artificial ion beam injected into ionosphere was observed either with a wave detector and ion gun attached to the rocket through out the flight, or when the gun was deployed on subpayload. Generally the observations show unstructured shape of the H.F. spectrum. In the PLAZMA active rocket experiment - when ionospheric plasma was perturbed by the operation of impulse ion gun, which injected 300 A, 8.3 eV Li+ions - the waves in the 0.1 - 10 MHz frequency range were observed. The results have shown, that when the wave detector and the ion gun are attached to the rocket the emission enhances in the lower as well as in the upper parts of the spectrum. On the other hand only the lower increase is maintained when ion gun is removing away on the subpayload. The observed sequence of H.F. spectra is presented.

e-POP RRI provides new opportunities for space-based, high-frequency radio science experiments

NASA Astrophysics Data System (ADS)

Burrell, Angeline G.

2017-04-01

Perry et al. (2016, https://doi.org/10.1002/2017JG003855) present the first results of the Radio Receiver Instrument (RRI), a part of the enhanced Polar Outflow Probe (e-POP) that flies on board the CAScade, Smallsat and IOnospheric Polar Explorer satellite. Using a matched filter technique, e-POP RRI was able to observe individual radio pulses transmitted by a ground-based radar. These results were used to examine the temporal variations in the dispersion, polarization, and power of the pulses, demonstrating the capacity for e-POP RRI to contribute to studies of radio propagation at high-frequency (HF) ranges. Understanding radio propagation in the presence and absence of ionospheric irregularities is crucial for ionospheric physics, as well as commercial and military radio applications. Conjunctions between e-POP RRI and ground- or space-based HF transmitters offer a new opportunity for coherent scatter experiments.

Composition measurements of the topside ionosphere using a magnetic mass spectrometer, ion mass spectrometer on ISIS-2 spacecraft

NASA Technical Reports Server (NTRS)

Hoffman, J. H.

1975-01-01

The ion mass spectrometer (IMS) on the ISIS-II satellite is described; it measures the composition and distribution of positive ions in the earth's ionosphere in the mass range of 1 to 64 atomic mass units. Significant data were received which show a wide variation in ion composition at night near the equator and in the daytime poleward of the plasmapause. It was found that these data enable further study of the polar wind and that the experiment produced timely data during the August, 1972 magnetic storm to show the development of a unique ionosphere above the plasmapause during the period of the storm. The scientific objectives and results of the experiment, the technical description of the instrument, a bibliography with sample papers attached, and a summary of recommendations for further study are presented.

Catalog of ionospheric and atmospheric data

NASA Technical Reports Server (NTRS)

Liles, J. N.

1975-01-01

Available data from planetary atmospheres and ionospheric physics (aeronomy) are announced. Most of the data sets identified result from individual experiments carried on board various spacecraft. A spacecraft Automated Internal Management File and a Nonsatellite Data File are utilized to maintain information on these data. Photoreduced reports produced by these information files are presented. A variety of user oriented indexes are included.

Dynamic properties of ionospheric plasma turbulence driven by high-power high-frequency radiowaves

NASA Astrophysics Data System (ADS)

Grach, S. M.; Sergeev, E. N.; Mishin, E. V.; Shindin, A. V.

2016-11-01

A review is given of the current state-of-the-art of experimental studies and the theoretical understanding of nonlinear phenomena that occur in the ionospheric F-layer irradiated by high-power high-frequency ground-based transmitters. The main focus is on the dynamic features of high-frequency turbulence (plasma waves) and low-frequency turbulence (density irregularities of various scales) that have been studied in experiments at the Sura and HAARP heating facilities operated in temporal and frequency regimes specially designed with consideration of the characteristic properties of nonlinear processes in the perturbed ionosphere using modern radio receivers and optical instruments. Experimental results are compared with theoretical turbulence models for a magnetized collisional plasma in a high-frequency electromagnetic field, allowing the identification of the processes responsible for the observed features of artificial ionospheric turbulence.

Chemical releases in the ionosphere

NASA Technical Reports Server (NTRS)

Davis, T. N.

1979-01-01

The study of the interaction between the atmosphere, ionosphere and magnetosphere is identified as a major task worthy of pursuit. The present review demonstrates the major contributions to this complex problem already made by active experiments involving the injection of chemicals and energetic electron beams into the atmosphere, ionosphere and magnetosphere. Through the use of chemical releases, it has been possible to investigate a number of quantities including high-altitude winds and electric fields, the detailed configurations of the geomagnetic field within the ionosphere and the magnetosphere, as well as the propagation of energetic particle beams and their interaction with natural neutral and ionized constituents of the high atmosphere. So far, virtually all of this effort has been accomplished using rockets. In the future, it is obvious that satellite platforms will play a greater role, both in making injections and in observing their effects.

First demonstration of HF-driven ionospheric currents

NASA Astrophysics Data System (ADS)

Papadopoulos, K.; Chang, C.-L.; Labenski, J.; Wallace, T.

2011-10-01

The first experimental demonstration of HF driven currents in the ionosphere at low ELF/ULF frequencies without relying in the presence of electrojets is presented. The effect was predicted by theoretical/computational means in a recent letter and given the name Ionospheric Current Drive (ICD). The effect relies on modulated F-region HF heating to generate Magneto-Sonic (MS) waves that drive Hall currents when they reach the E-region. The Hall currents inject ELF waves into the Earth-Ionosphere waveguide and helicon and Shear Alfven (SA) waves in the magnetosphere. The proof-of-concept experiments were conducted using the HAARP heater in Alaska under the BRIOCHE program. Waves between 0.1-70 Hz were measured at both near and far sites. The letter discusses the differences between ICD generated waves and those relying on modulation of electrojets.

Large ionospheric disturbances produced by the HAARP HF facility

NASA Astrophysics Data System (ADS)

Bernhardt, Paul A.; Siefring, Carl L.; Briczinski, Stanley J.; McCarrick, Mike; Michell, Robert G.

2016-07-01

The enormous transmitter power, fully programmable antenna array, and agile frequency generation of the High Frequency Active Auroral Research Program (HAARP) facility in Alaska have allowed the production of unprecedented disturbances in the ionosphere. Using both pencil beams and conical (or twisted) beam transmissions, artificial ionization clouds have been generated near the second, third, fourth, and sixth harmonics of the electron gyrofrequency. The conical beam has been used to sustain these clouds for up to 5 h as opposed to less than 30 min durations produced using pencil beams. The largest density plasma clouds have been produced at the highest harmonic transmissions. Satellite radio transmissions at 253 MHz from the National Research Laboratory TACSat4 communications experiment have been severely disturbed by propagating through artificial plasma regions. The scintillation levels for UHF waves passing through artificial ionization clouds from HAARP are typically 16 dB. This is much larger than previously reported scintillations at other HF facilities which have been limited to 3 dB or less. The goals of future HAARP experiments should be to build on these discoveries to sustain plasma densities larger than that of the background ionosphere for use as ionospheric reflectors of radio signals.

Studies of High Power RF-induced Turbulence in the Ionosphere over HAARP

NASA Astrophysics Data System (ADS)

Sheerin, J. P.; Watkins, B. J.; Bristow, W. A.; Bernhardt, P. A.

2016-12-01

The HAARP phased-array HF transmitter at Gakona, AK delivers up to 3.6 GW (ERP) of HF power in the range of 2.8 - 10 MHz to the ionosphere with millisecond pointing, power modulation, and frequency agility. HAARP's unique features have enabled the conduct of a number of nonlinear plasma experiments in the interaction region of overdense ionospheric plasma including stimulated electromagnetic emissions (SEE), artificial aurora, artificial ionization layers, VLF wave-particle interactions in the magnetosphere, strong Langmuir turbulence (SLT) and suprathermal electron acceleration. Diagnostics include the Modular UHF Ionospheric Radar (MUIR) sited at HAARP, the SuperDARN-Kodiak HF radar, spacecraft radio beacons, HF receivers to record stimulated electromagnetic emissions (SEE) and telescopes and cameras for optical emissions. We report on short timescale ponderomotive overshoot effects, artificial field-aligned irregularities (AFAI), the aspect angle dependence of the intensity of the plasma line, and production of suprathermal electrons. For a narrow range of HF pointing between Spitze and magnetic zenith, a reduced threshold for AFAI is observed. Recent results of simulations of these experiments enable interpretation of many observed features. Applications are made to the study of irregularities relevant to spacecraft communication and navigation systems.

Ionospheric Coherence Bandwidth Measurements in the Lower VHF Frequency Range

NASA Astrophysics Data System (ADS)

Suszcynsky, D. M.; Light, M. E.; Pigue, M. J.

2015-12-01

The United States Department of Energy's Radio Frequency Propagation (RFProp) experiment consists of a satellite-based radio receiver suite to study various aspects of trans-ionospheric signal propagation and detection in four frequency bands, 2 - 55 MHz, 125 - 175 MHz, 365 - 415 MHz and 820 - 1100 MHz. In this paper, we present simultaneous ionospheric coherence bandwidth and S4 scintillation index measurements in the 32 - 44 MHz frequency range collected during the ESCINT equatorial scintillation experiment. 40-MHz continuous wave (CW) and 32 - 44 MHz swept frequency signals were transmitted simultaneously to the RFProp receiver suite from the Reagan Test Site at Kwajalein Atoll in the Marshall Islands (8.7° N, 167.7° E) in three separate campaigns during the 2014 and 2015 equinoxes. Results show coherence bandwidths as small as ~ 1 kHz for strong scintillation (S4 > 0.7) and indicate a high degree of ionospheric variability and irregularity on 10-m spatial scales. Spread-Doppler clutter effects arising from preferential ray paths to the satellite due to refraction off of isolated density irregularities are also observed and are dominant at low elevation angles. The results are compared to previous measurements and available scaling laws.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kosch, M.J.; Nielsen, E.

The Scandinavian Twin Auroral Radar Experiment (STARE) and Sweden and Britain Radar Experiment (SABRE) bistatic coherent radar systems have been employed to estimate the spatial and temporal variation of the ionospheric Joule heating in the combined geographic latitude range 63.8 deg - 72.6 deg (corrected geomagnetic latitude 61.5 deg - 69.3 deg) over Scandinavia. The 173 days of good observations with all four radars have been analyzed during the period 1982 to 1986 to estimate the average ionospheric electric field versus time and latitude. The AE dependent empirical model of ionospheric Pedersen conductivity of Spiro et al. (1982) has beenmore » used to calculate the Joule heating. The latitudinal and diurnal variation of Joule heating as well as the estimated mean hemispherical heating of 1.7 x 10(exp 11) W are in good agreement with earlier results. Average Joule heating was found to vary linearly with the AE, AU, and AL indices and as a second-order power law with Kp. The average Joule heating was also examined as a function of the direction and magnitude of the interplanetary magnetic field. It has been shown for the first time that the ionospheric electric field magnitude as well as the Joule heating increase with increasingly negative (southward) Bz.« less

Low-latitude ionospheric research using the CIRCE Mission: instrumentation overview

NASA Astrophysics Data System (ADS)

Dymond, K. F.; Nicholas, A. C.; Budzien, S. A.; Stephan, A. W.; Marquis, P.; Brown, C. M.; Finne, T.; Wolfram, K. D.

2017-08-01

The Coordinated Ionospheric Reconstruction Cubesat Experiment (CIRCE) is a dual-satellite mission consisting of two 6U CubeSats actively maintaining a lead-follow configuration in the same orbit with a launch planned for the 2018-2019 time-frame. These nanosatellites will each feature two 1U size ultraviolet photometers, observing the 135.6 nm emission of atomic oxygen at nighttime. The primary objective is to characterize the two-dimensional distribution of electrons in the orbital plane of the vehicles with special emphasis on studying the morphology of the Equatorial Ionization Anomaly (EIA). The methodology used to reconstruct the nighttime ionosphere employs continuous UV photometry from four distinct viewing angles in combination with an additional data source, such as in situ plasma density measurements or a wide-band beacon data, with advanced image space reconstruction algorithm tomography techniques. The COSMIC/FORMOSAT-3 (CF3) constellation featured six Tiny Ionospheric Photometers, compact UV sensors which served as the pathfinder for the CIRCE instruments. The TIP instruments on the CF3 satellites demonstrated detection of ionospheric bubbles before they had penetrated the peak of the F-region ionosphere, showed the temporal evolution of the EIA, and observed a Medium Scale Travelling Ionospheric Disturbance. We present our mission concept, some pertinent information regarding the instrument design, the results of simulations illustrating the imaging capability of the sensor suite, and a range of science questions addressable using such a system.

Global Ionospheric Modelling using Multi-GNSS: BeiDou, Galileo, GLONASS and GPS.

PubMed

Ren, Xiaodong; Zhang, Xiaohong; Xie, Weiliang; Zhang, Keke; Yuan, Yongqiang; Li, Xingxing

2016-09-15

The emergence of China's Beidou, Europe's Galileo and Russia's GLONASS satellites has multiplied the number of ionospheric piercing points (IPP) offered by GPS alone. This provides great opportunities for deriving precise global ionospheric maps (GIMs) with high resolution to improve positioning accuracy and ionospheric monitoring capabilities. In this paper, the GIM is developed based on multi-GNSS (GPS, GLONASS, BeiDou and Galileo) observations in the current multi-constellation condition. The performance and contribution of multi-GNSS for ionospheric modelling are carefully analysed and evaluated. Multi-GNSS observations of over 300 stations from the Multi-GNSS Experiment (MGEX) and International GNSS Service (IGS) networks for two months are processed. The results show that the multi-GNSS GIM products are better than those of GIM products based on GPS-only. Differential code biases (DCB) are by-products of the multi-GNSS ionosphere modelling, the corresponding standard deviations (STDs) are 0.06 ns, 0.10 ns, 0.18 ns and 0.15 ns for GPS, GLONASS, BeiDou and Galileo, respectively in satellite, and the STDs for the receiver are approximately 0.2~0.4 ns. The single-frequency precise point positioning (SF-PPP) results indicate that the ionospheric modelling accuracy of the proposed method based on multi-GNSS observations is better than that of the current dual-system GIM in specific areas.

Global Ionospheric Modelling using Multi-GNSS: BeiDou, Galileo, GLONASS and GPS

PubMed Central

Ren, Xiaodong; Zhang, Xiaohong; Xie, Weiliang; Zhang, Keke; Yuan, Yongqiang; Li, Xingxing

2016-01-01

The emergence of China’s Beidou, Europe’s Galileo and Russia’s GLONASS satellites has multiplied the number of ionospheric piercing points (IPP) offered by GPS alone. This provides great opportunities for deriving precise global ionospheric maps (GIMs) with high resolution to improve positioning accuracy and ionospheric monitoring capabilities. In this paper, the GIM is developed based on multi-GNSS (GPS, GLONASS, BeiDou and Galileo) observations in the current multi-constellation condition. The performance and contribution of multi-GNSS for ionospheric modelling are carefully analysed and evaluated. Multi-GNSS observations of over 300 stations from the Multi-GNSS Experiment (MGEX) and International GNSS Service (IGS) networks for two months are processed. The results show that the multi-GNSS GIM products are better than those of GIM products based on GPS-only. Differential code biases (DCB) are by-products of the multi-GNSS ionosphere modelling, the corresponding standard deviations (STDs) are 0.06 ns, 0.10 ns, 0.18 ns and 0.15 ns for GPS, GLONASS, BeiDou and Galileo, respectively in satellite, and the STDs for the receiver are approximately 0.2~0.4 ns. The single-frequency precise point positioning (SF-PPP) results indicate that the ionospheric modelling accuracy of the proposed method based on multi-GNSS observations is better than that of the current dual-system GIM in specific areas. PMID:27629988

Two-dimensional numerical simulation of O-mode to Z-mode conversion in the ionosphere

NASA Astrophysics Data System (ADS)

Cannon, P. D.; Honary, F.; Borisov, N.

2016-03-01

Experiments in the illumination of the F region of the ionosphere via radio frequency waves polarized in the ordinary mode (O-mode) have revealed that the magnitude of artificial heating-induced effects depends strongly on the inclination angle of the pump beam, with a greater modification to the plasma observed when the heating beam is directed close to or along the magnetic zenith direction. Numerical simulations performed using a recently developed finite-difference time-domain (FDTD) code are used to investigate the contribution of the O-mode to Z-mode conversion process to this effect. The aspect angle dependence and angular size of the radio window for which conversion of an O-mode pump wave to the Z-mode occurs is simulated for a variety of plasma density profiles including 2-D linear gradients representative of large-scale plasma depletions, density-depleted plasma ducts, and periodic field-aligned irregularities. The angular shape of the conversion window is found to be strongly influenced by the background plasma profile. If the Z-mode wave is reflected, it can propagate back toward the O-mode reflection region leading to resonant enhancement of the electric field in this region. Simulation results presented in this paper demonstrate that this process can make a significant contribution to the magnitude of electron density depletion and temperature enhancement around the resonance height and contributes to a strong dependence of the magnitude of plasma perturbation with the direction of the pump wave.

A quasi-static model of global atmospheric electricity. I - The lower atmosphere

NASA Technical Reports Server (NTRS)

Hays, P. B.; Roble, R. G.

1979-01-01

A quasi-steady model of global lower atmospheric electricity is presented. The model considers thunderstorms as dipole electric generators that can be randomly distributed in various regions and that are the only source of atmospheric electricity and includes the effects of orography and electrical coupling along geomagnetic field lines in the ionosphere and magnetosphere. The model is used to calculate the global distribution of electric potential and current for model conductivities and assumed spatial distributions of thunderstorms. Results indicate that large positive electric potentials are generated over thunderstorms and penetrate to ionospheric heights and into the conjugate hemisphere along magnetic field lines. The perturbation of the calculated electric potential and current distributions during solar flares and subsequent Forbush decreases is discussed, and future measurements of atmospheric electrical parameters and modifications of the model which would improve the agreement between calculations and measurements are suggested.

Ionospheric disturbances in Asian region of Russia during sudden stratospheric warmings

NASA Astrophysics Data System (ADS)

Kurkin, Vladimir; Chernigovskaya, Marina; Medvedeva, Irina; Orlov, Igor

This paper presents an investigation of the subauroral and mid-latitude ionosphere variations in the Asian region of Russia during stratospheric warmings in 2008, 2009 and 2010. We used the data from network of vertical and oblique-incidence sounding ionosounders of ISTP SB RAS. Irkutsk chirp-sounder (vertical incidence sounding) run every 1 minute on 24-hour basis for 30 days in winter of 2008, 2009 and 2010 to study small-scale and medium-scale distur-bances. The experiments on the radio paths Magadan-Irkutsk, Khabarovsk-Irkutsk and Norilsk -Irkutsk were conducted in order to study large-scale ionospheric disturbances. The frequency range was from 4 to 30 MHz, the sweep rate used 500 kHz/sec. To identify the stratospheric warming events the Berlin Meteorological University data (http://strat-www.met.fu-berlin.de) on stratospheric warming at standard isobaric levels and the atmospheric temperature height profiles measured by the Microwave Limb Sounder (MLS) aboard the EOS Aura spacecraft were used. The increase of wave activity in upper ionosphere over Asian region of Russia has recorded during stratospheric warmings. Spectrums of multi-scale variations were derived from the data obtained during the prolonged experiments. The analysis of experimental data has revealed the amplitudes of planetary waves in ionosphere during stratospheric warmings in 2008 and 2010 larger than ones in winter 2009 as opposed to amplitude variations of temperature in stratosphere. This work was supported by Russian Foundation for Basic Research (grant 08-05-00658).

Radar measurement of the seasonal variation in the velocity of the sunrise terminator

NASA Astrophysics Data System (ADS)

Meehan, D. H.

1990-03-01

The HF phased-array radar at Bribie Island, Australia, used to measure horizontal movements of the ionosphere, has been calibrated using the known velocity of the sunrise terminator. The seasonal variation in the velocity of the terminator has been resolved, both in magnitud and direction. The technique uses single-station ionospheric sounding, and requires the angle of arrival and Doppler shift of ionospheric echoes to be measured as the terminator passes overhead. Pfister's (1971) theorem allows calculation of the velocity of the reflecting surface. The difference between theory and experiment is less than 3 percent in speed and 2 degrees in direction on average.

DEMETER observations of manmade waves that propagate in the ionosphere

NASA Astrophysics Data System (ADS)

Parrot, Michel

2018-01-01

This paper is a review of manmade waves observed by the ionospheric satellite DEMETER. It concerns waves emitted by the ground-based VLF and ELF transmitters, by broadcasting stations, by the power line harmonic radiation, by industrial noise, and by active experiments. Examples are shown including, for the first time, the record of a wave coming from an ELF transmitter. These waves propagate upwards in the magnetosphere and they can be observed in the magnetically conjugated region of emission. Depending on their frequencies, they perturb the ionosphere and the particles in the radiation belts, and additional emissions are triggered. xml:lang="fr"

Artificial Aurora Generated by HAARP (Invited)

NASA Astrophysics Data System (ADS)

Streltsov, A. V.; Kendall, E. A.

2013-12-01

We present results from the ionospheric heating experiment conducted on March 12, 2013 at the High Frequency Active Auroral Research Program (HAARP) facility in Alaska. During the experiment HAARP transmitted X-mode 4.57 MHz waves modulated with the frequency 0.9 mHz and pointed in the direction of the magnetic zenith. The beam was focused to ~20 km spot at the altitude 100 km. The heating produces two effects: First, it generates magnetic field-aligned currents producing D and H components of the magnetic field with frequency 0.9 mHz detected by fluxgate magnetometer in Gakona. Second, the heating produced bright luminous structures in the heated region detected with the SRI telescope in 427.8 nm, 557.7 nm, 630.0 nm wavelengths. We emphasize, that for the best of our knowledge, this is the first experiment where the heating of the ionosphere with X-mode produces luminous structures in the ionosphere. We classify this luminosity as an 'artificial aurora', because it correlate with the intensity of the magnetic field-aligned currents, and such correlation is constantly seen in the natural aurora.

The Ionosphere and Ocean Altimetry

NASA Technical Reports Server (NTRS)

Lindqwister, Ulf J.

1999-01-01

The accuracy of satellite-based single-frequency radar ocean altimeters benefits from calibration of the total electron content (TEC) of the ionosphere below the satellite. Data from the global network of Global Positioning System (GPS) receivers provides timely, continuous, and globally well-distributed measurements of ionospheric electron content. We have created a daily automated process called Daily Global Ionospheric Map (Daily-GIM) whose primary purpose is to use global GPS data to provide ionospheric calibration data for the Geosat Follow-On (GFO) ocean altimeter. This process also produces an hourly time-series of global maps of the electron content of the ionosphere. This system is designed to deliver "quick-look" ionospheric calibrations within 24 hours with 90+% reliability and with a root-mean-square accuracy of 2 cm at 13.6 GHz. In addition we produce a second product within 72 hours which takes advantage of additional GPS data which were not available in time for the first process. The diagram shows an example of a comparison between TEC data from the Topographic Experiment (TOPEX) ocean altimeter and Daily-GIM. TEC are displayed in TEC units, TECU, where 5 TECU is 1 cm at 13.6 GHz. Data from a single TOPEX track is shown. Also shown is the Bent climatological model TEC for the track. Although the GFO satellite is not yet in its operational mode, we have been running Daily-GIM reliably (much better than 90%) with better than 2-cm accuracy (based on comparisons against TOPEX) for several months. When timely ephemeris files for the European Remote Sensing Satellite 2 (ERS-2) are available, daily ERS-2 altimeter ionospheric calibration files are produced. When GFO ephemeris files are made available to us, we produce GFO ionosphere calibration files. Users of these GFO ionosphere calibration files find they are a great improvement over the alternative International Reference Ionosphere 1995 (IRI-95) climatological model. In addition, the TOPEX orbit determination team at JPL has been using the global ionospheric maps to calibrate the single frequency GPS data from the TOPEX receiver, and report highly significant improvements in the ephemeris. The global ionospheric maps are delivered daily to the International GPS Service (IGS), making them available to the scientific community. Additional information is contained in the original.

An Artificial Particle Precipitation Technique Using HAARP-Generated VLF Waves

DTIC Science & Technology

2006-11-02

AFRL-VS-HA-TR-2007-1021 An Artificial Particle Precipitation Technique Using HAARP -Generated VLF Waves O o o r- Q M. J. Kosch T. Pedersen J...Artificial Particle Precipitation Technique Using HAARP Generated VLF Waves. 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 62101F...model. The frequency-time modulated VLF wave patterns have been successfully implemented at the HAARP ionospheric modification facility in Alaska

Ionospheric modification with a VLF transmitter

NASA Technical Reports Server (NTRS)

Inan, Umran S.; Rodriguez, Juan V.; Lev-Tov, S.; Oh, J.

1992-01-01

Detectable heating of the nightime D region by a 28.5 kHz signal is observed in 16 out of 144 cases with events occurring under conditions of moderate to low D region electron densities as represented by the unperturbed VLF signal levels. Three dimensional modeling of the effects of NAU heating on a probe VLF signal predicts values in general agreement with observations and suggests that maximum effects should occur under tenuous D region conditions.

HAARP 2011 Summer Student Research Campaign

DTIC Science & Technology

2012-10-16

in order to take advantage of a wide variety of background ionospheric conditions and to provide ample time for each student to investigate...The SSRC expands on the PARS Summer School by providing a significant increase in facility operational time. This has advantages in several areas...in several advantages for scheduling and conducting experiments: (1) Higher ionospheric density yields higher F-region critical frequency (foF2

Lunar ionosphere exploration method using auroral kilometric radiation

NASA Astrophysics Data System (ADS)

Goto, Yoshitaka; Fujimoto, Takamasa; Kasahara, Yoshiya; Kumamoto, Atsushi; Ono, Takayuki

2011-01-01

The evidence of a lunar ionosphere provided by radio occultation experiments performed by the Soviet spacecraft Luna 19 and 22 has been controversial for the past three decades because the observed large density is difficult to explain theoretically without magnetic shielding from the solar wind. The KAGUYA mission provided an opportunity to investigate the lunar ionosphere with another method. The natural plasma wave receiver (NPW) and waveform capture (WFC) instruments, which are subsystems of the lunar radar sounder (LRS) on board the lunar orbiter KAGUYA, frequently observe auroral kilometric radiation (AKR) propagating from the Earth. The dynamic spectra of the AKR sometimes exhibit a clear interference pattern that is caused by phase differences between direct waves and waves reflected on a lunar surface or a lunar ionosphere if it exists. It was hypothesized that the electron density profiles above the lunar surface could be evaluated by comparing the observed interference pattern with the theoretical interference patterns constructed from the profiles with ray tracing. This method provides a new approach to examining the lunar ionosphere that does not involve the conventional radio occultation technique.

Vertical and Lateral Electron Content in the Martian Ionosphere

NASA Astrophysics Data System (ADS)

Paetzold, M. P.; Peter, K.; Bird, M. K.; Häusler, B.; Tellmann, S.

2016-12-01

The radio-science experiment MaRS (Mars Express Radio Science) on the Mars Express spacecraft sounds the neutral atmosphere and ionosphere of Mars since 2004. Approximately 800 vertical profiles of the ionospheric electron density have been acquired until today. The vertical electron content (TEC) is easily computed from the vertical electron density profile by integrating along the altitude. The TEC is typically a fraction of a TEC unit (1E16 m^-2) and depends on the solar zenith angle. The magnitude of the TEC is however fully dominated by the electron density contained in the main layer M2. The contributions by the M1 layer below M2 or the topside is marginal. MaRS is using two radio frequencies for the sounding of the ionosphere. The directly observed differential Doppler from the two received frequencies is a measure of the lateral electron content that means along the ray path and perpendicular to the vertical electron density profile. Combining both the vertical electron density profile, the vertical TEC and the directly observed lateral TEC describes the lateral electron density distribution in the ionosphere.

Implementation of an Electronic Ionosonde to Monitor the Earth's Ionosphere via a Projected Column through USRP.

PubMed

Barona Mendoza, Jhon Jairo; Quiroga Ruiz, Carlos Fernando; Pinedo Jaramillo, Carlos Rafael

2017-04-25

This document illustrates the processes carried out for the construction of an ionospheric sensor or ionosonde, from a universal software radio peripheral (USRP), and its programming using GNU-Radio and MATLAB. The development involved the in-depth study of the characteristics of the ionosphere, to apply the corresponding mathematical models used in the radar-like pulse compression technique and matched filters, among others. The sensor operates by firing electromagnetic waves in a frequency sweep, which are reflected against the ionosphere and are received on its return by the receiver of the instrument, which calculates the reflection height through the signal offset. From this information and a series of calculations, the electron density of the terrestrial ionosphere could be obtained. Improving the SNR of received echoes reduces the transmission power to a maximum of 400 W. The resolution associated with the bandwidth of the signal used is approximately 5 km, but this can be improved, taking advantage of the fact that the daughterboards used in the USRP allow a higher sampling frequency than the one used in the design of this experiment.

Feasibility of Coherent and Incoherent Backscatter Experiments from the AMPS Laboratory. Technical Section

NASA Technical Reports Server (NTRS)

Mozer, F. S.

1976-01-01

A computer program simulated the spectrum which resulted when a radar signal was transmitted into the ionosphere for a finite time and received for an equal finite interval. The spectrum derived from this signal is statistical in nature because the signal is scattered from the ionosphere, which is statistical in nature. Many estimates of any property of the ionosphere can be made. Their average value will approach the average property of the ionosphere which is being measured. Due to the statistical nature of the spectrum itself, the estimators will vary about this average. The square root of the variance about this average is called the standard deviation, an estimate of the error which exists in any particular radar measurement. In order to determine the feasibility of the space shuttle radar, the magnitude of these errors for measurements of physical interest must be understood.

The nighttime ionosphere of Mars from Mars-4 and Mars-5 radio occultation dual-frequency measurements

NASA Technical Reports Server (NTRS)

Savich, N. A.; Samovol, V. A.; Vasilyev, M. B.; Vyshlov, A. S.; Samoznaev, L. N.; Sidorenko, A. I.; Shtern, D. Y.

1976-01-01

Dual frequency radio sounding of the Martian nighttime ionosphere was carried out during the exits from behind the planet of the Mars-4 spacecraft on February 2, 1974 and the Mars-5 spacecraft on February 18, 1974. In these experiments, the spacecraft transmitter emitted two coherent monochromatic signals in decimeter and centimeter wavelength ranges. At the Earth receiving station, the reduced phase difference (or frequencies) of these signals was measured. The nighttime ionosphere of Mars measured in both cases had a peak electron density of approximately 5 X 1,000/cu cm at an altitude of 110 to 130 km. At the times of spacecraft exit, the solar zenith angles at the point of occultation were 127 deg and 106 deg, respectively. The height profiles of electron concentration were obtained assuming spherical symmetry of the Martian ionosphere.

Wide-field LOFAR-LBA power-spectra analyses: Impact of calibration, polarization leakage and ionosphere

NASA Astrophysics Data System (ADS)

Gehlot, Bharat K.; Koopmans, Léon V. E.

2018-05-01

Contamination due to foregrounds, calibration errors and ionospheric effects pose major challenges in detection of the cosmic 21 cm signal in various Epoch of Reionization (EoR) experiments. We present the results of a study of a field centered on 3C196 using LOFAR Low Band observations, where we quantify various wide field and calibration effects such as gain errors, polarized foregrounds, and ionospheric effects. We observe a `pitchfork' structure in the power spectrum of the polarized intensity in delay-baseline space, which leaks into the modes beyond the instrumental horizon. We show that this structure arises due to strong instrumental polarization leakage (~30%) towards Cas A which is far away from primary field of view. We measure a small ionospheric diffractive scale towards CasA resembling pure Kolmogorov turbulence. Our work provides insights in understanding the nature of aforementioned effects and mitigating them in future Cosmic Dawn observations.

Ionosphere of Venus - First observations of day-night variations of the ion composition

NASA Technical Reports Server (NTRS)

Taylor, H. A., Jr.; Brinton, H. C.; Bauer, S. J.; Hartle, R. E.; Cloutier, P. A.; Daniell, R. E., Jr.; Donahue, T. M.

1979-01-01

Preliminary observations of day-night variations in the ion composition of the ionosphere of Venus, obtained by the Pioneer Venus Orbiter ion mass spectrometer experiment, are reported. A remarkable abundance and extent of ionization in the deep regions of the nightside ionosphere was observed, in spite of the long Venus night. A comparison of dayside and nightside ion distributions reveals a nightside composition similar in several respects to that of the dayside, with the ions O(+) and O2(+) forming the nightside F 2 and F 1 regions, respectively, as in the dayside. Important differences include a greater abundance of low-latitude ionization in the nightside, a significant increase of H(+) and NO(+) ions with increasing solar zenith angle, and extreme dynamic variability of the nightside region above 160 km. Ion composition data support the view that the nightside ionosphere can be maintained by the transport of ionization from the dayside.

Faraday Rotation of Automatic Dependent Surveillance-Broadcast (ADS-B) Signals as a Method of Ionospheric Characterization

NASA Astrophysics Data System (ADS)

Cushley, A. C.; Kabin, K.; Noël, J.-M.

2017-10-01

Radio waves propagating through plasma in the Earth's ambient magnetic field experience Faraday rotation; the plane of the electric field of a linearly polarized wave changes as a function of the distance travelled through a plasma. Linearly polarized radio waves at 1090 MHz frequency are emitted by Automatic Dependent Surveillance Broadcast (ADS-B) devices that are installed on most commercial aircraft. These radio waves can be detected by satellites in low Earth orbits, and the change of the polarization angle caused by propagation through the terrestrial ionosphere can be measured. In this manuscript we discuss how these measurements can be used to characterize the ionospheric conditions. In the present study, we compute the amount of Faraday rotation from a prescribed total electron content value and two of the profile parameters of the NeQuick ionospheric model.

Ionospheric E-Region Response to Solar-Geomagnetic Storms Observed by TIMED/SABER and Application to IRI Storm-Model Development

NASA Technical Reports Server (NTRS)

Mertens, Christopher J.; Mast, Jeffrey C.; Winick, Jeremy R.; Russell, James M., III; Mlynczak, Martin G.; Evans, David S.

2007-01-01

The large thermospheric infrared radiance enhancements observed from the TIMED/SABER experiment during recent solar storms provide an exciting opportunity to study the influence of solar-geomagnetic disturbances on the upper atmosphere and ionosphere. In particular, nighttime enhancements of 4.3 um emission, due to vibrational excitation and radiative emission by NO+, provide an excellent proxy to study and analyze the response of the ionospheric E-region to auroral electron dosing and storm-time enhancements to the E-region electron density. In this paper we give a status report of on-going work on model and data analysis methodologies of deriving NO+ 4.3 um volume emission rates, a proxy for the storm-time E-region response, and the approach for deriving an empirical storm-time correction to International Reference Ionosphere (IRI) E-region NO+ and electron densities.

Generation of whistler waves by continuous HF heating of the upper ionosphere

NASA Astrophysics Data System (ADS)

Vartanyan, A.; Milikh, G. M.; Eliasson, B. E.; Sharma, A.; Chang, C.; Parrot, M.; Papadopoulos, K.

2013-12-01

We report observations of VLF waves by the DEMETER satellite overflying the HAARP facility during ionospheric heating experiments. The detected VLF waves were in the range 8-17 kHz and coincided with times of continuous heating. The experiments indicate whistler generation due to conversion of artificial lower hybrid waves to whistlers on small scale field-aligned plasma density striations. The observations are compared with theoretical models, taking into account both linear and nonlinear processes. Implications of the mode conversion technique on VLF generation with subsequent injection into the radiation belts to trigger particle precipitation are discussed.

A rocket radiobeacon experiment on the electron concentration profile measurements in the bottomside of the ionosphere

NASA Astrophysics Data System (ADS)

Sinelnikov, V. M.; Lvova, G. P.; Guliaeva, T. L.; Pakhomov, S. V.; Glotov, A. P.

The possibility of measuring the electron density profile in the height interval 70-110 km with a two-frequency coherent transmitter set mounted on a 'small' geophysical rocket of type M-100 is investigated. Results are presented of measurements using the phase Doppler method carried out at middle latitudes in May 1979 and February 1980. Good consistency of the profiles measured for the D and E regions of the ionosphere with those of IRI is not always obtained, even when the correct helio and geophysic conditions of the experiments are given for calculations with IRI.

First results from the ionospheric tomography experiment using beacon TEC data obtained by means of a network along a longitude of 136°E over Japan

NASA Astrophysics Data System (ADS)

Thampi, Smitha V.; Yamamoto, Mamoru

2010-03-01

A chain of newly designed GNU (GNU is not UNIX) Radio Beacon Receivers (GRBR) has recently been established over Japan, primarily for tomographic imaging of the ionosphere over this region. Receivers installed at Shionomisaki (33.45°N, 135.8°E), Shigaraki (34.8°N, 136.1°E), and Fukui (36°N, 136°E) continuously track low earth orbiting satellites (LEOS), mainly OSCAR, Cosmos, and FORMOSAT-3/COSMIC, to obtain simultaneous total electron content (TEC) data from these three locations, which are then used for the tomographic reconstruction of ionospheric electron densities. This is the first GRBR network established for TEC observations, and the first beacon-based tomographic imaging in Japanese longitudes. The first tomographic images revealed the temporal evolution with all of the major features in the ionospheric electron density distribution over Japan. A comparison of the tomographically reconstructed electron densities with the ƒ o F 2 data from Kokubunji (35°N, 139°E) revealed that there was good agreement between the datasets. These first results show the potential of GRBR and its network for making continuous, unattended ionospheric TEC measurements and for tomographic imaging of the ionosphere.

Theory of HF induced turbulence in the ionosphere: Status and challenges

NASA Astrophysics Data System (ADS)

Dubois, D. F.

In the past five years the combination of new theoretical concepts and computer simulations along with dramatically improved observational diagnostics appear to have led to a detailed, quantitative, understanding of the properties of the Langmuir turbulence induced in the unpreconditioned ionosphere at Arecibo during the first tens of milliseconds following the turn-on of the HF heater. This is the only observational regime in which the initial ionospheric conditions are known to a high level of confidence. The so called strong Langmuir turbulence (SLT) theory predicts observed features in this early time heating which are completely at odds with the prediction of the traditional weak turbulence approximation. The understanding of the observed signatures for times greater than say 30-50 ms following the onset of heating at Arecibo is still incomplete. The same is apparently true for the observations at Tromso where the unique predictions of SLT theory are not so clearly observed. Density irregularities, induced by heating at Arecibo and perhaps present in the ambient ionosphere at Tromso, appear to control the properties of the turbulence. The proper description of the coexistence of Langmuir turbulence with various density irregularities and accounting for the turbulent modification of the electron velocity distribution are challenges for the theory. In this paper the author reviews, starting from the Vlasov-Poisson equations, the fundamental basis of the reduced models used to describe SLT and suggest improvements to the standard model including a new local quasi linear theory for the treatment of hot electron acceleration and transit time damping or burnout of collapsing Langmuir cavitons.

Ionospheric Effects from the superbolid exploded over the Chelyabinsk area

NASA Astrophysics Data System (ADS)

Ruzhin, Yuri; Smirnov, Vladimir; Kuznetsov, Vladimir; Smirnova, Elena

The Chelyabinsk meteorite fall is undoubtedly the most documented in history. Its passage through the atmosphere was recorded by video and photographers, visual observers, infrasonic microphones, seismographs on the ground, and by satellites in orbit. The data of transionospheric sounding by signals from the GPS cluster satellites carried out in the zone of explosion of the Chelyabinsk meteoroid have been analyzed. The analysis has shown that the explosion had a very weak effect on the ionosphere. The observed ionospheric disturbances were asymmetric with respect to the explosion epicenter. The signals obtained were compared both in shape and in amplitude with the known surface explosions for which the diagnostics of the ionospheric effects had been made by radio techniques. Ionospheric effects in the form of acoustic-gravity waves (AGW) produced by 500-600 tons TNT explosions on the ground are detected with confidence both by vertical sounding and by GPS techniques. This allows us to suggest that the reported equivalent of the meteoroid explosion was obviously overestimated. The experiments on the injection of barium vapor (3.3 kg) carried out under similar conditions in the terminator zone revealed the response of the ionosphere in variations of the critical frequencies of the layer at a distance of 1500-2000 km (AGW with a period of 5-10 min). The absence of such ionospheric effects in the remote zone at 1500-1700 km from the epicenter of the bolide explosion in the case under discussion also makes us feel doubtful about the estimated explosion equivalent.

The impact of GPS receiver modifications and ionospheric activity on Swarm baseline determination

NASA Astrophysics Data System (ADS)

Mao, X.; Visser, P. N. A. M.; van den IJssel, J.

2018-05-01

The European Space Agency (ESA) Swarm mission is a satellite constellation launched on 22 November 2013 aiming at observing the Earth geomagnetic field and its temporal variations. The three identical satellites are equipped with high-precision dual-frequency Global Positioning System (GPS) receivers, which make the constellation an ideal test bed for baseline determination. From October 2014 to August 2016, a number of GPS receiver modifications and a new GPS Receiver Independent Exchange Format (RINEX) converter were implemented. Moreover, the on-board GPS receiver performance has been influenced by the ionospheric scintillations. The impact of these factors is assessed for baseline determination of the pendulum formation flying Swarm-A and -C satellites. In total 30 months of data - from 15 July 2014 to the end of 2016 - is analyzed. The assessment includes analysis of observation residuals, success rate of GPS carrier phase ambiguity fixing, a consistency check between the so-called kinematic and reduced-dynamic baseline solution, and validations of orbits by comparing with Satellite Laser Ranging (SLR) observations. External baseline solutions from The German Space Operations Center (GSOC) and Astronomisches Institut - Universität Bern (AIUB) are also included in the comparison. Results indicate that the GPS receiver modifications and RINEX converter changes are effective to improve the baseline determination. This research eventually shows a consistency level of 9.3/4.9/3.0 mm between kinematic and reduced-dynamic baselines in the radial/along-track/cross-track directions. On average 98.3% of the epochs have kinematic solutions. Consistency between TU Delft and external reduced-dynamic baseline solutions is at a level of 1 mm level in all directions.

Saving a Unique Data Set for Space Weather Research

NASA Astrophysics Data System (ADS)

Bilitza, D.; Benson, R. F.; Reinisch, B. W.; Huang, X. A.

2017-12-01

The Canadian/US International Satellites for Ionospheric Studies (ISIS) program included the four satellites Alouette 1 and 2, ISIS 1 and 2 launched in 1962, 1965, 1969, and 1971, respectively and in operation for 10, 10, 21, and 19 years, respectively. The core experiment on these satellites was a topside sounder that could determine the ionospheric electron density from the orbit altitude down to about 250-500 km near where the ionosphere reaches its point of highest density, the F-peak. The mission was long lasting and highly successful, producing a wealth of information about the topside ionosphere in the form of analog ionosphere soundings on 7-track tapes. The analysis process required a tedious manual scaling of ionogram traces that could then, with appropriate software, be converted into electron density profiles. Even with the combined effort involving ionospheric groups from many countries only a relatively small percentage of the huge volume of recorded ionograms could be converted to electron density profiles. Even with this limited number significant new insights were achieved documented by the many Alouette/ISIS-related papers published in the 1960s and 1970s. Recognizing the importance of this unique data set for space weather research a new effort was undertaken in the late Nineties to analyze more of the Alouette/ISIS ionograms. The immediate cause for action was the threat to the more than 100,000 analog telemetry tapes in storage in Canada because of space limitations and storage costs. We were able to have nearly 20,000 tapes shipped to the NASA Goddard Space Flight Center for analog-to-digital conversion and succeeded in developing software that automatically scales and converts the ionograms to electron density profiles. This rescue effort is still ongoing and has already produced a significant increase in the information available for the topside ionosphere and has resulted in numerous publications. The data have led to improvements of the representation of the topside ionosphere in the International Reference Ionosphere (IRI) the international standard for the ionosphere. The data are of particular interest for studying the effects of ionospheric storms on topside profiles and, together with newer data, for studying the solar cycle and long-term variations of the ionospheric topside.

Propagation of beam-driven VLF waves from the ionosphere toward the ground

NASA Technical Reports Server (NTRS)

Schriver, David; Sotnikov, Vladimir I.; Ashour-Abdalla, Maha; Ernstmeyer, James

1995-01-01

As part of the Cooperative High Altitude Rocket Gun Experiment (CHARGE-2B) rocket mission, an electron beam was injected into the ionosphere with a modulated beam current in an effort to generate very low frequency (VLF) waves. The propagation of the beam-driven VLF waves through the ionosphere is examined here to determine whether it is possible to detect these wave emissions with ground receivers. The paths of the VLF waves from where they were generated near the rocket were followed to the bottom of the ionosphere and the decrease in wave amplitude due to wave-particle resonance and collisional damping was calculated. It was found that due to collisional damping, which for these VLF waves becomes large at altitudes below about 150 km, wave amplitudes were decreased below the background atmospheric noise level. A number of different beam injection events have been examined and in all of these cases studied the waves were sufficiently damped such that detection on the ground would not be possible. This is in agreement with observations on the ground in which no wave emissions were observed during the CHARGE-2B mission. Control parameters that would be more favorable for beam-generated VLF propagation to the ground are discussed for future experiments of this type.

Multi-angle Spectra Evolution of Langmuir Turbulence Excited by RF Ionospheric Interactions at HAARP

NASA Astrophysics Data System (ADS)

Sheerin, J. P.; Rayyan, N.; Watkins, B. J.; Bristow, W. A.; Spaleta, J.; Watanabe, N.; Golkowski, M.; Bernhardt, P. A.

2013-12-01

The high power HAARP HF transmitter is employed to generate and study strong Langmuir turbulence (SLT) in the interaction region of overdense ionospheric plasma. Diagnostics included the Modular UHF Ionospheric Radar (MUIR) sited at HAARP, the SuperDARN-Kodiak HF radar, and HF receivers to record stimulated electromagnetic emissions (SEE). Dependence of diagnostic signals on HAARP HF parameters, including pulselength, duty-cycle, aspect angle, and frequency were recorded. Short pulse, low duty cycle experiments demonstrate control of artificial field-aligned irregularities (AFAI) and isolation of ponderomotive effects. Among the effects observed and studied are: SLT spectra including cascade, collapse, and co-existence spectra and an outshifted plasma line under certain ionospheric conditions. High time resolution studies of the temporal evolution of the plasma line reveal the appearance of an overshoot effect on ponderomotive timescales. Bursty turbulence is observed in the collapse and cascade lines. For the first time, simultaneous multi-angle radar measurements of plasma line spectra are recorded demonstrating marked dependence on aspect angle with the strongest interaction region observed displaced southward of the HF zenith pointing angle. Numerous measurements of the outshifted plasma line are observed. Experimental results are compared to previous high latitude experiments and predictions from recent modeling efforts.

Cold Ion Escape from Mars

NASA Astrophysics Data System (ADS)

Fränz, M.; Dubinin, E.; Wei, Y.; Morgan, D.; Andrews, D.; Barabash, S.; Lundin, R.; Fedorov, A.

2013-09-01

It has always been challenging to observe the flux of ions with energies of less than 10eV escaping from the planetary ionospheres. We here report on new measurements of the ionospheric ion flows at Mars by the ASPERA-3 experiment on board Mars Express in combination with the MARSIS radar experiment. We first compare calculations of the mean ion flux observed by ASPERA-3 alone with previously published results. We then combine observations of the cold ion velocity by ASPERA-3 with observations of the cold plasma density by MARSIS since ASPERA-3 misses the cold core of the ion distribution. We show that the mean density of the nightside plasma observed by MARSIS is about two orders higher than observed by ASPERA-3 (Fig.1). Combining both datasets we show that the main escape channel is along the shadow boundary on the tailside of Mars (Fig. 2). At a distance of about 0.5 R_M the flux settles at a constant value (Fig. 3) which indicates that about half of the transterminator ionospheric flow escapes from the planet. Possible mechanism to generate this flux can be the ionospheric pressure gradient between dayside and nightside or momentum transfer from the solar wind via the induced magnetic field since the flow velocity is in the Alfvénic regime.

VLF wave generation by beating of two HF waves in the ionosphere

NASA Astrophysics Data System (ADS)

Kuo, Spencer; Snyder, Arnold; Kossey, Paul; Chang, Chia-Lie; Labenski, John

2011-05-01

Theory of a beat-wave mechanism for very low frequency (VLF) wave generation in the ionosphere is presented. The VLF current is produced by beating two high power HF waves of slightly different frequencies through the nonlinearity and inhomogeneity of the ionospheric plasma. Theory also shows that the density irregularities can enhance the beat-wave generation. An experiment was conducted by transmitting two high power HF waves of 3.2 MHz and 3.2 MHz + f, where f = 5, 8, 13, and 2.02 kHz, from the HAARP transmitter. In the experiment, the ionosphere was underdense to the O-mode heater, i.e., the heater frequency f0 > foF2, and overdense or slightly underdense to the X-mode heater, i.e., f0 < fxF2 or f0 ≥ fxF2. The radiation intensity increased with the VLF wave frequency, was much stronger with the X-mode heaters, and was not sensitive to the electrojet. The strongest VLF radiation of 13 kHz was generated when the reflection layer of the X-mode heater was just slightly below the foF2 layer and the spread of the O-mode sounding echoes had the largest enhancement, suggesting an optimal setting for beat-wave generation of VLF waves by the HF heaters.

A sporadic third layer in the ionosphere of Mars.

PubMed

Pätzold, M; Tellmann, S; Häusler, B; Hinson, D; Schaa, R; Tyler, G L

2005-11-04

The daytime martian ionosphere has been observed as a two-layer structure with electron densities that peak at altitudes between about 110 and 130 kilometers. The Mars Express Orbiter Radio Science Experiment on the European Mars Express spacecraft observed, in 10 out of 120 electron density profiles, a third ionospheric layer at altitude ranges of 65 to 110 kilometers, where electron densities, on average, peaked at 0.8 x 10(10) per cubic meter. Such a layer has been predicted to be permanent and continuous. Its origin has been attributed to ablation of meteors and charge exchange of magnesium and iron. Our observations imply that this layer is present sporadically and locally.

The Effects of Magnetic Anomalies Discovered at Mars on the Structure of the Martian Ionosphere and the Solar Wind Interaction as Follows from Radio Occultation Experiments

NASA Technical Reports Server (NTRS)

Ness, N. F.; Acuna, M. H.; Connerney, J. E. P.; Cloutier, P.; Kliore, A. J.; Breus, T. K.; Krymskii, A. M.; Bauer, S. J.

1999-01-01

The electron density distribution in the ionosphere of nonmagnetic (or weakly magnetized) planet depends not only on the solar ultraviolet intensity, but also on the nature of the SW interaction with this planet. Two scenarios previously have been developed based on the observations of the bow shock crossings and on the electron density distribution within the ionosphere. According to one of them Mars has an intrinsic magnetosphere produced by a dipole magnetic field and the Martian ionosphere is protected from the SW flow except during "overpressure conditions, when the planetary magnetic field can not balance the SW dynamic pressure. In the second scenario the Martian intrinsic magnetic dipole field is so weak that Mars has mainly an induced magnetosphere and a Venus-like SW/ionosphere interaction. Today the possible existence of a sufficiently strong global magnetic field that participates in the SW/Mars interaction can no longer be supported. The results obtained by the Mars-Global-Surveyor (MGS) space-craft show the existence of highly variable, but also very localized magnetic fields of crustal origin at Mars as high as 400-1500 nT. The absence of the large-scale global magnetic field at Mars makes it similar to Venus, except for possible effects of the magnetic anomalies associated with the remnant crustal magnetization. However the previous results on the Martian ionosphere obtained mainly by the radio occultation methods show that there appears to be a permanent existence of a global horizontal magnetic field in the Martian ionosphere. Moreover the global induced magnetic field in the Venus ionosphere is not typical at the solar zenith angles explored by the radio occultation methods. Additional information is contained in the original extended abstract.

Waves in the middle and upper atmosphere of Mars as seen by the Radio Science Experiment MaRS on Mars Express

NASA Astrophysics Data System (ADS)

Tellmann, S.; Paetzold, M.; Häusler, B.; Hinson, D. P.; Peter, K.; Tyler, G. L.

2017-12-01

Atmospheric waves play a crucial role in the Martian atmosphere. They are responsible for the redistribution of momentum, energy and dust and for the coupling of the different atmospheric regions on Mars. Almost all kinds of waves have been observed in the lower atmosphere (e.g. stationary and transient waves, baroclinic waves as well as migrating and non-migrating thermal tides, gravity waves, etc...). Atmospheric waves are also known to exist in the middle atmosphere of Mars ( 70-120 km, e.g. by the SPICAM instrument on Mars Express). In the thermosphere, thermal tides have been observed e.g. by radio occultation or accelerometer measurements on MGS. Recently, the NGIMS instrument on MAVEN reported gravity waves in the thermosphere of Mars. Radio Science profiles from the Mars Express Radio Science experiment MaRS on Mars Express can analyse the temperature, pressure and neutral number density profiles in the lower atmosphere (from a few hundred metres above the surface up to 40-50 km) and electron density profiles in the ionosphere of Mars. Wavelike structures have been detected below the main ionospheric layers (M1 & M2) and in the topside of the ionosphere. The two coherent frequencies of the MaRS experiment allow to discriminate between plasma density fluctuations in the ionosphere and Doppler related frequency shifts caused by spacecraft movement. A careful analysis of the observed electron density fluctuations in combination with sensitivity studies of the radio occultation technique will be used to classify the observed fluctuations. The MaRS experiment is funded by DLR under grant 50QM1401.

Waves in the middle and upper atmosphere of Mars as seen by the Radio Science Experiment MaRS on Mars Express

NASA Astrophysics Data System (ADS)

Tellmann, Silvia Anna; Paetzold, Martin; Häusler, Bernd; Hinson, David P.; Peter, Kerstin; Tyler, G. Leonard

2017-10-01

Atmospheric waves play a crucial role for the dynamics in the Martian atmosphere. They are responsible for the redistribution of momentum, energy and dust and the coupling of the different atmospheric regions on Mars.Almost all kinds of waves have been observed in the lower atmosphere (e.g. stationary and transient waves, baroclinic waves as well as migrating and non-migrating thermal tides, and gravity waves). Atmospheric waves are also known to exist in the middle atmosphere of Mars (~70-120 km, e.g. by the SPICAM instrument on Mars Express). In the thermosphere, thermal tides have been observed e.g. by radio occultation or accelerometer measurements on MGS. Recently, the NGIMS instrument on MAVEN reported gravity waves in the thermosphere of Mars.Radio Science profiles from the Mars Express Radio Science experiment MaRS on Mars Express can analyse the temperature, pressure and neutral number density profiles in the lower atmosphere (from a few hundred metres above the surface up to ~ 40-50 km) and electron density profiles in the ionosphere of Mars.Wavelike structures have been detected below the main ionospheric layers (M1 & M2) and in the topside of the ionosphere. The two coherent frequencies of the MaRS experiment allow to discriminate between plasma density fluctuations in the ionosphere and Doppler related frequency shifts caused by spacecraft movement.A careful analysis of the observed electron density fluctuations in combination with sensitivity studies of the radio occultation technique will be used to classify the observed fluctuations.The MaRS experiment is funded by DLR under grant 50QM1401.

The photoelectron-driven polar wind: Coupled fluid- semikinetic simulations and measurements by the thermal ion dynamics experiment on the POLAR spacecraft

NASA Astrophysics Data System (ADS)

Su, Yi-Jiun

1998-11-01

The polar wind is an ambipolar outflow of thermal plasma from the terrestrial high latitude ionosphere to the magnetosphere along geomagnetic field lines. This dissertation comprises a simulation and data analysis investigation of the polar wind from the ionosphere to the magnetosphere. In order to study the transport of ionospheric plasma from the collisional lower ionosphere to the collisionless magnetosphere, a self-consistent steady state coupled fluid-semikinetic model has been developed, which incorporates photoelectron and magnetospheric plasma effects. In applying this treatment to the simulation of the photoelectron-driven polar wind, an electric potential layer of the order of 40 Volts which develops above 3 RE altitude is obtained, when the downward magnetospheric electron fluxes are insufficient to balance the ionospheric photoelectron flux. This potential layer accelerates the ionospheric ions to supersonic speeds at high altitudes, but not at low altitudes (as some previous theories have suggested). In order to experimentally investigate the polar wind, low-energy ion data obtained by the Thermal Ion Dynamics Experiment (TIDE) on the POLAR satellite has been analyzed. A survey of the polar wind characteristics as observed by TIDE at 5000 km and 8 RE altitudes is presented in this dissertation. At 5000 km altitude, the H+ polar wind exhibited a supersonic outflow, while O+ displayed subsonic downflow. Dramatic decreases of the 5000 km H+ and O+ ion densities and fluxes correlated with increasing solar zenith angle for the ionospheric base, which is consistent with solar illumination ionization control of the 5000 km ion densities. However, the polar cap downward O+ flow and the density declined from dayside to nightside, which is also consistent with a cleft ion fountain origin for the polar cap O+. At 8 RE altitude, both H+ and O+ outflows were supersonic, and H+ was the dominant ion species. The typical velocity ratios, VO+:VHe+:VH+~2:3:5, may suggest transport processes which result in comparable energy gains, such as electric potential layer produced by photoelectron effects.

Ionospheric Modification from Under-Dense Heating by High-Power HF Transmitter

DTIC Science & Technology

2011-03-03

Auroral Research Program ( HAARP ) is a HF transmitter, which delivers 0.36 to 3.6 GW effective isotropic radiated powers (F.IRP) for the radiation...dense heating, the EIRP of the HAARP heater can be increased significantly by increasing the heater frequency. With higher heater frequency, the loss...1304 local time) and on 13 April from 0812 to 0844 UTC (0012 to 0044 local time), using the HAARP transmitter facility at Gakona, AK, at full power

Nonlinear mixing of electromagnetic waves in plasmas.

PubMed

Stefan, V; Cohen, B I; Joshi, C

1989-01-27

Recently, a strong research effort has been focused on applications of beat waves in plasma interactions. This research has important implications for various aspects of plasma physics and plasma technology. This article reviews the present status of the field and comments on plasma probing, heating of magnetically confined and laser plasmas, ionospheric plasma modification, beat-wave particle acceleration, beat-wave current drive in toroidal devices, beat wave-driven free-electron lasers, and phase conjugation with beat waves.

Cold Ion Escape from the Martian Ionosphere

NASA Astrophysics Data System (ADS)

Fränz, M.; Dubinin, E.; Wei, Y.; Woch, J.; Morgan, D.; Barabash, S.; Fedorov, A.

2012-09-01

It has always been challenging to observe the flux of ions with energies of less than 10eV escaping from the planetary ionospheres. We here report on new measurements of the ionospheric ion flows at Mars by the ASPERA-3 experiment on board Mars Express. We first use support from the MARSIS radar experiment for some orbits with fortunate observation geometry. Here we have observed a transterminator flow of O+ and O+ 2 ions with a super-sonic velocity of around 5km/s and fluxes of 0.8 · 109/cm2s. If we assume a symmetric flux around the terminator this corresponds to an ion flow of 3.1 ± 0.5 × 1025/s half of which is expected to escape from Mars (Fraenz et al, 2010). This escape flux is significantly higher than previously observed on the tailside of Mars, we discuss possible reasons for the difference. Since 2008 the MARSIS radar does nightside local plasma density measurement which often coincide with ASPERA-3 measurements. In a new analysis of the combined nightside datasets (Fig. 1) we show that the main escape channel is along the shadow boundary on the tailside of Mars. At a distance of about 0.5 R_M the flux settles at a constant value (Fig. 2) which indicates that about half of the transterminator ionospheric flow escapes from the planet. Possible mechanism to generate this flux can be the ionospheric pressure gradient between dayside and nightside or momentum transfer from the solar wind via the induced magnetic field since the flow velocity is in the Alfvénic regime.

Cold Ion Escape from the Martian Ionosphere

NASA Astrophysics Data System (ADS)

Fränz, Markus; Dubinin, Eduard; Wei, Yong; Morgan, David; Barabash, Stas; Lundin, Rickard; Fedorov, Andrei

2013-04-01

It has always been challenging to observe the flux of ions with energies of less than 10eV escaping from the planetary ionospheres. We here report on new measurements of the ionospheric ion flows at Mars by the ASPERA-3 experiment on board Mars Express. We first use support from the MARSIS radar experiment for some orbits with fortunate observation geometry. Here we have observed a transterminator flow of O+ and O2+ ions with a super-sonic velocity of around 5km/s and fluxes of 0.8 ? 109/cm2s. If we assume a symmetric flux around the terminator this corresponds to an ion flow of 3.1 ± 0.5 × 1025-s half of which is expected to escape from Mars (Fraenz et al, Plan.Space Sci., 2010). This escape flux is significantly higher than previously observed on the tailside of Mars, we discuss possible reasons for the difference. Since 2008 the MARSIS radar does nightside local plasma density measurements which often coincide with ASPERA-3 measurements. In a new analysis of the combined nightside datasets we show that the main escape channel is along the shadow boundary on the tailside of Mars. At a distance of half a Martian radius the flux settles at a constant value which indicates that about half of the transterminator ionospheric flow escapes from the planet. Possible mechanism to generate this flux can be the ionospheric pressure gradient between dayside and nightside or momentum transfer from the solar wind via the induced magnetic field since the flow velocity is in the Alfvénic regime.

Nonlinear Plasma Experiments in Geospace with Gigawatts of RF Power at HAARP

NASA Astrophysics Data System (ADS)

Sheerin, J. P.; Rayyan, N.; Watkins, B. J.; Bristow, W. A.; Bernhardt, P. A.

2014-10-01

The HAARP phased-array HF transmitter at Gakona, AK delivers up to 3.6 GW (ERP) of HF power in the range of 2.8 - 10 MHz to the ionosphere with millisecond pointing, power modulation, and frequency agility. HAARP's unique features have enabled the conduct of a number of nonlinear plasma experiments in the interaction region of overdense ionospheric plasma including stimulated electromagnetic emissions (SEE), artificial aurora, artificial ionization layers, VLF wave-particle interactions in the magnetosphere, strong Langmuir turbulence (SLT) and suprathermal electron acceleration. Diagnostics include the Modular UHF Ionospheric Radar (MUIR) sited at HAARP, the SuperDARN-Kodiak HF radar, spacecraft radio beacons, HF receivers to record stimulated electromagnetic emissions (SEE) and telescopes and cameras for optical emissions. We report on short timescale ponderomotive overshoot effects, artificial field-aligned irregularities (AFAI), the aspect angle dependence of the intensity of the plasma line, and suprathermal electrons. Applications are made to the study and control of irregularities affecting spacecraft communication and navigation systems.

Space Experiments with Particle Accelerators (SEPAC)

NASA Technical Reports Server (NTRS)

Taylor, William W. L.

1994-01-01

The scientific emphasis of this contract has been on the physics of beam ionosphere interactions, in particular, what are the plasma wave levels stimulated by the Space Experiments with Particle Accelerators (SEPAC) electron beam as it is ejected from the Electron Beam Accelerator (EBA) and passes into and through the ionosphere. There were two different phenomena expected. The first was generation of plasma waves by the interaction of the DC component of the beam with the plasma of the ionosphere, by wave particle interactions. The second was the generation of waves at the pulsing frequency of the beam (AC component). This is referred to as using the beam as a virtual antenna, because the beam of electrons is a coherent electrical current confined to move along the earth's magnetic field. As in a physical antenna, a conductor at a radio or TV station, the beam virtual antenna radiates electromagnetic waves at the frequency of the current variations. These two phenomena were investigated during the period of this contract.

Estimation of the Total Electron Content of the Martian Ionosphere using Radar Sounder Surface Echoes

NASA Technical Reports Server (NTRS)

Safaeinili, Ali; Kofman, Wlodek; Mouginot, Jeremie; Gim, Yonggyu; Herique, Alain; Ivanov, Anton B.; Plaut, Jeffrey J.; Picardi, Giovanni

2007-01-01

The Martian ionosphere's local total electron content (TEC) and the neutral atmosphere scale height can be derived from radar echoes reflected from the surface of the planet. We report the global distribution of the TEC by analyzing more than 750,000 echoes of the Mars Advanced Radar for Subsurface and Ionospheric Sounding (MARSIS). This is the first direct measurement of the TEC of the Martian ionosphere. The technique used in this paper is a novel 'transmission-mode' sounding of the ionosphere of Mars in contrast to the Active Ionospheric Sounding experiment (AIS) on MARSIS, which generally operates in the reflection mode. This technique yields a global map of the TEC for the Martian ionosphere. The radar transmits a wideband chirp signal that travels through the ionosphere before and after being reflected from the surface. The received waves are attenuated, delayed and dispersed, depending on the electron density in the column directly below the spacecraft. In the process of correcting the radar signal, we are able to estimate the TEC and its global distribution with an unprecedented resolution of about 0.1 deg in latitude (5 km footprint). The mapping of the relative geographical variations in the estimated nightside TEC data reveals an intricate web of high electron density regions that correspond to regions where crustal magnetic field lines are connected to the solar wind. Our data demonstrates that these regions are generally but not exclusively associated with areas that have magnetic field lines perpendicular to the surface of Mars. As a result, the global TEC map provides a high-resolution view of where the Martian crustal magnetic field is connected to the solar wind. We also provide an estimate of the neutral atmospheric scale height near the ionospheric peak and observe temporal fluctuations in peak electron density related to solar activity.

Controlling Factors of the Fate of Ionospheric Outflow at Earth and Mars

NASA Astrophysics Data System (ADS)

Liemohn, M. W.; Welling, D. T.; Ilie, R.; Ganushkina, N. Y.; Johnson, B. C.; Xu, S.; Dong, C.

2015-12-01

Both Earth and Mars experience ionospheric outflow, but the radically different magnetic field configurations at the two planets yield significantly different patterns of outflow and processes governing outflow. This study examines a set of numerical simulations for Earth and Mars to explore the factors controlling ionospheric outflow and the fate of the escaping ions (immediate precipitation, magnetospheric recirculation, or loss to deep space). Specifically, simulation results from the Space Weather Modeling Framework (SWMF), which is capable of handling both planetary space environments, are analyzed to assess the physical processes governing the fate of ionospheric ions. Velocity streamlines from the SWMF results are traced from the high-latitude inner boundary of the BATS-R-US MHD simulation domain and followed through geospace. Some of these streamlines return to the inner boundary of the simulation domain, others extend to the outer boundary of the domain, while most others eventually cross (or at least approach) the magnetospheric equatorial plane. At Earth, this plane is well defined, while at Mars there are multiple mini-magnetospheres in which ionospheric ions can become trapped. These streamlines are categorized according to their eventual destination. Multi-fluid MHD simulations are examined in this study, assessing the influence of species mass on trajectories through near-planet space. Steady-state numerical experiments with different levels of solar driving are examined to quantify the influence of each driver on outflow characteristics and the fate of outflowing ions. Real event intervals are considered to assess flows in a time-varying magnetospheric system. For Earth, as solar wind dynamic pressure increases, the dominant outflow region moves to lower latitudes and significantly more of the outflowing ions escape to deep space. As the interplanetary magnetic field increases in southward magnitude, the region of dominant outflow shifts to lower latitudes and more is injected into the inner magnetosphere. The ionospheric regions dominantly contributing to mass within the magnetosphere are assessed and compared for the different driving conditions. At Mars, the situation is much more complicated.

GASCan 2 payload integration

NASA Technical Reports Server (NTRS)

Cody, Dennis J.; Concepcion, Allan G.; Watras, Edward C., III

1995-01-01

This project, conducted in cooperation with the NASA Advanced Space Design Program, is part of an ongoing effort to place an experiment package into space. The goal of this project is to build and test flight-ready hardware that can be launched from the Space Shuttle. Get Away Special Canister 2 (GASCan 2) consists of three separate experiments. The Ionospheric Properties and Propagation Experiment (IPPE) determines effects of the ionosphere on radio wave propagation. The Microgravity Ignition experiment (MGI) tests the effects of combustion in a microgravity environment. The Rotational Fluid Flow experiment (RFF) examines fluid behavior under varying levels of gravity. This year the following tasks were completed: design of the IPPE antenna, X- and J-cell battery boxes, J-cell battery box enclosure, and structural bumpers; construction of the MGI canisters, MGI mounting brackets, IPPE antenna, and battery boxes; and the selection of the RFF's operating fluid and the analysis of the fluid behavior under microgravity test conditions.

AMPS data management requirements study, appendix 1. [user manuals (computer programs)/display devices - computerized simulation/experimentation/ionosphere

NASA Technical Reports Server (NTRS)

1975-01-01

Flow charts and display formats for the simulation of five experiments are given. The experiments are: (1) electromagnetic wave transmission; (2) passive observations of ambient plasma; (3) ionospheric measurements with subsatellite; (4) electron accelerator beam measurements; and (5) measurement of acoustical gravity waves in the sodium layer using lasers. A detailed explanation of the simulation procedure, definition of variables, and an explanation of how the experimenter makes display choices is also presented. A functional description is included on each flow chart and the assumptions and definitions of terms and scope of the flow charts and displays are presented.

Errors incurred in profile reconstruction and methods for increasing inversion accuracies for occultation type measurements

NASA Technical Reports Server (NTRS)

Gross, S. H.; Pirraglia, J. A.

1972-01-01

A method for augmenting the occultation experiment is described for slightly refractive media. This method which permits separation of the components of the gradient of refractivity, appears applicable to most of the planets for a major portion of their atmospheres and ionospheres. The analytic theory is given, and the results of numerical tests with a radially and angularly varying model of an ionosphere are discussed.

Back-diffusion plasma generator for ionosphere study

NASA Astrophysics Data System (ADS)

Fang, H. K.; Oyama, K.-I.; Chen, A. B.

2017-11-01

To produce ionospheric plasma environments at ground level is essential to get information not only for the development of CubeSat-class spacecraft but also for the design of ionospheric plasma instruments and to confirm their performance. In this paper, we describe the principle of plasma generation and characteristics of the back-diffusion plasma source, which can produce in-lab plasma similar to the Earth’s ionosphere, E and F regions, conditions of electron and ion temperature and density. The ion and electron energy distributions of the plasma generated by a back-diffusion source are measured by means of a cleaned Langmuir probe and gridded particle energy analyzers. The ion motion in front of the source is investigated by a hard-sphere collision model in SIMION software and the simulation results are comparable with the findings of our experiment. Furthermore, plasma densities and ion temperatures at different positions in front of the source are also demonstrated. The back-diffusion source has been accommodated for ionospheric plasma productions in several Asian institutes. The plasma characteristics of the source shown in this paper will benefit space research groups in the development of space plasma instruments.

Study of GNSS Loss of Lock Characteristics under Ionosphere Scintillation with GNSS Data at Weipa (Australia) During Solar Maximum Phase.

PubMed

Liu, Yang; Fu, Lianjie; Wang, Jinling; Zhang, Chunxi

2017-09-25

One of the adverse impacts of scintillation on GNSS signals is the loss of lock status, which can lead to GNSS geometry and visibility reductions that compromise the accuracy and integrity of navigation performance. In this paper the loss of lock based on ionosphere scintillation in this solar maximum phase has been well investigated with respect to both temporal and spatial behaviors, based on GNSS observatory data collected at Weipa (Australia; geographic: 12.45° S, 130.95° E; geomagnetic: 21.79° S, 214.41° E) from 2011 to 2015. Experiments demonstrate that the percentage of occurrence of loss of lock events under ionosphere scintillation is closely related with solar activity and seasonal shifts. Loss of lock behaviors under ionosphere scintillation related to elevation and azimuth angles are statistically analyzed, with some distinct characteristics found. The influences of daytime scintillation and geomagnetic storms on loss of lock have also been discussed in details. The proposed work is valuable for a deeper understanding of theoretical mechanisms of-loss of lock under ionosphere scintillation in global regions, and provides a reference for GNSS applications in certain regions at Australian low latitudes.

Distributed processing of a GPS receiver network for a regional ionosphere map

NASA Astrophysics Data System (ADS)

Choi, Kwang Ho; Hoo Lim, Joon; Yoo, Won Jae; Lee, Hyung Keun

2018-01-01

This paper proposes a distributed processing method applicable to GPS receivers in a network to generate a regional ionosphere map accurately and reliably. For accuracy, the proposed method is operated by multiple local Kalman filters and Kriging estimators. Each local Kalman filter is applied to a dual-frequency receiver to estimate the receiver’s differential code bias and vertical ionospheric delays (VIDs) at different ionospheric pierce points. The Kriging estimator selects and combines several VID estimates provided by the local Kalman filters to generate the VID estimate at each ionospheric grid point. For reliability, the proposed method uses receiver fault detectors and satellite fault detectors. Each receiver fault detector compares the VID estimates of the same local area provided by different local Kalman filters. Each satellite fault detector compares the VID estimate of each local area with that projected from the other local areas. Compared with the traditional centralized processing method, the proposed method is advantageous in that it considerably reduces the computational burden of each single Kalman filter and enables flexible fault detection, isolation, and reconfiguration capability. To evaluate the performance of the proposed method, several experiments with field collected measurements were performed.

Study of GNSS Loss of Lock Characteristics under Ionosphere Scintillation with GNSS Data at Weipa (Australia) During Solar Maximum Phase

PubMed Central

Liu, Yang; Fu, Lianjie; Wang, Jinling; Zhang, Chunxi

2017-01-01

One of the adverse impacts of scintillation on GNSS signals is the loss of lock status, which can lead to GNSS geometry and visibility reductions that compromise the accuracy and integrity of navigation performance. In this paper the loss of lock based on ionosphere scintillation in this solar maximum phase has been well investigated with respect to both temporal and spatial behaviors, based on GNSS observatory data collected at Weipa (Australia; geographic: 12.45° S, 130.95° E; geomagnetic: 21.79° S, 214.41° E) from 2011 to 2015. Experiments demonstrate that the percentage of occurrence of loss of lock events under ionosphere scintillation is closely related with solar activity and seasonal shifts. Loss of lock behaviors under ionosphere scintillation related to elevation and azimuth angles are statistically analyzed, with some distinct characteristics found. The influences of daytime scintillation and geomagnetic storms on loss of lock have also been discussed in details. The proposed work is valuable for a deeper understanding of theoretical mechanisms of—loss of lock under ionosphere scintillation in global regions, and provides a reference for GNSS applications in certain regions at Australian low latitudes. PMID:28946676

Implementation of an Electronic Ionosonde to Monitor the Earth’s Ionosphere via a Projected Column through USRP

PubMed Central

Barona Mendoza, Jhon Jairo; Quiroga Ruiz, Carlos Fernando; Pinedo Jaramillo, Carlos Rafael

2017-01-01

This document illustrates the processes carried out for the construction of an ionospheric sensor or ionosonde, from a universal software radio peripheral (USRP), and its programming using GNU-Radio and MATLAB. The development involved the in-depth study of the characteristics of the ionosphere, to apply the corresponding mathematical models used in the radar-like pulse compression technique and matched filters, among others. The sensor operates by firing electromagnetic waves in a frequency sweep, which are reflected against the ionosphere and are received on its return by the receiver of the instrument, which calculates the reflection height through the signal offset. From this information and a series of calculations, the electron density of the terrestrial ionosphere could be obtained. Improving the SNR of received echoes reduces the transmission power to a maximum of 400 W. The resolution associated with the bandwidth of the signal used is approximately 5 km, but this can be improved, taking advantage of the fact that the daughterboards used in the USRP allow a higher sampling frequency than the one used in the design of this experiment. PMID:28441329

The impact of spherical symmetry assumption on radio occultation data inversion in the ionosphere: An assessment study

NASA Astrophysics Data System (ADS)

Shaikh, M. M.; Notarpietro, R.; Nava, B.

2014-02-01

'Onion-peeling' is a very common technique used to invert Radio Occultation (RO) data in the ionosphere. Because of the implicit assumption of spherical symmetry for the electron density (N(e)) distribution in the ionosphere, the standard Onion-peeling algorithm could give erroneous concentration values in the retrieved electron density profile. In particular, this happens when strong horizontal ionospheric electron density gradients are present, like for example in the Equatorial Ionization Anomaly (EIA) region during high solar activity periods. In this work, using simulated RO Total Electron Content (TEC) data computed by means of the NeQuick2 ionospheric electron density model and ideal RO geometries, we tried to formulate and evaluate an asymmetry level index for quasi-horizontal TEC observations. The asymmetry index is based on the electron density variation that a signal may experience along its path (satellite to satellite link) in a RO event and is strictly dependent on the occultation geometry (e.g. azimuth of the occultation plane). A very good correlation has been found between the asymmetry index and errors related to the inversion products, in particular those concerning the peak electron density NmF2 estimate and the Vertical TEC (VTEC) evaluation.

Current limiting mechanisms in electron and ion beam experiments

NASA Technical Reports Server (NTRS)

Olsen, R. C.

1990-01-01

The emission and collection of current from satellites or rockets in the ionosphere is a process which, at equilibrium, requires a balance between inward and outward currents. In most active experiments in the ionosphere and magnetosphere, the emitted current exceeds the integrated thermal current by one or more orders of magnitude. The system response is typically for the emitted current to be limited by processes such as differential charging of insulating surfaces, interactions between an emitted beam and the local plasma, and interactions between the beam and local neutral gas. These current limiting mechanisms have been illustrated for 20 years in sounding rocket and satellite experiments, which are reviewed here. Detailed presentations of the Spacecraft Charging at High Altitude (SCATHA) electron and ion gun experiments are used to demonstrate the general range of observed phenomena.

Effects of electrojet turbulence on a magnetosphere-ionosphere simulation of a geomagnetic storm

NASA Astrophysics Data System (ADS)

Wiltberger, M.; Merkin, V.; Zhang, B.; Toffoletto, F.; Oppenheim, M.; Wang, W.; Lyon, J. G.; Liu, J.; Dimant, Y.; Sitnov, M. I.; Stephens, G. K.

2017-05-01

Ionospheric conductance plays an important role in regulating the response of the magnetosphere-ionosphere system to solar wind driving. Typically, models of magnetosphere-ionosphere coupling include changes to ionospheric conductance driven by extreme ultraviolet ionization and electron precipitation. This paper shows that effects driven by the Farley-Buneman instability can also create significant enhancements in the ionospheric conductance, with substantial impacts on geospace. We have implemented a method of including electrojet turbulence (ET) effects into the ionospheric conductance model utilized within geospace simulations. Our particular implementation is tested with simulations of the Lyon-Fedder-Mobarry global magnetosphere model coupled with the Rice Convection Model of the inner magnetosphere. We examine the impact of including ET-modified conductances in a case study of the geomagnetic storm of 17 March 2013. Simulations with ET show a 13% reduction in the cross polar cap potential at the beginning of the storm and up to 20% increases in the Pedersen and Hall conductance. These simulation results show better agreement with Defense Meteorological Satellite Program observations, including capturing features of subauroral polarization streams. The field-aligned current (FAC) patterns show little differences during the peak of storm and agree well with Active Magnetosphere and Planetary Electrodynamics Response Experiment (AMPERE) reconstructions. Typically, the simulated FAC densities are stronger and at slightly higher latitudes than shown by AMPERE. The inner magnetospheric pressures derived from Tsyganenko-Sitnov empirical magnetic field model show that the inclusion of the ET effects increases the peak pressure and brings the results into better agreement with the empirical model.

A theoretical investigation on the parametric instability excited by X-mode polarized electromagnetic wave at Tromsø

NASA Astrophysics Data System (ADS)

Wang, Xiang; Cannon, Patrick; Zhou, Chen; Honary, Farideh; Ni, Binbin; Zhao, Zhengyu

2016-04-01

Recent ionospheric modification experiments performed at Tromsø, Norway, have indicated that X-mode pump wave is capable of stimulating high-frequency enhanced plasma lines, which manifests the excitation of parametric instability. This paper investigates theoretically how the observation can be explained by the excitation of parametric instability driven by X-mode pump wave. The threshold of the parametric instability has been calculated for several recent experimental observations at Tromsø, illustrating that our derived equations for the excitation of parametric instability for X-mode heating can explain the experimental observations. According to our theoretical calculation, a minimum fraction of pump wave electric field needs to be directed along the geomagnetic field direction in order for the parametric instability threshold to be met. A full-wave finite difference time domain simulation has been performed to demonstrate that a small parallel component of pump wave electric field can be achieved during X-mode heating in the presence of inhomogeneous plasma.

Reaction of the high-latitude lower ionosphere to solar proton events from observations in the ELF range

NASA Astrophysics Data System (ADS)

Lebed', O. M.; Larchenko, A. V.; Pil'gaev, S. V.; Fedorenko, Yu. V.

2017-01-01

The reaction of the lower ionosphere to the solar proton events that occurred in 2011-2012 is studied in this paper based on the results of measurements of the propagation velocity and the E z / H τ ratio of the low-frequency electromagnetic pulses (atmospherics) in the ELF range at the high-latitude observatories Lovozero and Barentsburg. With numerical modeling methods, it is shown that horizontal local irregularities of the lower ionosphere conductivity profile could be a cause of the splashes in the E z / H τ ratio observed in the experiment during the solar proton event of March 7, 2012, which was a unique event in both the proton flux value and energy.

Ionospheric Outflow in the Magnetosphere: Circulation and Consequences

NASA Astrophysics Data System (ADS)

Welling, D. T.; Liemohn, M. W.

2017-12-01

Including ionospheric outflow in global magnetohydrodynamic models of near-Earth outer space has become an important step towards understanding the role of this plasma source in the magnetosphere. Such simulations have revealed the importance of outflow in populating the plasma sheet and inner magnetosphere as a function of outflow source characteristics. More importantly, these experiments have shown how outflow can control global dynamics, including tail dynamics and dayside reconnection rate. The broad impact of light and heavy ion outflow can create non-linear feedback loops between outflow and the magnetosphere. This paper reviews some of the most important revelations from global magnetospheric modeling that includes ionospheric outflow of light and heavy ions. It also introduces new advances in outflow modeling and coupling outflow to the magnetosphere.

A regional peculiarity of the low-latitude lower ionosphere

NASA Astrophysics Data System (ADS)

Givishvili, G. V.; Afinogenov, Iu. A.

1985-02-01

Experiments performed with the Al method at frequencies of 2.0 and 2.8 MHz on the ship Akademik Kurchatov during March-June 1976 in the Indian Ocean (28 deg N to 18 deg S, 40-79 deg E) revealed an area (Persian Gulf, 28-24 deg N) with a highly unusual diurnal variation of the ionospheric absorption of radio waves. This peculiarity consisted in extremely small prenoon values of absorption; the difference between the prenoon values and the higher postnoon absorption values at the two frequencies used was considerably higher than the measurement error (+ or - 3 dB). It is suggested that this peculiarity was connected with anomalously high rates of recombination processes in the morning hours in the lower ionosphere in this region.

A case study of the aurora, high-latitude ionosphere, and particle precipitation during near-steady state conditions

NASA Technical Reports Server (NTRS)

Winningham, J. D.; Anger, C. D.; Shepherd, G. G.; Weber, E. J.; Wagner, R. A.

1978-01-01

An Isis 2 pass studied in related experiments was singled out for a detailed examination of the particle fluxes, optical emissions, and ionospheric parameters observed during a quiescent period (late recovery) between two substorms. Since both long-duration measurements (aircraft) and transient snapshot (spacecraft) data are available, space and time effects can, on a macroscopic level, be separated. The latitudinal morphology observed by the satellite is found to be basically spatial in nature. It is suggested that the observed particle fluxes can be explained in terms of precipitation from the quiet time plasma sheet without intervening acceleration. The agreement of the observed optical emissions and ionospheric parameters with the electron fluxes is discussed.

The Ivory Coral Program on Ionospheric Modification

DTIC Science & Technology

1974-09-01

k . and \\..1-- y - Transmitterlooosonde rl IDENVER I /240 km WESTCLIFFE Photometer 8727-65-396 FIGURE 5 LOCATION OF PHOTOMETERS TO MEASURE 6300-A...Nebraska 4ro ns Trc nsmitter 400J DEUVER Co Io ado Co’orodo Springs 38° Westcliffe 080 0I1020 8727-65-397 UGURE 6 TYPICAL AIRGLOW REGION AT ABOUT...FIGURE 7 AIRGLQW OF 18 SEPTEMBER 1972 AT 2130 MST 4-4- - ~ ml <~,ele ero sko Craig 400 Erie ~ ATrasmiter DENVERI Colorado Springs 380 Westcliffe 1080

Polarimetry Studies of Ionospheric Modification by Rocket boosters.

DTIC Science & Technology

1981-05-27

Chemical Releases Polarimetry Studies Rocket Booster Effects Faraday Rotation 20. ABSTRACT (Coniros an ,Oer* e side It necessary and Identify by block...1112 InL I X (I _ Tl : YI) Rijl I ± ,2 for the radiowave whose electric field is given by E - E ,(z) exp ( w) + c.c. - i + Ej (2) 3 REILLY, |tARNISH, AND...has a simple phasor represen- ta "n through the definition F - E , +j E ,. (3) The linearly polarized radiowave is represented in terms of the

The Production and Modification of Ionospheric Irregularities by Powerful HF Radio Transmissions

DTIC Science & Technology

1990-09-11

BASE, MASSACHUSETS 01731,-5000 ’_hi techn-ical report has been reviewed and is approved for publication" S A WIT B ASI X._____ ~ f Contract Manager ...energy ’lec- 0. 12 trons decelerated. The maximum power in the 5.25- to 5.35-MHz Doppler range is reached without a measurable dehly according to o...vacuum. In principle the nonlinear effects of heating and of the pondcromotive force (the nonlinearity results from the depen- dence of both effects

On the lower altitude limit of the Venusian ionopause

NASA Astrophysics Data System (ADS)

Mahajan, K. K.; Mayr, H. G.; Brace, L. H.; Cloutier, P. A.

1989-07-01

It has been observed from the plasma experiments on the Pioneer Venus Orbiter that the altitude of the upper boundary of the ionosphere decreases in response to increasing solar wind dynamic pressure. However, at pressures above about 2.5 x 10 to the -8th dynes/sq cm, the further decrease in the ionopause height is rather small. Following the model of Cloutier et al. (1969), it is suggested that during high solar wind conditions, when the ionopause is formed at lower altitudes, the solar wind induces vertical and horizontal flows which sweep away the ionospheric plasma that is produced locally by photoionization. As a result, a disturbed photodynamical ionosphere is formed which has the scale height of the ionizable neutral constituent. It is shown that such a photodynamical ionosphere is observed at the subsolar ionopause under these conditions. As a consequence of this interaction, the ionopause altitude is observed to follow the small-scale height of the ionizable species, atomic oxygen, showing only small changes with solar wind pressure.

Analysis of Ionospheric Scintillation Characteristics in Sub-Antarctica Region with GNSS Data at Macquarie Island.

PubMed

Guo, Kai; Liu, Yang; Zhao, Yan; Wang, Jinling

2017-01-12

Ionospheric scintillation has a great impact on radio propagation and electronic system performance, thus is extensively studied currently. The influence of scintillation on Global Navigation Satellite System (GNSS) is particularly evident, making GNSS an effective medium to study characteristics of scintillation. Ionospheric scintillation varies greatly in relation with temporal and spatial distribution. In this paper, both temporal and spatial characteristics of scintillation are investigated based on Macquarie Island's GNSS scintillation data collected from 2011 to 2015. Experiments demonstrate that occurrence rates of amplitude scintillation have a close relationship with solar activity, while phase scintillation is more likely to be generated by geomagnetic activity. In addition, scintillation distribution behaviors related to elevation and azimuth angles are statistically analyzed for both amplitude and phase scintillation. The proposed work is valuable for a deeper understanding of theoretical mechanisms of ionospheric scintillation in this region, and provides a reference for GNSS applications in certain regions around sub-Antarctica.

Effects of the major sudden stratospheric warming event of 2009 on the subionospheric very low frequency/low frequency radio signals

NASA Astrophysics Data System (ADS)

Pal, S.; Hobara, Y.; Chakrabarti, S. K.; Schnoor, P. W.

2017-07-01

This paper presents effects of the major sudden stratospheric warming (SSW) event of 2009 on the subionospheric very low frequency/low frequency (VLF/LF) radio signals propagating in the Earth-ionosphere waveguide. Signal amplitudes from four transmitters received by VLF/LF radio networks of Germany and Japan corresponding to the major SSW event are investigated for possible anomalies and atmospheric influence on the high- to middle-latitude ionosphere. Significant anomalous increase or decrease of nighttime and daytime amplitudes of VLF/LF signals by ˜3-5 dB during the SSW event have been found for all propagation paths associated with stratospheric temperature rise at 10 hPa level. Increase or decrease in VLF/LF amplitudes during daytime and nighttime is actually due to the modification of the lower ionospheric boundary conditions in terms of electron density and electron-neutral collision frequency profiles and associated modal interference effects between the different propagating waveguide modes during the SSW period. TIMED/SABER mission data are also used to investigate the upper mesospheric conditions over the VLF/LF propagation path during the same time period. We observe a decrease in neutral temperature and an increase in pressure at the height of 75-80 km around the peak time of the event. VLF/LF anomalies are correlated and in phase with the stratospheric temperature and mesospheric pressure variation, while minimum of mesospheric cooling shows a 2-3 day delay with maximum VLF/LF anomalies. Simulations of VLF/LF diurnal variation are performed using the well-known Long Wave Propagating Capability (LWPC) code within the Earth-ionosphere waveguide to explain the VLF/LF anomalies qualitatively.

STS-93 Post Flight Presentation

NASA Technical Reports Server (NTRS)

1999-01-01

An overview of Flight STS-93 is presented. The primary objective of the STS-93 mission was to deploy the Advanced X-Ray Astrophysics Facility (AXAF), also known as the Chandra X-ray Observatory. The mission flew on the Columbia Shuttle, on July 22, 1999. This facility is the most sophisticated X-ray observatory ever built. Other payloads on STS-93 were: (1) the Midcourse Space Experiment (MSX), (2) Shuttle Ionospheric Modification with Pulsed Local Exhaust (SIMPLEX), (3) Southwest Ultraviolet Imaging System (SWUIS), (4) Gelation of Sols: Applied Microgravity Research (GOSAMR), Space Tissue Loss-B (STL-B), (5) Light Weight Flexible Solar Array Hinge (LFSAH), (6) Cell Culture Module (CCM), and (7) the Shuttle Amateur Radio Experiment-II (SAREX-II), (8) EarthKam, (9) Plant Growth Investigations in Microgravity (PGIM), (10) Commercial Generic Bioprocessing Apparatus (CGBA), (11) Micro-Electrical Mechanical System (MEMS), and (12) the Biological Research in Canisters (BRIC). The crew was: Eileen M. Collins, Mission Commander, the first female shuttle commander; Jeffrey S. Ashby, Pilot; Steven A. Hawley , Mission Specialist; Catherine G. Coleman, Mission Specialist; Michel Tognini (CNES), Mission Specialist. The video contains views of life aboard the space shuttle. This mission featured both a night launching and a night landing at the Kennedy Space Center.

Investigating magnetospheric interaction effects on Titan's ionosphere with the Cassini orbiter Ion Neutral Mass Spectrometer, Langmuir Probe and magnetometer observations during targeted flybys

NASA Astrophysics Data System (ADS)

Luhmann, J. G.; Ulusen, D.; Ledvina, S. A.; Mandt, K.; Magee, B.; Waite, J. H.; Westlake, J.; Cravens, T. E.; Robertson, I.; Edberg, N.; Agren, K.; Wahlund, J.-E.; Ma, Y.-J.; Wei, H.; Russell, C. T.; Dougherty, M. K.

2012-06-01

In the ˜6 years since the Cassini spacecraft went into orbit around Saturn in 2004, roughly a dozen Titan flybys have occurred for which the Ion Neutral Mass Spectrometer (INMS) measured that moon's ionospheric density and composition. For these, and for the majority of the ˜60 close flybys probing to altitudes down to ˜950 km, Langmuir Probe electron densities were also obtained. These were all complemented by Cassini magnetometer observations of the magnetic fields affected by the Titan plasma interaction. Titan's ionosphere was expected to differ from those of other unmagnetized planetary bodies because of significant contributions from particle impact due to its magnetospheric environment. However, previous analyses of these data clearly showed the dominance of the solar photon source, with the possible exception of the nightside. This paper describes the collected ionospheric data obtained in the period between Cassini's Saturn Orbit Insertion in 2004 and 2009, and examines some of their basic characteristics with the goal of searching for magnetospheric influences. These influences might include effects on the altitude profiles of impact ionization by magnetospheric particles at the Titan orbit location, or by locally produced pickup ions freshly created in Titan's upper atmosphere. The effects of forces on the ionosphere associated with both the draped and penetrating external magnetic fields might also be discernable. A number of challenges arise in such investigations given both the observed order of magnitude variations in the magnetospheric particle sources and the unsteadiness of the magnetospheric magnetic field and plasma flows at Titan's (˜20Rs (Saturn Radius)) orbit. Transterminator flow of ionospheric plasma from the dayside may also supply some of the nightside ionosphere, complicating determination of the magnetospheric contribution. Moreover, we are limited by the sparse sampling of the ionosphere during the mission as the Titan interaction also depends on Saturn Local Time as well as possible intrinsic asymmetries and variations of Titan's neutral atmosphere. We use organizations of the data by key coordinate systems of the plasma interaction with Titan's ionosphere to help interpret the observations. The present analysis does not find clear characteristics of the magnetosphere's role in defining Titan's ionosphere. The observations confirm the presence of an ionosphere produced mainly by sunlight, and an absence of expected ionospheric field signatures in the data. Further investigation of the latter, in particular, may benefit from numerical experiments on the inner boundary conditions of 3D models including the plasma interaction and features such as neutral winds.

Initial Results from CASSIOPE/ePOP Satellite Overpasses above HAARP in 2014

NASA Astrophysics Data System (ADS)

Siefring, C. L.; Bernhardt, P. A.; Briczinski, S. J., Jr.; James, H. G.; Yau, A. W.; Knudsen, D. J.

2015-12-01

The High Frequency Active Auroral Research Program (HAARP) facility was operated in conjunction with overpasses of the enhanced Polar Outflow Probe (ePOP) instruments on the Canadian CASSIOPE satellite. During these overpasses HAARP was operated in several different heating modes and regimes as diagnosed by the characteristics of Stimulated Electromagnetic Emissions (SEE) using ground-based receivers while simultaneously ePOP monitored in-situ HF and VLF signals, looked for ion and electron heating, and provided VHF and UHF signals for propagation effects studies. The e-POP suite of instruments and particularly the ePOP Radio Receiver Instrument (RRI) offer a unique combination diagnostics appropriate for studying the non-linear plasma effects generated high-power HF waves in the ionosphere. In this presentation, the initial results from ePOP observations from two separate 2014 measurement campaigns at HAARP (April 16 to April 29 and May 25 to June 9) will be discussed. Several innovative experiments were performed during the campaign. Experiments explored a wide range of ionospheric effects. These include: 1) Penetration of HF pump waves into the ionosphere via large and small scale irregularities, 2) effects of gyro-harmonic heating and artificial ionization layers, 3) effects of HAARP beam shape with O- and X-mode transmissions, 4) coupling of Lower Hybrid modes into Whistler waves, 5) D/E-region VLF generation in the ionosphere using VLF modulation of the HF pump 6) scattering of VHF and UHF signals and 7) scattering and non-linear modulation of a 9.5 MHz probe wave propagating through the region of the ionosphere modified by HAARP. This work supported by the Naval Research Laboratory Base Program.

The effect of tail stretching on the ionospheric accessibility of relativistic electron beam experiments

NASA Astrophysics Data System (ADS)

Willard, J.; Johnson, J.; Sanchez, E. R.; Kaganovich, I.; Greklek-McKeon, M.; Powis, T.

2017-12-01

New accelerator technologies have made it possible to install a lightweight electron beam accelerator onto small to medium satellites. Electron beams fired along the geomagnetic field would be able to carry energy flux into the ionosphere if they were fired into the loss cone, making these particles observable from the ground. Such an experiment would provide a way to accurately map field lines. One of the important challenges to utilizing this concept is understanding accessibility of these electrons to the ionosphere. While relativistic electron beams are generally more stable than lower energy beams, they are more sensitive to the effects of field-line curvature, which can significantly modify the loss cone [Porazik et al., 2014] making accessibility to the ionosphere sensitive to the launch angle with respect to the magnetic field. We examine the loss cone for 1 MeV electrons in a realistic magnetospheric geometry considering, in particular, the role of field-line stretching. To map the loss cone, we consider conservation of the first adiabatic invariant to second order in ρ/L using the asymptotic series derived by Gardner [Phys Fluids, 1966], which is valid on the midnight meridian. We investigate the loss cones for different magnetic field models controlled by a stretching parameter over the entire midnight meridian. We found that, because tail stretching increases field line curvature near the midplane but decreases curvature elsewhere, accessibility to the ionosphere is increased by tail stretching in regions above and below the midplane, although accessibility of particles passing through the midplane is reduced. This result implies that satellites armed with electron beam accelerators may be able to visibly affect the atmosphere from distances greater than previously anticipated.

Remote Sensing of the Upper Atmosphere and the Ionosphere in the Extreme and Far Ultraviolet: Results from the LITES Experiment aboard the IS

NASA Astrophysics Data System (ADS)

Finn, S. C.; Chakrabarti, S.; Stephan, A. W.; Geddes, G.; Budzien, S. A.; Cook, T.; Aryal, S.; Martel, J.; Galkin, I. A.; Erickson, P. J.

2017-12-01

The Limb-Imaging Ionospheric and Thermospheric Extreme-ultraviolet Spectrograph (LITES) was launched as part of the Space Test Program Houston #5 (STP-H5) payload aboard a commercial resupply flight on February 19, 2017 and was subsequently installed on the International Space Station (ISS). LITES is an imaging spectrograph that spans the 60 - 140 nm wavelength range at 1 nm spectral resolution and samples tangent altitudes 150 - 350 km with 0.2° angular resolution. LITES, in combination with the GPS Radio Occultation and Ultraviolet Photometry - Colocated (GROUP-C) experiment, which includes a GPS receiver and a nadir viewing 135.6 nm photometer, jointly collect new information on the thermosphere and the ionosphere using simultaneous UV and radio emissions. LITES, which uses standard stars to perform in-flight calibration, observes altitude profiles of day and night airglow emissions that are being used to infer thermospheric and ionospheric density profiles. Furthermore, due to the inclination of the ISS, LITES has also observed auroral spectrum and their altitude and spatial variations. Finally, geomagnetic storm effects on its UV emissions can be used to remotely sense their effects on the upper atmospheric morphology. These ISS observations,which are complement to the upcoming ICON and GOLD NASA missions, are focused on ionosphere-atmosphere coupling and global-scale atmospheric response to space weather observed from higher altitudes . We will present an overview of the LITES instrument, some early results from the first few months of operations. We will also summarize the advantages in calibration and validation activities that are possible through space-based LITES, GROUP-C and stellar measurements and simultaneous ground-based optical and radar observations.

Rocket experiments for spectral estimation of electron density fine structure in the auroral and equatorial ionosphere and preliminary results

NASA Technical Reports Server (NTRS)

Tomei, B. A.; Smith, L. G.

1986-01-01

Sounding rockets equipped to monitor electron density and its fine structure were launched into the auroral and equatorial ionosphere in 1980 and 1983, respectively. The measurement electronics are based on the Langmuir probe and are described in detail. An approach to the spectral analysis of the density irregularities is addressed and a software algorithm implementing the approach is given. Preliminary results of the analysis are presented.

Coordinated ionospheric and magnetospheric observations from the ISIS 2 satellite by the ISIS 2 experimenters. Volume 3: High-latitude charged particle, magnetic field and ionospheric plasma observations during northern summer

NASA Technical Reports Server (NTRS)

1980-01-01

A list of ISIS 2 experiments and a description of the satellite are presented. Instrumentation of the satellite included an auroral scanning photometer, a red line photometer, a swept frequency sounder, an ion mass spectrometer, and triaxial fluxgate magnetometer. Data format descriptions are provided. Included with the geophysical data set is a list of all passes.

Limitations to Dual Frequency Ionosphere Corrections for Frequency Switched K-Q-Band Observations with the VLBA

NASA Technical Reports Server (NTRS)

Lanyi, Gabor; Gordon, David; Sovers, Ojars J.

2004-01-01

A series of VLBA experiments were carried out at K and Q bands for astrometry and imaging within the KQ VLBI Survey Collaboration. The paired K and Q observations of each source are separated by approximately 3 minutes of time. We investigate the delay effect of the ionosphere between K and Q bands involving the interscan separation. This differential delay effect is intermixed with the differential fluctuation effect of the troposphere.

High Frequency Propagation modeling in a disturbed background ionosphere: Results from the Metal Oxide Space Cloud (MOSC) experiment

NASA Astrophysics Data System (ADS)

Joshi, D. R.; Groves, K. M.

2015-12-01

The Air Force Research Laboratory (AFRL) launched two sounding rockets in the Kwajalein Atoll, Marshall Islands, in May 2013 known as the Metal Oxide Space Cloud (MOSC) experiment to study the interactions of artificial ionization and the background plasma. The rockets released samarium metal vapor in the lower F-region of the ionosphere that ionized forming a plasma cloud. A host of diagnostic instruments were used to probe and characterize the cloud including the ALTAIR incoherent scatter radar, multiple GPS and optical instruments, satellite radio beacons, and a dedicated network of high frequency (HF) radio links. Data from ALTAIR incoherent scatter radar and HF radio links have been analyzed to understand the impacts of the artificial ionization on radio wave propagation. During the first release the ionosphere was disturbed, rising rapidly and spread F formed within minutes after the release. To address the disturbed conditions present during the first release, we have developed a new method of assimilating oblique ionosonde data to generate the background ionosphere that can have numerous applications for HF systems. The link budget analysis of the received signals from the HF transmitters explains the missing low frequencies in the received signals along the great circle path. Observations and modeling confirm that the small amounts of ionized material injected in the lower-F region resulted in significant changes to the natural propagation environment.

Excitation of the ionospheric Alfvén resonator from the ground: Theory and experiments

NASA Astrophysics Data System (ADS)

Streltsov, A. V.; Chang, C.-L.; Labenski, J.; Milikh, G.; Vartanyan, A.; Snyder, A. L.

2011-10-01

We report results from numerical and experimental studies of the excitation of ULF shear Alfvén waves inside the ionospheric Alfvén resonator (IAR) by heating the ionosphere with powerful HF waves launched from the High Frequency Active Auroral Research Program (HAARP) facility in Alaska. Numerical simulations of the two-fluid MHD model describing IAR in a dipole magnetic field geometry with plasma parameters taken from the observations at HAARP during the October-November 2010 experimental campaign reveal that the IAR quality is higher during nighttime conditions, when the ionospheric conductivity is very low. Simulations also reveal that the resonance wave cannot be identified from the magnetic measurements on the ground or at an altitude above 600 km because the magnetic field in this wave has nodes on both ends of the resonator, and the best way to detect IAR modes is by measuring the electric field on low Earth orbit satellites. These theoretical predictions are in good, quantitative agreement with results from observations: In particular, (1) observations from the ground-based magnetometer at the HAARP site demonstrate no significant difference in the amplitudes of the magnetic field generated by HAARP in the frequency range from 0 to 5 Hz, and (2) the DEMETER satellite detected the electric field of the IAR first harmonic at an altitude of 670 km above HAARP during the heating experiment.

Ionospheric signatures of cusp latitude Pc 3 pulsations

NASA Technical Reports Server (NTRS)

Engebretson, M. J.; Anderson, B. J.; Cahill, L. J., Jr.; Arnoldy, R. L.; Rosenberg, T. J.

1990-01-01

Search coil magnetometer, riometer, photometer, and ELF-VLF receiver data obtained at South Pole Station and McMurdo, Antarctica during selected days in March and April 1986 are compared. Narrow-band magnetic pulsations in the Pc 3 period range are observed simultaneously at both stations in the dayside sector during times of low IMF cone angle, but are considerably stronger at South Pole, which is located at a latitude near the nominal foot point of the dayside cusp/cleft region. Pulsations in auroral light at 427.8 nm wavelength are often observed with magnetic pulsations at South Pole, but such optical pulsations are not observed at McMurdo. The observations suggest that precipitating magnetosheathlike electrons at nominal dayside cleft latitudes are at times modulated with frequencies similar to those of upstream waves. These particles may play an important role, via modification of ionospheric currents and conductivities, in the transmission of upstream wave signals into the magnetosphere and in the generation of dayside high-latitude Pc 3 pulsations.

The simulation of electromagnetically driven strong Langmuir turbulence effect on the backscatter radiation from ionosphere

NASA Astrophysics Data System (ADS)

Kochetov, Andrey

2016-07-01

Numerical simulations of the dynamics of electromagnetic fields in a smoothly inhomogeneous nonlinear plasma layer in frameworks of the nonlinear Schrödinger equation with boundary conditions responsible for the pumping of the field in the layer by an incident wave and the inverse radiation losses supplemented the volume field dissipation due to the electromagnetic excitation of Langmuir turbulence are carried out. The effects of the threshold of non-linearity and it's evolution, of the threshold and saturation levels of dissipation in the vicinity of the wave reflection point on the features of the dynamics of reflection and absorption indexes are investigated. We consider the hard drive damping depending on the local field amplitude and hysteresis losses with different in several times "on" and "off" absorption thresholds as well. The dependence of the thresholds of the steady-state, periodic and chaotic regimes of plasma-wave interaction on the scenario of turbulence evolution is demonstrated. The results are compared with the experimental observations of Langmuir stage ionospheric modification.

The Fading Behavior of the Propagating VLF Signal during the Recovery Time of Solar Flares

NASA Astrophysics Data System (ADS)

Yasmina, B.

2016-12-01

The VLF radio signal propagating in the waveguide delimited by the Earth's surface and the D-layer of the ionosphere undergoes important modifications due to solar flares. In this work we focus on the NRK (37.5 kHz) VLF transmitter signal that propagates along the medium path to Algiers receiver (distance=3495 km). The signal analysis of two different flare classes shows that the perturbation due to a week flare of C2.1 (Imax=2.1 x 10-6 W/m2) class are less important than the medium one of M3.2 (Imax=3.2 x 10-5 W/m2) class. This leads to the fast recovery to the normal ionospheric condition after the weak solar flare while the medium solar flare takes more time. Additionally, the study of the signal amplitude behaviors by means of the LWPC code shows that the fading displacement toward the transmitter is more significant in the case of M3.2 flare than C2.1 class.

Possibility of magnetospheric VLF response to atmospheric infrasonic waves

NASA Astrophysics Data System (ADS)

Bespalov, P. A.; Savina, O. N.

2012-06-01

In this paper, we consider a model of the influence of atmospheric infrasonic waves on VLF magnetospheric whistler wave excitation. This excitation occurs as a result of a succession of processes: a modulation of the plasma density by acoustic-gravity waves in the ionosphere, a reflection of the whistlers by ionosphere modulation, and a modification of whistler wave generation in the magnetospheric resonator. A variation of the magnetospheric resonator Q-factor has an influence on the operation of the plasma magnetospheric maser, where the active substances are radiation belt particles, and the working modes are electromagnetic whistler waves. The magnetospheric maser is an oscillating system which can be responsible for the excitation of self-oscillations. These self-oscillations are frequently characterized by alternating stages of accumulation and precipitation of energetic particles into the ionosphere during a pulse of whistler emissions. Numerical and analytical investigations of the response of self-oscillations to harmonic oscillations of the whistler reflection coefficient shows that even a small modulation rate can significantly change magnetospheric VLF emissions. Our results can explain the causes of the modulation of energetic electron fluxes and whistler wave intensity with a time scale from 10 to 150 s in the day-side magnetosphere. Such quasi-periodic VLF emissions are often observed in the sub-auroral and auroral magnetosphere and have a noticeable effect on the formation of space weather phenomena.

Interaction with the lower ionosphere of electromagnetic pulses from lightning - Heating, attachment, and ionization

NASA Technical Reports Server (NTRS)

Taranenko, Y. N.; Inan, U. S.; Bell, T. F.

1993-01-01

A Boltzmann formulation of the electron distribution function and Maxwell's equations for the EM fields are used to simulate the interaction of lightning radiated EM pulses with the lower ionosphere. Ionization and dissociative attachment induced by the heated electrons cause significant changes in the local electron density, N(e). Due to 'slow' field changes of typical lightning EM pulses over time scales of tens of microsec, the distribution function follows the quasi-equilibrium solution of the Boltzmann equation in the altitude range of interest (70 to 100 km). The EM pulse is simulated as a planar 100 microsec long single period oscillation of a 10 kHz wave injected at 70 km. Under nighttime conditions, individual pulses of intensity 10-20 V/m (normalized to 100 km horizontal distance) produce changes in N(e) of 1-30 percent while a sequence of pulses leads to strong modification of N(e) at altitudes less than 95 km. The N(e) changes produce a 'sharpening' of the lower ionospheric boundary by causing a reduction in electron density at 75-85 km (due to attachment) and a substantial increase at 85-95 km (due to ionization) (e.g., the scale height decreases by a factor of about 2 at about 85 km for a single 20 V/m EM pulse). No substantial N(e) changes occur during daytime.

Equatorial Plasma Bubble Development and Dynamics, and Sporadic E Layer Structuring, under Storm Time Electric Fields.

NASA Astrophysics Data System (ADS)

Abdu, M. A.; Batista, I. S.; Sobral, J. H. A.; Souza, J.; Santos, A.

2016-12-01

Equatorial and low - midlatitude ionospheric plasma dynamics and related phenomenology can be severely affected by disturbance electric fields associated with magnetic storms. Penetration electric fields, of under-shielding or over-shielding types, can cause anomalous development of plasma bubbles even during their non-occurrence season, or can lead to suppression of their normal development. Depending upon the longitude sector and local time, large relative changes in the Hall and Pedersen conductivities can occur due to storm induced extra E layer ionization or modifications in F layer plasma density, as a result of which the penetration electric fields may produce, among other effects, (1) plasma bubble zonal drift velocity reversal to westward, (2) large/abnormal F layer plasma uplift, (3) sporadic E layer disruption or its formation with instabilities. Beside these effects, the equatorial ionization anomaly is known to suffer latitudinal expansion and retraction. In this paper we will discuss some outstanding response features of the low altitude ionosphere under disturbance electric field as diagnosed by Digisondes, radars and optical imagers in the South American longitude sector, a region that is strongly influenced by the South Atlantic Magnetic anomaly (SAMA). The results will be discussed in the context of satellite observations (from C/NOFS) and modeling results based on SUPIM simulation of a realistic low latitude ionosphere.

Investigating the ionosphere response to exhaust products of ``Progress'' cargo spacecraft engines on the basis of Irkutsk Incoherent Scatter Radar data

NASA Astrophysics Data System (ADS)

Shpynev, Boris; Alsatkin, Sergei; Khakhinov, Vitaliy; Lebedev, Valentin

2017-04-01

The FSUE Central Research Institute of Machine Building (TsNIIMash), Rocket and Space Corporation "Energia", and Institute of Solar-Terrestrial Physics of Siberian Branch of Russian Academy of Sciences (ISTP SB RAS) jointly conducted the active space experiment "Radar-Progress" in 2007-2015. During this experiment, we used the Irkutsk Incoherent Scatter Radar to study space-time characteristics of ionospheric disturbances generated by exhaust products of "Progress" cargo spacecraft engines. As the basic effect during exhaust product injection, we consider the formation of new centers for recombination of ambient ionospheric ions O+ on molecules of water and carbon dioxide. This produces an ionization "hole" in the region of injection. In nighttime conditions when the majority of experiments were performed, this hole was filled by hydrogen ions from the plasmasphere, thus the ion composition in the vicinity of the hole and incoherent scatter spectra were changed. For successful observation of the ionization hole dynamics, the critical factors are the degree of radar antenna diagram filling by exhaust products and the velocity of the thermospheric neutral wind, which makes exhaust gases move from the antenna diagram. These two factors lead to the poor repeatability of successful experiments. Successful experiments recorded a decrease in electron density up to 35 % in the hole that existed for 30 min. The lifetime of the region with high concentration of H+ ions can be as long as one hour.

Surface Penetrating Radar Simulations for Europa

NASA Technical Reports Server (NTRS)

Markus, T.; Gogineni, S. P.; Green, J. L.; Fung, S. F.; Cooper, J. F.; Taylor, W. W. L.; Garcia, L.; Reinisch, B. W.; Song, P.; Benson, R. F.

2004-01-01

The space environment above the icy surface of Europa is a source of radio noise in this frequency range from natural sources in the Jovian magnetosphere. The ionospheric and magnetospheric plasma environment of Europa affects propagation of transmitted and return signals between the spacecraft and the solid surface in a frequency-dependent manner. The ultimate resolution of the subsurface sounding measurements will be determined, in part, by a capability to mitigate these effects. We discuss an integrated multi-frequency approach to active radio sounding of the Europa ionospheric and local magnetospheric environments, based on operational experience from the Radio Plasma Imaging @PI) experiment on the IMAGE spacecraft in Earth orbit, in support of the subsurface measurement objectives.

Modeling study of the ionospheric responses to the quasi-biennial oscillations of the sun and stratosphere

NASA Astrophysics Data System (ADS)

Wang, Jack C.; Tsai-Lin, Rong; Chang, Loren C.; Wu, Qian; Lin, Charles C. H.; Yue, Jia

2018-06-01

The Quasi-biennial Oscillation (QBO) is a persistent oscillation in the zonal mean zonal winds of the low latitude middle atmosphere that is driven by breaking planetary and gravity waves with a period near two years. The atmospheric tides that dominate the dynamics of the mesosphere and lower thermosphere region (MLT, between heights of 70-120 km) are excited in the troposphere and stratosphere, and propagate through QBO-modulated zonal mean zonal wind fields. This allows the MLT tidal response to also be modulated by the QBO, with implications for ionospheric/thermospheric variability. Interannual oscillations in solar radiation can also directly drive the variations in the ionosphere with similar periodicities through the photoionization. Many studies have observed the connection between the solar activity and QBO signal in ionospheric features such as total electron content (TEC). In this research, we develop an empirical model to isolate stratospheric QBO-related tidal variability in the MLT diurnal and semidiurnal tides using values from assimilated TIMED satellite data. Migrating tidal fields corresponding to stratospheric QBO eastward and westward phases, as well as with the quasi-biennial variations in solar activity isolated by the Multi-dimensional Ensemble Empirical Mode Decomposition (MEEMD) analysis from Hilbert-Huang Transform (HHT), are then used to drive the NCAR Thermosphere-Ionosphere-Electrodynamics General Circulation Model (TIE-GCM). The numerical experiment results indicate that the ionospheric QBO is mainly driven by the solar quasi-biennial variations during the solar maximum, since the solar quasi-biennial variation amplitude is directly proportionate to the solar cycle. The ionospheric QBO in the model is sensitive to both the stratospheric QBO and solar quasi-biennial variations during the solar minimum, with solar effects still playing a stronger role.

Ionospheric plasma deterioration in the area of enhanced seismic activity as compared to antipodal sites far from seismicity

NASA Astrophysics Data System (ADS)

Gulyaeva, Tamara; Arikan, Feza; Poustovalova, Ljubov; Stanislawska, Iwona

2016-07-01

The early magnetogram records from two nearly antipodal sites at Greenwich and Melbourne corresponding to the activity level at the invariant magnetic latitude of 50 deg give a long series of geomagnetic aa indices since 1868. The aa index derived from magnetic perturbation values at only two observatories (as distinct from the planetary ap index) experiences larger extreme values if either input site is well situated to the overhead ionospheric and/or field aligned current systems producing the magnetic storm effects. Analysis of the earthquakes catalogues since 1914 has shown the area of the peak global earthquake occurrence in the Pacific Ocean southwards from the magnetic equator, and, in particular, at Australia. In the present study the ionospheric critical frequency, foF2, is analyzed from the ionosonde measurements at the nearby observatories, Canberra and Slough (Chilton), and Moscow (control site) since 1944 to 2015. The daily-hourly-annual percentage occurrence of positive ionospheric W index (pW+) and negative index (pW-) is determined. It is found that the ionospheric plasma depletion pW- of the instant foF2 as compared to the monthly median is well correlated to the aa index at all three sites but the positive storm signatures show drastic difference at Canberra (no correlation of pW+ with aa index) as compared to two other sites where the high correlation is found of the ionospheric plasma density enhancement with the geomagnetic activity. A possible suppression of the enhanced ionospheric variability over the region of intense seismicity is discussed in the paper. This study is supported by TUBITAK EEEAG 115E915.

Characteristics of High Latitude Ionosphere Scintillations

NASA Astrophysics Data System (ADS)

Morton, Y.

2012-12-01

As we enter a new solar maximum period, global navigation satellite systems (GNSS) receivers, especially the ones operating in high latitude and equatorial regions, are facing an increasing threat from ionosphere scintillations. The increased solar activities, however, also offer a great opportunity to collect scintillation data to characterize scintillation signal parameters and ionosphere irregularities. While there are numerous GPS receivers deployed around the globe to monitor ionosphere scintillations, most of them are commercial receivers whose signal processing mechanisms are not designed to operate under ionosphere scintillation. As a result, they may distort scintillation signal parameters or lose lock of satellite signals under strong scintillations. Since 2008, we have established and continuously improved a unique GNSS receiver array at HAARP, Alaska. The array contains high ends commercial receivers and custom RF front ends which can be automatically triggered to collect high quality GPS and GLONASS satellite signals during controlled heating experiments and natural scintillation events. Custom designed receiver signal tracking algorithms aim to preserve true scintillation signatures are used to process the raw RF samples. Signal strength, carrier phase, and relative TEC measurements generated by the receiver array since its inception have been analyzed to characterize high latitude scintillation phenomena. Daily, seasonal, and solar events dependency of scintillation occurrence, spectral contents of scintillation activities, and plasma drifts derived from these measurements will be presented. These interesting results demonstrate the feasibility and effectiveness of our experimental data collection system in providing insightful details of ionosphere responses to active perturbations and natural disturbances.

The Role of Ionospheric Outflow Preconditioning in Determining Storm Geoeffectiveness

NASA Astrophysics Data System (ADS)

Welling, D. T.; Liemohn, M. W.; Ridley, A. J.

2012-12-01

It is now well accepted that ionospheric outflow plays an important role in the development of the plasma sheet and ring current during geomagnetic storms. Furthermore, even during quiet times, ionospheric plasma populates the magnetospheric lobes, producing a reservoir of hydrogen and oxygen ions. When the Interplanetary Magnetic Field (IMF) turns southward, this reservoir is connected to the plasma sheet and ring current through magnetospheric convection. Hence, the conditions of the ionosphere and magnetospheric lobes leading up to magnetospheric storm onset have important implications for storm development. Despite this, there has been little research on this preconditioning; most global simulations begin just before storm onset, neglecting preconditioning altogether. This work explores the role of preconditioning in determining the geoeffectiveness of storms using a coupled global model system. A model of ionospheric outflow (the Polar Wind Outflow Model, PWOM) is two-way coupled to a global magnetohydrodynamic model (the Block-Adaptive Tree Solar wind Roe-type Upwind Scheme, BATS-R-US), which in turn drives a ring current model (the Ring current Atmosphere interactions Model, RAM). This unique setup is used to simulate an idealized storm. The model is started at many different times, from 1 hour before storm onset to 12 hours before. The effects of storm preconditioning are examined by investigating the total ionospheric plasma content in the lobes just before onset, the total ionospheric contribution in the ring current just after onset, and the effects on Dst, magnetic elevation angle at geosynchronous, and total ring current energy density. This experiment is repeated for different solar activity levels as set by F10.7 flux. Finally, a synthetic double-dip storm is constructed to see how two closely spaced storms affect each other by changing the preconditioning environment. It is found that preconditioning of the magnetospheric lobes via ionospheric outflow greatly influences the geoeffectiveness of magnetospheric storms.

Ionospheric Electron Density Measurements Using COSMIC

NASA Astrophysics Data System (ADS)

Dymond, K. F.; Budzien, S. A.; Bernhardt, P. A.; Rocken, C.; Syndergaard, S.

2007-12-01

At 0140 UTC on April 15, 2006, the joint Taiwan-U.S. COSMIC/FORMOSAT-3 (Constellation Observing System for Meteorology, Ionosphere, and Climate and Formosa Satellite mission #3; hereafter COSMIC) mission, a constellation of six micro-satellites, was launched into a 512-km orbit from Vandenberg Air Force Base in California. Using on-board propulsion these satellites have been deployed to their final orbits at 800 km with 30 degrees of separation. This process has taken about 17 months following the launch. There are three instruments aboard each COSMIC satellite: the GPS Occultation Experiment (GOX), the Tri-Band Beacon (TBB), and the Tiny Ionospheric Photometer (TIP). These three instruments constitute a unique suite of instruments for studying the Earth's ionosphere. The GOX instrument operates by inferring the slant total electron content (the integral of the electron density along the line-of-sight) between the COSMIC satellites and the GPS satellites as a function of tangent height above the Earth's limb. These data can be inverted to produce electron density profiles in the E and F regions of the ionosphere. The TBB is a three frequency radio beacon that radiates coherently at 150, 400, and 1067 MHz. When the relative phases of the signals are measured between the COSMIC satellites and ground-based or space-based receivers, the total electron content along the line-of-sight can be determined. By making the measurements from a set of receivers, the two-dimensional distribution of electrons beneath the satellite can be determined using tomographic techniques. The TIP instrument measures the optical signature of the natural decay of the ionosphere produced via ecombination of the O+ ions and electrons. The TIP measurements can be used to characterize the morphology and dynamics of the global ionosphere. Additionally, the TIP measurements can be inverted in conjunction with the GPS occultation measurements, using tomographic techniques, to produce the two- dimensional distribution of electrons beneath the satellite. We present an overview of the COSMIC mission, the instruments, and their application to ionospheric sensing.

Initial observations of the pioneer venus orbiter solar wind plasma experiment.

PubMed

Wolfe, J; Intriligator, D S; Mihalov, J; Collard, H; McKibbin, D; Whitten, R; Barnes, A

1979-02-23

Initial results of observations of the solar wind interaction with Venus indicate that Venus has a well-defined, strong, standing bow shock wave. Downstream from the shock, an ionosheath is observed in which the compressed and heated postshock plasma evidently interacts directly with the Venus ionosphere. Plasma ion velocity deflections observed within the ionosheath are consistent with flow around the blunt shape of the ionopause. The ionopause boundary is observed and defined by this experiment as the location where the ionosheath ion flow is first excluded. The positions of the bow shock and ionopause are variable and appear to respond to changes in the external solar wind pressure. Near the terminator the bow shock was observed at altitudes of approximately 4600 to approximately 12,000 kilometers. The ionopause altitutde ranged fromn as low as approximately 450 to approximately 1950 kilometers. Within the Venus ionosphere low-energy ions (energy per untit charge < 30 volts) were detected and have been tentatively idtentified as nonflowing ionospheric ions incident from a direction along the spacecraft velocity vector.

Signal distortion on VHF/UHF transionospheric paths: First results from the Wideband Ionospheric Distortion Experiment

NASA Astrophysics Data System (ADS)

Cannon, Paul S.; Groves, Keith; Fraser, David J.; Donnelly, William J.; Perrier, Kathleen

2006-10-01

To the best of our knowledge, we report the first determination of ionospheric distortion, comprising the simultaneous characterization of both multipath and Doppler, on wideband, transionospheric VHF (158 MHz) and UHF (422 MHz) signals. The measurements took place as part of the test phase of the United Kingdom-United States Wideband Ionospheric Distortion Experiment during the evening (˜1000 UT) of 18 January 2005. This characterization has been achieved using the ALTAIR radar at the Ronald Reagan Ballistic Missile Defense Test Site on Kwajalein Atoll (9.395°N, 167.469°E (12.87°N, 237.16°E corrected geomagnetic)) in the Pacific, in conjunction with a low Earth orbiting, constant radar cross-section, passive satellite (calibration sphere). During the period when the two-way S4 index was above ˜0.8 on both channels, the median coherency times were 43 and 96 ms at VHF and UHF, respectively (at 1.5σ). The corresponding median coherency bandwidths were 0.8 and 2.1 MHz.

Studies of the Ionospheric Turbulence Excited by the Fourth Gyroharmonic at HAARP

NASA Astrophysics Data System (ADS)

Milikh, G. M.; Najmi, A. C.; Mahmoudian, A.; Bernhardt, P. A.; Briczinski, S.; Siefring, C. L.; Yampolski, Y.; Alexander, K.; Sopin, A.; Zalizovski, A.; Chiang, K.; Psiaki, M. L.; Morton, Y.; Taylor, S.; Papadopoulos, K.

2014-12-01

We report the results of a set of experiments conducted during the HAARP June 2014 campaign, whose objective was to study the development of artificial ionospheric turbulence. During the experiments, the heating frequency was stepped up and down near the 4th gyroharmonic, and the power of the heating HF radiation was varied. Our diagnostics included: measurements of phase-derived Slant Total Electron Content using the L1/L2 signals from PRN 25 GPS satellite received at HAARP; measurements of Stimulated Electromagnetic Emission (SEE) conducted 15 km away from the HAARP site; detection of the HAARP HF radiation at Vernadsky station located in Antarctica ~15.6 Mm from HAARP; ionograms from HAARP's digisonde and reflectance data from Kodiak radar. Our observations showed: a distinct correlation between the broad upshifted maximum detected by the SEE and strong suppression of the HF signals detected at Vernadsky station; drift velocity of the ionospheric irregularities causing HF scattering detected at Vernadsky station corresponds to that measured by the Kodiak radar; the intensity of the scattered radar signals by Kodiak correlates with the amplitude of downshifted maximum observed by the SEE.

Ionospheric response over Europe during the solar eclipse of March 20, 2015

NASA Astrophysics Data System (ADS)

Hoque, Mohammed Mainul; Wenzel, Daniela; Jakowski, Norbert; Gerzen, Tatjana; Berdermann, Jens; Wilken, Volker; Kriegel, Martin; Sato, Hiroatsu; Borries, Claudia; Minkwitz, David

2016-10-01

The solar eclipse on March 20, 2015 was a fascinating event for people in Northern Europe. From a scientific point of view, the solar eclipse can be considered as an in situ experiment on the Earth's upper atmosphere with a well-defined switching off and on of solar irradiation. Due to the strong changes in solar radiation during the eclipse, dynamic processes were initiated in the atmosphere and ionosphere causing a measurable impact, for example, on temperature and ionization. We analyzed the behavior of total ionospheric ionization over Europe by reconstructing total electron content (TEC) maps and differential TEC maps. Investigating the large depletion zone around the shadow spot, we found a TEC reduction of up to 6 TEC units, i.e., the total plasma depletion reached up to about 50%. However, the March 20, 2015 eclipse occurred during the recovery phase of a strong geomagnetic storm and the ionosphere was still perturbed and depleted. Therefore, the unusual high depletion is due to the negative bias of up to 20% already observed over Northern Europe before the eclipse occurred. After removing the negative storm effect, the eclipse-induced depletion amounts to about 30%, which is in agreement with previous observations. During the solar eclipse, ionospheric plasma redistribution processes significantly affected the shape of the electron density profile, which is seen in the equivalent slab thickness derived by combining vertical incidence sounding (VS) and TEC measurements. We found enhanced slab thickness values revealing, on the one hand, an increased width of the ionosphere around the maximum phase and, on the other, evidence for delayed depletion of the topside ionosphere. Additionally, we investigated very low frequency (VLF) signal strength measurements and found immediate amplitude changes due to ionization loss at the lower ionosphere during the eclipse time. We found that the magnitude of TEC depletion is linearly dependent on the Sun's obscuration function. By modelling TEC depletion and knowing the Sun's obscuration function in advance, Global Navigation Satellite System (GNSS) operators may improve the broadcast ionospheric correction during a solar eclipse day.

THE IMPACT OF THE IONOSPHERE ON GROUND-BASED DETECTION OF THE GLOBAL EPOCH OF REIONIZATION SIGNAL

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sokolowski, Marcin; Wayth, Randall B.; Tremblay, Steven E.

2015-11-01

The redshifted 21 cm line of neutral hydrogen (H i), potentially observable at low radio frequencies (∼50–200 MHz), is a promising probe of the physical conditions of the intergalactic medium during Cosmic Dawn and the Epoch of Reionization (EoR). The sky-averaged H i signal is expected to be extremely weak (∼100 mK) in comparison to the Galactic foreground emission (∼10{sup 4} K). Moreover, the sky-averaged spectra measured by ground-based instruments are affected by chromatic propagation effects (∼tens of kelvin) originating in the ionosphere. We analyze data collected with the upgraded Broadband Instrument for Global Hydrogen Reionization Signal system deployed atmore » the Murchison Radio-astronomy Observatory to assess the significance of ionospheric effects on the detection of the global EoR signal. The ionospheric effects identified in these data are, particularly during nighttime, dominated by absorption and emission. We measure some properties of the ionosphere, such as the electron temperature (T{sub e} ≈ 470 K at nighttime), magnitude, and variability of optical depth (τ{sub 100} {sub MHz} ≈ 0.01 and δτ ≈ 0.005 at nighttime). According to the results of a statistical test applied on a large data sample, very long integrations (∼100 hr collected over approximately 2 months) lead to increased signal-to-noise ratio even in the presence of ionospheric variability. This is further supported by the structure of the power spectrum of the sky temperature fluctuations, which has flicker noise characteristics at frequencies ≳10{sup −5} Hz, but becomes flat below ≈10{sup −5} Hz. Hence, we conclude that the stochastic error introduced by the chromatic ionospheric effects tends to zero in an average. Therefore, the ionospheric effects and fluctuations are not fundamental impediments preventing ground-based instruments from integrating down to the precision required by global EoR experiments, provided that the ionospheric contribution is properly accounted for in the data analysis.« less

Unusual ionospheric variations before the strong Auckland Islands, New Zealand earthquake of 30th September, 2007

NASA Astrophysics Data System (ADS)

Ibanga, J. I.; Akpan, A. E.; George, N. J.; Ekanem, A. M.; George, A. M.

2018-06-01

Using the IAP experiment on board, the DEMETER and TEC from GPS data, unusual ionospheric variations have been observed some days before the 7.4 magnitude New Zealand earthquake. Both sets of data recorded perturbations 10 days before the earthquake at about the same time. The total ion density per centimeter cube (cm-3), recorded a variation of 6.94 while the differential total electron content (DTEC) in total electron content unit 1016 electron per metre square gave a value of 2.93TECU. The observed anomalies were screened for false alarm using the geomagnetic indices of Kernnifzer digit (Kp) and disturbance storm time (Dst.) It was however seen that the state of the ionosphere was geomagnetically quiet during this period; hence the observed variations were seismogenic.

Rocket measurements within a polar cap arc - Plasma, particle, and electric circuit parameters

NASA Technical Reports Server (NTRS)

Weber, E. J.; Ballenthin, J. O.; Basu, S.; Carlson, H. C.; Hardy, D. A.; Maynard, N. C.; Kelley, M. C.; Fleischman, J. R.; Pfaff, R. F.

1989-01-01

Results are presented from the Polar Ionospheric Irregularities Experiment (PIIE), conducted from Sondrestrom, Greenland, on March 15, 1985, designed for an investigation of processes which lead to the generation of small-scale (less than 1 km) ionospheric irregularities within polar-cap F-layer auroras. An instrumented rocket was launched into a polar cap F layer aurora to measure energetic electron flux, plasma, and electric circuit parameters of a sun-aligned arc, coordinated with simultaneous measurements from the Sondrestrom incoherent scatter radar and the AFGL Airborne Ionospheric Observatory. Results indicated the existence of two different generation mechanisms on the dawnside and duskside of the arc. On the duskside, parameters are suggestive of an interchange process, while on the dawnside, fluctuation parameters are consistent with a velocity shear instability.

Energy coupling during the August 2011 magnetic storm

NASA Astrophysics Data System (ADS)

Huang, C. Y.; Su, Y.; Sutton, E. K.; Weimer, D. R.; Davidson, R.

2013-12-01

We present results from an analysis of high-latitude ionosphere-thermosphere (IT) coupling to the solar wind during a moderate magnetic storm which occurred on 5-6 August 2011. During the storm, a multi-point set of observations of the ionosphere and thermosphere was available. We make use of ionospheric measurements of electromagnetic and particle energy made by the Defense Meteorological Satellite Program (DMSP), and neutral densities measured by the Gravity Recovery and Climate Experiment (GRACE) satellite to infer: (1) the energy budget and (2) timing of the energy transfer process during the storm. We conclude that the primary location for energy input to the IT system is the extremely high latitude region. We suggest that the total energy available to the IT system is not completely captured either by observation or empirical models.

Profile inversion in presence of ray bending

NASA Technical Reports Server (NTRS)

Wallio, H. A.; Grossi, M. D.

1972-01-01

Inversion of radio occultation data for planetary atmospheres and ionospheres has been performed using the seismological Herglotz-Wiechert method, as adapted by Phinney and Anderson to the radio-occultation case. Profile reconstruction performed in computer simulated experiments with this approach have been compared with the ones obtained with the straight-ray Abel transform. For a thin atmosphere and ionosphere, like the ones encountered on Mars, microwave occultation data can be inverted accurately with both methods. For a dense ionosphere like the sun's corona, ray bending of microwaves is severe, and recovered refractivity by the Herglotz-Wiechert method provides significant improvement over the straight-ray Abel transform: the error reduces from more than 60% to less than 20% at a height of 60,000 km above the base of the corona.

Topside and ground ionosonde observations of a mid-latitude scintillation region

NASA Astrophysics Data System (ADS)

Hajkowicz, L. A.

1982-02-01

Ionospheric amplitude scintillations of transmissions in the VHF range from orbiting satellites were compared with topside and ground (bottomside) ionograms of an inhomogeneous region in southern mid-latitudes. It is evident that, for the event considered, there is a good spatial correlation between intense topside and bottomside spread-F and scintillations. The ionospheric disturbance pattern appears to agree with a quasi-sinusoidal model of frontal disturbances (derived from the angle-of-arrival experiments) in the F-region at these geographic latitudes.

Determining the VLF/ULF source height using phase measurements

NASA Astrophysics Data System (ADS)

Ryabov, A.; Kotik, D. S.

2012-12-01

Generation of ULF/VLF waves in the ionosphere using powerful RF facilities has been studied for the last 40 years, both theoretically and experimentally. During this time, it was proposed several mechanisms for explaining the experimental results: modulation of ionospheric currents based on thermal nonlinearity, ponderomotive mechanisms for generation both VLF and ULF signals, cubic nonlinearity, etc. According mentioned above mechanisms the VLF/ULF signal source could be located in the lower or upper ionosphere. The group velocity of signal propagation in the ionosphere is significantly smaller than speed of light. As a result the appreciable time delay of the received signals will occur at the earth surface. This time delay could be determine by measuring the phase difference between received and reference signals, which are GPS synchronized. The experiment on determining the time delay of ULF signal propagation from the ionospheric source was carried out at SURA facility in 2012 and the results are presented in this paper. The comparison with numerical simulation of the time delay using the adjusted IRI model and ionosonde data shows well agreement with the experimental observations. The work was supported by RFBR grant 11-02-00419-a and RF Ministry of education and science by state contract 16.518.11.7066.

Excitation of Earth-ionosphere waveguide in the ELF and lower VLF bands by modulated ionospheric current

NASA Astrophysics Data System (ADS)

Field, E. C.; Bloom, R. M.

1993-05-01

In this report, the principal of reciprocity is used in conjunction with a full-wave propagation code to calculate ground-level fields excited by ionospheric currents modulated at frequencies between 50 and 100 Hz with HF heaters. Results show the dependence on source orientation, altitude, and dimension and therefore pertain to experiments using the HIPAS or HAARP ionospheric heaters. In the end-fire mode, the waveguide excitation efficiency of an ELF HED in the ionosphere is up to 20 dB greater than for a ground-based antenna, provided its altitude does not exceed 80 to 90 km. The highest efficiency occurs for a source altitude of around 70 km; if that altitude is raised to 100 km, the efficiency drops by about 20 dB in the day and 10 dB at night. That efficiency does not account for the greater conductivity modulation that might be achieved at altitudes greater than 70 km, however. The trade-off between the altitude dependencies of the excitation efficiency and maximum achievable modulation depends on the ERP of the HF heater, the optimum altitude increasing with increasing ERP. For HIPAS the best modulation altitude is around 70 km, whereas for HAARP there might be marginal value in modulating at attitudes as high as 100 km.

Small-scale plasma turbulence and intermittency in the high latitude F region based on the ICI-2 sounding rocket experiment

NASA Astrophysics Data System (ADS)

Spicher, A.; Miloch, W.; Moen, J. I.; Clausen, L. B. N.

2015-12-01

Small-scale plasma irregularities and turbulence are common phenomena in the F layer of the ionosphere, both in the equatorial and polar regions. A common approach in analyzing data from experiments on space and ionospheric plasma irregularities are power spectra. Power spectra give no information about the phases of the waveforms, and thus do not allow to determine whether some of the phases are correlated or whether they exhibit a random character. The former case would imply the presence of nonlinear wave-wave interactions, while the latter suggests a more turbulent-like process. Discerning between these mechanisms is crucial for understanding high latitude plasma irregularities and can be addressed with bispectral analysis and higher order statistics. In this study, we use higher order spectra and statistics to analyze electron density data observed with the ICI-2 sounding rocket experiment at a meter-scale resolution. The main objective of ICI-2 was to investigate plasma irregularities in the cusp in the F layer ionosphere. We study in detail two regions intersected during the rocket flight and which are characterized by large density fluctuations: a trailing edge of a cold polar cap patch, and a density enhancement subject to cusp auroral particle precipitation. While these two regions exhibit similar power spectra, our analysis reveals that their internal structure is different. The structures on the edge of the polar cap patch are characterized by significant coherent mode coupling and intermittency, while the plasma enhancement associated with precipitation exhibits stronger random characteristics. This indicates that particle precipitation may play a fundamental role in ionospheric plasma structuring by creating turbulent-like structures.

Simultaneous Multi-angle Observations of Strong Langmuir Turbulence at HAARP

NASA Astrophysics Data System (ADS)

Watanabe, Naomi; Golkowski, Mark; Sheerin, James P.; Watkins, Brenton J.

2015-10-01

We report results from a recent series of experiments employing the HF transmitter of the High Frequency Active Auroral Research Program (HAARP) to generate and study strong Langmuir turbulence (SLT) in the interaction region of overdense ionospheric plasma. The Modular UHF Ionospheric Radar (MUIR) located at the HAARP facility is used as the primary diagnostic. Short pulse, low duty cycle experiments are used to avoid generation of artificial field-aligned irregularities and isolate ponderomotive plasma turbulence effects. The HF pump frequency is close to the 3rd gyro-harmonic frequency and the HF pointing angle and MUIR look angle are between the HF Spitze angle and Magnetic Zenith angle. Plasma line spectra measured simultaneously in different spots of the interaction region display differences dependent on the aspect angle of the HF pump beam in the boresight direction and the pointing angle of the MUIR diagnostic radar. Outshifted Plasma Lines, cascade, collapse, coexistence, spectra are observed in agreement with existing theory and simulation results of Strong Langmuir Turbulence in ionospheric interaction experiments. It is found that SLT at HAARP is most readily observed at a HF pointing angle of 11° and UHF observation angle of 15°, which is consistent with the magnetic zenith effect as documented in previous works and optimal orientation of the refracted HF electric field vector.

Analysis of Fluctuations of Electron Density in the D-region During the 2017 Solar Eclipse using a Very Low Frequency Receiver

NASA Astrophysics Data System (ADS)

Hernandez, E.; Mathur, S.; Fenton, A.; Behrend, C. C.; Bering, E., III

2017-12-01

As part of the Undergraduate Student Instrumentation Project (USIP) at the University of Houston, multiple Very Low Frequency (VLF) Radio Receivers will be set up during the 2017 solar eclipse. They will be taking data from Omaha, Nebraska and Casper, Wyoming. The receiver, using an air loop antenna, will record magnetic field fluctuations caused by VLF waves. The purpose of this experiment is to study the effects of the sudden change in electromagnetic radiation from the sun on the D-region of the ionosphere. VLF waves were chosen for measurement because naturally occurring VLF waves propagate through the Earth-ionosphere waveguide, which can be used to remotely observe the ionosphere. The D-region reduces the energy in propagating waves due to absorption. This means that any fluctuations in the D-region are inversely correlated to the strength of VLF waves being received. The experiment will focus on receiving waves transmitted from specific stations that are on the other side of totality. The amplitude and phase of the received waves will be measured and analyzed. It is hoped that this experiment will help us gain a better understanding of VLFs from the D-region during the solar eclipse, as well as increasing the overall data available for use by the community.

Inspire Your Students.

ERIC Educational Resources Information Center

Pine, William E.; Taylor, William W. L.

1991-01-01

Describes a science project, Interactive Space Physics Ionosphere Radio Experiments (INSPIRE), that allows students to work with physicists to address unanswered questions about the physics of space. (ZWH)

In-Band and Out-of-Band VLF Scattering by Modulated D-region Heating at the Arecibo Observatory

NASA Astrophysics Data System (ADS)

Burch, H.; Moore, R. C.

2017-12-01

The HF heating facility at the Arecibo Observatory is able to create an artificial disturbance in the D-region ionosphere through HF heating, a phenomenon which has been well documented at HAARP. Very Low Frequency (VLF, 3-30 kHz) waves radiated by Navy transmitters propagate around the globe in the Earth-Ionosphere waveguide and scatter from this artificially disturbed region. We investigated this effect at the Arecibo Observatory during the July 2017 HF heating campaign using an amplitude-modulated HF signal at modulation frequencies from below 1 Hz to approximately 5 kHz. VLF receivers stationed in Puerto Rico measured the amplitude and phase of propagating VLF transmitter signals under HF-heated and ambient ionospheric conditions. We interpret the scattered VLF signals in the context of an ionospheric HF heating model that has been successfully used to interpret the results of HAARP experiments for a number of years. We present initial results regarding the generation and detection of nonlinear mixing components at the VLF transmitter frequency +/- the HF modulation frequency.

Ionospheric Turbulence and the Evolution of Artificial Irregularities Excited by RF Interactions at HAARP

NASA Astrophysics Data System (ADS)

Sheerin, J. P.; Rayyan, N.; Watkins, B. J.; Bristow, W. A.; Bernhardt, P. A.

2015-12-01

The HAARP phased-array HF transmitter at Gakona, AK delivers up to 3.6 GW (ERP) of HF power in the range of 2.8 - 10 MHz to the ionosphere with millisecond pointing, power modulation, and frequency agility. HAARP's unique features have enabled the conduct of a number of nonlinear plasma experiments in the interaction region of overdense ionospheric plasma including stimulated electromagnetic emissions (SEE), artificial aurora, artificial ionization layers, VLF wave-particle interactions in the magnetosphere, strong Langmuir turbulence (SLT) and suprathermal electron acceleration. Diagnostics include the Modular UHF Ionospheric Radar (MUIR) sited at HAARP, the SuperDARN-Kodiak HF radar, spacecraft radio beacons, HF receivers to record stimulated electromagnetic emissions (SEE) and telescopes and cameras for optical emissions. We report on short timescale ponderomotive overshoot effects, artificial field-aligned irregularities (AFAI), the aspect angle dependence of the intensity of the plasma line, and suprathermal electrons. For a narrow range of HF pointing between Spitze and magnetic zenith, a reduced threshold for AFAI is observed. Applications are made to the study of irregularities relevant to spacecraft communication and navigation systems.

HF Propagation Effects Caused by an Artificial Plasma Cloud in the Ionosphere

NASA Astrophysics Data System (ADS)

Joshi, D. R.; Groves, K. M.; McNeil, W. J.; Caton, R. G.; Parris, R. T.; Pedersen, T. R.; Cannon, P. S.; Angling, M. J.; Jackson-Booth, N. K.

2014-12-01

In a campaign carried out by the NASA sounding rocket team, the Air Force Research Laboratory (AFRL) launched two sounding rockets in the Kwajalein Atoll, Marshall Islands, in May 2013 known as the Metal Oxide Space Cloud (MOSC) experiment to study the interactions of artificial ionization and the background plasma and measure the effects on high frequency (HF) radio wave propagation. The rockets released samarium metal vapor in the lower F-region of the ionosphere that ionized forming a plasma cloud that persisted for tens of minutes to hours in the post-sunset period. Data from the experiments has been analyzed to understand the impacts of the artificial ionization on HF radio wave propagation. Swept frequency HF links transiting the artificial ionization region were employed to produce oblique ionograms that clearly showed the effects of the samarium cloud. Ray tracing has been used to successfully model the effects of the ionized cloud. Comparisons between observations and modeled results will be presented, including model output using the International Reference Ionosphere (IRI), the Parameterized Ionospheric Model (PIM) and PIM constrained by electron density profiles measured with the ALTAIR radar at Kwajalein. Observations and modeling confirm that the cloud acted as a divergent lens refracting energy away from direct propagation paths and scattering energy at large angles relative to the initial propagation direction. The results confirm that even small amounts of ionized material injected in the upper atmosphere can result in significant changes to the natural propagation environment.

SPEAR-1: An experiment to measure current collection in the ionosphere by high voltage biased conductors

NASA Astrophysics Data System (ADS)

Raitt, W. John; Myers, Neil B.; Roberts, Jon A.; Thompson, D. C.

1990-12-01

An experiment is described in which a high electrical potential difference, up to 45 kV, was applied between deployed conducting spheres and a sounding rocket in the ionosphere. Measurements were made of the applied voltage and the resulting currents for each of 24 applications of different high potentials. In addition, diagnostic measurements of optical emissions in the vicinity of the spheres, energetic particle flow to the sounding rocket, dc electric field and wave data were made. The ambient plasma and neutral environments were measured by a Langmuir probe and a cold cathode neutral ionization gauge, respectively. The payload is described and examples of the measured current and voltage characteristics are presented. The characteristics of the measured currents are discussed in terms of the diagnostic measurements and the in-situ measurements of the vehicle environment. In general, it was found that the currents observed were at a level typical of magnetically limited currents from the ionospheric plasma for potentials less than 12 kV, and slightly higher for larger potentials. However, due to the failure to expose the plasma contactor, the vehicle sheath modified the sphere sheaths and made comparisons with the analytic models of Langmuir-Blodgett and Parker-Murphy less meaningful. Examples of localized enhancements of ambient gas density resulting from the operation of the attitude control system thrusters (cold nitrogen) were obtained. Current measurements and optical data indicated localized discharges due to enhanced gas density that reduced the vehicle-ionosphere impedance.

Possibility of weather and climate change by active experiments

NASA Astrophysics Data System (ADS)

Avakyan, Sergey; Voronin, Nikolai; Troitsky, Arkadil; Chernouss, Sergey

The anonymous remote impact on weather and climatic characteristics permanently discussed in last decade despite the fact that the UN Convention forbid to use the weather as a weapon since the 1970's. For example, Ross N. Hoffman proposed to operate weather conditions by direct flux of microwave radiation from space. This flux could affects on water vapor in the troposphere. The development of an optically thin cirrus cloud is especially promising situation because even the formation of the aeroplane cirrus-track can stimulate disturbance, which is necessary to development of an initial cyclone stage. Our studies confirmed the results of experiments of NIRFI on sporadic appearance of the microwave radiation of ionospheric nature during periods of solar flares and geomagnetic storms, and also during work of the "Sura” ionospheric heating facility. Such microwave radiation also occurs, when precipitation of particles from radiation belts stimulated by work of powerful (˜ 1 MW) navigation transmitters at frequencies ˜ 5 - 22 kHz. This effect was discovered by measurements at the Intercosmos satellite Bulgaria-1300 in 1982, and recently was confirmed by the spacecraft DEMETER measurements Leningrad State University measurements 1990-1991 at altitude about 2100 m proved the impact of microwave radiation from solar radiobursts on the amount of water vapor in the upper troposphere column. 25 - 40% of the vapour are involved into the formation of clusters decreased an atmospheric transparency. Papers of State Optical Institute (2008) proposed to account the electron-stimulated precipitation from the radiation belts over powerful radio transmitters (registered on the spacecraft DEMETER) as an additional source of microwave radiation of the ionosphere. This source can participate in the condensation-cluster mechanism changes of atmospheric transparency by the same way as natural geomagnetic storm. (Grach et al) also recorded stream microwave ionospheric disturbance stimulated by HF heating in an experiment at the "Sura" even earlier (2002) This led to the appearance of Rydberg states exited by the accelerated electrons impact (Troitskii et al.) found that at the threshold of sensitivity of radiometric measurements in 0.006 g/cm(2) observed a decrease in the water vapor content in the troposphere at 0.05 g/cm(2) at a total natural content 1.8-2.1 g/cm(2) in a special experiment on the basis of "Sura" facility to study the cluster-condensation mechanism. These reductions were observed almost simultaneously with the work of facility and time delay was about 1 minute. It should be noted that the heating power was 20 times less than the maximal reached power in such facilities. The extending of the experimental possibilities on the clustering in the troposphere by ionospheric microwave radiation (SPbSU) supposedly can give us the same result as an active impact on the ionosphere by heating facilities and power transmitters. We believe that manifestation of the described effects give a contribution to change of climatic characteristics: cloud formation, cyclogenesis, temperature anomalies and precipitation. This follows from the results of the analysis of correlation between cloud cover, temperature and precipitation and solar-geomagnetic activity over secular and annual (2 - 5 years) scales. Authors propose to use an optical method for detecting emissions of atomic oxygen in those electronic transitions between Rydberg states, which wavelengths are located in the atmospheric spectral windows in the visible and IR ranges. It will be the test for contribution of the Rydberg excitation processes in the formation of the flux of microwave active effects of the ionosphere. Corresponding lines for the visible region of the spectrum in low-lying Rydberg levels (with principal quantum number n of about 10) are in the blue region of the spectrum: 448.4 nm (the electronic transition is 11d - 3p), 452,3 nm (10d - 3p), and 457.7 nm (9d - 3p). Application of the optical recording channel in active experiments (i.e., at a fixed space-time artificial ionospheric disturbances) allow: - to confirm experimentally the Rydberg channel of generating microwave fluxes from the ionosphere at its perturbations; - to offer remote monitoring as international control of sources of artificial influence on weather and climatic characteristics.

Ionospheric Modification by Powerful Radio Waves-the Suzdal Symposium (2th) Held in Tromso, Norway on September 1988

DTIC Science & Technology

1989-03-21

fitting computer S - band KlyStrons , of the type developed at the Stanford program, and he now states that Ti does not change very Linear Accelerator...shift of the seems well justified. heating pattern, intense rapid heating in preexisting den- S . Kuo reported small-chamber studies with S - band sity...21989 U r A 1 0P oJ S - - I-P, r?-Ew (e 0 DGeorge J. Morales 21 March 1989 Approved for public release; distribution unlimited Office of Naval Research

HAARP-Induced Ionospheric Ducts

DOE Office of Scientific and Technical Information (OSTI.GOV)

Milikh, Gennady; Vartanyan, Aram

2011-01-04

It is well known that strong electron heating by a powerful HF-facility can lead to the formation of electron and ion density perturbations that stretch along the magnetic field line. Those density perturbations can serve as ducts for ELF waves, both of natural and artificial origin. This paper presents observations of the plasma density perturbations caused by the HF-heating of the ionosphere by the HAARP facility. The low orbit satellite DEMETER was used as a diagnostic tool to measure the electron and ion temperature and density along the satellite orbit overflying close to the magnetic zenith of the HF-heater. Thosemore » observations will be then checked against the theoretical model of duct formation due to HF-heating of the ionosphere. The model is based on the modified SAMI2 code, and is validated by comparison with well documented experiments.« less

Parallel electric fields detected via conjugate electron echoes during the Echo 7 sounding rocket flight

NASA Technical Reports Server (NTRS)

Nemzek, R. J.; Winckler, J. R.

1991-01-01

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.

Galileo radio science investigations

NASA Technical Reports Server (NTRS)

Howard, H. T.; Eshleman, V. R.; Hinson, D. P.; Kliore, A. J.; Lindal, G. F.; Woo, R.; Bird, M. K.; Volland, H.; Edenhoffer, P.; Paetzold, M.

1992-01-01

Galileo radio-propagation experiments are based on measurements of absolute and differential propagation time delay, differential phase delay, Doppler shift, signal strength, and polarization. These measurements can be used to study: the atmospheric and ionospheric structure, constituents, and dynamics of Jupiter; the magnetic field of Jupiter; the diameter of Io, its ionospheric structure, and the distribution of plasma in the Io torus; the diameters of the other Galilean satellites, certain properties of their surfaces, and possibly their atmospheres and ionospheres; and the plasma dynamics and magnetic field of the solar corona. The spacecraft system provides linear rather than circular polarization on the S-band downlink signal, the capability to receive X-band uplink signals, and a differential downlink ranging mode. A highly-stable, dual-frequency, spacecraft radio system is developed that is suitable for simultaneous measurements of all the parameters normally attributed to radio waves.

Charcateristics of Plasma Waves Excited During Gas Release and Plasma Injection Into The Ionosphere

NASA Astrophysics Data System (ADS)

Klos, Z.; Gdalevich, G. L.; Mikhailov, I.

Waves in broad frequency range are generated during the injection of fast plasma as well as release of neutral gas into ionosphere from the spacecraft. The excited wave modes depend on the environmental plasma parameters, geometry of injection as well as on the rate of ionisation of plasma in the stream. The neutral xenon gas was released from the board of the ACTIVE satellite (in 1989) and parallel with the release process the VLF as well as HF waves were diagnosed. On the other hand the xenon plasma from gun generator was injected into the ionosphere from the board of APEX satellite (in 1991) and also broad frequency range of emission was registered. In the present paper are compared the plasma waves characteristics observed in these two types of experiments.

Faraday rotation of Automatic Dependent Surveillance Broadcast (ADS-B) signals as a method of ionospheric characterization

NASA Astrophysics Data System (ADS)

Cushley, A. C.; Kabin, K.; Noel, J. M. A.

2017-12-01

Radio waves propagating through plasma in the Earth's ambient magnetic field experience Faraday rotation; the plane of the electric field of a linearly polarized wave changes as a function of the distance travelled through a plasma. Linearly polarized radio waves at 1090 MHz frequency are emitted by Automatic Dependent Surveillance Broadcast (ADS-B) devices which are installed on most commercial aircraft. These radio waves can be detected by satellites in low earth orbits, and the change of the polarization angle caused by propagation through the terrestrial ionosphere can be measured. In this work we discuss how these measurements can be used to characterize the ionospheric conditions. In the present study, we compute the amount of Faraday rotation from a prescribed total electron content value and two of the profile parameters of the NeQuick model.

Indirect Phase Height Measurements in Central and Eastern Europe for Monitoring D Region Plasma

NASA Technical Reports Server (NTRS)

Cossart, G. V.; Pakhomov, S. V.

1984-01-01

Low-frequency propagation experiments for the investigation of the lower part of the ionospheric D region were at first used by BRACEWELL et al. (1951) in the early fifties. Among these was the method of indirect phase height measurements for continuous monitoring of the lower ionosphere. It is based upon field strength measurements of commercial radio transmitters in the frequency range between 50 and 200 kHz at distances from 500 to 1500 km. The field strength records show characteristic diurnal variations with maxima and minima, produced by interference between the ground wave and the ionospherically reflected sky wave, the phase difference between varies in correspondence to the diurnal variation of the reflection height. In order to check the validity of interpretations of indirect phase height data, comparisons were made with simultaneous rocket soundings. Results are summarized.

Research in aeronomy

NASA Technical Reports Server (NTRS)

Edwards, B. (Editor)

1981-01-01

Progress in aeronomic research is reported. The following topics are discussed: ionospheric theory; rocket experiments; system development for Urbana measurements; meteor radar; coherent and incoherent scatter radar; and laser radar.

History of Los Alamos Participation in Active Experiments in Space

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pongratz, Morris B.

Beginning with the Teak nuclear test in 1958, Los Alamos has a long history of participation in active experiments in space. The last pertinent nuclear tests were the five explosions as part of the Dominic series in 1962. The Partial Test Ban Treaty signed in August 1963 prohibited all test detonations of nuclear weapons except for those conducted underground. Beginning with the “Apple” thermite barium release in June 1968 Los Alamos has participated in nearly 100 non-nuclear experiments in space, the last being the NASA-sponsored “AA-2” strontium and europium doped barium thermite releases in the Arecibo beam in July ofmore » 1992. The rationale for these experiments ranged from studying basic plasma processes such as gradientdriven structuring and velocity-space instabilities to illuminating the convection of plasmas in the ionosphere and polar cap to ionospheric depletion experiments to the B.E.A.R. 1-MeV neutral particle beam test in 1989. This report reviews the objectives, techniques and diagnostics of Los Alamos participation in active experiments in space.« less

ELF Sferics Produced by Rocket-Triggered Lightning and Observed at Great Distances

NASA Astrophysics Data System (ADS)

Dupree, N. A.; Moore, R. C.; Fraser-Smith, A. C.

2013-12-01

Experimental observations of ELF radio atmospherics produced by rocket-triggered lightning flashes are used to analyze Earth-ionosphere waveguide excitation and propagation characteristics as a function of return stroke. Rocket-triggered lightning experiments are performed at the International Center for Lightning Research and Testing (ICLRT) located at Camp Blanding, Florida. Long-distance ELF observations are performed in California, Greenland, and Antarctica, although this work focuses on observations performed in Greenland. The lightning current waveforms directly measured at the base of the lightning channel (at the ICLRT) are used together with the Long Wavelength Propagation Capability (LWPC) code to predict the sferic waveform observed at the receiver locations under various ionospheric conditions. LWPC was developed by the Naval Ocean Systems Center over a period of many years. It is an inherently narrowband propagation code that has been modified to predict the broadband response of the Earth-ionosphere waveguide to an impulsive lightning flash while preserving the ability of LWPC to account for an inhomogeneous waveguide. This paper critically compares observations with model predictions, and in particular analyzes Earth-ionosphere waveguide excitation as a function of return stroke. The ability to infer source characteristics using observations at great distances may prove to greatly enhance the understanding of lightning processes that are associated with the production of transient luminous events (TLEs) as well as other ionospheric effects associated with lightning.

The International Reference Ionosphere 2012 - a model of international collaboration

NASA Astrophysics Data System (ADS)

Bilitza, Dieter; Altadill, David; Zhang, Yongliang; Mertens, Chris; Truhlik, Vladimir; Richards, Phil; McKinnell, Lee-Anne; Reinisch, Bodo

2014-02-01

The International Reference Ionosphere (IRI) project was established jointly by the Committee on Space Research (COSPAR) and the International Union of Radio Science (URSI) in the late sixties with the goal to develop an international standard for the specification of plasma parameters in the Earth's ionosphere. COSPAR needed such a specification for the evaluation of environmental effects on spacecraft and experiments in space, and URSI for radiowave propagation studies and applications. At the request of COSPAR and URSI, IRI was developed as a data-based model to avoid the uncertainty of theory-based models which are only as good as the evolving theoretical understanding. Being based on most of the available and reliable observations of the ionospheric plasma from the ground and from space, IRI describes monthly averages of electron density, electron temperature, ion temperature, ion composition, and several additional parameters in the altitude range from 60 km to 2000 km. A working group of about 50 international ionospheric experts is in charge of developing and improving the IRI model. Over time as new data became available and new modeling techniques emerged, steadily improved editions of the IRI model have been published. This paper gives a brief history of the IRI project and describes the latest version of the model, IRI-2012. It also briefly discusses efforts to develop a real-time IRI model. The IRI homepage is at http://IRImodel.org.

Wide-field LOFAR-LBA power-spectra analyses: Impact of calibration, polarization leakage and ionosphere

NASA Astrophysics Data System (ADS)

Gehlot, B. K.; Koopmans, L. V. E.; de Bruyn, A. G.; Zaroubi, S.; Brentjens, M. A.; Asad, K. M. B.; Hatef, M.; Jelić, V.; Mevius, M.; Offringa, A. R.; Pandey, V. N.; Yatawatta, S.

2018-05-01

Contamination due to foregrounds (Galactic and Extra-galactic), calibration errors and ionospheric effects pose major challenges in detection of the cosmic 21 cm signal in various Epoch of Reionization (EoR) experiments. We present the results of a pilot study of a field centered on 3C196 using LOFAR Low Band (56-70 MHz) observations, where we quantify various wide field and calibration effects such as gain errors, polarized foregrounds, and ionospheric effects. We observe a `pitchfork' structure in the 2D power spectrum of the polarized intensity in delay-baseline space, which leaks into the modes beyond the instrumental horizon (EoR/CD window). We show that this structure largely arises due to strong instrumental polarization leakage (˜30%) towards Cas A (˜21 kJy at 81 MHz, brightest source in northern sky), which is far away from primary field of view. We measure an extremely small ionospheric diffractive scale (rdiff ≈ 430 m at 60 MHz) towards Cas A resembling pure Kolmogorov turbulence compared to rdiff ˜ 3 - 20 km towards zenith at 150 MHz for typical ionospheric conditions. This is one of the smallest diffractive scales ever measured at these frequencies. Our work provides insights in understanding the nature of aforementioned effects and mitigating them in future Cosmic Dawn observations (e.g. with SKA-low and HERA) in the same frequency window.

Plasma disturbances observed in the ionosphere in the vicinity of a highly charged space vehicle

NASA Astrophysics Data System (ADS)

Maehlum, B. N.; Denig, W. F.; Friedrich, M.; Torkar, K. M.; Svenes, K.; Maynard, N. C.; Trøim, J.; Holmgren, G.; Burke, W. J.

A mother-daughter rocket code named Maimik was launched from Andoya Rocket Range on November 10, 1985, near 20.00 local time. The daughter carried an electron accelerator, and a series of plasma diagnostic instruments were installed both on the daughter and on the trailing mother. The main aims of the experiment were to investigate (1) beam-plasma interaction processes in the ionosphere, (2) occurrence of dc and ac electric fields generated by the beam and (3) charging and neutralization of the vehicles.

Using Remote Sensing as a Plasma Diagnostic: A Discussion of Techniques Being Used to Probe the Ionosphere in Order to Determine the Energy and Spectral Characteristics of Precipitating Electrons and Protons

NASA Technical Reports Server (NTRS)

Spann, J.; Parks, G.; Brittnacher, M.; Germany, G.; Mende, S.; Frey, H.; Chenette, D.; Schulz, M.; Petrinec, S.

1999-01-01

Spectrally resolved global images of the Earth from recent (and planned) missions are being (and will be) used to probe the ionosphere in order to determine the energy characteristics of precipitating electrons and protons. We describe the techniques that are being used, discuss the extent to which they are successful, and envision the approach that future space experiments should take in order to improve on current techniques.

Cold Ion Escape from the Martian Ionosphere

NASA Astrophysics Data System (ADS)

Fränz, Markus; Dubinin, Eduard; Andrews, David; Nilsson, Hans; Fedorov, Andrei

2014-05-01

It has always been challenging to observe the flux of ions with energies of less than 10eV escaping from the planetary ionospheres. We here report on new measurements of the ionospheric ion flows at Mars by the ASPERA-3 experiment on board Mars Express. The ion sensor IMA of this experiment has in principle a low-energy cut-off at 10eV but in negative spacecraft charging cold ions are lifted into the range of measurement but the field of view is restricted to about 4x360 deg. In a recent paper Nilsson et al. (Earth Planets Space, 64, 135, 2012) tried to use the method of long-time averaged distribution functions to overcome these constraints. In this paper we first use the same method to show that we get results consistent with this when using ASPERA-3 observations only. But then we can show that these results are inconsistent with observations of the local plasma density by the MARSIS radar instrument on board Mars Express. We demonstrate that the method of averaged distribution function can deliver the mean flow speed of the plasma but the low-energy cut-off does usually not allow to reconstruct the density. We then combine measurements of the cold ion flow speed with the plasma density observations of MARSIS to derive the cold ion flux. In an analysis of the combined nightside datasets we show that the main escape channel is along the shadow boundary on the tailside of Mars. At a distance of about 0.5 Martian radii the flux settles at a constant value which indicates that about half of the transterminator ionospheric flow escapes from the planet. Possible mechanism to generate this flux can be the ionospheric pressure gradient between dayside and nightside or momentum transfer from the solar wind via the induced magnetic field since the flow velocity is in the Alfvénic regime.

Aerosol chemistry in Titan's ionosphere: simultaneous growth and etching processes

NASA Astrophysics Data System (ADS)

Carrasco, Nathalie; Cernogora, Guy; Jomard, François; Etcheberry, Arnaud; Vigneron, Jackie

2016-10-01

Since the Cassini-CAPS measurements, organic aerosols are known to be present and formed at high altitudes in the diluted and partially ionized medium that is Titan's ionosphere [1]. This unexpected chemistry can be further investigated in the laboratory with plasma experiments simulating the complex ion-neutral chemistry starting from N2-CH4 [2]. Two sorts of solid organic samples can be produced in laboratory experiments simulating Titan's atmospheric reactivity: grains in the volume and thin films on the reactor walls. We expect that grains are more representative of Titan's atmospheric aerosols, but films are used to provide optical indices for radiative models of Titan's atmosphere.The aim of the present study is to address if these two sorts of analogues are chemically equivalent or not, when produced in the same N2-CH4 plasma discharge. The chemical compositions of both these materials are measured by using elemental analysis, XPS analysis and Secondary Ion Mass Spectrometry. We find that films are homogeneous but significantly less rich in nitrogen and hydrogen than grains produced in the same experimental conditions. This surprising difference in their chemical compositions is explained by the efficient etching occurring on the films, which stay in the discharge during the whole plasma duration, whereas the grains are ejected after a few minutes [3]. The impact for our understanding of Titan's aerosols chemical composition is important. Our study shows that chemical growth and etching process are simultaneously at stake in Titan's ionosphere. The more the aerosols stay in the ionosphere, the more graphitized they get through etching process. In order to infer Titan's aerosols composition, our work highlights a need for constraints on the residence time of aerosols in Titan's ionosphere. [1] Waite et al. (2009) Science , 316, p. 870[2] Szopa et al. (2006) PSS, 54, p. 394[3] Carrasco et al. (2016) PSS, 128, p. 52

Update on the Commensal VLA Low-band Ionospheric and Transient Experiment (VLITE)

NASA Astrophysics Data System (ADS)

Kassim, Namir E.; Clarke, Tracy E.; Ray, Paul S.; Polisensky, Emil; Peters, Wendy M.; Giacintucci, Simona; Helmboldt, Joseph F.; Hyman, Scott D.; Brisken, Walter; Hicks, Brian; Deneva, Julia S.

2017-01-01

The JVLA Low-band Ionospheric and Transient Experiment (VLITE) is a commensal observing system on the NRAO JVLA. The separate optical path of the prime-focus sub-GHz dipole feeds and the Cassegrain-focus GHz feeds provided an opportunity to expand the simultaneous frequency operation of the JVLA through joint observations across both systems. The low-band receivers on 10 JVLA antennas are outfitted with dedicated samplers and use spare fibers to transport the 320-384 MHz band to the VLITE correlator. The initial phase of VLITE uses a custom-designed real-time DiFX software correlator to produce autocorrelations, as well as parallel and cross-hand cross-correlations from the linear dipole feeds. NRL and NRAO have worked together to explore the scientific potential of the commensal low frequency system for ionospheric remote sensing, astrophysics and transients. VLITE operates at nearly 70% wall time with roughly 6200 hours of JVLA time recorded each year.VLITE data are used in real-time for ionospheric research and are transferred daily to NRL for processing in the astrophysics and transient pipelines. These pipelines provide automated radio frequency interference excision, calibration, imaging and self-calibration of data.We will review early scientific results from VLITE across all three science focus areas, including the ionosphere, slow (> 1 sec) transients, and astrophysics. We also discuss the future of the project, that includes its planned expansion to eVLITE including the addition of more antennas, and a parallel capability to search for fast (< 1 sec), dispersed transients, such as Fast Radio Bursts and Rotating Radio Transients. We will also present early results of commissioning tests to utilize VLITE data products to complement NRAO’s 3 GHz VLA Sky Survey (VLASS). Revised pipelines are under development for operation during the on-the-fly operation mode of the sky survey.

A Massively Parallel Hybrid Dusty-Gasdynamics and Kinetic Direct Simulation Monte Carlo Model for Planetary Applications

NASA Technical Reports Server (NTRS)

Combi, Michael R.

2004-01-01

In order to understand the global structure, dynamics, and physical and chemical processes occurring in the upper atmospheres, exospheres, and ionospheres of the Earth, the other planets, comets and planetary satellites and their interactions with their outer particles and fields environs, it is often necessary to address the fundamentally non-equilibrium aspects of the physical environment. These are regions where complex chemistry, energetics, and electromagnetic field influences are important. Traditional approaches are based largely on hydrodynamic or magnetohydrodynamic (MHD) formulations and are very important and highly useful. However, these methods often have limitations in rarefied physical regimes where the molecular collision rates and ion gyrofrequencies are small and where interactions with ionospheres and upper neutral atmospheres are important. At the University of Michigan we have an established base of experience and expertise in numerical simulations based on particle codes which address these physical regimes. The Principal Investigator, Dr. Michael Combi, has over 20 years of experience in the development of particle-kinetic and hybrid kinetichydrodynamics models and their direct use in data analysis. He has also worked in ground-based and space-based remote observational work and on spacecraft instrument teams. His research has involved studies of cometary atmospheres and ionospheres and their interaction with the solar wind, the neutral gas clouds escaping from Jupiter s moon Io, the interaction of the atmospheres/ionospheres of Io and Europa with Jupiter s corotating magnetosphere, as well as Earth s ionosphere. This report describes our progress during the year. The contained in section 2 of this report will serve as the basis of a paper describing the method and its application to the cometary coma that will be continued under a research and analysis grant that supports various applications of theoretical comet models to understanding the inner comae of comets (grant NAGS- 13239 from the Planetary Atmospheres program).

SPEAR-induced field-aligned irregularities observed from bi-static HF radio scattering in the polar ionosphere

NASA Astrophysics Data System (ADS)

Blagoveshchenskaya, N. F.; Borisova, T. D.; Kornienko, V. A.; Kalishin, A. S.; Robinson, T. R.; Yeoman, T. K.; Wright, D. M.; Baddeley, L. J.

2009-01-01

Experimental results from SPEAR HF heating experiments in the polar ionosphere are examined. Bi-static scatter measurements of HF diagnostic signals were carried out on the Pori (Finland)-SPEAR-St. Petersburg path at operational frequencies of 11,755 and 15,400 kHz and the London-SPEAR-St. Petersburg path at frequencies of 12,095 and 17,700 kHz, using a Doppler spectral method. The SPEAR HF heating facility generates heater-induced artificial field-aligned small-scale irregularities (AFAIs), which can be detected by HF diagnostic bi-static radio scatter techniques at St. Petersburg at a distance of about 2000 km. In accordance with the Bragg condition, HF bi-static backscatters were sensitive to small-scale irregularities having spatial sizes of the order of 9-13 m across the geomagnetic field line. The properties and behaviour of AFAIs have been considered in the winter and summer seasons under quiet magnetic conditions and under various status of the polar ionosphere (the presence of "thick" and "thin" sporadic Es layers, different structures of the F2 layer). The experimental results obtained have shown that AFAIs can be excited in the F as well as in the E regions of the polar ionosphere. The excitation of a very intense wide-band spectral component with an abrupt increase in the spectral width up to 16-20 Hz has been found in the signals scattered from striations. Along with a wide-band component, a narrow-band spectral component can be also seen in the Doppler sonograms and in the average spectra of the signals scattered from the SPEAR-induced striations. AFAIs were excited even when the HF heater frequency was up to 0.5 MHz larger than the critical frequency. A simulation of the ray geometry for the diagnostic HF radio waves scattered from AFAIs in the polar ionosphere has been made for the geophysical conditions prevailing during experiments carried out in both the winter and summer seasons.

Multi-angle Spectra Evolution of Ionospheric Turbulence Excited by RF Interactions at HAARP

NASA Astrophysics Data System (ADS)

Sheerin, J. P.; Rayyan, N.; Watkins, B. J.; Watanabe, N.; Golkowski, M.; Bristow, W. A.; Bernhardt, P. A.; Briczinski, S. J., Jr.

2014-12-01

The high power HAARP HF transmitter is employed to generate and study strong Langmuir turbulence (SLT) in the interaction region of overdense ionospheric plasma. Diagnostics included the Modular UHF Ionospheric Radar (MUIR) sited at HAARP, the SuperDARN-Kodiak HF radar, and HF receivers to record stimulated electromagnetic emissions (SEE). Dependence of diagnostic signals on HAARP HF parameters, including pulselength, duty-cycle, aspect angle, and frequency were recorded. Short pulse, low duty cycle experiments demonstrate control of artificial field-aligned irregularities (AFAI) and isolation of ponderomotive effects. For the first time, simultaneous multi-angle radar measurements of plasma line spectra are recorded demonstrating marked dependence on aspect angle with the strongest interaction region observed displaced southward of the HF zenith pointing angle. For a narrow range of HF pointing between Spitze and magnetic zenith, a reduced threshold for AFAI is observed. High time resolution studies of the temporal evolution of the plasma line reveal the appearance of an overshoot effect on ponderomotive timescales. Numerous measurements of the outshifted plasma line are observed. Experimental results are compared to previous high latitude experiments and predictions from recent modeling efforts

The design and implementation of the Dynamic Ionosphere Cubesat Experiment (DICE) science instruments

NASA Astrophysics Data System (ADS)

Burr, Steven Reed

Dynamic Ionosphere Cubesat Experiment (DICE) is a satellite project funded by the National Science Foundation (NSF) to study the ionosphere, more particularly Storm Enhanced Densities (SED) with a payload consisting of plasma diagnostic instrumentation. Three instruments onboard DICE include an Electric Field Probe (EFP), Ion Langmuir Probe (ILP), and Three Axis Magnetometer (TAM). The EFP measures electric fields from +/-8V and consists of three channels a DC to 40Hz channel, a Floating Potential Probe (FPP), and an spectrographic channel with four bands from 16Hz to 512Hz. The ILP measures plasma densities from 1x104 cm--3 to 2x107 cm--3. The TAM measures magnetic field strength with a range +/-0.5 Gauss with a sensitivity of 2nT. To achieve desired mission requirements careful selection of instrument requirements and planning of the instrumentation design to achieve mission success. The analog design of each instrument is described in addition to the digital framework required to sample the science data at a 70Hz rate and prepare the data for the Command and Data Handing (C&DH) system. Calibration results are also presented and show fulfillment of the mission and instrumentation requirements.

Imaging Ionospheric/Plasmaspheric Disturbances Triggered by the 2017 Total Solar Eclipse with the Very Large Array

NASA Astrophysics Data System (ADS)

Helmboldt, Joseph; Schinzel, Frank K.; VLA Low-band Ionosphere and Transient Experiment (VLITE)

2018-01-01

Along with many Americans and several other observatories, the Karl G. Jansky Very Large Array (VLA) was observing the Sun before, during, and after the total solar eclipse on 21 August 2017. However, the VLA also simultaneously conducted a unique set of observations aimed at characterizing the effects of the eclipse on Earth’s ionosphere/plasmasphere. While most of the VLA antennas were pointed at the Sun, 12 were looking at the bright radio galaxy M87. These 12 antennas are part of the VLA Low-band Ionosphere and Transient Experiment (VLITE; http://vlite.nrao.edu), a dedicated backend that continuously captures, correlates, and analyzes data in the 320-384 MHz frequency range. In addition to traditional synthesis imaging, VLITE also characterizes fluctuations in ionospheric/plasmaspheric density via measured variations in visibility phases. When observing a bright cosmic source, this can be done with unmatched precision, the equivalent of ~1-10 ppm. To look for ionospheric/plasmaspheric disturbances tied to the eclipse, a specialized spectral decomposition was applied to the M87 VLITE data. This method exploits the fact that disturbed flux tubes within the plasmasphere appear as magnetic eastward-directed waves to the VLA because the plasmasphere is dynamically dominated by co-rotation. The phase speeds of these waves are proportional to distance, allowing for a reconstruction of the electron density gradient as a function of (slant) range and time. The time ranges spanned by the large-scale ionospheric depletion seen within concurrent Global Positioning System (GPS) data as a function of longitude were mapped to the flux tubes imaged with this method using the M87 observations. With the exception of some solar flare-induced fluctuations, the observed disturbances appear confined to this part of the range/time image. This strongly implies the disturbances resulted from the rapid depletion and slower recovery of the ionosphere/plasmasphere system brought on by the eclipse. It should be noted that these disturbances are not apparent within the GPS data, highlighting VLITE as a uniquely capable ionospheric/plasmaspheric disturbance hunter.

Ionospheric corrections to precise time transfer using GPS

NASA Technical Reports Server (NTRS)

Snow, Robert W.; Osborne, Allen W., III; Klobuchar, John A.; Doherty, Patricia H.

1994-01-01

The free electrons in the earth's ionosphere can retard the time of reception of GPS signals received at a ground station, compared to their time in free space, by many tens of nanoseconds, thus limiting the accuracy of time transfer by GPS. The amount of the ionospheric time delay is proportional to the total number of electrons encountered by the wave on its path from each GPS satellite to a receiver. This integrated number of electrons is called Total Electron Content, or TEC. Dual frequency GPS receivers designed by Allen Osborne Associates, Inc. (AOA) directly measure both the ionospheric differential group delay and the differential carrier phase advance for the two GPS frequencies and derive from this the TEC between the receiver and each GPS satellite in track. The group delay information is mainly used to provide an absolute calibration to the relative differential carrier phase, which is an extremely precise measure of relative TEC. The AOA Mini-Rogue ICS-4Z and the AOA TurboRogue ICS-4000Z receivers normally operate using the GPS P code, when available, and switch to cross-correlation signal processing when the GPS satellites are in the Anti-Spoofing (A-S) mode and the P code is encrypted. An AOA ICS-Z receiver has been operated continuously for over a year at Hanscom AFB, MA to determine the statistics of the variability of the TEC parameter using signals from up to four different directions simultaneously. The 4-channel ICS-4Z and the 8-channel ICS-4000Z, have proven capabilities to make precise, well calibrated, measurements of the ionosphere in several directions simultaneously. In addition to providing ionospheric corrections for precise time transfer via satellite, this dual frequency design allows full code and automatic codeless operation of both the differential group delay and differential carrier phase for numerous ionospheric experiments being conducted. Statistical results of the data collected from the ICS-4Z during the initial year of ionospheric time delay in the northeastern U.S., and initial results with the ICS-4000Z, will be presented.

Results From YOUTHSAT - Indian experiment in earths thermosphere-ionosphere region.

NASA Astrophysics Data System (ADS)

Tarun Kumar, Pant

It is known that the characterization and modeling of the ionosphere/thermosphere necessitates a comprehensive understanding of the various processes prevailing therein. India’s first, indigenous and dedicated aeronomy satellite 'YOUTHSAT' carrying two Indian payloads - RaBIT (Radio Beacon for Ionospheric Tomography), and LiVHySI (Limb Viewing Hyper Spectral Imager) and one Russian payload SOLRAD, was conceived primarily to address to this aspect and launched on April 20, 2011 in an 818 Km polar orbit from SHAR on ISRO launch vehicle PSLV. The payloads RaBIT and LiVHySI were designed specifically to observe the ionised and neutral components of the upper atmosphere respectively. YOUTHSAT is a small satellite quiet advanced in its class having all the functionalities which are normally associated with a bigger satellite. The rising phase of the 23rd solar cycle was considered to be the best window for various observations from onboard YOUTHSAT. As an Indo Russian endeavour, it was launched with an objective of investigating the terrestrial upper atmosphere vis-a-vis the activity on the sun. RaBIT, an ISRO venture, is a radio beacon emitting coherent radio signal at 150 and 400 MHz frequencies. These are received using a chain of five receivers deployed along the ~76oE meridian at Trivandrum, Bangalore, Hyderabad, Bhopal and Delhi. The receivers estimate the Total Electron Content (TEC) of the ionosphere through the relative phase change of the received radio signals. The TECs thus estimated near simultaneously, are used to generate a tomogram, which gives an Altitude-Latitude distribution of the ionospheric electron density. For YOUTHSAT configuration, the tomogram covers the ionosphere from a few degrees (5-6o) south of Trivandrum to about 3-4o north of Delhi depending upon the satellite elevation. The RaBIT tomography network is by far the longest network existing anywhere in the world, and is unique therefore. Through RaBIT, a unique dataset leading to ionospheric tomograms representing altitude-latitude variation of electron density over the 77oE meridian over the Indian region has been generated around specific times (~10:30 AM/PM). These tomograms have provided, among others: (a) First ever images of the ionospheric nighttime ESF irregularities (b) Quantification of the topside F3 ionospheric layers using Tomography (c) Evidence of wavelike modulations in the overall low and equatorial ionospheric region using tomography (d) Day and night differences in the electron density distribution, (e) Evidence of the presence of the ionospheric top-side layer (f) Modulations in the ionosphere due to space weather activity and (g) Direct evidence of the presence of Travelling Atmospheric Disturbance (TAD). YOUTHSAT recently completed its mission life time of about two years, after having generated a comprehensive set of data on terrestrial upper atmosphere. The YOUTHSAT data are being analysed by various researchers and more results providing a new insight into the upper atmospheric processes are in offing. Some of the important outcomes mentioned above will be discussed in detail.

Analysis of strong ionospheric scintillation events measured by means of GPS signals at low latitudes during disturbed conditions

NASA Astrophysics Data System (ADS)

Forte, B.

2012-08-01

Drifting structures characterized by inhomogeneities in the spatial electron density distribution at ionospheric heights cause the scintillation of radio waves propagating through. The fractional electron density fluctuations and the corresponding scintillation levels may reach extreme values at low latitudes during high solar activity. Different levels of scintillation were observed on experimental data collected in the Asian sector at low latitudes by means of a GPS dual frequency receiver under moderate solar activity (2005). The GPS receiver used in these campaigns was particularly modified in firmware in order to record power estimates on the C/A code as well as on the carriers L1 and L2. Strong scintillation activity was recorded in the post-sunset period (saturatingS4 and SI as high as 20 dB). Spectral modifications and broadening was observed during high levels of scintillation possibly indicating refractive scattering taking place instead of diffractive scattering. A possible interpretation of those events was attempted on the basis of the refractive scattering theory developed by Uscinski (1968) and Booker and MajidiAhi (1981).

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fox, M.W.; Pi, X.; Forbes, J.M.

Firstly, a series of new applications for the PHILLIPS Laboratory ionospheric model have been developed; a version has been prepared that allows restarts from specified background conditions, and runs have been made of both impulsive (e.g., storm onset) and periodic (e.g., atmospheric wave) perturbed conditions. Comparison studies are the subject of ongoing work. Secondly, tests of a new plasmaspheric model have been conducted with a view to merging it with the PL model in a new version of PRISM. Thirdly, the PL model has been applied to a study of the low latitude ionosphere involving comparisons of the observed longitudinalmore » and seasonal morphology of irregularities. Next, a version of the model has been prepared that permits a study of the effects of substorms through modifications of the vertical drift and neutral wind fields. Case studies at different longitudes identified increases in TEC with substorm expansion phases and decreases with substorm subsidence. Finally, SETA measurements of neutral density variations have been utilized in a study of both small-scale (up to 2500 km) larger scale wave phenomena, including descriptions of diurnal and magnetic activity dependencies.« less

Ionospheric electron number densities from CUTLASS dual-frequency velocity measurements using artificial backscatter over EISCAT

NASA Astrophysics Data System (ADS)

Sarno-Smith, Lois K.; Kosch, Michael J.; Yeoman, Timothy; Rietveld, Michael; Nel, Amore'; Liemohn, Michael W.

2016-08-01

Using quasi-simultaneous line-of-sight velocity measurements at multiple frequencies from the Hankasalmi Cooperative UK Twin Auroral Sounding System (CUTLASS) on the Super Dual Auroral Radar Network (SuperDARN), we calculate electron number densities using a derivation outlined in Gillies et al. (2010, 2012). Backscatter targets were generated using the European Incoherent Scatter (EISCAT) ionospheric modification facility at Tromsø, Norway. We use two methods on two case studies. The first approach is to use the dual-frequency capability on CUTLASS and compare line-of-sight velocities between frequencies with a MHz or greater difference. The other method used the kHz frequency shifts automatically made by the SuperDARN radar during routine operations. Using ray tracing to obtain the approximate altitude of the backscatter, we demonstrate that for both methods, SuperDARN significantly overestimates Ne compared to those obtained from the EISCAT incoherent scatter radar over the same time period. The discrepancy between the Ne measurements of both radars may be largely due to SuperDARN sensitivity to backscatter produced by localized density irregularities which obscure the background levels.

The fading behavior of the propagating VLF signal during the recovery time of solar flares.

NASA Astrophysics Data System (ADS)

Bouderba, Yasmina; Tribeche, Mouloud; Nait Amor, Samir

2016-07-01

The VLF radio signal propagating in the waveguide delimited by the Earth's surface and the D-layer of the ionosphere undergoes important modifications due to solar flares. In this work we focus on the NRK (37.5 kHz) VLF transmitter signal that propagates along the medium path to Algiers receiver (distance=3495 km). The signal analysis of two different flare classes shows that the perturbation due to a week flare of C2.1 (I _{max}=2.1 x 10 ^{-6} W/m ^{2}) class are less important than the medium one of M3.2 (I _{max}=3.2 x 10 ^{-5} W/m ^{2}) class. This leads to the fast recovery to the normal ionospheric condition after the weak solar flare while the medium solar flare takes more time. Additionally, the study of the signal amplitude behaviors by means of the LWPC code shows that the fading displacement toward the transmitter is more significant in the case of M3.2 flare than C2.1 class.

Transition region response of the symmetric double probe and its application in the lower ionosphere

NASA Technical Reports Server (NTRS)

Szuszczewicz, E. P.

1972-01-01

The technique is discussed of the symmetric double-probe which readily lends itself to the in situ measurement of plasma temperature in the ionospheric D-region because it can lead to meaningful results under relatively high collision frequencies where the Langmuir probe has been observed to fail. It is shown that the modification to the original collision-free double-probe theory of Johnson and Malter for the determination of electron temperature is never greater than + or - 12%, with a value of (8 + or - 2)% nominally applicable in the case of D-region diagnostics. This technique was successfully operated on a Nike-Cajun payload flown at mid-day from White Sands, New Mexico to an apogee of 78.5 km. The associated electronics and deployed double-probe configuration are presented, and a current-voltage characteristic collected in the ascent stage at 73.7 km is briefly discussed. The values of electron temperature indicated by the sampled data are approximately 30% higher than those predicted by theory for the anticipated state of thermal equilibrium with the ambient neutrals.

An Artificial Neural Network-Based Ionospheric Model to Predict NmF2 and hmF2 Using Long-Term Data Set of FORMOSAT-3/COSMIC Radio Occultation Observations: Preliminary Results

NASA Astrophysics Data System (ADS)

Sai Gowtam, V.; Tulasi Ram, S.

2017-11-01

Artificial Neural Networks (ANNs) are known to be capable of solving linear as well as highly nonlinear problems. Using the long-term and high-quality data set of Formosa Satellite-3/Constellation Observing System for Meteorology, Ionosphere, and Climate (FORMOSAT-3/COSMIC, in short F3/C) from 2006 to 2015, an ANN-based two-dimensional (2-D) Ionospheric Model (ANNIM) is developed to predict the ionospheric peak parameters, such as NmF2 and hmF2. In this pilot study, the ANNIM results are compared with the original F3/C data, GRACE (Gravity Recovery and Climate Experiment) observations as well as International Reference Ionosphere (IRI)-2016 model to assess the learning efficiency of the neural networks used in the model. The ANNIM could well predict the NmF2 (hmF2) values with RMS errors of 1.87 × 105 el/cm3 (27.9 km) with respect to actual F3/C; and 2.98 × 105 el/cm3 (40.18 km) with respect to independent GRACE data. Further, the ANNIM predictions found to be as good as IRI-2016 model with a slightly smaller RMS error when compared to independent GRACE data. The ANNIM has successfully reproduced the local time, latitude, longitude, and seasonal variations with errors ranging 15-25% for NmF2 and 10-15% for hmF2 compared to actual F3/C data, except the postsunset enhancement in hmF2. Further, the ANNIM has also captured the global-scale ionospheric phenomena such as ionospheric annual anomaly, Weddell Sea Anomaly, and the midlatitude summer nighttime anomaly. Compared to IRI-2016 model, the ANNIM is found to have better represented the fine longitudinal structures and the midlatitude summer nighttime enhancements in both the hemispheres.

Upgrades to the Mars Initial Reference Ionosphere (MIRI) Model Due to Observations from MAVEN, MEX and MRO.

NASA Astrophysics Data System (ADS)

Narvaez, C.; Mendillo, M.; Trovato, J.

2017-12-01

A semi-empirical model of the maximum electron density (Nmax) of the martian ionosphere [MIRI-mark-1](1) was derived from an initial set radar observations by the MEX/MARSIS instrument. To extend the model to full electron density profiles, normalized shapes of Ne(h) from a theoretical model(2) were calibrated by MIRI's Nmax. Subsequent topside ionosphere observations from MAVEN indicated that topside shapes from MEX/MARSIS(3) offered improved morphology. The MEX topside shapes were then merged to the bottomside shapes from the theoretical model. Using a larger set of MEX/MARSIS observations (07/31/2005 - 05/24/2015), a new specification of Nmax as a function of solar zenith angle and solar flux is now used to calibrate the normalized Ne(h) profiles. The MIRI-mark-2 model includes the integral with height of Ne(h) to form total electron content (TEC) values. Validation of the MIRI TEC was accomplished using an independent set of TEC derived from the SHARAD(4) experiment on MRO. (1) M. Mendillo, A. Marusiak, P. Withers, D. Morgan and D. Gurnett, A New Semi-empirical Model of the Peak Electron Density of the Martian Ionosphere, Geophysical Research Letters, 40, 1-5, doi:10.1002/2013GL057631, 2013. (2) Mayyasi, M. and M. Mendillo (2015), Why the Viking descent probes found only one ionospheric layer at Mars, Geophys. Res. Lett., 42, 7359-7365, doi:10.1002/2015GL065575 (3) Němec, F., D. Morgan, D. Gurnett, and D. Andrews (2016), Empirical model of the Martian dayside ionosphere: Effects of crustal magnetic fields and solar ionizing flux at higher altitudes, J. Geophys. Res. Space Physics, 121, 1760-1771, doi:10.1002/2015/A022060.(4) Campbell, B., and T. Watters (2016), Phase compensation of MARSIS subsurface sounding and estimation of ionospheric properties: New insights from SHARAD results, J.Geophys. Res. Planets, 121, 180-193, doi:10.1002/2015JE004917.

Monitoring of sporadic plasma layers in the lower ionosphere in the communication link satellite-to-satellite

NASA Astrophysics Data System (ADS)

Pavelyev, Alexander; Matyugov, Stanislav; Wickert, Jens; Liou, Yuei An; Yakovlev, Oleg

Method of global monitoring of sporadic plasma layers in the lower ionosphere is developed. In-vestigations were carried out by use of analysis of the amplitude and phase components of radio holograms obtained during the radio occultation missions CHAMP, FORMOSAT-3. Sporadic amplitude scintillation observed in RO experiments contain important information concerning the seasonal, geographical, and temporal distributions of the ionospheric disturbances and de-pend on solar activity. The geographical and seasonal distributions of sporadic layers in the lower ionosphere as function of solar activity in the period 2002-2008 years is obtained. The general number of RO events with strong amplitude variations can be used as an indicator of the ionospheric activity. We found that during 2001-2008 the daily averaged S4 index measured during CHAllenging Minisatellite Payload (CHAMP) mission depends essentially on solar ac-tivity. The maximum occurred in January 2002, minimum has been observed in summer 2008. Different temporal behavior of S4 index has been detected for polar (with latitude greater than 55 degrees) and low latitude (moderate and equatorial) regions. For polar regions S4 index is slowly decreasing with solar activity. In the low latitude areas S4 index is sharply oscillat-ing, depending on the solar ultraviolet emission variations. The geographical distribution of S4 index variations indicates different origin of ionospheric plasma disturbances in polar and low latitude areas. Origin of the plasma disturbances in the polar areas may be connected with influence of solar wind, the ultraviolet emission of the Sun may be the main cause of the ionospheric irregularities in the low latitude zone. Analysis reveals global oscillations of S4 index with the periods of 5-7 months. Analysis of these oscillations may provide additional connection with solar activity. Therefore, the S4 index of RO signal is important radio physical indicator of solar activity.

Exciting Alfven Waves using Modulated Electron Heating by High Power Microwaves

NASA Astrophysics Data System (ADS)

Wang, Yuhou; Gekelman, Walter; Pribyl, Patrick; van Compernolle, Bart; Papadopoulos, Konstantinos

2014-10-01

Experiments exploring the physics of ionospheric modification with intense perpendicular propagating waves (k-> ⊥B->0) on the Large Plasma Device (LaPD) at UCLA have been upgraded with the addition of a high power rapidly pulsed microwave source. The plasma is irradiated with ten pulses (250 kW X-band) near the upper-hybrid frequency. The pulses are modulated at a frequency of a fraction (0.1-1.0) of fci (ion cyclotron frequency). Based on a previous single-pulse experiment, the modulated electron heating may drive a large amplitude shear Alfvén wave (f

Mexican Space Weather Service (SCIESMEX)

NASA Astrophysics Data System (ADS)

Gonzalez-Esparza, A.; De la Luz, V.; Mejia-Ambriz, J. C.; Aguilar-Rodriguez, E.; Corona-Romero, P.; Gonzalez, L. X.

2015-12-01

Recent modifications of the Civil Protection Law in Mexico include now specific mentions to space hazards and space weather phenomena. During the last few years, the UN has promoted international cooperation on Space Weather awareness, studies and monitoring. Internal and external conditions motivated the creation of a Space Weather Service in Mexico (SCIESMEX). The SCIESMEX (www.sciesmex.unam.mx) is operated by the Geophysics Institute at the National Autonomous University of Mexico (UNAM). The UNAM has the experience of operating several critical national services, including the National Seismological Service (SSN); besides that has a well established scientific group with expertise in space physics and solar- terrestrial phenomena. The SCIESMEX is also related with the recent creation of the Mexican Space Agency (AEM). The project combines a network of different ground instruments covering solar, interplanetary, geomagnetic, and ionospheric observations. The SCIESMEX has already in operation computing infrastructure running the web application, a virtual observatory and a high performance computing server to run numerical models. SCIESMEX participates in the International Space Environment Services (ISES) and in the Inter-progamme Coordination Team on Space Weather (ICTSW) of the Word Meteorological Organization (WMO).

Study of interaction of ELF-ULF range (0.1-200 Hz) electromagnetic waves with the earth's crust and the ionosphere in the field of industrial power transmission lines (FENICS experiment)

NASA Astrophysics Data System (ADS)

Zhamaletdinov, A. A.; Shevtsov, A. N.; Velikhov, E. P.; Skorokhodov, A. A.; Kolesnikov, V. E.; Korotkova, T. G.; Ryazantsev, P. A.; Efimov, B. V.; Kolobov, V. V.; Barannik, M. B.; Prokopchuk, P. I.; Selivanov, V. N.; Kopytenko, Yu. A.; Kopytenko, E. A.; Ismagilov, V. S.; Petrishchev, M. S.; Sergushin, P. A.; Tereshchenko, P. E.; Samsonov, B. V.; Birulya, M. A.; Smirnov, M. Yu.; Korja, T.; Yampolski, Yu. M.; Koloskov, A. V.; Baru, N. A.; Poljakov, S. V.; Shchennikov, A. V.; Druzhin, G. I.; Jozwiak, W.; Reda, J.; Shchors, Yu. G.

2015-12-01

This article is devoted to describing the theory, technique, and first experimental results of a control source electromagnetic (CSEM) study of the Earth's crust and ionosphere with the use of two mutually orthogonal industrial transmission lines 109 and 120 km in length in the frame of FENICS (Fennoscandian Electrical Conductivity from Natural and Induction Control Source Soundings) experiment. The main part of the measurements is executed on the territory of the Fennoscandian shield at distances from the first hundreds kilometers up to 856 km from the source with the purpose of the deep electromagnetic sounding of the Earth's crust and upper mantle. According to the results of these studies clarifying the parameters of "normal" (standard) geoelectric section of the lithosphere to a depth of 60-70 km, the anisotropy parameters are evaluated and a geothermal and rheological interpretation in conjunction with the analysis of the seismic data is executed. Furthermore, to study the propagation of ELF-LLF waves (0.1-200 Hz) in an "Earth-Ionosphere" waveguide, the measurements are carried out apart from Fennoscandian shield at distances up to 5600 km from the source (in Ukraine, Spitsbergen, Poland, Kamchatka, and other areas). According to the results of these studies, the experimental estimates of the influence of the ionosphere and of the displacement currents on the propagation of ELF-ULF waves in the upper half-space at the different azimuths generation of the primary field are obtained.

MGS Radio Science Electron Density Profiles: Interannual Variability and Implications for the Martian Neutral Atmosphere

NASA Technical Reports Server (NTRS)

Bougher, S. W.; Engel, S.; Hinson, D. P.; Murphy, J. R.

2004-01-01

Martian electron density profiles provided by the Mars Global Surveyor (MGS) Radio Science (RS) experiment over the 95-200 km altitude range indicate what the height of the electron peak and the longitudinal structure of the peak height are sensitive indicators of the physical state of the Mars lower and upper atmospheres. The present analysis is carried out on five sets of occultation profiles, all at high solar zenith angles (SZA). Variations spanning 2 Martian years are investigated near aphelion conditions at high northern latitudes (64.7 - 77.6 N) making use of four of these data sets. A mean ionospheric peak height of 133.5 - 135 km is obtained near SZA = 78 - 82 deg.; a corresponding mean peak density of 7.3 - 8.5 x l0(exp 4)/ qu cm is also measured during solar moderate conditions at Mars. Strong wave number 2 - 3 oscillations in peak heights are consistently observed as a function of longitude over the 2 Martian years. These observed ionospheric features are remarkably similar during aphelion conditions 1 Martian year apart. This year-to-year repeatability in the thermosphere-ionosphere structure is consistent with that observed in multiyear aphelion temperature data of the Mars lower atmosphere. Coupled Mars general circulation model (MGCM) and Mars thermospheric general circulation model (MTGCM) codes are run for Mars aphelion conditions, yielding mean and longitude variable ionospheric peak heights that reasonably match RS observations. A tidal decomposition of MTGCM thermospheric densities shows that observed ionospheric wave number 3 features are linked to a non-migrating tidal mode with semidiurnal period (sigma = 2) and zonal wave number 1 (s = -1) characteristics. The height of this photochemically determined ionospheric peak should be monitored regularly.

SUPRATHERMAL ELECTRONS IN TITAN’S SUNLIT IONOSPHERE: MODEL–OBSERVATION COMPARISONS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Vigren, E.; Edberg, N. J. T.; Wahlund, J.-E.

2016-08-01

The dayside ionosphere of the Saturnian satellite Titan is generated mainly from photoionization of N{sub 2} and CH{sub 4}. We compare model-derived suprathermal electron intensities with spectra measured by the Cassini Plasma Spectrometer/Electron Spectrometer (CAPS/ELS) in Titan's sunlit ionosphere (altitudes of 970–1250 km) focusing on the T40, T41, T42, and T48 Titan flybys by the Cassini spacecraft. The model accounts only for photoelectrons and associated secondary electrons, with a main input being the impinging solar EUV spectra as measured by the Thermosphere Ionosphere Mesosphere Energy and Dynamics/Solar EUV Experiment and extrapolated to Saturn. Associated electron-impact electron production rates have beenmore » derived from ambient number densities of N{sub 2} and CH{sub 4} (measured by the Ion Neutral Mass Spectrometer/Closed Source Neutral mode) and related energy-dependent electron-impact ionization cross sections. When integrating up to electron energies of 60 eV, covering the bulk of the photoelectrons, the model-based values exceed the observationally based values typically by factors of ∼3 ± 1. This finding is possibly related to current difficulties in accurately reproducing the observed electron number densities in Titan's dayside ionosphere. We compare the utilized dayside CAPS/ELS spectra with ones measured in Titan's nightside ionosphere during the T55–T59 flybys. The investigated nightside locations were associated with higher fluxes of high-energy (>100 eV) electrons than the dayside locations. As expected, for similar neutral number densities, electrons with energies <60 eV give a higher relative contribution to the total electron-impact ionization rates on the dayside (due to the contribution from photoelectrons) than on the nightside.« less

Microbiological studies on the radiation environment of the ionosphere and stratosphere.

PubMed

Petras, E; Bisa, K

1968-01-01

Rocket, balloon and laboratory experiments have been performed in order to study the survival chances of microorganisms, which exist under the environmental conditions of ionosphere and stratosphere. The main results are: 1. Not only near the earth, but also in the stratosphere and even in the ionosphere, microorganisms are endangered primarily by UV- and EUV-light irradiation. 2. The observed effect of more penetrating kinds of radiation was relatively unimportant. High-vacuum and temperature effects have not been observed at all. Even membrane filters and thin protein layers protected the exposed spores of Bacillus subtilis var. niger (= Bac. globigii) in a clear-cut manner. 3. UV-light with a wavelength between 200 and 300 nm reduces the number of cells able to divide much quicker, than EUV-light of the same energy level does, but damages caused by EUV-light can not be reversed by photoreactivation. 4. Microbes which have been damaged by solar radiation, can be photoreactivated to a degree. Photoreactivation is high after exposure near the Earth and significant after exposure within the stratosphere. 5. After exposure to ionospheric irradiations no changes in the antigenic behavior of E. coli cells could be detected.

Analysis of rocket beacon transmissions for computerized reconstruction of ionospheric densities

NASA Technical Reports Server (NTRS)

Bernhardt, P. A.; Huba, J. D.; Chaturvedi, P. K.; Fulford, J. A.; Forsyth, P. A.; Anderson, D. N.; Zalesak, S. T.

1993-01-01

Three methods are described to obtain ionospheric electron densities from transionospheric, rocket-beacon TEC data. First, when the line-of-sight from a ground receiver to the rocket beacon is tangent to the flight trajectory, the electron concentration can be obtained by differentiating the TEC with respect to the distance to the rocket. A similar method may be used to obtain the electron-density profile if the layer is horizontally stratified. Second, TEC data obtained during chemical release experiments may be interpreted with the aid of physical models of the disturbed ionosphere to yield spatial maps of the modified regions. Third, computerized tomography (CT) can be used to analyze TEC data obtained along a chain of ground-based receivers aligned along the plane of the rocket trajectory. CT analysis of TEC data is used to reconstruct a 2D image of a simulated equatorial plume. TEC data is computed for a linear chain of nine receivers with adjacent spacings of either 100 or 200 km. The simulation data are analyzed to provide an F region reconstruction on a grid with 15 x 15 km pixels. Ionospheric rocket tomography may also be applied to rocket-assisted measurements of amplitude and phase scintillations and airglow intensities.

Online, automatic, ionospheric maps: IRI-PLAS-MAP

NASA Astrophysics Data System (ADS)

Arikan, F.; Sezen, U.; Gulyaeva, T. L.; Cilibas, O.

2015-04-01

Global and regional behavior of the ionosphere is an important component of space weather. The peak height and critical frequency of ionospheric layer for the maximum ionization, namely, hmF2 and foF2, and the total number of electrons on a ray path, Total Electron Content (TEC), are the most investigated and monitored values of ionosphere in capturing and observing ionospheric variability. Typically ionospheric models such as International Reference Ionosphere (IRI) can provide electron density profile, critical parameters of ionospheric layers and Ionospheric electron content for a given location, date and time. Yet, IRI model is limited by only foF2 STORM option in reflecting the dynamics of ionospheric/plasmaspheric/geomagnetic storms. Global Ionospheric Maps (GIM) are provided by IGS analysis centers for global TEC distribution estimated from ground-based GPS stations that can capture the actual dynamics of ionosphere and plasmasphere, but this service is not available for other ionospheric observables. In this study, a unique and original space weather service is introduced as IRI-PLAS-MAP from http://www.ionolab.org

The Mars Express/NASA Project at JPL

NASA Technical Reports Server (NTRS)

Thompson, Thomas W.; Horttor, R. L.; Acton, C. H., Jr.; Zamani, P.; Johnson, W. T. K.; Plaut, J. J.; Holmes, D. P.; No, S.; Asmar, S. W.; Goltz, G.

2005-01-01

An overview of the Mars Express/NASA Project at JPL is presented. The topics include: 1) Mars Express Mission Experiments and Investigators; 2) Mars Advanced Radar for Subsurface and Ionospheric Soundig (MARSIS) Overview; 3) MARSIS Experiment Overview; 4) Interoperability Concept; 5) Mars Express Science Operations; 6) Mars Express Schedule (2003-2007);

SEE Observations of Ionospheric Heating from HAARP Using Orbital Angular Momentum

NASA Astrophysics Data System (ADS)

Briczinski, S. J.; Bernhardt, P. A.; Siefring, C. L.

2013-12-01

High power HF radio waves exciting the ionosphere provide aeronomers with a unique space-based laboratory capability. The High-Frequency Active Auroral Research Program (HAARP) in Gakona, Alaksa is the world's largest heating facility, providing effective radiated powers in the gigawatt range. Experiments performed at HAARP have allowed researchers to study many non-linear effects of wave-plasma interactions. Stimulated Electromagnetic Emission (SEE) is of interest to the ionospheric community for its diagnostic purposes. Typical SEE experiments at HAARP have focused on characterizing the parametric decay of the electromagnetic pump wave into several different wave modes such as upper and lower hybrid, ion acoustic, ion-Bernstein and electron-Bernstein. These production modes have been extensively studied at HAARP using traditional beam heating patterns and SEE detection. New results are present from HAARP experiments using an excitation mode that attempts to impart orbital angular momentum (OAM) into the heating region. This OAM mode is also referred to as a 'twisted beam.' Previous analysis of twisted beam heating shows that the SEE results obtained are nearly identical to the modes without OAM. Recent twisted beam heating experiments have produced SEE modes not previously characterized. These new modes are presented and discussed. One difference in the twisted beam mode is the heating region produced is in the shape of a ring as opposed to the more traditional 'solid spot' region. The ring heating pattern may be more conducive to the creation of artificial ionization clouds. The results of these runs include artificial ionization creation and evolution as pertaining to the twisted beam pattern.

Validation of ionospheric electron density profiles inferred from GPS occultation observations of the GPS/MET experiment

NASA Astrophysics Data System (ADS)

Kawakami, Todd Mori

In April of 1995, the launch of the GPS Meteorology Experiment (GPS/MET) onboard the Orbview-1 satellite, formerly known as Microlab-1, provided the first technology demonstration of active limb sounding of the Earth's atmosphere with a low Earth orbiting spacecraft utilizing the signals transmitted by the satellites of the Global Positioning System (GPS). Though the experiment's primary mission was to probe the troposphere and stratosphere, GPS/MET was also capable of making radio occultation observations of the ionosphere. The application of the GPS occultation technique to the upper atmosphere created a unique opportunity to conduct ionospheric research with an unprecedented global distribution of observations. For operational support requirements, the Abel transform could be employed to invert the horizontal TEC profiles computed from the L1 and L2 phase measurements observed by GPS/MET into electron density profiles versus altitude in near real time. The usefulness of the method depends on how effectively the TEC limb profiles can be transformed into vertical electron density profiles. An assessment of GPS/MET's ability to determine electron density profiles needs to be examined to validate the significance of the GPS occultation method as a new and complementary ionospheric research tool to enhance the observational databases and improve space weather modeling and forecasting. To that end, simulations of the occultation observations and their inversions have been conducted to test the Abel transform algorithm and to provide qualitative information about the type and range of errors that might be experienced during the processing of real data. Comparisons of the electron density profiles inferred from real GPS/MET observations are then compared with coincident in situ measurements from the satellites of Defense Meteorological Satellite Program (DMSP) and ground-based remote sensing from digisonde and incoherent scatter radar facilities. The principal focus of this study is the validation of the electron density profiles inferred from GPS occultation observations using the Abel transform.

Zonally Symmetric Oscillations of the Thermosphere at Planetary Wave Periods

NASA Astrophysics Data System (ADS)

Forbes, Jeffrey M.; Zhang, Xiaoli; Maute, Astrid; Hagan, Maura E.

2018-05-01

New mechanisms for imposing planetary wave (PW) variability on the ionosphere-thermosphere system are discovered in numerical experiments conducted with the National Center for Atmospheric Research thermosphere-ionosphere-electrodynamics general circulation model. First, it is demonstrated that a tidal spectrum modulated at PW periods (3-20 days) entering the ionosphere-thermosphere system near 100 km is responsible for producing ±40 m/s and ±10-15 K PW period oscillations between 110 and 150 km at low to middle latitudes. The dominant response is broadband and zonally symmetric (i.e., "S0") over a range of periods and is attributable to tidal dissipation; essentially, the ionosphere-thermosphere system "vacillates" in response to dissipation of the PW-modulated tidal spectrum. In addition, some specific westward propagating PWs such as the quasi-6-day wave are amplified by the presence of the tidal spectrum; the underlying mechanism is hypothesized to be a second-stage nonlinear interaction. The S0 total neutral mass density (ρ) response at 325 km consists of PW period fluctuations of order ±3-4%, roughly equivalent to the day-to-day variability associated with low-level geomagnetic activity. The variability in ρ over short periods (˜< 9 days) correlates with temperature changes, indicating a response of hydrostatic origin. Over longer periods ρ is also controlled by composition and mean molecular mass. While the upper-thermosphere impacts are modest, they do translate to more significant changes in the F region ionosphere.

The Seismo-Generated Electric Field Probed by the Ionospheric Ion Velocity

NASA Astrophysics Data System (ADS)

(Tiger) Liu, Jann-Yenq

2017-04-01

The ion density, ion temperature, and the ion velocity probed by IPEI (ionospheric Plasma and Electrodynamics Instrument) onboard ROCSAT (i.e. FORMOSAT-1), and the global ionospheric map (GIM) of the total electron content (TEC) derived from measurements of ground-based GPS receivers are employed to study seismo-ionospheric precursors (SIPs) of the 31 March 2002 M6.8 Earthquake in Taiwan. The GIM TEC and ROCSAT/IPEI ion density significantly decrease specifically over the epicenter area 1-5 days before the earthquake, which suggests that the associated SIPs have observed. The ROCSAT/IPEI ion temperature reveals no significant changes before and after the earthquake, while the latitude-time-TEC plots extracted from the GIMs along the Taiwan longitude illustrate that the equatorial ionization anomaly significantly weakens and moves equatorward, which indicates that the daily dynamo electric field has been disturbed and cancelled by possible seismo-generated electric field on 2 days before (29 March) the earthquake. Here, for the first time a vector parameter of ion velocity is employed to study SIPs. It is found that ROCSAT/IPEI ion velocity becomes significantly downward, which confirms that a westward electric field of about 0.91mV/m generated during the earthquake preparation period being essential 1-5 days before the earthquake. Liu, J. Y., and C. K. Chao (2016), An observing system simulation experiment for FORMOSAT-5/AIP detecting seismo-ionospheric precursors, Terrestrial Atmospheric and Oceanic Sciences, DOI: 10.3319/TAO.2016.07.18.01(EOF5).

Methodology and consistency of slant and vertical assessments for ionospheric electron content models

NASA Astrophysics Data System (ADS)

Hernández-Pajares, Manuel; Roma-Dollase, David; Krankowski, Andrzej; García-Rigo, Alberto; Orús-Pérez, Raül

2017-12-01

A summary of the main concepts on global ionospheric map(s) [hereinafter GIM(s)] of vertical total electron content (VTEC), with special emphasis on their assessment, is presented in this paper. It is based on the experience accumulated during almost two decades of collaborative work in the context of the international global navigation satellite systems (GNSS) service (IGS) ionosphere working group. A representative comparison of the two main assessments of ionospheric electron content models (VTEC-altimeter and difference of Slant TEC, based on independent global positioning system data GPS, dSTEC-GPS) is performed. It is based on 26 GPS receivers worldwide distributed and mostly placed on islands, from the last quarter of 2010 to the end of 2016. The consistency between dSTEC-GPS and VTEC-altimeter assessments for one of the most accurate IGS GIMs (the tomographic-kriging GIM `UQRG' computed by UPC) is shown. Typical error RMS values of 2 TECU for VTEC-altimeter and 0.5 TECU for dSTEC-GPS assessments are found. And, as expected by following a simple random model, there is a significant correlation between both RMS and specially relative errors, mainly evident when large enough number of observations per pass is considered. The authors expect that this manuscript will be useful for new analysis contributor centres and in general for the scientific and technical community interested in simple and truly external ways of validating electron content models of the ionosphere.

Effects of Meteorological Variability on the Thermosphere-Ionosphere System during the Moderate Geomagnetic Disturbed January 2013 Period As Simulated By Time-GCM

NASA Astrophysics Data System (ADS)

Maute, A. I.; Hagan, M. E.; Richmond, A. D.; Liu, H.; Yudin, V. A.

2014-12-01

The ionosphere-thermosphere system is affected by solar and magnetospheric processes and by meteorological variability. Ionospheric observations of total electron content during the current solar cycle have shown that variability associated with meteorological forcing is important during solar minimum, and can have significant ionospheric effects during solar medium to maximum conditions. Numerical models can be used to study the comparative importance of geomagnetic and meterological forcing.This study focuses on the January 2013 Stratospheric Sudden Warming (SSW) period, which is associated with a very disturbed middle atmosphere as well as with moderately disturbed solar geomagntic conditions. We employ the NCAR Thermosphere-Ionosphere-Mesosphere-Electrodynamics General Circulation Model (TIME-GCM) with a nudging scheme using Whole-Atmosphere-Community-Climate-Model-Extended (WACCM-X)/Goddard Earth Observing System Model, Version 5 (GEOS5) results to simulate the effects of the meteorological and solar wind forcing on the upper atmosphere. The model results are evaluated by comparing with observations e.g., TEC, NmF2, ion drifts. We study the effect of the SSW on the wave spectrum, and the associated changes in the low latitude vertical drifts. These changes are compared to the impact of the moderate geomagnetic forcing on the TI-system during the January 2013 time period by conducting numerical experiments. We will present select highlights from our study and elude to the comparative importance of the forcing from above and below as simulated by the TIME-GCM.

Scientific Studies of the High-Latitude Ionosphere with the Ionosphere Dynamics and ElectroDynamics - Data Assimilation (IDED-DA) Model

DTIC Science & Technology

2014-09-23

conduct simulations with a high-latitude data assimilation model. The specific objectives are to study magnetosphere-ionosphere ( M -I) coupling processes...based on three physics-based models, including a magnetosphere-ionosphere ( M -I) electrodynamics model, an ionosphere model, and a magnetic...inversion code. The ionosphere model is a high-resolution version of the Ionosphere Forecast Model ( IFM ), which is a 3-D, multi-ion model of the ionosphere

INSPIRE

NASA Technical Reports Server (NTRS)

Taylor, Bill; Pine, Bill

2003-01-01

INSPIRE (Interactive NASA Space Physics Ionosphere Radio Experiment - http://image.gsfc.nasa.gov/poetry/inspire) is a non-profit scientific, educational organization whose objective is to bring the excitement of observing natural and manmade radio waves in the audio region to high school students and others. The project consists of building an audio frequency radio receiver kit, making observations of natural and manmade radio waves and analyzing the data. Students also learn about NASA and our natural environment through the study of lightning, the source of many of the audio frequency waves, the atmosphere, the ionosphere, and the magnetosphere where the waves travel.

A comparison of current-voltage relationships of collectors in the earth's ionosphere with and without electron beam emission

NASA Technical Reports Server (NTRS)

Myers, Neil B.; Raitt, W. John; Gilchrist, Brian E.; Banks, Peter M.; Neubert, Torsten

1989-01-01

Currents measurements obtained by the two sections of the Cooperative High Altitude Rocket Gun Experiment-2 sounding rocket, a mother vehicle carrying a 1-keV electron gun and a daughter vehicle tethered to the mother, are compared with the results of previous models of current collection by a charged conductor in a plasma. The current collection of the daughter vehicle, a conducting body in the ionosphere, is found to agree with the Parker-Murphy (1967) limit. The additional current collection found for the mother vehicle is attributed to beam-plasma interactions.

Venus nightside ionosphere - A model with KeV electron impact ionization

NASA Technical Reports Server (NTRS)

Kumar, S.

1982-01-01

The impact of keV electrons is proposed as the strongest source of ionization in a full-up Venus nightside ionosphere model for the equatorial midnight region. The electron impacts lead to a peak ion density of 100,000/cu cm, which was observed by the PV-OIMS experiment on several occasions. In addition, the observed altitude profiles of CO2(+), O(+), O2(+), H(+), and H2(+) can be reproduced by the model on condition that the available keV electron flux is approximated by a reasonable extrapolation from fluxes observed at lower energies.

A comparison of current-voltage relationships of collectors in the earth's ionosphere with and without electron beam emission

NASA Astrophysics Data System (ADS)

Myers, Neil B.; Raitt, W. John; Gilchrist, Brian E.; Banks, Peter M.; Neubert, Torsten; Williamson, P. Roger; Sasaki, Susumu

1989-05-01

Currents measurements obtained by the two sections of the Cooperative High Altitude Rocket Gun Experiment-2 sounding rocket, a mother vehicle carrying a 1-keV electron gun and a daughter vehicle tethered to the mother, are compared with the results of previous models of current collection by a charged conductor in a plasma. The current collection of the daughter vehicle, a conducting body in the ionosphere, is found to agree with the Parker-Murphy (1967) limit. The additional current collection found for the mother vehicle is attributed to beam-plasma interactions.

Low frequency electric field variations during HF transmissions on a mother-daughter rocket

NASA Technical Reports Server (NTRS)

Rosenberg, T. J.; Maynard, M. C.; Holtet, J. A.; Karlsen, N. O.; Egeland, A.; Moe, T. E.; Troim, J.

1977-01-01

HF wave propagation experiments were conducted on Mother-Daughter rockets in the polar ionosphere. Swept frequency transmissions from the Mother, nominally covering the range from 0.5 to 5 MHz in both CW and pulse modes, are received by the Daughter. In the most recent rocket of the series, the Mother also contained an AC electric field spectrometer covering the frequency range from 10 Hz to 100 kHz in four decade bands. The low frequency response of the ionosphere with respect to waves emitted from the onboard HF transmitter is examined.

Scientific activity program for 1989

NASA Astrophysics Data System (ADS)

1989-04-01

The current research projects are summarized. The research is grouped into four main directions: infrared astronomy, interplanetary media, cosmic rays and gravitational fields. The projects include instruments for the Infrared Space Observatory (ISO) satellite, problems of star formation and star evolution, Tethered Satellite System (TSS) experiment, Opera experiment, propagation of cosmic rays in the ionosphere, design of a solar neutron detector, and gravitational wave antennas experiments.

The ionospheric impact on GPS performance in southern polar region

USGS Publications Warehouse

Hong, C.-K.; Grejner-Brzezinska, D. A.; Arslan, N.; Willis, M.; Hothem, L.

2006-01-01

The primary objective of this paper is to present the results of the study of the effects of varying ionospheric conditions on the GPS signal tracking in the southern polar region. In the first stage of this study, the data collected by the OSU/USGS team in October-November 2003 within the TAMDEF (Transantarctic Mountains Deformation) network were used together with some IGS Antarctic stations to study the effect of severe ionospheric storms on GPS hardware. Note that TAMDEF is a joint USGS/OSU project with the primary objective of measuring crustal motion in the Transantarctic Mountains of Southern Victoria Land using GPS techniques. This study included ten Antarctic stations equipped with different dual-frequency GPS hardware, and the data were evaluated for two 24-hour periods of severe ionospheric storm (2003/10/29) and moderate ionospheric conditions (minor storm of 2003/11/11). The results of this study were presented at the LAG Assembly in Cairns, Australia (Grejner-Brzezinska et al., 2005). Additional tests, in a more controlled environment, were carried out at the US Antarctic station, McMurdo, between January 10 and February 6, 2006, under varying ionospheric conditions, where several different types of receivers were connected to the same antenna located on the rooftop of the Crary Laboratory (the primary test site). In this scenario, each antenna was subject to identical ionospheric effects during each day of the test, and no spatial decorrelation effects were present, as seen in the previous study, due to the spatial separation of the receivers tested. It should be noted, however, that no moderate or severe ionospheric storms occurred during the experiment, so, unfortunately, this type of conditions was not tested here. The test was repeated with different receivers connected to different antenna types; a total of four 5-day sessions were carried out. The following receiver types were used at the primary site: Trimble 5700, Ashtech Z-Surveyor, JNS Euro-80 and Novatel DL-4, with the following antennas: Trimble Zephyr Geodetic, Ashtech D/M and Ashtech E/M chokering. In addition, data collected by the MCM4 IGS station, MCMD UNAVCO station, and CRAR USGS station, all located within 300 m from the primary test site, were used in the analyses. These stations were equipped with the following receiver/antenna combinations: ADA SNR-12/AOAD/MJT chokering (MCM4), Trimble NETRS/AOAD/MJT chokering (MCMD), and TPS ODYSEY_E/JPSREGANT_DD_E (CRAR). The UNAVCO TEQC software was used to carry out the analyses. Depending on the data sampling rate and the mask angle, the expected numbers of observations per receiver/satellite were compared to the actual number of measurements collected during the ionospheric events, with a special emphasis on L2 data. A total number of cycle slips and losses of lock were computed and compared among the hardware types. The results presented here indicate that there is no significant effects on the GPS receivers during minor ionospheric storms (Kp<5). However, the results reported in ibid, indicate significant differences in the hardware performance under severe ionospheric storms. Thus, careful hardware selection is needed to assure data quality/continuity when observations may be affected by severe ionospheric disturbances, while under calm to minor ionospheric activity level there is no significant difference in performance among the hardware tested here.

The dayside ionospheres of Mars and Venus: Comparing a one-dimensional photochemical model with MaRS (Mars Express) and VeRa (Venus Express) observations

NASA Astrophysics Data System (ADS)

Peter, Kerstin; Pätzold, Martin; Molina-Cuberos, Gregorio; Witasse, Olivier; González-Galindo, F.; Withers, Paul; Bird, Michael K.; Häusler, Bernd; Hinson, David P.; Tellmann, Silvia; Tyler, G. Leonard

2014-05-01

The electron density distributions of the lower ionospheres of Mars and Venus are mainly dependent on the solar X-ray and EUV flux and the solar zenith angle. The influence of an increasing solar flux is clearly seen in the increase of the observed peak electron density and total electron content (TEC) of the main ionospheric layers. The model “Ionization in Atmospheres” (IonA) was developed to compare ionospheric radio sounding observations, which were performed with the radio science experiments MaRS on Mars Express and VeRa on Venus Express, with simulated electron density profiles of the Mars and Venus ionospheres. This was done for actual observation conditions (solar flux, solar zenith angle, planetary coordinates) from the bases of the ionospheres to ∼160 km altitude. IonA uses models of the neutral atmospheres at ionospheric altitudes (Mars Climate Database (MCD) v4.3 for Mars; VenusGRAM/VIRA for Venus) and solar flux information in the 0.5-95 nm wavelength range (X-ray to EUV) from the SOLAR2000 data base. The comparison between the observed electron density profiles and the IonA profiles for Mars, simulated for a selected MCD scenario (background atmosphere), shows that the general behavior of the Mars ionosphere is reproduced by all scenarios. The MCD “low solar flux/clear atmosphere” and “low solar flux/MY24” scenarios agree best (on average) with the MaRS set of observations, although the actual Mars atmosphere seemed to be still slightly colder at ionospheric altitudes. For Venus, the VenusGRAM model, based on VIRA, is too limited to be used for the IonA simulation of electron density profiles. The behavior of the V2 peak electron density and TEC as a function of solar zenith angle are in general reproduced, but the peak densities and the TEC are either over- or underestimated for low or high solar EUV fluxes, respectively. The simulated V2 peak altitudes are systematically underestimated by 5 km on average for solar zenith angles less than 45° and the peak altitudes rise for zenith angles larger than 60°. The latter is the opposite of the observed behavior. The explanation is that VIRA and VenusGRAM are valid only for high solar activity, although there is also very poor agreement with VeRa observations from the recent solar cycle, in which the solar activity increases to high values. The disagreement between the observation and simulation of the Venus electron density profiles proves, that the true encountered Venus atmosphere at ionospheric altitudes was denser but locally cooler than predicted by VIRA.

Digital beacon receiver for ionospheric TEC measurement developed with GNU Radio

NASA Astrophysics Data System (ADS)

Yamamoto, M.

2008-11-01

A simple digital receiver named GNU Radio Beacon Receiver (GRBR) was developed for the satellite-ground beacon experiment to measure the ionospheric total electron content (TEC). The open-source software toolkit for the software defined radio, GNU Radio, is utilized to realize the basic function of the receiver and perform fast signal processing. The software is written in Python for a LINUX PC. The open-source hardware called Universal Software Radio Peripheral (USRP), which best matches the GNU Radio, is used as a front-end to acquire the satellite beacon signals of 150 and 400 MHz. The first experiment was successful as results from GRBR showed very good agreement to those from the co-located analog beacon receiver. Detailed design information and software codes are open at the URL http://www.rish.kyoto-u.ac.jp/digitalbeacon/.

Characteristics of ionospheric storms in East Asia

NASA Astrophysics Data System (ADS)

Wang, Xiao; Wang, Guojun; Shi, Jiankui

The ionosphere experiences intense response during the geomagnetic storm and it varies with latitude and longitude. The DPS-4 digisonde measurements and GPS-TEC data of ionospheric stations located at different latitudes in the longitudinal sector of 90-130E during 2002 to 2012 were analyzed to investigate the ionospheric effects in the different latitude of East Asia during geomagnetic storm. About 70 geomagnetic storms are selected according to the Dst index and observed data and they are in different seasons and different solar activity levels. A few quiet days’ averages of data before geomagnetic storm were used as the undisturbed level. Results show that for the middle and high latitude, the short-lived positive disturbance associated with the initial phase of the every storm was observed in each season and then the disturbances were negative till the termination of storm. At the low latitude, storm-time disturbances of foF2 have obvious diurnal, seasonal and solar cycle characteristics. Generally, geomagnetic activity will cause foF2 to increase at daytime and decrease at nighttime except for the summer in low solar activity period. The intensity of response of foF2 is stronger at nighttime than that at daytime. The negative ionospheric storm effect is the strongest in summer and the positive ionospheric storm effect is the strongest in winter. In high solar activity period, the diurnal variation of the response of foF2 is very pronounced in each season, and the strong ionospheric response can last several days. In low solar activity period, ionospheric response has very pronounced diurnal variation in winter only. It’s notable that geomagnetic activities occurred at local time nighttime can cause stronger and longer responses of foF2 at the low latitude. All in all, the obvious negative phase ionospheric storms often occurred at the low latitude. Moreover a notable phenomenon was observed for the low latitude, there are the intensive oscillations of foF2 occurring during the main storm phase of enhanced storm in Hainan, and it occurred in the morning generally. For the TEC data, strong disturbances can be observed simultaneously from high latitude to low latitude during the main phase of some storms. Generally strong/weak storms can cause the negative/positive phase storms of TEC in the low latitude and which are obvious in the daytime for the summer and winter and in the period from noon to midnight for the equinox. The differences of the responses of foF2 and TEC are also investigated.

Dynamics of Exploding Plasma Within a Magnetized Plasma

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dimonte, G; Dipeso, G; Hewett, D

2002-02-01

This memo describes several possible laboratory experiments on the dynamics of an exploding plasma in a background magnetized plasma. These are interesting scientifically and the results are applicable to energetic explosions in the earth's ionosphere (DOE Campaign 7 at LLNL). These proposed experiments are difficult and can only be performed in the new LAPD device at UCLA. The purpose of these experiments would be to test numerical simulations, theory and reduced models for systems performance codes. The experiments are designed to investigate the affect of the background plasma on (1) the maximum diamagnetic bubble radius given by Eq. 9; andmore » (2) the Alfven wave radiation efficiency produced by the induced current J{sub A} (Eqs. 10-12) These experiments involve measuring the bubble radius using a fast gated optical imager as in Ref [1] and the Alfven wave profile and intensity as in Ref [2] for different values of the exploding plasma energy, background plasma density and temperature, and background magnetic field. These experiments extend the previously successful experiments [2] on Alfven wave coupling. We anticipate that the proposed experiments would require 1-2 weeks of time on the LAPD. We would perform PIC simulations in support of these experiments in order to validate the codes. Once validated, the PIC simulations would then be able to be extended to realistic ionospheric conditions with various size explosions and altitudes. In addition to the Alfven wave coupling, we are interested in the magnetic containment and transport of the exploding ''debris'' plasma to see if the shorting of the radial electric field in the magnetic bubble would allow the ions to propagate further. This has important implications in an ionospheric explosion because it defines the satellite damage region. In these experiments, we would field fast gated optical cameras to obtain images of the plasma expansion, which could then be correlated with magnetic probe measurements. In this regard, it would be most helpful to have a more powerful laser more than 10J in order to increase the extent of the magnetic bubble.« less

Excitation thresholds of field-aligned irregularities and associated ionospheric hysteresis at very high latitudes observed using SPEAR-induced HF radar backscatter

NASA Astrophysics Data System (ADS)

Wright, D. M.; Dhillon, R. S.; Yeoman, T. K.; Robinson, T. R.; Thomas, E. C.; Baddeley, L. J.; Imber, S.

2009-07-01

On 10 October 2006 the SPEAR high power radar facility was operated in a power-stepping mode where both CUTLASS radars were detecting backscatter from the SPEAR-induced field-aligned irregularities (FAIs). The effective radiated power of SPEAR was varied from 1-10 MW. The aim of the experiment was to investigate the power thresholds for excitation (Pt) and collapse (Pc) of artificially-induced FAIs in the ionosphere over Svalbard. It was demonstrated that FAI could be excited by a SPEAR ERP of only 1 MW, representing only 1/30th of SPEAR's total capability, and that once created the irregularities could be maintained for even lower powers. The experiment also demonstrated that the very high latitude ionosphere exhibits hysteresis, where the down-going part of the power cycle provided a higher density of irregularities than for the equivalent part of the up-going cycle. Although this second result is similar to that observed previously by CUTLASS in conjunction with the Tromsø heater, the same is not true for the equivalent incoherent scatter measurements. The EISCAT Svalbard Radar (ESR) failed to detect any hysteresis in the plasma parameters over Svalbard in stark contract with the measurements made using the Tromsø UHF.

Low-pressure electrical discharge experiment to simulate high-altitude lightning above thunderclouds

NASA Technical Reports Server (NTRS)

Jarzembski, M. A.; Srivastava, V.

1995-01-01

Recently, extremely interesting high-altitude cloud-ionosphere electrical discharges, like lightning above thunderstorms, have been observed from NASA's space shuttle missions and during airborne and ground-based experiments. To understand these discharges, a new experiment was conceived to simulate a thundercloud in a vacuum chamber using a dielectric in particulate form into which electrodes were inserted to create charge centers analogous to those in an electrified cloud. To represent the ionosphere, a conducting medium (metallic plate) was introduced at the top of the chamber. It was found that for different pressures between approximately 1 and 300 mb, corresponding to various upper atmospheric altitudes, different discharges occurred above the simulated thundercloud, and these bore a remarkable similarity to the observed atmospheric phenomena. At pressures greater than 300 mb, these discharges were rare and only discharges within the simulated thundercloud were observed. Use of a particulate dielectric was critical for the successful simulation of the high-altitude lightning.

Transequatorial Propagation and Depletion Precursors

NASA Astrophysics Data System (ADS)

Miller, E. S.; Bust, G. S.; Kaeppler, S. R.; Frissell, N. A.; Paxton, L. J.

2014-12-01

The bottomside equatorial ionosphere in the afternoon and evening sector frequently evolves rapidly from smoothly stratified to violently unstable with large wedges of depleted plasma growing through to the topside on timescales of a few tens of minutes. These depletions have numerous practical impacts on radio propagation, including amplitude scintillation, field-aligned irregularity scatter, HF blackouts, and long-distance transequatorial propagation at frequencies above the MUF. Practical impacts notwithstanding, the pathways and conditions under which depletions form remain a topic of vigorous inquiry some 80 years after their first report. Structuring of the pre-sunset ionosphere---morphology of the equatorial anomalies and long-wavelength undulations of the isodensity contours on the bottomside---are likely to hold some clues to conditions that are conducive to depletion formation. The Conjugate Depletion Experiment is an upcoming transequatorial forward-scatter HF/VHF experiment to investigate pre-sunset undulations and their connection with depletion formation. We will present initial results from the Conjugate Depletion Experiment, as well as a companion analysis of a massive HF propagation data set.

Investigation of ionospheric stimulated Brillouin scatter generated at pump frequencies near electron gyroharmonics

NASA Astrophysics Data System (ADS)

Mahmoudian, A.; Scales, W. A.; Bernhardt, P. A.; Fu, H.; Briczinski, S. J.; McCarrick, M. J.

2013-11-01

Stimulated Electromagnetic Emissions (SEEs), secondary electromagnetic waves excited by high power electromagnetic waves transmitted into the ionosphere, produced by the Magnetized Stimulated Brillouin Scatter (MSBS) process are investigated. Data from four recent research campaigns at the High Frequency Active Auroral Research Program (HAARP) facility is presented in this work. These experiments have provided additional quantitative interpretation of the SEE spectrum produced by MSBS to yield diagnostic measurements of the electron temperature and ion composition in the heated ionosphere. SEE spectral emission lines corresponding to ion acoustic (IA) and electrostatic ion cyclotron (EIC) mode excitation were observed with a shift in frequency up to a few tens of Hz from the pump frequency for heating near the third harmonic of the electron gyrofrequency 3fce. The threshold of each emission line has been measured by changing the pump wave power. The excitation threshold of IA and EIC emission lines originating at the reflection and upper hybrid altitudes is measured for various beam angles relative to the magnetic field. Variation of strength of MSBS emission lines with pump frequency relative to 3fce and 4fce is also studied. A full wave solution has been used to estimate the amplitude of the electric field at the interaction altitude. The estimated instability threshold using the theoretical model is compared with the threshold of MSBS lines in the experiment and possible diagnostic information for the background ionospheric plasma is discussed. Simultaneous formation of artificial field-aligned irregularities (FAIs) and suppression of the MSBS process is investigated. This technique can be used to estimate the growth time of artificial FAIs which may result in determination of plasma waves and physical process involved in the formation of FAIs.