In this study we also describe the typical plasma and wave parameters observed in L and magnetic local time for quiet, storm, and storm phase.
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These results are given in a tabular format in the supporting information so that more accurate statistics of EMIC wave parameters can be incorporated into modeling efforts. Solar-terrestrial physics research in Australia began in when de Rossel measured the southern hemisphere geomagnetic field at Recherche Bay on the sout Solar-terrestrial physics research in Australia began in when de Rossel measured the southern hemisphere geomagnetic field at Recherche Bay on the southern tip of Tasmania, proving the field magnitude and direction varied with latitude. This was the time when the French and British were competing to chart and explore the new world.
From the early twentieth century Australian solar-terrestrial physics research concentrated on radio wave propagation and communication, which by the s fed into the International Geophysical Year in the areas of atmosphere and ionosphere physics, and geomagnetism, with some concentration on Antarctic research. This was also the era of increased studies of solar activity and the discovery of the magnetosphere and the beginning of the space age. In the s, Australia became a world leader in solar physics which led to radio astronomy discoveries.
This paper outlines the historical development of solar-terrestrial physics in Australia and its international connections over the years and concludes with examples of specific research areas where Australia has excelled. Electromagnetic Ion Cyclotron EMIC waves cause electron loss in the radiation belts by resonating with high-energy electr Electromagnetic Ion Cyclotron EMIC waves cause electron loss in the radiation belts by resonating with high-energy electrons at energies greater than about keV.
However, their effectiveness has not been fully quantified. To determine the electron loss, EMIC diffusion rates were included in the British Antarctic Survey Radiation Belt Model together with whistler mode chorus, plasmaspheric hiss, and radial diffusion. By simulating a day period in , we show that EMIC waves caused a significant reduction in the electron flux for energies greater than 2 MeV but only for pitch angles lower than about The simulations show that the distribution of electrons left behind in space looks like a pancake distribution.
Since EMIC waves cannot remove electrons at all pitch angles even at 30 MeV, our results suggest that EMIC waves are unlikely to set an upper limit on the energy of the flux of radiation belt electrons. Gyroresonant wave-particle interactions with electromagnetic ion cyclotron EMIC waves are a potentially important loss process for relativistic electrons in the Earth's radiation belts. Here we perform a statistical analysis of the EMIC waves observed by the Combined Release and Radiation Effects Satellite CRRES to determine the global morphology and spectral properties of the waves and to help assess their role in radiation belt dynamics.
Hydrogen band EMIC wave events, with intensities greater than 0. However, the time-averaged properties are very different, being a factor of lower for helium and hydrogen band EMIC waves, respectively, suggesting that the overall effect will be correspondingly weaker.
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From to From to UT on October 30 the Cluster spacecrafts ran along an orbit of southern cuspplasmasphere-northern cusp that provides an excellent observation of ULF waves in dayside magnetosphere. Flux gate magnetometer FGM data in the GSE system from the spacecrafts were transformed in a field aligned coordinated system, and the results showed that in the equatorial side of the cusp existed plenty of narrow band ULF waves in Pc range. The frequency band of the ULF waves is confined in narrow Pc5 band near the cusp and evolved into Pc3 band when the spacecrafts went to about L-5 where the plasmasphere is situated.
This is consistent with the geomagnetic field line resonance FLR theory. However, in the cusp region only broadband waves were observed, which seem to be a magnetosheath-like turbulence due to that the cusp is located in the open field line area where the condition to excite FLR does not be satisfied but plasma disturbance from upstream solar wind is allowed to come into. By this way, a clear wave boundary of the cusp is identified, that is, the transferring position from the broadband waves to the narrow band waves is the right boundary of open field lines to the closed ones.
We report the observation of two stellar occultations by Titan on 14 November , using stations in the Indian Ocean, southern Africa, Spain, and northern and southern Americas We report the observation of two stellar occultations by Titan on 14 November , using stations in the Indian Ocean, southern Africa, Spain, and northern and southern Americas. This layer is close to an inversion layer observed fourteen months later by the Huygens HASI instrument during the entry of the probe in Titan's atmosphere on 14 January [Fulchignoni et al.
The haze distribution around Titan's limb at km altitude is close to that predicted by the Global Circulation Model of Rannou et al. This contrasts with Rannou et al.
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Copyright by the American Geophysical Union. Discrete harmonically structured ULF waves in the mHz band seen by ISEE-1 over a radial range of Re in the daytime magnetosphere can be explained in detail by the field Discrete harmonically structured ULF waves in the mHz band seen by ISEE-1 over a radial range of Re in the daytime magnetosphere can be explained in detail by the field line resonance mechanism. The frequency of these resonances depends on the Alfven velocity VA which is a function of the magnetic field strength and plasma density.
ISEE-1 magnetic field and cold electron density data are used to calculate radial VA profiles, both in the presence and the absence of a plasmapause. The toroidal mode resonance frequency structure is modelled for the first four harmonics. Agreement between the modelled and observed harmonics is excellent for a pass which does not show a plasmapause gradient.
In the presence of a steep plasmapause gradient the model predicts a correspondingly steep increase in the resonance frequencies at the plasmapause by about 5 mHz for the first harmonic and 20 mHz for the fourth harmonic.
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The observed resonances show a corresponding increase in frequency but the rate of increase is not as rapid as that predicted by the model. The effects of heavy ion mass loading on the modelling are discussed. Pc2 electromagnetic ion cyclotron waves at 0. Wave polarization is predominantly left-handed with propagation almost parallel to the ambient magnetic field, and the spectral slot and polarization reversal predicted by multicomponent cold plasma propagation theory are identified in the wave data. The results are considered an example of wave-particle interactions occurring during the outer plasmasphere refilling process at the time of the substorm recovery phase.
The aim of the symposium was to bring together investigators with interests in low latitude hydromagnetic waves in order to review the present state of knowledge in this area of m The aim of the symposium was to bring together investigators with interests in low latitude hydromagnetic waves in order to review the present state of knowledge in this area of magnetospheric physics.
Of particular importance is the means by which wave energy is transferred to low latitudes to produce geomagnetic pulsations on the ground. The group of contributed papers reviewed shows that definitive experiments are underway and new theories capable of providing resonant wave energy at low latitudes are being developed. Particular topics covered by the review include solar wind control, wave spectra, array studies of wave parameters, storm time waves, and global wave resonance theory involving the coupling of compressional and transverse waves in the magnetosphere.
Dispersion measurements were performed on geomagnetic pulsation data recorded over an Australasian network in a search for evidence of ionospheric dispersion of Pc 1 signals. A method of analysis was adopted in which the slope of emission elements of a selected Pc 1 event are examined individually. It has been found that there are no significant ionospheric dispersion effects for propagation between middle and low latitudes.
Magnetospheric propagation paths calculated from dispersion measurements show large variations and are not considered generally reliable. This paper presents a theoretical investigation of the ducting of Pc1 hydromagnetic waves in an ionospheric layer situated above the F2 region.
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Theoretical calculations show that Theoretical calculations show that this upper ionospheric duct may also sustain horizontal propagation of Pc1 pulsations over appreciable distances. It is found that there is a low-frequency cutoff as in the case of the F2 layer waveguide. The group velocity of waves in the upper ionospheric duct is considerably greater, and dispersion is more pronounced compared to the ducted propagation in the F2 region. Polarization studies of hydromagnetic emission type Pc 1 micropulsation events in the plane of the Earth's surface have been undertaken using a three station network in South-East Australia.
Using selected data over a three year period a consistent polarization pattern has been observed from the three stations. This is discussed in terms of temporal variations in the ellipse major axis direction, ellipticity and direction of rotation of the perturbation vector. Interpretation of these results in terms of ionospheric waveguide propagation is also considered. The dispersive propagation of Pcl hydromagnetic emissions in a proton-helium magnetosphere is considered. The addition of singly charged helium ions to the medium allows the propa The addition of singly charged helium ions to the medium allows the propagation of hydromagnetic nose emissions.
A graphical method which determines the nose emission propagation path, and the proton and helium concentrations at the top of the path, is presented. Only three of twelve nose emissions considered are consistent with the proton-helium explanation. The propagation of two or more adjacent narrow-band emissions along different tubes of force in a proton magnetosphere is considered as an alternative explanation.
It is also shown that propagation path L values of normally dispersed hydromagnetic emissions may be increased by 0. Analysis of occurrence of hydromagnetic emissions recorded during at two Australian stations, Newcastle and Hobart, has shown that about two thirds of the activity recorded a Analysis of occurrence of hydromagnetic emissions recorded during at two Australian stations, Newcastle and Hobart, has shown that about two thirds of the activity recorded at a given station, including most large amplitude events, is recorded simultaneously at the other station.
Most events having a mid-frequency above Hz occurred simultaneously at the two stations. Propagation of these events in the ionospheric hydromagnetic duct is shown to have a significant influence on the middle latitude occurrence statistics. It is suggested that the diurnal variation in propagation paths may provide a simple explanation for the variation in hydromagnetic emission occurrence with latitude.
The magnitude of the diurnal and storm-time variations support the idea of hydromagnetic emission generation by low energy trapped protons. Magnetic pulsations in the Pc 5 band s are often considered as a result of the interaction between the solar wind and magnetosphere at the magnetopause via Magnetic pulsations in the Pc 5 band s are often considered as a result of the interaction between the solar wind and magnetosphere at the magnetopause via the K-H instability.
Comparing data between dawn and dusk, asymmetry in the Pc 5 occurrence exists. Rostoker and Sullivan investigated the polarization characteristics and found that the Pc 5 polarization in the afternoon is inconsistent with K-H instability theory. They suggested that another origination mechanism for Pc 5 pulsations in the afternoon.
Two induction magnetometers were installed successfully in Jan.
Near‐Earth magnetotail shape and size as determined from the magnetopause flaring angle
The time accuracy between the two magnetometers can reach 1 ms through the advance embedding time board and the GPS receiving system. Here we adopt the cross-spectral analysis technique, analyze the data obtained by the two induction magnetometers in the Pc 5 frequency band and present the results. The emphasis was on the physics and techniques underlying the entire frequency range.
Topics solicited included nonlinear electron and ion cyclotron wave growth; wave-wave interactions, such as VLF-Pcl 0.
Related Magnetospheric Research with Advanced Techniques: Proceedings of the 9th COSPAR Colloquium Held in B
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