High-latitude electric fields and the three-dimensional interaction between the interplanetary and terrestrial magnetic fields
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Engineering topics
Publications and source records attributed to Mozer, F. S..
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Energetic particle observations from ATS-5 are presented that directly show asymmetric injection of 30- to 300-keV proton fluxes into the nightside magnetosphere to form the asymmetric ring current. The temporal structure of these substorm-correlated proton bursts is consistent with a westward gradient drift from the nightside acceleration region. The drifting protons tend to be accompanied by nondiamagnetic decreases of the magnetic field at the satellite. Adiabatic decreases of the energetic electron fluxes often occur with these changes in the field strength. Nearly 200 proton-only events have been observed, occurring uniformly between 1500 and 2200 LT and not at all before 1200 LT or after 2300 LT.
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A review is given of present theoretical and experimental information on quasistatic electric fields in and near the plasmasphere with the aim of discussing plasma flow within the plasmasphere, dynamo electric fields, and the penetration of electric fields of magnetospheric origin to low latitudes. Data are presented that suggest that the mean temporal variation of electric fields at all latitudes is diurnal, that dynamo electric fields are more important near L = 3 and are less important near and beyond L = 4 than are fields of magnetospheric origin, and that magnetospheric fields with periods that are a reasonable fraction of one day efficiently penetrate the plasmapause.
The definition of the growth and expansion phases of substorms is considered in terms of temporal sequences of magnetospheric convection. It is suggested that the definition of these phases should rest on magnetospheric convection theories and data because of the ambiguities in the interpretation of ground magnetometer records from which these concepts arose originally. Reviewed data are shown to offer strong evidence for the validity and usefulness of the concepts of substorm growth and expansion phases.
Balloon-borne electric field and X ray detectors have been flown from Fort Churchill and from near the foot of the magnetic field line on which the ATS 5 satellite is located in order to obtain satellite and balloon measurements of trapped and precipitating particles and to compare them with balloon measurements of the ionospheric electric field. The approximately 80 hours of coordinated data show that nighttime precipitation events (1) are preceded by enhancements of the westward component of ionospheric electric field about 70% of the time, (2) cause the westward electric field strength to decrease about 70% of the time, (3) are unrelated to variations of the southward component of the ionospheric electric field. The westward electric field enhancement before many precipitation events occurs when the trapped electron flux is at or near the stable trapping limit.
Electric-field payloads were flown simultaneously on two balloons from Great Whale River, Canada, on September 21, 1971, to provide data at two points in the upper atmosphere that differed in altitude by more than one atmospheric density scale height and in horizontal position by 30-140 km. The altitude dependences in the two sets of data prove conclusively that the vertical electric field at balloon altitudes stems from fair-weather atmospheric electricity sources and that the horizontal fields are mapped down ionospheric fields, since the weather-associated horizontal fields were smaller than 2 mV/m.
It is suggested that the definition of the growth and expansion phases of substorms should rest on magnetospheric convection theories and data because of the ambiguities in interpretation of ground magnetometer records from which these concepts arose originally. Data such as that discussed in the report offers strong evidence for the validity and usefulness of the concepts of the growth and expansion phases.
A theoretical explanation for the dependence of the Jovian decametric radiation on the position of its satellite Io is advanced in terms of electrostatic instabilities created by injection into the hot natural plasma of cold photoelectrons from Io. This may be tested with appropriately positioned and presently planned deep-space probes that search for variations of the Jovian decametric radiation at times following local sunset and sunrise at Io.
Examination of measurements of 40- and 75-keV electrons and 60and 120-keV protons on the ATS 5 satellite in synchronous orbit in order to show that fluxes of such particles often approach but rarely exceed limiting values that agree within a factor of about 2 with the fluxes predicted by Kennel and Petschek (1966) from consideration of whistler-mode wave-particle interactions. A study is made of the proton and electron fluxes for evidence of the stably trapped flux limits in order to determine them, and to study the local-time dependences of their existence.
Balloon-measured electric-field data for five-hour periods during each of 19 substorms near local midnight have been analyzed and averaged. Results are applied to an improved model of the magnetospheric substorm in which the origin of the electric fields, the flow of cold plasma and magnetic-field lines, and many observed particle phenomena are more naturally explained.
Equatorial proton and electron pitch angle distributions in loss cone and at large angles from geostationary ATS 5 satellite observation
Balloon-measured magnetospheric electric fields comparison with all sky camera pictures of large scale visible auroral form motions, noting relationship
Local time variations of power spectra of magnetospheric electric field from balloon flight data
Magnetospheric electric fields properties via simultaneous balloon flights between plasmapause and polar cap, indicating fields and bulk plasma flow turbulence
Magnetopause electric field accounting for ATS 5 energetic proton and electron flux measurements, comparing to various models
Vertical and horizontal atmospheric electric fields measurements at balloon altitudes, considering magnetospheric processes effect and potential differences
Balloon measurements of ionospheric electric fields