The statistical character of Pc 4 magnetic pulsations at synchronous orbit

A statistical study of 215 magnetic pulsation events identified on the basis of waveform and period as Pc 4 (45- to 150-s period) observed at synchronous orbit by ATS 6 is reported. The study was designed to be similar to that done with Pc 3 (10- to 45-s period) by Arthur et al. (1977). These Pc 4 are found to occur most often near 1800 local time but are observed at all local times. The dominant period is ∼100 s, but a secondary peak in the distribution occurred at ∼53 s. They tend to be nearly linearly polarized, principally transverse to the ambient magnetic field. The Pc 4 are found to divide naturally into two classes (radial and azimuthal) on the basis of the azimuth of the major axis of polarization. These classes divide further into low-frequency (≤0.015 Hz) and high-frequency (≥0.015 Hz) classes. These four classes organize the remaining wave characteristics quite well. Division of the Pc 4 events into these classes does not lead to identification of a single source mechanism as it did with Pc 3. However, some correspondence between the classes and various proposed mechanisms does exist.

[1]  D. Baker,et al.  Multispacecraft Observations of Energetic Electron Flux Pulsations at 6.6 Re' (Paper 80A0571) , 1980 .

[2]  R. Greaves,et al.  Dodge satellite observations of Pc 3 and Pc 4 magnetic pulsations and correlated effects in the ground observations , 1979 .

[3]  A. Hasegawa.  Excitation of Alfvén waves by bouncing electron beams ‐ An origin of nightside magnetic pulsations , 1979 .

[4]  B. Mauk,et al.  A compressional Pc4 pulsation observed by three satellites in geostationary orbit near local midnight , 1979 .

[5]  B. Mauk,et al.  Alfvén waves generated by an inverted plasma energy distribution , 1978 .

[6]  R. McPherron,et al.  Geomagnetic pulsations observed simultaneously on three geostationary satellites , 1978 .

[7]  R. McPherron,et al.  Measurements of the Poynting vector of standing hydromagnetic waves at geosynchronous orbit , 1978 .

[8]  R. McPherron,et al.  Interplanetary magnetic field conditions associated with synchronous orbit observations of Pc 3 magnetic pulsations , 1977 .

[9]  R. McPherron,et al.  Micropulsations in the morning sector, 3. Simultaneous ground‐satellite observations of 10‐ to 45‐s period waves near L = 6.6 , 1977 .

[10]  D. Southwood.  Localised compressional hydromagnetic waves in the magnetospheric ring current , 1977 .

[11]  A. Hasegawa,et al.  Kinetic processes in plasma heating by resonant mode conversion of Alfvén wave , 1976 .

[12]  C. Russell,et al.  A statistical study of Pc 3 magnetic pulsations at synchronous orbit, ATS 6 , 1976 .

[13]  J. Means,et al.  A comparative study of three techniques for using the spectral matrix in wave analysis. [for magnetospheric ULF waves , 1976 .

[14]  David J. Southwood,et al.  A general approach to low‐frequency instability in the ring current plasma , 1976 .

[15]  R. McPherron,et al.  Micropulsations in the morning sector: 2. Satellite observations of 10‐ to 45‐s waves at synchronous orbit, ATS 1 , 1975 .

[16]  R. Snare,et al.  ATS-6 UCLA Fluxgate Magnetometer , 1975, IEEE Transactions on Aerospace and Electronic Systems.

[17]  W. D. Cummings,et al.  The dominant mode of standing Alfven waves at the synchronous orbit , 1975 .

[18]  D. Southwood.  Comments on Field Line Resonances and Micropulsations , 1975 .

[19]  A. Hasegawa,et al.  Theory of magnetic pulsations , 1974 .

[20]  D. Southwood.  Some features of field line resonances in the magnetosphere , 1974 .

[21]  A. Hasegawa,et al.  A theory of long period magnetic pulsations 1 , 1974 .

[22]  A. Hasegawa,et al.  A theory of long‐period magnetic pulsations: 2. Impulse excitation of surface eigenmode , 1974 .

[23]  H. Radoski.  A theory of latitude dependent geomagnetic micropulsations: The asymptotic fields , 1974 .

[24]  C. Uberoi.  Alfven waves in inhomogeneous magnetic fields , 1972 .

[25]  P. Coleman,et al.  Some characteristics of low-frequency oscillations observed at ATS 1. , 1972 .

[26]  L. Lanzerotti,et al.  Quiettime observation of a coherent compressional Pc-4 micropulsation at synchronous altitude , 1971 .

[27]  M. L. Dwarkin,et al.  HYDROMAGNETIC WAVES AT 6.25 EARTH RADII WITH PERIODS BETWEEN 3 AND 240 SECONDS. , 1971 .

[28]  J. Mcclay.  On the resonant modes of a cavity and the dynamical properties of micropulsations , 1970 .

[29]  J. W. Dungey,et al.  BOUNCE-RESONANT INTERACTION BETWEEN PULSATIONS AND TRAPPED PARTICLES. , 1969 .

[30]  P. Coleman,et al.  Standing Alfvén waves in the magnetosphere , 1969 .

[31]  H. Radoski,et al.  The hydromagnetic toroidal resonance , 1967 .

[32]  H. Radoski.  Highly asymmetric MHD resonances: The guided poloidal mode , 1967 .

[33]  H. Radoski,et al.  Axisymmetric Plasmasphere Resonances: Toroidal Mode , 1966 .

[34]  V. L. Patel.  Low frequency hydromagnetic waves in the magnetosphere: Explorer XII☆ , 1965 .

[35]  Masahisa Sugiura,et al.  OSCILLATION OF THE GEOMAGNETIC FIELD LINES AND ASSOCIATED MAGNETIC PERTURBATIONS AT CONJUGATE POINTS , 1964 .

[36]  D. Southwood.  The behaviour of ulf waves and particles in the magnetosphere , 1973 .

[37]  R. McPherron,et al.  Storm-associated Pc 5 micropulsation events observed at the synchronous equatorial orbit. , 1972 .

[38]  J. Dungey,et al.  Ultra low frequency waves in the magnetosphere , 1970 .

[39]  A. Hasegawa.  Drift Mirror Instability in the Magnetosphere , 1969 .

[40]  V. Troitskaya,et al.  Geomagnetic micropulsations and diagnostics of the magnetosphere , 1967 .

[41]  H. Radoski.  A note on oscillating field lines , 1967 .