On the extraterrestrial ring current during geomagnetic storms

Measurements of the differential energy spectrums of protons and electrons, separately, over the energy range extending from ∼200 ev to 50 kev with a sensitive array of electrostatic analyzers borne on the earth-satellite OGO 3 reveal large temporal variations in intensities of these low-energy charged particles at low and moderate latitudes in the outer radiation zone during two moderate geomagnetic storms in late June and early July 1966. At L = 3.5 on July 9, for example, the intensities of protons (31 ≤ E ≤ 49 kev) increased by factors ≳30 over the pre-storm intensities. The peak proton (200 ev ≤ E ≤ 50 kev) energy densities at the magnetic equator for June 23 (relative magnetic quiescence), June 25 (DST(H) ≃ −30 γ), and July 9 (DST(H) ≃ −50 γ) were 9 × 10−8 erg(cm)−3 at L = 6.8, 2 × 10−7 erg(cm)−3 at L = 4.5, and 5 × 10−7 erg (cm)−3 at L = 3.3, respectively. This energy density is predominantly shared by protons in the energy range ∼3–50 kev. The total energy of these low-energy protons and electrons within the earth's magnetosphere is sufficient to account for the depression of the geomagnetic field (DST(H)) observed at the earth's surface over low and moderate latitudes; hence these charged particles may be identified as the major contributors to the storm-time extraterrestrial ring current. Electrons (200 ev ≤ E ≤ 50 kev) are found to provide approximately 25% of this storm-time ring current. The apparent mean lifetimes of low-energy protons in the outer radiation zone are in agreement with calculated lifetimes assuming charge-exchange collisions with the ambient neutral and charged constituents of the terrestrial exosphere as the predominant loss mechanism.

[1]  L. Frank.  Several observations of low‐energy protons and electrons in the Earth's magnetosphere with OGO 3 , 1967 .

[2]  J. Maguire,et al.  Energy principles for the confinement of a magnetic field , 1966 .

[3]  L. J. Cahill,et al.  INFLATION OF THE INNER MAGNETOSPHERE DURING A MAGNETIC STORM , 1966 .

[4]  L. Frank.  Explorer 12 observations of the temporal variations of low-energy electron intensities in the outer radiation zone during geomagnetic storms , 1966 .

[5]  S. Akasofu.  Electrodynamics of the magnetosphere: Geomagnetic storms , 1966 .

[6]  Norbert Sckopke,et al.  A general relation between the energy of trapped particles and the disturbance field near the Earth , 1966 .

[7]  L. Block.  On the distribution of electric fields in the magnetosphere , 1966 .

[8]  J. Wilcox,et al.  Quasi‐stationary corotating structure in the interplanetary medium , 1965 .

[9]  R. Hoffman,et al.  Magnetic effects of the quiet-time proton belt. , 1965 .

[10]  N. Ness.  The Earth's magnetic tail , 1965 .

[11]  S. Akasofu.  A source of the energy for geomagnetic storms and auroras. , 1964 .

[12]  J. Dungey,et al.  Satellite observations of the geomagnetic field during magnetic storms , 1964 .

[13]  S.-I. Akasofu,et al.  On the asymmetric development of magnetic storm fields in low and middle latitudes , 1964 .

[14]  U. R. Rao,et al.  The solar wind velocity and its correlation with cosmic-ray variations and with solar and geomagnetic activity , 1963 .

[15]  S. Chapman,et al.  THE MAIN PHASE OF GREAT MAGNETIC STORMS , 1963 .

[16]  J. D. Stolarik,et al.  Vanguard 3 magnetic-field observations , 1962 .

[17]  E. Parker.  Dynamics of the geomagnetic storm , 1962 .

[18]  J. Freeman.  Detection of an intense flux of low‐energy protons or ions trapped in the inner radiation zone , 1962 .

[19]  J. E. Hammel,et al.  DEMONSTRATION OF CLASSICAL PLASMA BEHAVIOR IN A TRANSVERSE MAGNETIC FIELD , 1962 .

[20]  E. Parker,et al.  Formation of the geomagnetic storm main‐phase ring current , 1961 .

[21]  C. O. Hines,et al.  A UNIFYING THEORY OF HIGH-LATITUDE GEOPHYSICAL PHENOMENA AND GEOMAGNETIC STORMS , 1961 .

[22]  H. Liemohn.  The lifetime of radiation belt protons with energies between 1 kev and 1 Mev , 1961 .

[23]  Syun-Ichi Akasofu,et al.  The ring current, geomagnetic disturbance, and the Van Allen radiation belts , 1961 .

[24]  C. Sonett,et al.  Characteristics of the extraterrestrial current system: Explorer VI and Pioneer V , 1960 .

[25]  E. Parker,et al.  Hydromagnetic theory of geomagnetic storms , 1959 .

[26]  S. Chapman.  The Energy of Magnetic Storms , 1918 .

[27]  L. Frank.  Initial observations of low-energy electrons in the earth's magnetosphere with OGO 3. , 1967 .

[28]  E. Parker.  Particle Effects in the Geomagnetic Field , 1966 .

[29]  L. R. Davis.  Low Energy Trapped Protons and Electrons , 1965 .

[30]  S. Chapman,et al.  The lower limit of latitude (US sector) of northern quiet auroral arcs, and its relation to Dst(H) , 1963 .

[31]  S. Singer,et al.  Effects of Trapped Particles on the Geomagnetic Field , 1962 .

[32]  S. Chapman,et al.  A new theory of magnetic storms , 1931 .