Spread F and ionospheric currents

It is shown that the widely used equilibrium in which the nighttime F region is supported by E×B drifts is unstable if, in addition to the supporting eastward field, a north-south electric field component exists. The instability, which takes the form of rising and falling sheets of ionization, has a growth rate γ ≈ 3 × 10−4 νin−1 sec−1, where νin is ion-neutral collision frequency at the F region peak. These conclusions are based on a set of new moment equations that govern the time evolution of the Pedersen conductance and the plasma content of a flux tube. It is argued that temperate- and high-latitude spread F are a result of this instability. The new moment equations also predict: (1) that there is a maximum height-integrated Pedersen current that the F region can carry; and (2) that barium clouds deform in agreement with observations of recent releases.

[1]  A. Simon.  GROWTH AND STABILITY OF ARTIFICIAL ION CLOUDS IN THE IONOSPHERE. , 1970 .

[2]  Henry Rishbeth,et al.  Introduction to ionospheric physics , 1969 .

[3]  F. Perkins,et al.  Auroral phenomena driven by the magnetospheric plasma , 1971 .

[4]  Ronald F. Woodman,et al.  Equatorial spread F: Implications of VHF radar observations , 1970 .

[5]  D. Singleton.  Spread-F and the parameters of the F-layer of the ionosphere—I: Spread-F and F-layer electron density , 1962 .

[6]  George C. Reid,et al.  The formation of small‐scale irregularities in the ionosphere , 1968 .

[7]  F. W. Perkins,et al.  Deformation and striation of plasma clouds in the ionosphere: 2. Numerical simulation of a nonlinear two‐dimensional model , 1973 .

[8]  G. Haerendel,et al.  Striations in ionospheric ion clouds, 1 , 1971 .

[9]  D. Singleton.  Dependence of satellite scintillations on zenith angle and azimuth. , 1970 .

[10]  J. HOLLINGWORTH,et al.  Structure of the Ionosphere , 1934, Nature.

[11]  D. Martyn.  The Normal F Region of the Ionosphere , 1959, Proceedings of the IRE.

[12]  T. VanZandt,et al.  Electromagnetic drift of the midlatitude F 2 Layer during a storm , 1971 .

[13]  T. Patterson,et al.  The maintenance of the night-time F-layer , 1964 .

[14]  S. Kato,et al.  Electrodynamics of the ionosphere , 1966 .

[15]  L. Linson,et al.  Formation of striations in ionospheric plasma clouds , 1970 .

[16]  R. Wolf.  Effects of ionospheric conductivity on convective flow of plasma in the magnetosphere , 1970 .

[17]  R. Rüster.  Theoretical treatment of the dynamical behaviour of the F-region during geomagnetic bay disturbances , 1969 .

[18]  P. Stubbe.  Theory of the night-time F-layer , 1968 .

[19]  D. Cunnold.  Drift‐dissipative plasma instability and equatorial spread F , 1969 .

[20]  D. Singleton.  Spread-F and the parameters of the F-layer of the ionosphere—II: Spread-F and F-layer height , 1962 .

[21]  D. Moorcroft,et al.  The shape of the F-region irregularities which produce satellite scintillations Evidence for axial asymmetry. , 1972 .

[22]  F. W. Perkins,et al.  Deformation and striation of plasma clouds in the ionosphere: 1 , 1973 .

[23]  J. R. Herman,et al.  Spread F and ionospheric F‐region irregularities , 1966 .