High-latitude F-region irregularities: a review and synthesis. Technical report, 1 January 1986-1 July 1987

The most intense, F region irregularities in the high-latitude ionosphere appear to be produced by convective plasma processes and in particular, by the fluid (gradient drift) interchange instability. Such irregularities are produced by convectively mixing plasma across a mean plasma density gradient with the transport of higher-density plasma into regions of lower-density plasma (and vice versa) leading to the development of an irregularity spectrum that extends in scale from about 10 km down to the ion gyroradius. The mean plasma density gradient that must be present to allow irregularity production by this interchange process appears to be associated with larger-scale (>10 km) plasma structure produced by other means. Because much of the recent progress on this research topic stems from this recognition, a significant portion of this review is dedicated to a description of the characteristics and processes of 10-km plasma structure and their relationships to those of smaller-scale irregularities. From this review, we synthesize a descriptive model of plasma structures in the high-latitude F layer that unifies most of the diverse and independent observations. For the large-scale plasma processes, the model includes (1) the formation of 1000-km-scale “patches” in the polar cap from solar-produced plasma that is transported poleward from lower latitudes; (2) the reconfiguration of patches as they convect into the auroral region and become the latitudinally confined, but longitudinally extended, plasma density enhancements near the equatorward auroral boundary; and (3) the production of localized enhancements and depletions along the poleward auroral boundary by soft-particle precipitation and large but localized electric fields. In the model, the most intense, smaller-scale irregularities are in spatial proximity to these large-scale plasma features, the implication being that the presence of the latter allows formation of the former. The irregularity characteristics are consistent with production by the instability and a morphology controlled by (1) a “slip” velocity (i.e., plasma drift relative to the neutral gas) that is moderately small except in regions of nonuniform plasma convection or under time-varying conditions (e.g., substorms, pulsation events) and (2) a highly conducting auroral E layer that damps irregularity growth and enhances decay. The final irregularity spectrum appears to be produced by (1) global convective processes acting on solar-produced plasma at the largest scales (>50 km), (2) particle precipitation at scales greater than 10 km, (3) perhaps some form of wave activity around 10 km, and (4) the instability at the smaller scales (<10 km).

[1]  S. L. Ossakow,et al.  Morphological studies of rising equatorial Spread F bubbles. Interim report , 1977 .

[2]  D. Klumpar,et al.  Numerical model of the convecting F 2 ionosphere at high latitudes , 1977 .

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

[4]  Michael C. Kelley,et al.  The effects of a conducting E layer on classical F region cross‐field plasma diffusion , 1982 .

[5]  A. Bourdillon,et al.  Velocity characteristics of F region irregularities at sub-auroral latitudes , 1982 .

[6]  H. Bates.  Direct HF backscatter from the F region , 1960 .

[7]  J. Winningham,et al.  Equatorward shift of the cleft during magnetospheric substorms as observed by Isis 1 , 1973 .

[8]  G. Caudal,et al.  Universal time dependence of nighttime F region densities at high latitudes , 1985 .

[9]  J. Meriwether,et al.  The Meridional Thermospheric Neutral Wind Measured by Radar and Optical Techniques in the Auroral Region , 1984 .

[10]  C. Rino,et al.  On the morphology of auroral zone radio wave scintillation , 1980 .

[11]  N. Zabusky,et al.  Scale sizes and lifetimes of f region plasma cloud striations as determined by the condition of marginal stability. Memorandum report , 1980 .

[12]  G. S. Stiles,et al.  Radar observations of cleft dynamics , 1980 .

[13]  D. Köhn,et al.  Active experiments stimulating waves and particle precipitation with small ionospheric barium releases , 1974 .

[14]  S. Ossakow,et al.  Effect of an electron beam on the current-convective instability , 1983 .

[15]  J. L. Sperling,et al.  Short-circuiting, ion-viscous, and ion-inertial effects in striation “freezing” , 1985 .

[16]  A. Pellinen-Wannberg,et al.  DIRECT EVIDENCE OF PLASMA-DENSITY STRUCTURING IN THE AURORAL F-REGION IONOSPHERE , 1985 .

[17]  Charles L Rino,et al.  Chatanika/Triad observations of unstable ionization enhancements in the auroral F‐region , 1980 .

[18]  L. Liszka.  A STUDY OF IONOSPHERIC IRREGULARITIES USING SATELLITE TRANSMISSIONS AT 54 Mc/s , 1965 .

[19]  M. Baron,et al.  F region ion temperature enhancements resulting from Joule heating , 1983 .

[20]  H. C. Carlson,et al.  Coordinated measurements of low-energy electron precipitation and scintillations/TEC in the auroral oval , 1983 .

[21]  A. Shirochkov,et al.  Investigation of the irregular structure of the polar ionosphere using oblique incidence soundings , 1982 .

[22]  E. J. Weber,et al.  Observations of Plasma Structure and Transport at High Latitudes , 1985 .

[23]  M. Kelley.  Relationship between electrostatic turbulence and spread F , 1972 .

[24]  J. Foster,et al.  Plasma convection in the vicinity of the dayside cleft , 1984 .

[25]  C. Rino,et al.  Evidence for sheet‐like auroral ionospheric irregularities , 1978 .

[26]  A. Das,et al.  Generation of ionospheric irregularities by thermal-source: A new mechanism , 1983 .

[27]  S. Basu,et al.  Morphology of phase and intensity scintillations in the auroral oval and polar cap , 1985 .

[28]  W. J. Burke,et al.  Intense poleward‐directed electric fields near the ionospheric projection of the plasmapause , 1977 .

[29]  J. Aarons.  High-Latitude Irregularities During the Magnetic Storm of October 31 to , 1976 .

[30]  T. Potemra,et al.  The amplitude distribution of field-aligned currents at northern high latitudes observed by TRIAD. Interim report , 1975 .

[31]  R. Schunk,et al.  Effect of displaced geomagnetic and geographic poles on high‐latitude plasma convection and ionospheric depletions , 1979 .

[32]  G. E. Hill.  Sudden Enhancements of F-Layer Ionization in Polar Regions , 1963 .

[33]  J. Wild,et al.  The spectrum of radio-star scintillations and the nature of irregularities in the ionosphere , 1956 .

[34]  P. Bernhardt,et al.  Density drift instabilities and weak collisions , 1983 .

[35]  V. Wickwar,et al.  Sondrestrom radar observations of the effect of the IMF B(y) component on polar cap convection , 1986 .

[36]  David N. Anderson,et al.  Ionospheric structures in the polar cap: Their origin and relation to 250‐MHz scintillation , 1985 .

[37]  S. Ossakow,et al.  High altitude limit of the gradient drift instability. Interim report , 1977 .

[38]  LATITUDINAL EFFECTS ON SATELLITE SCINTILLATIONS. , 1966 .

[39]  C. Rino,et al.  Simultaneous rocket probe, scintillation, and incoherent scatter radar observations of irregularities in the auroral zone ionosphere , 1980 .

[40]  L. Liszka.  A Type of Variation of the Signal Strength from 1958 δ2 (Sputnik 3) , 1959, Nature.

[41]  Frihagen.  SATELLITE SCINTILLATION AT HIGH LATITUDES AND ITS POSSIBLE RELATION TO PRECIPITATION OF SOFT PARTICLES. Progress Report No. 4, August 1965--April 1966. , 1968 .

[42]  S. Zalesak,et al.  Finite Temperature Effects on the Evolution of Ionospheric Barium Clouds in the Presence of a Conducting Background Ionosphere. , 1984 .

[43]  Raymond A. Greenwald,et al.  Initial Studies of Small-Scale F Region Irregularities at Very High Latitudes , 1983 .

[44]  R. Greenwald,et al.  Very high latitude F‐region irregularities observed by HF‐radar backscatter , 1983 .

[45]  P. Rodriguez,et al.  High-latitude irregularities in the lower F region: Intensity and scale size distributions , 1984 .

[46]  N. Maynard.  On large poleward-directed electric fields at sub-auroral latitudes , 1978 .

[47]  C. Senior,et al.  E and F region study of the evening sector auroral oval: A Chatanika/Dynamics Explorer 2/NOAA 6 comparison , 1987 .

[48]  A. Simon.  Instability of a Partially Ionized Plasma in Crossed Electric and Magnetic Fields , 1963 .

[49]  B. Reinisch,et al.  Structure and dynamics of the winter polar cap F region , 1983 .

[50]  P. Richards,et al.  A theoretical investigation of the role of neutral winds and particle precipitation in the formation of the auroral F-region ionosphere , 1979 .

[51]  K. H. Bhavnani,et al.  High‐latitude analytical formulas for scintillation levels , 1980 .

[52]  R. A. Greenwald,et al.  A case study of plasma processes in the dayside cleft , 1986 .

[53]  C. P. Pike.  A latitudinal survey of the daytime polar F layer , 1971 .

[54]  H. G. Möller,et al.  Observations of intense irregularities in the polar F-region by HF backscatter and satellite scintillation measurements , 1975 .

[55]  W. Raitt,et al.  Characteristics of the high-latitude ionospheric irregularity boundary, as monitored by the total ion current probe on ESPO-4 , 1975 .

[56]  H. G. Möller.  Backscatter results from Lindau—II. The movement of curtains of intense irregularities in the polar F-layer , 1974 .

[57]  N. Rosenberg.  Observations of striation formation in a barium ion cloud , 1971 .

[58]  W. Stoffregen.  Electron density variation observed in the E-layer below an artificial barium cloud , 1970 .

[59]  E. Fremouw,et al.  Worldwide Behavior of Average VHF-UHF Scintillation , 1971 .

[60]  R. Greenwald,et al.  An HF phased‐array radar for studying small‐scale structure in the high‐latitude ionosphere , 1985 .

[61]  E. W. Kleckner,et al.  Correlated observations of the equatorward diffuse auroral boundary , 1980 .

[62]  Huba.  Long wavelength limit of the current convective instability. Memorandum report , 1984 .

[63]  R. Greenwald,et al.  Drift motions of very high latitude F region irregularities: Azimuthal Doppler analysis , 1985 .

[64]  Sidney L. Ossakow,et al.  Nonlinear equatorial spread F: The effect of neutral winds and background Pedersen conductivity , 1982 .

[65]  C. Rino,et al.  A power law phase screen model for ionospheric scintillation: 1. Weak scatter , 1979 .

[66]  S. Zalesak,et al.  Nonlinear evolution of the Kelvin-Helmholtz instability in the high-latitude ionosphere. Interim report , 1987 .

[67]  S. Basu,et al.  F‐layer irregularities as determined by backscatter studies at 19 MHz over half of a solar cycle , 1974 .

[68]  G. L. Hower,et al.  Comparison of HF radar echoes and high‐latitude spread‐F measurements , 1966 .

[69]  R. Greenwald,et al.  Equatorial spread F: Recent observations and a new interpretation , 1972 .

[70]  Raymond G. Roble,et al.  Time-dependent studies of the aurora: Effects of particle precipitation on the dynamic morphology of ionospheric and atmospheric properties , 1977 .

[71]  R. Livingston,et al.  On the current‐voltage relationship of the magnetospheric generator at intermediate spatial scales , 1986 .

[72]  J. Aarons,et al.  Geometrical considerations of 136 MHz amplitude scintillation in the auroral oval , 1978 .

[73]  S. Ossakow,et al.  Nonlinear evolution of plasma enhancements in the auroral ionosphere 1. Long wavelength irregularities , 1981 .

[74]  H. Carlson,et al.  Plasma characteristics of polar cap F-layer arcs , 1984 .

[75]  D. Gurnett,et al.  Electric and magnetic field observations during a substorm on February 24, 1970 , 1974 .

[76]  S. Matthews,et al.  The diurnal and latitudinal variation of auroral zone ionospheric conductivity , 1981 .

[77]  P. Kintner,et al.  The status of observations and theory of high latitude ionospheric and magnetospheric plasma turbulence , 1985 .

[78]  C. Hanuise,et al.  Spectral studies of F region irregularities in the auroral zone , 1981 .

[79]  J. Kelly,et al.  F‐region ionospheric structure associated with antisunward flow near the dayside polar cusp , 1984 .

[80]  Jules Aarons,et al.  Scintillation boundary during quiet and disturbed magnetic conditions , 1971 .

[81]  J. L. Sperling,et al.  The role of finite parallel length on the stability of barium clouds , 1984 .

[82]  T. Patterson,et al.  Influence of the E region dynamo on equatorial spread F , 1983 .

[83]  J. Aarons,et al.  The scintillation boundary , 1969 .

[84]  C. Meng,et al.  Intensity distribution of dayside polar soft electron precipitation and the IMF , 1983 .

[85]  S. R. Goldman,et al.  Low‐altitude image striations associated with bottomside equatorial spread F: Observations and theory , 1984 .

[86]  F. W. Perkins,et al.  Deformation and striation of plasma clouds in the ionosphere, 3. Numerical simulations of a multilevel model with recombination chemistry , 1976 .

[87]  C. Heinselman,et al.  Solar cycle and seasonal variations of the ionosphere observed with the Chatanika incoherent scatter radar , 1983 .

[88]  L. J. Cahill,et al.  Rocket observations at the northern edge of the eastward electrojet , 1980 .

[89]  Paul F. Fougere,et al.  Velocity shears and sub‐km scale irregularities in the nighttime auroral F‐region , 1986 .

[90]  G. Lakhina,et al.  Short-wavelength drift dissipative instability in the presence of field-aligned currents , 1982 .

[91]  C. Hanuise.  High‐latitude ionospheric irregularities: A review of recent radar results , 1983 .

[92]  T. Moore,et al.  Precipitating electrons associated with the diffuse aurora: Evidence for electrons of atmospheric origin in the plasma sheet , 1979 .

[93]  W. C. Knudsen.  Magnetospheric convection and the high‐latitude F 2 ionosphere , 1974 .

[94]  R. Schunk,et al.  Comparison of model high‐latitude electron densities with Millstone Hill observations , 1983 .

[95]  J. L. Sperling,et al.  Striation eigenmodes along the geomagnetic field and eigenvalues in the limit of strong ion‐neutral collisions , 1985 .

[96]  D. Anderson,et al.  Ionospheric conditions affecting the evolution of equatorial plasma depletions , 1983 .

[97]  T. Jacobsen,et al.  In situ observations of high latitude F-region irregularities , 1971 .

[98]  S. Zalesak,et al.  Long‐wavelength limit of the E×B instability , 1983 .

[99]  M. J. Keskinen,et al.  Theories of high-latitude ionospheric irregularities: A review , 1982 .

[100]  Sidney L. Ossakow,et al.  Plasma cloud late time striation spectra , 1976 .

[101]  J. V. Evans,et al.  The Fossil Theory of nighttime high latitude F region troughs , 1983 .

[102]  D. H. Clark,et al.  The global morphology of irregularities in the topside ionosphere, as measured by the total ion current probe on ESRO-4 , 1976 .

[103]  C. Rino,et al.  Incoherent scatter radar observations of westward electric fields and plasma densities in the auroral ionosphere, 1 , 1974 .

[104]  Robert H. Holzworth,et al.  Mathematical representation of the auroral oval , 1975 .

[105]  R. Hoffman,et al.  Properties of spikelike shear flow reversals observed in the auroral plasma by Atmosphere Explorer C , 1976 .

[106]  J. Berthelier,et al.  Unstable density gradients in the high‐latitude ionosphere , 1985 .

[107]  E. Fremouw,et al.  Spectral behavior of phase scintillation in the nighttime auroral region , 1985 .

[108]  M. Kelley,et al.  Irregularities and Instabilities in the Auroral F Region , 1983 .

[109]  S. Gary.  Kinetic theory of current and density drift instabilities with weak charged-neutral collisions. [in space plasmas] , 1984 .

[110]  S. Zalesak,et al.  Finite temperature stabilization of the gradient drift instability in barium clouds , 1985 .

[111]  A. Tauriainen,et al.  On annual movements of the scintillation boundary of satellite signals , 1971 .

[112]  J. Fedder,et al.  Convection electric fields and polar thermospheric winds , 1972 .

[113]  S. Ossakow,et al.  Nonlinear stabilization of the current convective instability in the diffuse aurora. Memorandum report , 1979 .

[114]  C. Rino,et al.  Recent results in auroral-zone scintillation studies , 1982 .

[115]  R. A. Jeffries,et al.  Observations of the development of striations in large barium ion clouds , 1974 .

[116]  M. Rycroft,et al.  Statistical analysis of movements of the ionospheric trough and the plasmapause , 1970 .

[117]  F. Mozer,et al.  A satellite survey of vector electric fields in the ionosphere at frequencies of 10 to 500 Hertz: 1. Isotropic, high‐latitude electrostatic emissions , 1972 .

[118]  G. L. Hower,et al.  Further comparison of spread‐F and backscatter sounder measurements , 1969 .

[119]  L. S. Yevlashin,et al.  Some features of disturbances in the ionosphere F-region during the red aurora of the type A☆ , 1971 .

[120]  C. Rino,et al.  The structure of localized nighttime auroral zone scintillation enhancements , 1980 .

[121]  W. J. Burke,et al.  Observations of field‐aligned currents in association with strong convection electric fields at subauroral latitudes , 1980 .

[122]  M. Gussenhoven,et al.  Systematics of the equatorward diffuse auroral boundary , 1983 .

[123]  S. Basu.  Ogo 6 observations of small‐scale irregularity structures associated with subtrough density gradients , 1978 .

[124]  R. Heelis.  The effects of interplanetary magnetic field orientation on dayside high‐latitude ionospheric convection , 1984 .

[125]  R. Sagalyn,et al.  High-latitude irregularities in the top side ionosphere based on Isis 1 Thermal Ion Probe data , 1974 .

[126]  P. Kintner,et al.  Evidence for two-dimensional inertial turbulence in a cosmic-scale low-beta plasma. [polar magnetosphere dynamics , 1978 .

[127]  R. Heelis,et al.  Rapid subauroral ion drifts observed by Atmosphere Explorer C , 1979 .

[128]  Ronald F. Woodman,et al.  Radar observations of F region equatorial irregularities , 1976 .

[129]  H. G. Möller,et al.  Comparison of ground HF backscatter and simultaneous particle and plasma pause measurements from a polar orbiting satellite , 1975 .

[130]  J. Winningham,et al.  The development of auroral and geomagnetic substorm activity after a southward turning of the interplanetary magnetic field following several hours of magnetic calm , 1977 .

[131]  R. Debrie,et al.  The ARCAD-3 ISOPROBE experiment for high time resolution thermal plasma measurements , 1982 .

[132]  C. P. Pike,et al.  The day-sector polar F-layer during a magnetospheric substorm , 1973 .

[133]  I. Schwartz,et al.  Ionospheric turbulence: Interchange instabilities and chaotic fluid behavior , 1984 .

[134]  W. J. Burke,et al.  DMSP optical and electron measurements in the vicinity of polar cap arcs , 1982 .

[135]  D. Gurnett,et al.  Satellite measurements of high latitude convection electric fields , 1972 .

[136]  F. Perkins,et al.  Determination of striation scale sizes for plasma clouds in the ionosphere , 1975 .

[137]  James C. G. Walker,et al.  Comparison of electrical conductivities in the E-AND F-regions of the nocturnal ionosphere , 1977 .

[138]  J. Huba,et al.  Linear theory of the E×B instability with an inhomogeneous electric field , 1983 .

[139]  W. M. Cronyn.  The analysis of radio scattering and space-probe observations of small-scale structure in the interplanetary medium , 1970 .

[140]  Myoungkyu Lee.  Ohmic dissipation of Pedersen current as the cause of high‐latitude F region ionospheric irregularities , 1984 .

[141]  G. Caudal,et al.  A SAFARI-EISCAT comparison between the velocity of F region small-scale irregularities and the ion drift , 1985 .

[142]  D. Hardy.  Intense fluxes of low‐energy electrons at geomagnetic latitudes above 85° , 1984 .

[143]  N. Zabusky,et al.  Stability and nonlinear evolution of plasma clouds via regularized contour dynamics , 1980 .

[144]  Robert H. Holzworth,et al.  Auroral circle—delineating the poleward boundary of the quiet auroral belt , 1977 .

[145]  S. Basu,et al.  F region electron density irregularity spectra near auroral acceleration and shear regions , 1984 .

[146]  E. J. Weber,et al.  Polar cap F‐layer auroras , 1981 .

[147]  Michael C. Kelley,et al.  On the origin and spatial extent of high-latitude F region irregularities , 1982 .

[148]  C. Rino,et al.  Simultaneous Rocket-Borne Beacon and In Situ Measurements of Equatorial Spread F - Intermediate Wavelength Results , 1981 .

[149]  R. Hunsucker,et al.  Aurora and the poleward edge of the main ionospheric trough , 1973 .

[150]  E. Szuszczewicz.  Theoretical and experimental aspects of ionospheric structure: A global perspective on dynamics and irregularities , 1986 .

[151]  S. Ossakow,et al.  Current convective instability in the diffuse aurora , 1979 .

[152]  Bodo W. Reinisch,et al.  F layer ionization patches in the polar cap , 1983 .

[153]  J. Aarons,et al.  Production and Dynamics of High‐Latitude Irregularities During Magnetic Storms , 1981 .

[154]  S. Basu,et al.  Geomagnetic control of satellite scintillations , 1963 .

[155]  R. Robinson,et al.  Radar and satellite measurements of an F‐region ionization enhancement in the post‐noon sector , 1984 .

[156]  John A. Klobuchar,et al.  Recent studies of the structure and morphology of auroral zone F region irregularities , 1983 .

[157]  A. Maude,et al.  Short bursts of scintillation of satellite radio signals , 1967 .

[158]  S. Basu,et al.  The morphology of high‐latitude VHF scintillation near 70°W , 1980 .

[159]  J. Winningham,et al.  Satellite observations of suprathermal electron bursts , 1982 .

[160]  C. Rino,et al.  A persistent subauroral scintillation enhancement observed in Alaska , 1977 .

[161]  S. Gary,et al.  Pedersen density drift instabilities , 1983 .

[162]  T. Sato,et al.  F‐region enhancements in the Antarctic , 1964 .

[163]  G. F. Stuart,et al.  The distribution of irregularities in the Antarctic ionosphere-II Diurnal, magnetic and solar cycle effects , 1969 .

[164]  H. Bates.  A PROPOSED POLAR AURORAL RADAR SYSTEM , 1966 .

[165]  G. Haerendel,et al.  MOTION OF ARTIFICIAL ION CLOUDS IN THE UPPER ATMOSPHERE. , 1967 .

[166]  R. Robinson,et al.  Sources of F region ionization enhancements in the nighttime auroral zone , 1985 .

[167]  M. J. Keskinen,et al.  Nonlinear theory of the E × B instability with an inhomogeneous electric field , 1984 .

[168]  F. Mozer.  On the relationship between the growth and expansion phases of substorms and magnetospheric convection , 1973 .

[169]  R. A. Greenwald,et al.  HF ray tracing at high latitudes using measured meridional electron density distributions J.P. Villain Laboratoire de Sondages Electromagntiques de l'Environnement Terrestre, Universitde Toulon , 1984 .

[170]  R. Sheehan,et al.  Coordinated measurements of auroral zone plasma enhancements , 1985 .

[171]  R. Tsunoda.  Time evolution and dynamics of equatorial backscatter plumes 1. Growth phase , 1981 .

[172]  J. Foster.  Ionospheric signatures of magnetospheric convection , 1984 .

[173]  S. Ossakow,et al.  Nonlinear evolution of convecting plasma enhancements in the auroral ionosphere II. Small scale irregularities. Memorandum report , 1982 .

[174]  I. Mikkelsen.  Enhancements of the auroral zone ionization during substorms , 1975 .

[175]  R. Sica,et al.  Auroral zone thermospheric dynamics: 1. Averages , 1986 .

[176]  P. Bernhardt,et al.  Dissipation of ionospheric irregularities by wave-particle and collisional interactions , 1982 .

[177]  P. L. Dyson,et al.  In situ measurements of the spectral characteristics of F region ionospheric irregularities , 1974 .

[178]  R. Livingston,et al.  Polar cap F layer patches: Structure and dynamics , 1986 .

[179]  C. J. Burns,et al.  EISCAT studies of F region irregularities using beam scanning , 1985 .

[180]  D. Köhn,et al.  A possible connection between a barium cloud and electron intensity fluctuations observed on a rocket flight at Kiruna , 1972 .

[181]  R. Huffman,et al.  Earthward directed high‐density Birkeland currents observed by HILAT , 1984 .

[182]  R. M. Robinson,et al.  On calculating ionospheric conductances from the flux and energy of precipitating electrons , 1987 .

[183]  T. Turunen,et al.  On the relative location of the plasmapause and the HF backscatter curtains , 1978 .

[184]  L. Smith,et al.  Auroral enhancement associated with injection of barium along a geomagnetic field line , 1974 .

[185]  R. Robinson,et al.  Measurements of E region ionization and conductivity produced by solar illumination at high latitudes , 1984 .

[186]  S. Ossakow,et al.  The current convective instability as applied to the auroral ionosphere , 1981 .

[187]  E. Fremouw,et al.  Dominant configurations of scintillation‐producing irregularities in the auroral zone , 1981 .

[188]  D. Muldrew,et al.  High‐latitude F region irregularities observed simultaneously with ISIS 1 and the Chatanika radar , 1982 .

[189]  R. W. Spiro,et al.  A model of the high‐latitude ionospheric convection pattern , 1982 .

[190]  W. J. Burke,et al.  Spectral characteristics of precipitating electrons associated with visible aurora in the premidnight oval during periods of substorm activity , 1981 .

[191]  P. Rodriguez,et al.  Spectral classification of medium‐scale high‐latitude F region plasma density irregularities , 1985 .

[192]  Alan D. R. Phelps,et al.  Plasma density irregularities in the high-latitude top side ionosphere , 1976 .

[193]  C. Rino,et al.  The Anisotropy of High Latitude Nighttime F-Region Irregularities. , 1982 .

[194]  W. J. Burke,et al.  Large‐amplitude electric field fluctuations near the Harang discontinuity , 1985 .

[195]  T. Jones,et al.  A search for E-region disturbances induced by ion cloud releases at F-region heights , 1978 .

[196]  J. Huba,et al.  The Effect of Finite 'Blob' Size on the Current Convective Instability in the Auroral Ionosphere. , 1986 .

[197]  R. Heelis,et al.  VELOCITY SPIKE AT THE POLEWARD EDGE OF THE AURORAL ZONE. , 1984 .

[198]  J. Meek.  Sporadic ionization at high latitudes , 1949 .

[199]  J. Shiau,et al.  Barium cloud growth and striation in a conducting background , 1974 .

[200]  C. Chappell,et al.  Twin payload observations of incident and backscattered auroral electrons , 1973 .

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

[202]  S. Ossakow,et al.  Velocity shear stabilization of the current convective instability , 1984 .

[203]  L. Liszka.  Dropout phenomenon observed in the satellite 1958 δ2 transmissions , 1961 .

[204]  W. J. Burke,et al.  Electric and magnetic field characteristics of discrete arcs in the polar cap , 1982 .

[205]  J. Winningham,et al.  Polar cap auroral electron fluxes observed with Isis 1 , 1974 .

[206]  Anthony J. Scannapieco,et al.  Nonlinear equatorial spread F , 1976 .

[207]  S. Ossakow,et al.  Preliminary numerical study of the outer scale size of ionospheric plasma cloud striations. Memorandum report , 1979 .

[208]  Jules Aarons,et al.  UHF scintillation activity over polar latitudes , 1981 .

[209]  W. Kofman,et al.  Very High Electron Temperatures in the Daytime F-Region at Sondrestrom , 1984 .

[210]  Andrew F. Nagy,et al.  A new model for the interaction of auroral electrons with the atmosphere: Spectral degradation, backscatter, optical emission, and ionization , 1974 .

[211]  B. Watkins.  A numerical computer investigation of the polar F-region ionosphere , 1978 .

[212]  W. J. Burke,et al.  Observations of small‐scale auroral vortices by the S3‐2 satellite , 1983 .

[213]  G. Hartmann,et al.  The electron content of the ionosphere and the Southern boundary of diffuse Aurora , 1982 .

[214]  F. Mozer.  Origin and effects of electric fields during isolated magnetospheric substorms , 1971 .

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

[216]  P. Bernhardt,et al.  The nonlocal theory of periodic density drift instabilities , 1983 .

[217]  P. Satyanarayana,et al.  Effects of finite-current-channel width on the current convective instability. Memorandum report, October 1983-October 1984 , 1985 .

[218]  S. Ossakow,et al.  Nonlinear evolution of convecting plasma enhancements in the auroral ionosphere: 2. Small scale irregularities , 1983 .

[219]  G. N. Taylor.  Structure at the poleward edge of a mid-latitude F-region trough , 1973 .

[220]  C. Rino,et al.  Incoherent scatter radar observations of westward electric fields. II. [in ionosphere] , 1974 .

[221]  S. Akasofu,et al.  First results from the north polar auroral radar , 1973 .

[222]  J. Aarons.  A descriptive model of F layer high‐latitude irregularities as shown by scintillation observations , 1973 .

[223]  S. Ossakow,et al.  Nonlinear evolution of diffuse auroral f region ionospheric irregularities. Memorandum report , 1980 .

[224]  P. Dyson.  Direct measurements of the size and amplitude of irregularities in the topside ionosphere , 1969 .

[225]  A. Egeland,et al.  Intense, variable electric fields at ionospheric altitudes in the high latitude regions as observed by DE‐2 , 1982 .

[226]  B. Maehlum.  In situ observations of enhancements in the F-region electron density associated with the occurrence of a ‘sporadic-F’ trace on the ionogram , 1972 .

[227]  R. Heelis,et al.  Electrical coupling effects on the temporal evolution of F layer plasma structure , 1985 .

[228]  C. P. Pike.  Equatorward shift of the polar F layer irregularity zone as a function of the Kp index , 1972 .

[229]  M. Thomsen,et al.  An electrostatic parabolic density drift instability , 1982 .

[230]  S. Ossakow,et al.  On the spatial power spectrum of the E x B gradient drift instability in ionospheric plasma clouds. Memorandum report , 1981 .

[231]  R. Schunk,et al.  A theoretical study of the production and decay of localized electron density enhancements in the polar ionosphere , 1986 .

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

[233]  J. L. Sperling,et al.  Electric field limitation of drift dissipative wave generation in ionospheric structures , 1982 .

[234]  C. Rino,et al.  Simultaneous measurement of ion and neutral motions by radar and optical techniques , 1974 .

[235]  S. Zalesak,et al.  A simulation of high latitude F‐layer instabilities in the presence of magnetosphere‐ionosphere coupling , 1985 .

[236]  J. L. Sperling.  Finite parallel wavelengths and ionospheric structuring , 1983 .

[237]  E. W. Hones,et al.  Energy spectra and angular distributions of particles in the plasma sheet and their comparison with rocket measurements over the auroral zone , 1971 .

[238]  J. Doles,et al.  Velocity shear and the E × B instability , 1975 .