Scintillations associated with bottomside sinusoidal irregularities in the equatorial F region

Technical Report · Wed Jan 01 00:00:00 EST 1986

OSTI ID:5796894

Valladares, C E; DasGupta, A; Whitney, H E

A new category of equatorial F region plasma irregularities characterized by nearly sinusoidal wave forms in the ion number density N/sub i/ was observed by the Atmosphere Explorer satellites. Multisatellite scintillation observations made at Huancayo, Peru and spaced-receiver drive measurements made at Ancon, Peru are associated with such irregularities observed by AE-E on a few nights in December 1979. The scintillations continue for a period of almost 6 hours, at a level that varies from moderate to fairly intense (S4 = 0.1-0.8 at 250 MHz), and these S4 fluctuations are quite well correlated, even over a distance of 1000 km. The irregularities constituting the large patch are found to drift eastward at a velocity of approximately 140 m/s. This and other such events are accompanied by the frequency spread signatures on Huancayo ionograms, as previously reported. The unique feature of the Fourier spectra associated with such bottomside sinusiodal (BSS) irregularities is the presence of Fresnel oscillations, which allow a determination of the velocity of the diffraction pattern perpendicular to the direction of the ray from the satellite to the ground station. The velocity so determined agrees well with the results of simultaneously performed spaced-receiver drift measurements. The presence of Fresnel oscillations indicates that the BSS irregularities occur in a relatively thin layer. However, while the scintillation data indicate a high frequency, roll off with a spectral index of the order of -3 to -4, the in-situ data tend to indicate that the index is of the order -5 to -6. Modeling studies are necessary to resolve this difference.

• Research Organization: Air Force Geophysics Lab., Hanscom AFB, MA (USA)
• OSTI ID: 5796894
• Report Number(s): AD-A-164917/7/XAB; AFGL-TR-86-0039
• Country of Publication: United States
• Language: English

Related Subjects

71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
F REGION
ION DENSITY
SCINTILLATIONS
DIFFRACTION
EXPLORER SATELLITES
FOURIER ANALYSIS
PERU
VARIATIONS
COHERENT SCATTERING
DEVELOPING COUNTRIES
EARTH ATMOSPHERE
IONOSPHERE
LATIN AMERICA
PLANETARY IONOSPHERES
SATELLITES
SCATTERING
SOUTH AMERICA
640201* - Atmospheric Physics- Auroral
Ionospheric
& Magetospheric Phenomena