Equatorial scintillations: advances since ISEA-6

Technical Report · Tue Jan 01 00:00:00 EST 1985

OSTI ID:5798703

Our understanding of the morphology of equatorial scintillations has advanced due to more intensive observations at the equatorial anomaly locations in the different longitude zones. The unmistakable effect of the sunspot cycle in controlling irregularity belt width and electron concentration responsible for strong scintillation in the controlling the magnitude of scintillations has been recognized by interpreting scintillation observations inthe light of realistic models of total electron content at various longitudes. A hypothesis based on the alignment of the solar terminator with the geomagnetic flux tubes as an indicator of enhanced scintillation occurrence and another based on the influence of a transequatorial thermospheric neutral wind have been postulated to describe the observed longitudinal variation. A distinct class of equatorial irregularities known as the bottomside sinusoidal (BSS) type was identified. These irregularities occur in very large patches, sometimes in excess of several thousand kilometers in the E-W direction and are associated with frequency spread on ionograms. Scintillations caused by such irregularities exist only in the VHF band, exhibit Fresnel oscillations in intensity spectra and are found to give rise to extremely long durations (approx. several hours) of uninterrrupted scintillations.

• Research Organization: Air Force Geophysics Lab., Hanscom AFB, MA (USA)
• OSTI ID: 5798703
• Report Number(s): AD-A-164801/3/XAB; AFGL-TR-86-0027
• Country of Publication: United States
• Language: English

Related Subjects

71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
EARTH MAGNETOSPHERE
SOLAR WIND
IONOSPHERE
SOLAR CYCLE
ELECTRON DENSITY
MORPHOLOGY
SCINTILLATIONS
SPECTRA
SUNSPOTS
VARIATIONS
EARTH ATMOSPHERE
PLANETARY IONOSPHERES
SOLAR ACTIVITY
STARSPOTS
STELLAR ACTIVITY
640201* - Atmospheric Physics- Auroral
Ionospheric
& Magetospheric Phenomena
640203 - Atmospheric Physics- Magnetospheric Phenomena- (-1987)
640104 - Astrophysics & Cosmology- Solar Phenomena