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(Reference retrieved automatically from Web of Science through information on FAPESP grant and its corresponding number as mentioned in the publication by the authors.)

GPS L1-Frequency Observations of Equatorial Scintillations and Irregularity Zonal Velocities

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Muella, Marcio T. A. H. [1] ; de Paula, Eurico R. [2] ; Jonah, Olusegun F. [2]
Total Authors: 3
[1] Univ Vale Paraiba, Lab Fis & Astron, IP&D, BR-12244000 Sao Paulo - Brazil
[2] Natl Inst Space Res, Aeron Div, BR-12227010 Sao Paulo - Brazil
Total Affiliations: 2
Document type: Review article
Source: SURVEYS IN GEOPHYSICS; v. 35, n. 2, p. 335-357, MAR 2014.
Web of Science Citations: 6

In this work, the climatology of ionospheric scintillations at global positioning system (GPS) L-band frequency and the zonal drift velocities of scintillation-producing irregularities were depicted for the equatorial observatory of So Luis (2.33A degrees S; 44.21A degrees W; dip latitude 1.3A degrees S), Brazil. This is the first time that the hourly, monthly, and seasonal variations of scintillations and irregularity zonal drifts at So Luis were characterized during periods of different solar activity levels (from December 1998 to February 2007). The percentage occurrence of scintillations at different sectors of the sky was also investigated, and the results revealed that the scintillations are more probable to be observed in the west sector of the sky above So Luis, whereas the north-south asymmetries are possibly related to asymmetries in the plasma density distribution at off-equatorial latitudes. The scintillations on GPS signals occurred more frequently around solar maximum years, but it is also clear from the results of a strong variability in the scintillation activity in the years with moderate solar flux during the descending phase of the solar cycle. The equatorial scintillations occur predominantly during pre-midnight hours with a broad maximum near the December solstice months. In general, weak level of scintillations (S (4) index between 0.2 and 0.4) dominated at all seasons; however, during the winter months around solar maximum years (although the scintillation occurrence is extremely low), stronger levels of scintillations (S (4) > 0.6) may occur at comparable rate with the weak scintillations. The irregularity zonal velocities, as estimated from the GPS spaced-receiver technique, presented a different scenario for the two seasons analyzed; during the equinoxes, the magnitude of the zonal velocities appeared not to change with the solar activity, whereas during the December solstice months, the larger magnitudes were observed around solar maximum years. Other relevant aspects of the observations are highlighted and discussed. (AU)

FAPESP's process: 08/04892-5 - Study of the temporal and spatial dependence between plasma irregularities and total electron content as a basis to the development of a ionospheric scintillation model: simultaneous investigation of ionospheric radiotomography
Grantee:Marcio Tadeu de Assis Honorato Muella
Support type: Scholarships in Brazil - Post-Doctorate
FAPESP's process: 12/06598-2 - 39th committee on space research (COSPAR)
Grantee:Marcio Tadeu de Assis Honorato Muella
Support type: Research Grants - Meeting - Abroad