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

Conjugate Point Equatorial Experiment (COPEX) campaign in Brazil: Electrodynamics highlights on spread F development conditions and day-to-day variability

Full text
Abdu, M. A. [1] ; Batista, I. S. [1] ; Reinisch, B. W. [2] ; de Souza, J. R. [1] ; Sobral, J. H. A. [1] ; Pedersen, T. R. [3] ; Medeiros, A. F. [4] ; Schuch, N. J. [5] ; de Paula, E. R. [1] ; Groves, K. M. [3]
Total Authors: 10
[1] Inst Nacl Pesquisas Espaciais, BR-12201970 Sao Jose Dos Campos - Brazil
[2] Univ Massachusetts, Ctr Atmospher Res, Lowell, MA 01854 - USA
[3] AFRL VSBXI, AF Res Lab, Hanscom AFB, MA 01731 - USA
[4] Univ Fed Campina Grande, Dept Fis, BR-58109970 Campina Grande - Brazil
[5] INPE, Centro Reg Pesquisas Espaciais, BR-97110970 Santa Maria, RS - Brazil
Total Affiliations: 5
Document type: Journal article
Web of Science Citations: 66

A Conjugate Point Equatorial Experiment (COPEX) campaign was conducted during the October-December 2002 period in Brazil, with the objective to investigate the equatorial spread F/plasma bubble irregularity (ESF) development conditions in terms of the electrodynamical state of the ionosphere along the magnetic flux tubes in which they occur. A network of instruments, including Digisondes, optical imagers, and GPS receivers, was deployed at magnetic conjugate and dip equatorial locations in a geometry that permitted field line mapping of the conjugate E layers to dip equatorial F layer bottomside. We analyze in this paper the extensive Digisonde data from the COPEX stations, complemented by limited all-sky imager conjugate point observations. The Sheffield University Plasmasphere-Ionosphere Model (SUPIM) is used to assess the transequatorial winds (TEW) as inferred from the observed difference of h(m)F(2) at the conjugate sites. New results and evidence on the ESF development conditions and the related ambient electrodynamic processes from this study can be highlighted as follows: (1) large-scale bottomside wave structures/satellite traces at the equator followed by their simultaneous appearance at conjugate sites are shown to be indicative of the ESF instability initiation; (2) the evening prereversal electric field enhancement (PRE)/vertical drift presents systematic control on the time delay in SF onset at off-equatorial sites indicative of the vertical bubble growth, under weak transequatorial wind; (3) the PRE presents a large latitude/height gradient in the Brazilian sector; (4) conjugate point symmetry/asymmetry of large-scale plasma depletions versus smaller-scale structures is revealed; and (5) while transequatorial winds seem to suppress ESF development in a case study, the medium-term trend in the ESF seems to be controlled more by the variation in the PRE than in the TEW during the COPEX period. Competing influences of the evening vertical plasma drift in favoring the ESF development and that of the TEW in suppressing its growth are discussed, presenting a perspective on the ESF day-to-day and medium-term variabilities. (AU)

FAPESP's process: 99/00437-0 - Studies of the interactive processes of the equatorial ionosphere-thermosphere system
Grantee:Mangalathayil Ali Abdu
Support Opportunities: Research Projects - Thematic Grants