Thermospheric Meridional Wind Control on Equatorial Scintillations and the Role of the Evening F-Region Height Rise, E x B Drift Velocities and F2-Peak Density Gradients

Autor(es)

Muella, M. T. A. H. ^[1] ; de Paula, E. R. ^[1] ; Fagundes, P. R. ^[2] ; Bittencourt, J. A. ^[1] ; Sahai, Y. ^[2]

Afiliação do(s) autor(es)

^[1] Inst Nacl Pesquisas Espaciais, Div Aeron, Sao Paulo - Brazil

^[2] Univ Vale Paraiba, IP&D, Lab Fis & Astron, Sao Paulo - Brazil

• Tipo de documento: Artigo de Revisão
• Fonte: SURVEYS IN GEOPHYSICS; v. 31, n. 5, p. 509-530, SEP 2010.
• Citações Web of Science: 11

Resumo

The possible role, on L-band scintillation activity, played by the nighttime magnetic meridional component of the thermospheric horizontal neutral winds, the post-sunset F-layer base height, the electrical field pre-reversal enhancement (PRE) and the latitudinal gradients of the F2-layer peak density is analyzed, considering different cases of scintillation occurrence (and their latitudinal extent) during August and September 2002. The meridional winds were derived over low-latitudes from a modified form of the nonlinear time-dependent servo-model. A chain of two scintillation monitors and three digital ionosondes was operational in Brazil and used to collect, respectively, global positioning system signal amplitude scintillation and ionospheric height (h'F; hpF2) and frequency (foF2) parameters. From the overall behavior in the 2 months analyzed, the results suggest that high near sunset upward vertical plasma drifts are conducive for the generation of spread-F irregularities, whereas large poleward meridional winds tend to suppress the development of plasma bubble irregularities and the occurrence of their associated scintillations. Even when generated, a reduced fountain effect, due to weak electric field PRE, acts for the bubbles to be expanded less effectively to higher latitudes. The results also reveal that high F-layer base and peak heights (at equatorial and off-equatorial latitudes), and intense gradients in the F2-peak density between the dip equator and the equatorial anomaly crests, are favorable conditions for the generation of F-region irregularities and increased scintillation activity. Other distinct features of the controlling factors in the cases of occurrence and non-occurrence of equatorial scintillations are presented and discussed. (AU)

• Processo FAPESP: 08/05482-5 - Estudo da geração, evolução e dinâmica das irregularidades ionosféricas na região equatorial e baixas latitudes
• Beneficiário: Paulo Roberto Fagundes
• Modalidade de apoio: Auxílio à Pesquisa - Regular
• Processo FAPESP: 08/04892-5 - Estudo da dependência temporal e espacial entre as irregularidades do plasma e o conteúdo eletrônico total como fundamentos para o desenvolvimento de um modelo de cintilação ionosférica: investigação simultânea de radiotomografia ionosférica
• Beneficiário: Marcio Tadeu de Assis Honorato Muella
• Modalidade de apoio: Bolsas no Brasil - Pós-Doutorado