Estudo das propriedades da região C ionosférica utilizando a rede SAVNET / Study of the properties of the ionospheric C-region using the SOUTH AMÉRICA VLF NETWORK

AUTOR(ES)
DATA DE PUBLICAÇÃO

2009

RESUMO

This work aims to study the intensity of the phase advance, Δc, due to the appearance of the C region at sunrise. For this purpose, we use the data-base supplied by South America VLF Network (SAVNET) and similar additional data for the period 1970 1972. We show that on long-term time scales, of the order of the solar cycle, the phase advance Δc is related to the flux of the solar Lyman- α radiation. During the period 2007-2009, changes of the Lyman-α flux are not intense enough to be detected through Δc parameter. From the daily variability of Δc, two well defined regimes were identified: a slow varying regime between March and October, where we show that Δc is driven by solar illumination conditions over the VLF propagation paths; and between October and March, Δc presents a regime with sudden changes that coincide with the appearance of the winter anomaly. We show that for this period there is no direct relationship between time variations of Δc and mesospheric temperature variations recorded by the SABER/TIMED, and that temperature changes alone can not explain the Δc time variations.

ASSUNTO(S)

ondas de muito baixa frequência (vlf) savnet região-c baixa ionosfera lyman-α very low frequency (vlf) savnet c-region low ionosphere lyman-α

ACESSO AO ARTIGO

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