Periodic and quiescent solar activity effects in the low ionosphere, using SAVNET data

Author(s)

Bertoni, F. C. P. ; Raulin, J-P. ; Gavilan, H. R. ; Kaufmann, P. ; Raymundo, T. E. ; Chakrabarti, SK

• Document type: Journal article
• Source: MAGNETIC FIELDS IN THE UNIVERSE: FROM LABORATORY AND STARS TO PRIMORDIAL STRUCTURES; v. 1286, p. 3-pg., 2010-01-01.

Abstract

Important results have been acquired using the measurements of VLF amplitude and phase signals from the South America VLF Network (SAVNET) stations. This network is an international project coordinated by CRAAM, Brazil in cooperation with Peru and Argentina. It started operating in April 2006, and now counts on eight stations (Atibaia, Palmas, Santa Maria and Estacao Antartica Comandante Ferraz in Brazil; Piura, Punta-Lobos and Ica, in Peru; CASLEO, in Argentina). Researches, through the last decades, have demonstrated the versatility of the VLF technique for many scientific and technological purposes. In this work, we summarize some recent results using SAVNET data base. We have obtained daily maximum diurnal amplitude time series that exhibited behavior patterns in different time scales: 1) long term variations indicating the solar activity level control of the low ionosphere; 2) characteristic periods of alternated slow and fast variations, the former being related to solar illumination conditions, and the latter that have been associated with the winter anomaly at high latitudes; 3) 27-days period related to the solar rotation and consequently associated to the solar Lyman-alpha radiation flux variations, reinforcing earlier theories about the importance of this spectral line for the D-region formation. Finally, we conclude presenting preliminary results of simulation using LWPC, which showed very good agreement at times of observed modal amplitude minima for a given VLF propagation path. (AU)

• FAPESP's process: 07/05630-1 - Ionospheric effects of magnetic storms in global scale
• Grantee: Fernando Celso Perin Bertoni
• Support Opportunities: Research Grants - Young Investigators Grants
• FAPESP's process: 06/02979-0 - Monitoring the solar activity and the South Atlantic Magnetic Anomaly (SAMA) using a network of very low frequency (VLF) receivers: SAVNET - South America VLF NETwork
• Grantee: Jean Pierre Raulin
• Support Opportunities: Regular Research Grants