Nighttime F2 layer trend analysis

ANA G. ELIAS; JOSE V. VENCHIARUTTI; BLAS F. DE HARO BARBAS

Praga

Congreso; 26th IUGG General Assembly (International Union of Geodesy and Geophysics); 2015

IUGG - IAGA - IAMAS

The behavior of the daytime ionosphere is strongly controlled by solar radiation, while nighttime ionosphere is controlled mainly by recombination processes and ionospheric dynamics. The F2-layer is uplifted to higher altitudes during night by the upward plasma drift caused by equatorward neutral winds, strongly affecting the recombination processes in the F-region, and making it may be more sensitive to ionospheric dynamics. In this work, foF2 and hmF2 trends at 0 LT are analyzed in view of the expected effects of Earth?s magnetic field secular variation and of greenhouse gases concentration increase. Due to dynamic processes importance is enhanced during night we expect also a higher impact of the Earth´s magntic field effects over trend values, taking into account that secular changes in the dip and declination angles affect the vertical component of the thermosphere neutral wind that moves the conducting plasma of the ionosphere. Considering that one of the most significant factors affecting trend estimates is the removal of the solar cycle, different trend estimations are studied. foF2 and hmF2 data for several stations together with IRI model predictions are analyzed to detect the importance of the Earth?s magnetic field as a possible source of nighttime ionospheric trends relative to the anthropogenic trend forcing linked to greenhouse gases increase.