|
|
 |
|
|
Ann. Geophys., 21, 1167-1176, 2003
www.ann-geophys.net/21/1167/2003/
© European Geosciences Union 2003
Long-term trends of foF2 independent of geomagnetic activity
A. D. Danilov
Institute of Applied Geophysics, Rostokinskaya 9, Moscow 129 128, Russia
Abstract. A detailed analysis of
the foF2 data at a series of ionospheric stations is performed to reveal
long-term trends independent of the long-term changes in geomagnetic activity
during the recent decades (nongeomagnetic trends). The method developed by the
author and published earlier is used. It is found that the results for 21 out
of 23 stations considered agree well and give a relative nongeomagnetic trend
of -0.0012 per year (or an absolute nongeomagnetic trend of about -0.012 MHz
per year) for the period between 1958 and the mid-nineties. The trends derived
show no dependence on geomagnetic latitude or local time, a fact confirming
their independence of geomagnetic activity. The consideration of the earlier
period (1948–1985) for a few stations for which the corresponding data are
available provides significantly lower foF2 trends, the difference
between the later and earlier periods being a factor of 1.6. This is a strong
argument in favor of an anthropogenic nature of the trends derived.
Key words. Ionosphere
(ionosphere-atmosphere interactions; ionospheric disturbances; mid-latitude
ionosphere)
Full Article in PDF (190 KB) |
|
|
