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Using a method suggested by the authorsearlier, the long-term trends of the F2-layer critical frequency, <i>fo</i>F2are derived for a set of ionospheric stations with a wide latitudinal andlongitudinal coverage. All the trends are found to be negative. A pronounceddependence on geomagnetic latitude is found, the trend magnitude increasing withthe latter. No globe scale longitudinal effect in trends is detected. For themajority of the stations there is also a pronounced seasonal effect, the trendmagnitude being higher in summer than in winter.  <b>Key words.</b> Ionosphere (ionospheric disturbances;mid-latitude ionosphere

annales geophysicae

&amp;lt;i&amp;gt;Letter to the Editor&amp;lt;/i&amp;gt;: Spatial and seasonal variations of the &amp;lt;i&amp;gt;fo&amp;lt;/i&amp;gt;F2 long-term trends