For comparative study of h’F (virtual height of ionospheric F-layer) at Islamabad (33.75oN, 72.87oE) during Solar Minimum (1996) and Solar Maximum (2000) years, the seasonal and annual means of monthly medians of h’F are used. The h’F are determined by the ionograms recorded at Islamabad using the Digisonde DGS-256. The comparison shows that the seasonal means of h’F are greater during Solar Maximum (2000) than those during Solar Minimum (1996) in all the seasons both on day and night. During Solar Minimum (1996), the seasonal means of h’F are the highest in summer and the lowest in winter on day as well as at night. However, during Solar Maximum (2000), the seasonal means of h’F are found to be the highest in equinoxes and equal in winter and summer on daytime, whereas at night these are the highest in summer and the lowest in winter. |
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