geomagnetic latitude
1.The F2 layer disturbances at large range have been studied during 19 greatmagnetic storms (minimum Dst depletion is smaller than-100γ) from 1969 to 1972. It is fouad that storm - time variation of the F2 layer disturbance for 30 °N-42°N and 43°N-50°N geomagnetic latitude zones follows reasonably well the equatorial Dst variation of magnetic storm.
2.The values of ionospheric parameters for control points of a given circuit can be predictedby means of a seven-day weighted mean method, using the real-time measured data at the ionosonde stations and considering the relation between the ionospheric parameter and the geomagnetic latitude, then the maximum usable frequency, MUF, will be given out for the next day by interpolation, expolation or by using the maps of short-term frequency prediction.
3.Using the ionosonde data of 12 stations at East Asia,the responses of mid-and low-latitude ionosphere to two types of geomagnetic storms,i. e. instantaneous intense main phase and delayed weak main phase storms were analyzed.
4.Using data observed simultaneously from about 50 stations distributed worldwidearound mid-latitude zone, the case analyses of ionospheric disturbances accompaniedby geomagnetic storms indicate that the variation of the geomagnetic Dst index andthat of the storm time variation of mean f0F2 (average departure of f0F2 frommonthly median value), Dst(f0F2), obtained by Fourier expansion have similar tendency.
5.Using the recorded phase data of VLF wave (16 kc/s) transmitted by GBR (England) we have obtained the VLF phase drift and the electron density change in the D-region in the mid-latitude during the galactic cosmic ray storms (Forbush decrease) and the strong geomagnetic storms.
