F₂-LAYER RESPONSE TO GEOMAGNETIC DISTURBANCES

Using the data observed in 37 ionosonde stations during 1974-1986 and adopting the correlation analysis method for the deviation of the daily f₀F₂ value from its monthly median to ap index, the geomagnetic latitude distribution of the F₂-layer response to geomagnetic disturbance is obtained for the first time in every year of one solar activity cycle in the East Asia-Australia sector, Europe-Africa sector and America-East Pacific Ocean sector. The results showed that the negative response appeared at the high and middle geomagnetic latitude, the positive response appeared at the low latitude and geomagnetic equator, the response sign changes at the geomagnetic latitude of about ±30°, the maximum positive response appeared at geomagnetic equator and maximum negative response appeared at the geomagnetic latitude of about ±50°, and the amplitude of maximum negative response is larger than the amplitude of maximum positive response. The responses have obvious longitude dependence and the asymmetry between the Southern hemisphere and the Northern hemisphere. The geomagnetic latitude distribution of the response is symmetrical between the Northern and Southern Hemispheres in the East Asia-Australia sector. But in the Europe-Africa sector and America-East Pacific Ocean sector, the asymmetry between the Northern and Southern Hemispheres is obvious, the amplitude of maximum negative response is larger in the Northern Hemispheres than in the Southern Hemispheres.