Differences in Seasonal Variation of Noon F2-ionization at Dip-conjugate Places

Abstract

A study is made of noon <i>f_o</i>F2over a period of one solar cycle (<i>1958-69</i>) at some pairs of magnetically near-conjugate places in the eastern and central zones with dips (<i>I</i>) 0-60°, Seasonal dependence of the sensitivity of <i>f_o</i>F2 on solar activity is studied and the differences in the seasonal variation of <i> f_o</i>F2 are shown for low and high solar activity epochs, It is found that the seasonal variation of noon <i> f_o</i>F2 at dip-conjugates are significantly different, and the change-over seems to occur at the geographic equator, The midlatitude winter anomaly of <i> f_o</i>F2 found in north is not observed at the southern dip-conjugate till near the peak of the sunspot cycle, The results are discussed specially with reference to the neutral wind and the associated changes in the gas composition.