SOLAR CYCLE AND SEAS0NAL VARIATIONS OF THE SOLAR AND LUNAR DAILY VARIATIONS OF TOTAL ELECTRON CONTENT AT LUNPING.

The solar and lunar daily variations of the ionospheric total electron content observed at Lunping, which lies close to the crest zone of the so-called equatorial anomaly, were analyzed by Chapman-Miller method. The lunisolar diurnal variation L//1 and lunar semidiurnal variation L//2 were found to have significant seasonal variations, with amplitude increasing steadily from summer to winter. The hours for L//1 and L//2 variations to attain their respective maximum values also increase steadily from summer to winter. The seasonal variation of the semidiurnal variation L//2 was found to be explainable by the additional fountain effect caused by the similar seasonal variation of the lunar semidiurnal electric field induced at the equatorial region. However, the seasonal variation of the lunisolar variation L//1 was found not to be explainable by the additional fountain effect. Seasonal variations for the harmonic components of the solar daily variation were found to be different from those of lunar daily variation. Solar cycle variations of the harmonic components of the solar and lunar daily variations were found and described.