CORRELATION BETWEEN foEs AT ISLAMABAD AND THE SUNSPOT NUMBERS OVER THE SOLAR CYCLE (1986-97)

摘要

Ionospheric data of Islamabad (33.75°N, 72.87°E) have been used for studying the correlation between annual means of foEs and that of the Smoothed Sunspot Numbers (SSN) during the day and night -time over the Solar Cycle (1986-97). Also, the variations of seasonal means of foEs over this solar cycle have been studied. It is observed that the variations of annual means of foEs and SSN during the day-time are positively correlated over the period 1987-94, while they are overall negatively correlated at and near the Solar Minima (1986 & 1996). Moreover, the variations of annual means offoEs and SSN at night are also positively correlated over the period 1987-93, whereas negatively correlated at and near the Solar Minima (1986 & 1996). The comparison of the three seasons has shown that the maximum of seasonal means offoEs occurs in summer and the minimum in winter, both for day and night -time during the complete solar cycle.