Day-to-day variability of the quiet-day daily range of equatorial geomagnetic field and its relationship with ionospheric dynamics

Abstract

To study the day-to-day variability of the daily range ΔH = H max − H min of the H component of geomagnetic field at the Equator, quiet days ( A p = 0–8) in the quiet sun year 1964 were divided into four ranges viz. 0–69 gamma, 70–89 gamma, 90–109 gamma and 110 or more gamma of ascending ΔH values at Trivandrum for the three seasons J, D, E separately. Average daily variation patterns of several parameters for these 12 groups were studied. It was found that enhanced ΔH at Trivandrum was well correlated with the northern S q current strength only in winter when the latter was weak. ΔH at Trivandrum was poorly correlated with ΔH at Alibag as also with solar radiation parameters (10.7 cm and X-ray fluxes) in all seasons, and moderately correlated with the southern component of interplanetary magnetic field B z t. In contrast, ΔH at Alibag was moderately correlated with the B x and B v components. Sevral other peculiarities of corresponding ΔY and ΔZ components and associated upheavals in ionospheric F-region parameters at equatorial and middle latitudes are presented and discussed. It is concluded that the day-to-day variability of ΔH at equatorial and middle latitudes is primarily connected with ionospheric upheavals which seem to be connected with different interplanetary parameters for different latitudes.