Abstract

A comprehensive study of Solar Flare Effects (SFE) across latitudes has been carried out using an extensive data set of two geomagnetic elements H and Z selected from 1997 to 2005. The X (intense) and M (medium) solar flares were examined under quiet conditions. Nine stations extending from equatorial to high latitudes were used in the study. Data employed in this work include minute data of geomagnetic field, solar flare and hourly data of geomagnetic field. On the whole, about one hundred and fifty four (154) solar flares were selected. Each of these flares was critically studied and analyzed to see its response on the geomagnetic H and Z components. Only fifteen to thirty four flares showed the signature in the different stations. The study revealed that pre-solar flare and solar flare amplitude variations are least in the mid latitude stations, followed by the equatorial and low latitude stations and the highest in the high latitude stations. The pre-solar flare amplitude variations and solar flare amplitude variations of Z failed to show any clear pattern. Correlation existed between the solar flare amplitude variations of H and the pre-solar flare amplitude variations. The ratios of ∆HSFE/∆Ho and ∆ZSFE/∆Zo were greater than zero for all the stations used in the study. This implies that the solar flare effects enhance geomagnetic field across latitudes. 

Key words: Solar fare, geomagnetic component, variation, latitude, amplitude.