Effects of 6 January 1997 space weather related processes in the low latitude thermosphere-ionosphere system

OI 630.0 nm dayglow data from Mt. Abu, India, along with ground based ionosonde data, were scrutinized for the 6-12 January 1997 space weather related event. The OI 630.0 nm dayglow intensities registered an enhancement by a factor of 2-2.5 on 11 January, in the morning hours, as compared to 9 and 12 January, i.e. one day later than when auroral activities were noted at unusual latitudes and on the day when the magnetosphere was compressed to <6RE. The ionosonde data did not show any such dramatic increase in the F-region electron densities for the same period. Various plausible mechanisms that could cause the observed enhancement in the dayglow without altering the F-region of the ionosphere are discussed in the context of the actual measurements