Modeling investigation of ionospheric storm effects over Millstone Hill during August 4-5,1992

【摘要】：正We examine the physical mechanism of the negative and positive storm at middle latitude in August 1992, based on incoherent scatter radar(ISR) observations over Millstone Hill(42.6°N,288.5°E) and a first-principles ionospheric model.The exospheric temperature T_(ex),thermospheric composition and neutral winds,inferred from the ion temperature T_i profile using the ion energy balance calculation(e.g.,Bauer et al.,1970;Oliver,1979) and from the electron density N_e profile using an ISR data assimilation method(Zhang et al.,2001,2002),are employed to investigate the storm effects.The derived thermospheric information shows that the negative phase on August 5 is attributed to both the large poleward wind and the reduced[O]/[N_2]and[O]/[O_2]ratio at F_2-layer.For the daytime positive storm on August 4,the thermospheric composition perturbation,in addition to the enhanced equatorward wind,plays a significant role.This study also suggests that the data assimilation technique can provide useful information to understand some physical mechanisms of the ionospheric storm when direct experimental data are not available.