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Daytime enhancement of size of sudden commencements and initial phase of magnetic storms at Huancayo

1955; American Geophysical Union; Volume: 60; Issue: 3 Linguagem: Inglês

10.1029/jz060i003p00299

2156-2202

Scott E. Forbush, E. H. Vestine,

Geomagnetism and Paleomagnetism Studies

Applying statistical tests to 428 SC's, the frequency of occurrence is found to be independent of time of day. Statistical tests indicate that the average sizes of SC's and of IP are both significantly greater during the daylight hours at Huancayo. Also from 102 SC's occurring between 08h and 14h 75° WMT at Huancayo, we find that the average size of SC's is greater for those days with the larger diurnal variation (Sq) in H. This result is not only statistically significant but also the average size of SC's was about 50 per cent greater for the group of days with 50 per cent greater diurnal variation in H. The diurnal variation of SC'S averaged on 75° WMT for San Juan and Honolulu is practically negligible. The augmentation of SC sizes at Huancayo with Sq in H at Huancayo was found to be the same whether the average size of the same SC's at San Juan and Honolulu was large or small. No significant diurnal variation was found in the frequency of occurrence of SC's observed both at Huancayo and Watheroo. A simple explanation is offered for the diurnal variation in the frequency of SC's found by Newton from Greenwich results. The relation of daytime enhancement of the size of SC's to Sq in H at Huancayo indicates that the current system responsible is closely associated with the electrojet effect responsible for the large diurnal variation in H at Huancayo. The effects found are not predicted on the basis of the Chapman-Ferraro theory of magnetic storms in its present form. One possibility being examined is that the electric currents in the atmosphere near Huancayo are driven by electrojets of polar regions.