On the Regional Effect in the Global Atmospheric Electric Field
The fair-weather electric field on the oceans displays a typical universal-time dependent diurnal pattern superposed on an almost steady value. A fractional portion of this may still be variable with the geographic position. Several possible factors will be considered as causes of regional differences in the universal field. A long established factor is the latitude dependence relating to that of cosmic ray ionization. Global pollution of the atmosphere associated with the human activity may affect it through gradual decrease of conductivity even in the middle of the oceans. Seasonal effects lead to negative correlation of annual variation of the field between northern and southern hemispheres. Coupling of thunderstorm current in the global circuit with ionospheric current may modify the diurnal variation. If the propagation in the global circuit is not perfect, distribution of thunderstorm areas geographically localized will affect the pattern of diurnal variation.
Observation of electric field carried out onboard over almost the whole area of the Pacific Ocean will be compared with the above consideration. Although the data are not sufficient as to cancel ambiguity resulting from the daily fluctuation and to introduce a general trend, the results suggest that those factors may more or less influence the universal electric field.
KeywordsDiurnal Variation Geomagnetic Latitude Ionospheric Current Atmospheric Electric Field Global Circuit
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