Surplus of negative charge flow in point-discharge current as shown by variations on different time scales at Nagycenk station

Data of point-discharge current measurements at the Nagycenk station coveri ng more than three decades have been used for demonstrating the variations of this atmospheric electric parameter on different time scales. The diurna l variation of the point-discharge current shows an early morning minimum a nd an afternoon maximum as represented by charges brought down to ground by a metal point (elevated to a height of about 8 m), and this is valid for c harges of both signs. On the diurnal time scale, there is a surplus of nega tive charge flow which peaks in the afternoon. A predominance of negative c harge flow was also found on the annual time scale as indicated by the mont hly mean values of transported charges of both signs. The monthly mean rati o of negative to positive charge is well above 1.0 from April to October an d it is below 1.0 merely in the first three months of the year. Determining an average ratio of negative to positive charge for each individual year b etween 1961 and 1996, it was shown that the yearly average ratio is usually above 1.0 (except for 4 years). Some comparisons between results of Nagyce nk and those obtained simultaneously at other stations showed a certain agr eement; however, they also revealed discrepancies between individual values of the transported charges. Notwithstanding, a surplus of negative charge how was detected even by these comparisons. The results derived on differen t time scales do confirm that point-discharge current plays an important ro le in the transfer of charges to the Earth; at the same time a predominance of negative charge Bow could be proved. (C) 1998 Elsevier Science Ltd. All rights reserved.