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Abstract Air conductivity and atmospheric electric potential gradient measured at Świder observatory (Poland) between 1965 and 1995 have been investigated around days with increased number of condensation nuclei (NCN). Data determined for the evening hours have been analysed by the superposed epoch method. Two groups of days with increased NCN were selected by distinguishing two different degrees of the increase (group 1: from 50% to 75%, group 2: >75%, as related to the actual monthly average of NCN). These days have been used as key days for independent superposed epoch analyses. The analyses have shown a decreased air conductivity around the days with increased NCN. A rather significant decrease appears on the key days and its significance depends on the degree of the NCN increase. The latter also seems to influence the duration of the air conductivity decrease after the key days. Using atmospheric electric potential gradient data around the selected key days, two more analyses were carried out. The results show that the potential gradient also responds to the increased NCN: it enhances both in the case of the moderately (group 1) and the highly (group 2) increased NCN. This is in accordance with the decreased air conductivity. A significant enhancement of the potential gradient appears on the key days, however, this diminishes more slowly after the key days than the opposite effect in air conductivity. The potential gradient apparently rises even before the key days, especially in the case of the stronger NCN events.
Abstract Air conductivity and atmospheric electric potential gradient measured at Świder observatory (Poland) between 1965 and 1995 have been investigated around days with increased number of condensation nuclei (NCN). Data determined for the evening hours have been analysed by the superposed epoch method. Two groups of days with increased NCN were selected by distinguishing two different degrees of the increase (group 1: from 50% to 75%, group 2: >75%, as related to the actual monthly average of NCN). These days have been used as key days for independent superposed epoch analyses. The analyses have shown a decreased air conductivity around the days with increased NCN. A rather significant decrease appears on the key days and its significance depends on the degree of the NCN increase. The latter also seems to influence the duration of the air conductivity decrease after the key days. Using atmospheric electric potential gradient data around the selected key days, two more analyses were carried out. The results show that the potential gradient also responds to the increased NCN: it enhances both in the case of the moderately (group 1) and the highly (group 2) increased NCN. This is in accordance with the decreased air conductivity. A significant enhancement of the potential gradient appears on the key days, however, this diminishes more slowly after the key days than the opposite effect in air conductivity. The potential gradient apparently rises even before the key days, especially in the case of the stronger NCN events.
Atmospheric Electric Parameters Around Days with Increased Number of Condensation Nuclei
Märcz, F. (author)
2000
Article (Journal)
English
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