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The vertical downward component of the DC atmospheric electric field, or potential gradient (PG), at Kakioka 150 km southwest of the Fukushima Dai-ichi Nuclear Power Plant (FNPP1) was analyzed before and after the FNPP1 accident to examine possible influence of floating radioactive particles on the PG under the highly electrified clouds. Using 1-min PG data from March 13 to April 30 (late April 2011 corresponding to the time when floating radioactive materials decreased significantly) from 2006 to 2015, time profiles to/from the PG peaks (< $$-\,100$$ or > $$+\,100\,\hbox {V/m}$$ ) for 2011 are compared with other years. The PG developed toward and decays from its negative peaks faster in the first 50 days after the FNPP1 accident than for the same period in other years, making the 10-min averaged PG values for the same negative PG peak higher (smaller in terms of absolute value) during the first 50 days after the FNPP1 accident than those in other years in the study period, while the distribution of peak PG values is similar between 2011 and the other years. The observed shortening of the timescale is symmetric between the rise and decay and is the most clear when the negative PG peak is about $$-\,200$$ to $$-\,400\,\hbox {V/m}$$ . For positive peaks, the change of the baseline resulting from the radioactive contamination on the ground in 2011 caused superficial difference on such time profiles. Otherwise, there are no significant difference between 2011 and the other years. Possible explanations based on increased ionizing radiation from floating radioactive particles, which are found to be concentrated at low altitudes ( $$

Results of near-surface measurements of atmospheric electric field and meteorological parameters at the Indian Antarctic station, Maitri, during 12 fair-weather days of January and February, 2005, are presented. Data are analyzed to study the diurnal variation of the electric field and its departure, if any, from the global electric fields. Fair-weather days are classified into two groups depending upon the average of the hourly surface temperature. Group one, when the average of the hourly surface temperature is mostly above the freezing point, and group two, when the same is below the freezing point. The role of different ion sizes on the Maxwell current density and the air-Earth current density for the two groups are quite different under different conditions. To study the effect of ions on the atmospheric electric fields, ions are grouped as small ions, intermediate ions and large ions. We find that the small and the large ions largely influence the air-Earth current density with a correlation coefficient higher than 70%. The intermediate ions have a negative correlation in the case of group one fair-weather days, whereas for group two days no correlation is found. The diurnal variations of the Maxwell current density and the electric field show a peak between 1800 UT and 2000 UT and the nature of the variation can be attributed to the variation in worldwide thunderstorm activity. The correlation coefficient between the measured electric field and the electric field from the Carnegie curve is 0.93 with a

The effects of a geomagnetic storm on 5 April 2010 on electric parameters of the atmospheric near-ground layer in Kamchatka have been investigated. Three processes over the course of the storm were identified. Air electroconductivity began to decrease 4 h before the storm, and this lasted for 20 h. The storm's sudden commencement caused potential gradient oscillations with amplitudes up to 300 V/m. During the stages of the storm, a significant increase in the atmosphere ion content unipolarity coefficient occurred.

Systematic analysis of the surface fair-weather potential gradient (PG) measured for 13 months (July 2005–July 2006) at 10 s resolution over a small tropical island station Suva (18.08°S, 178.45°E), Fiji is presented. Based on the solar radiation (>800 W m−2) and surface wind speed (−1) conditions, 63 fair-weather days were selected. After sorting the data into a range of 0–1000 V m−1, the average PG was ∼139 V m−1. The measured fair-weather PG had a semi-diurnal structure, with a more pronounced peak at 0730 LT (1930 UT) and a reduced peak at 2200 LT (1000 UT). The time of occurrence of the morning peak and the noontime minima agreed well with the Carnegie curve. However, the variation about the global mean in the measured PG was 150% whereas for the Carnegie curve it was only 35%. The effects of the local meteorological parameters on the PG measurements were found to be small. On average, the PG during the dry season (May–October) was always greater than in the wet season (November–April). In contrast, analysis of regional (0–60°S and 100°E–160°W) lightning activity on fair-weather days showed a peak at ∼2000 LT and higher lightning activity during the wet season. These results indicate that the regional thunderstorm activity has no direct connection with the local fair-weather PG at the site.

We are operating atmospheric electrical instruments like long wire antenna, electric field meter, wire antenna and passive antenna for atmospheric Maxwell current, electric field, conduction current and atmospheric potential gradient. This year (December 2008) we have installed Electric Field Meter (EFM-100) and wire antenna for measuring the atmospheric electric field and conduction current. This instrument is deployed at Maitri, Antarctica and will be operated under any weather conditions like snow fall and strong blizzard etc. The study have been carried out during austral summer for the period of 2008 and 2009 at the Indian station, Maitri (70.75°S, 11.75°E, 117 m above mean sea level). The present work has been to understand the new instrument system in response to different meteorological conditions and on fairweather days. In this paper we have selected the data of the days during magnetically quiet period to minimize the upper atmospheric contribution. Fairweather’ conditions, i.e., days with absence of high winds, drifting or falling snow and clouds. The diurnal variation curve of electric field during fairweather days is a single periodic with a minimum at 04:00 UT and a maximum at 19:00 UT. But atmospheric current variation has minimum 03:00 UT for Maxwell current and conduction current. The maximum for Maxwell current is at 20:00 UT and 19:00 UT for the conduction current, which is very similar to the Carnegie curve. The measured electric field from the Passive antenna and EFM-100 compared and is behaving similar variation. Using Maxwell current density and conduction current density we have separated the displacement current density.