Fair-weather Potential Gradient Research Articles

Periodicities in fair weather potential gradient data from multiple stations at different latitudes

Analysis of the variation of the potential gradient (PG) at ground level is important to monitor the global electric circuit and the different solar and geophysical phenomena affecting it. However, this is challenging since several local factors (e.g., meteorological) produce perturbations in the potential gradient. Time series and spectral analysis of PG at several stations can help to minimise local effects so that global effects may be more clearly observed. In this work, for the first time we performed spectral analysis of the potential gradient recorded at several sites located at Vostok, Concordia, Halley and Casleo (Southern Hemisphere), and Sodankyla and Reading (Northern Hemisphere). In order to find the main periodicities and how the amplitude of those periods change as a function of time we use the Lomb-Scargle periodogram and the wavelet transform, respectively. For all PG sites we found periodicities of 0.5-, 1-, ~180- and 365-day. Our results show that the 0.5-day (1-day) periodicity is more prominent during the months of June–July-August (December–January-February). Evidence of ~27- and ~ 45-day periods was also observed at multiple sites. Further analysis using the cross-wavelet transform for PG versus cosmic rays, PG versus Madden-Julian Oscillation index, and PG versus meteorological parameters, show clues that the 27- and 45-day periods are likely related to the solar rotation and Madden-Julian Oscillation, respectively. Furthermore, our results show that during the passages of co-rotating interaction regions, the 27-day period for PG vs cosmic rays XWT is stronger than for the other XWT analysis.

Impact of local and global factors and meteorological parameters in temporal variation of atmospheric potential gradient

In this research work, we have performed comparative diurnal variations of atmospheric Potential Gradient (PG) of fair-weather days by using the data of three stations installed in Northern, Pakistan for the year 2018. We investigated the impact of both local and global factors and meteorological parameters in the diurnal variation of atmospheric Potential Gradient on the annual and seasonal time scale. We observed two peaks, primary and secondary. This is because of the land-based measurements of annual and seasonal variations. The annual average curve of Potential Gradient of all three stations: Islamabad (CES), Muzaffarabad (MZF), and Balakot (BKT) demonstrated a notable deviation from the standard oceanic Carnegie curve. The atmospheric Potential Gradient variations are due to numerous meteorological factors e.g., air pollution, humidity, aerosol particles, fog, and temperature. Among three stations, the MZF station is located in highland (mountainous) and it demonstrated a higher atmospheric Potential Gradient. We further differentiate the results of our three stations with global results for authenticity and observed coherence between them. In addition, a positive correlation of fair-weather Potential Gradient is observed with temperature and a notable correlation between relative humidity and atmospheric Potential Gradient for all the three observatories.

Fair-weather potential gradient and its coupling with ionospheric potential from three Antarctic stations: Case studies

Simultaneous measurements of potential gradient (PG) from Antarctica stations, Vostok (78° 27′ S, 106° 52′ E), Dome C (75° 06′ S, 123° 20′ E) and Maitri (70° 45′ S, 11°44′ E) during magnetically disturbed days under fair-weather conditions are discussed. An attempt has been made to study the influence of solar wind-magnetosphere interaction on PG. During magnetic daytime (0600–1800 UT), linear relation between ΔPG and associated ionospheric potential from Dome C and Vostok are observed. The liner response is poor during the magnetic night time (1800-0600 UT). This trend has been addressed by the sun-aligned two-cell plasma convection flow and its differential motion over the stations. It is found that linear relation decreased when negative convection pattern moves towards, overhead and away from the stations under dawnward motion of plasma (IMF By < 0). In addition, the ionospheric potential at dusk sector modulated the PG if the plasma flow remained stable for more than 1 h. The results further showed that the scale size factor between ionospheric potential and PG may influence up to some extent in coupling efficiency. Month-wise Fair-weather PG pattern effectively accounts the ambient PG variation.

Aerosol-induced correlation between visibility and atmospheric electricity

Atmospheric aerosol acts both to reduce the background concentration of natural cluster ions, and to attenuate optical propagation. Hence, the presence of aerosol has two consequences, the reduction of the air's electrical conductivity and the visual range. Ion-aerosol theory and Koschmieder's visibility theory are combined here to derive the associated non-linear variation of the atmospheric electric potential gradient with visual range. A substantial sensitivity is found under poor visual range conditions, but, for good visual range conditions the sensitivity diminishes and little influence of local aerosol on the fair weather potential gradient occurs. This allows visual range measurements, made simply and routinely at many meteorological sites, to provide inference about the local air's electrical properties.

Surface fair-weather potential gradient measurements from a small tropical island station Suva, Fiji

Abstract 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 (&gt;800 W m−2) and surface wind speed (&lt;4.5 m s−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.

Response of ‘atmospheric’ lightning to systematic changes in the global electric field

A wide-angle photomultiplier system has detected optical pulses of lightning origin while searching for atmospheric fluorescence emissions from cosmic X-ray and gamma ray bursts. A broad-band spectral analysis of these events has helped identify lightning discharges which preferentially occur in the atmosphere and are similar in morphology to the ‘A-events’ seen by previous fluorescence experiments elsewhere. We show here that these events are facilitated by increases in the global fair-weather potential gradient, occurring as a result of its diurnal variation or brought about by a decrease in the flux of the galactic cosmic radiation that may accompany moderate changes in the level of geomagnetic activity.

The ionosphere as the source of the atmospheric electric sunrise effect

A number of mechanisms have been suggested to explain the increase in the fair weather potential gradient which occurs at about sunrise. These mechanisms have all been concerned with processes occurring in the lower atmosphere. In this paper it is suggested that an increase in the electrosphere potential could be the source of the sunrise effect. A mechanism is proposed which would account for the increase in electrosphere potential. This proposed mechanism would identify the electrosphere with a specific part of the ionosphere.

The Effect of Potential Gradient on the Charge Separation During Interactions of Snow Crystals with an Ice Sphere

Abstract Charge separation which occurs when polarized ice particles collide in a potential gradient has been found to be an extremely important charge generating mechanism. The fair weather potential gradient is sufficient to initiate considerable charge separation (3 × 10−5 esu per collision). Then positive feedback effects inherent in this polarization charging mechanism can readily explain the strong charging found in glaciated clouds or thunderclouds in general. This theoretical prediction is well corroborated by the present experimental results obtained during simulated experiments in the field with potential gradients <5000 V m−1. However, higher potential gradients produced even more charge than predicted by theory. Also shown are distributions of the original charges carried by the ice particles, the charges transferred to the ice sphere, and the charges carried off after separation. The distributions also support the theory of polarization charging which predicts charging in proportion to the sq...

Studies of fair weather atmospheric electrical potential gradient in the free atmosphere over Poona during IQSY

The results of upper air soundings made during the IQSY (1964-65) at Poona to study the fair weather potential gradient in the free atmosphere are presented. The variations in the troposphere are large and shown to be mainly meteorological in origin. Small but significant variations are also noticed in the stratosphere. Values of ionosphere potential integrated from vertical profiles of the electric field, range from 260 360 kv, with a maximum during December-February and a minimum during June-August

The effect of a living tree upon the fair weather potential gradient

The effect of a living tree upon the fair weather potential gradient

Effect of atmospheric space charge on initial electrification of cumulus clouds

During the summer of 1960, experiments were conducted in Illinois to determine how the electrical potential gradient and space charge above and beneath fair-weather cumulus clouds depend on the polarity and concentration of the space charge in the air from which they grow. Artificially produced space charge was released into the atmosphere near the ground during convection. Measurements showed that clouds that form in the electrically modified region exhibited significantly larger potential gradient perturbations than otherwise similar clouds forming nearby. When the charge released was negative, the fair-weather potential gradient over the cloud was enhanced; when it was positive, the potential gradient was decreased or of reversed polarity. Measurements just beneath the cloud base showed that space charge of the polarity released near the ground was being carried up into the center of the cloud and that space charge of the opposite sign was descending around the outer portions of the cloud. The experimental results show that the polarity and intensity of electrification of small nonprecipitating cumulus clouds is determined primarily by the polarity and concentration of the space charge in the air from which they grow. The agreement between the observations and predictions based on the convective electrification process proposed by Grenet and Vonnegut is consistent with the idea that electric charge is being carried by updrafts and by downdrafts as they have suggested.

Preliminary results of an experiment to determine initial precedence of organized electrification and precipitation in thunderstorms

Observations of summer thunderstorms developing over Mt. Withington, New Mexico, show that electrification begins early in the cloud's development. Measurements within the cloud and above it show that electric charge accumulations similar in polarity to those of the mature storm begin to form before any echo can be seen with an x-band radar and before any electrical perturbations can be detected on the mountain summit beneath the cloud. Measurements of potential gradient were made within the cloud with radiosondes supported on tethered balloons. It was found that the gradient within the cloud was far larger than that outside the cloud and that it reached values as high as 20 v cm−1 before the appearance of the radar echo. Measurements made from an airplane flying over the top of the growing cloud showed that here the fair weather potential gradient reversed before any radar echo could be seen. The development of the initial electrical activity appeared to be closely related to convective activity as indicated by tension on the line holding the tethered balloon and by the rapid rise of the cloud tops. The initial radar precipitation echo within the cloud was frequently in the form of a hollow inverted cup that usually filled in and became solid in a few minutes.

The Distribution of the Two Electrical Zones in the Atmosphere

I HAVE examined the fair weather potential gradient on several mountains in the Bernese Oberland, and find that the positive zone, in summer at midday, extends from sea-level to above the Jungfrau (13,671 ft.). When observations at greater heights are available it may be found that it reaches up to between that and 20,000 ft. above sea-level in Central Europe.