A study of enhanced fair‐weather electric fields occurring soon after sunrise

Abstract

Abstract. In this paper we describe several series of electric field soundings made in the lowest few hundred meters above the ground on 6 days at Kennedy Space Center in Florida. These soundings are used to determine the charge density and thickness of the charged electrode layer just above the surface of the Earth both before and after sunrise during fair weather. On most of the days considered, there was an anomalous enhancement in the ground-level electric field that was probably associated with the "sunrise effect" previously described by others. At our tether site we found that the electrode-layer charge density began increasing at about the same time as the local enhancement in the electric field magnitude at the ground. Shortly before the peak in the local E enhancement, the electrode-layer charge density decreased while the charge thickness increased; these changes were coincident with a decrease in relative humidity, a shift in the average wind direction, and increases in the fluctuations in relative humidity, wind speed, and wind direction.The typical decrease in charge density was from 0.2 to 0.05 nC m -3, while the charge layer thickness increased from less than 20 m to almost 200 m. Our measurements suggest that enhanced positive electrode layers accumulate before sunrise very close to the surface because there is relatively little radioactivity in the soil or air. Local, upward mixing of the denser, low-lying, electrode-layer charge may account for the observed sunrise enhancement in electric field. The larger enhancements observed at some sites may indicate that upward convection is supplemented by advection of denser charge from above water surfaces a few tens of meters (or less) from the measurement sites.

Diurnal variation of surface electric field at a tropical station in different seasons: a study of plausible influences

“…Franke (1949) mathematically proved that the diurnal variation of the E would generally be a curve with double oscillations following vertical atmospheric mass exchange over land. Muhleisen (1956) has experimentally dealt with the effect of presence of water in different forms and condensation nuclei on atmospheric potential to a great extent. The 'Sunrise Effect' observations of E by Law (1963) showed that space charge and E appears to be more closely related to each other than to any other variable.…”

“…The 'Sunrise Effect' observations of E by Law (1963) showed that space charge and E appears to be more closely related to each other than to any other variable. Marshall et al (1999) studied the 'Enhanced Sunrise Effect' to show that it does not contain to the layers close to ground and nearness to water bodies significantly elevates the values reached. Of recent a school of thought (Delgado et al, 2003) is evolving that it is not the E that is controlled by pollution dependent conductivity but the pollutants rearrange themselves as per the prevalent E depending on their dipole moment.…”

Characteristics of the atmospheric electric field and correlation with CO2 at a rural site in southern Balkans

“…The sunrise effect was extensively described by Marshall et al (1999), who focused particularly on PG response to positive space charge transpositions. Other authors (Law 1963;Chalmers 1967;Kamra 1982) also mentioned the sunrise effect, among which Kamra (1982) and Law (1963) observed a sign reversal of space charge from negative to positive at the moment of sunrise, coinciding with PG increase.…”

“…Other authors (Law 1963;Chalmers 1967;Kamra 1982) also mentioned the sunrise effect, among which Kamra (1982) and Law (1963) observed a sign reversal of space charge from negative to positive at the moment of sunrise, coinciding with PG increase. According to Marshall et al (1999), the start of the morning convection caused by solar heating leads to the destruction of a shallow positively charged layer (electrode layer) that was built up during the night and overlies the very first decimeters of the ground (Crozier 1963). The dilution of the electrode layer just after sunrise owing to increasing turbulence transports gradually more and more positive charges over the EFM enhancing eventually PG (Marshall et al 1999).…”

“…According to Marshall et al (1999), the start of the morning convection caused by solar heating leads to the destruction of a shallow positively charged layer (electrode layer) that was built up during the night and overlies the very first decimeters of the ground (Crozier 1963). The dilution of the electrode layer just after sunrise owing to increasing turbulence transports gradually more and more positive charges over the EFM enhancing eventually PG (Marshall et al 1999). The mechanism weakens as time passes and the boundary layer becomes well mixed (Moore et al 1962).…”