Atmospheric electrical profiles below three meters

Abstract

Passive antennas were used to make precise measurements of potential at heights of 0.25, 0.50, 1.0, and 3.0 m. These measurements, combined with space charge measurements at ground level and at 1.0 m, permit construction of reasonably definite potential gradient and space‐charge profiles up to the 3.0‐m height. Profiles are exhibited for three types of fair weather situations: (1) normal daytime, (2) nighttime with wind speed greater than 1 m sec−1, and (3) nighttime with wind speed below 0.5 m sec−1. Profiles for the first two situations are of the type to be expected in the presence of electrode effect and eddy diffusion. In the nighttime low‐wind situation, on the average, a stratum of dense positive space charge approximately 0.25 m deep lies next to the ground; negative space charge of moderate density is present above this for the rest of the 3 m. This space charge profile would appear to be a manifestation of the presence of a shallow stratum of relatively intense ionization close to the ground during the nighttime periods of low wind, and thus of the accumulation of Rn222 and Rn220; radioactive elements in the soil near the surface also would contribute.

Vertical profiles of atmospheric electric parameters close to ground

“…In a nonturbulent atmosphere he considers (1) a constant conduction current density with height, (2) normal downward electric field, and (3) downward gradient of conductivity and concludes that there are convection currents which are stronger in daytime and weaker in nighttime. On calm nights, Crozier [1965] has also observed the reverse electrode effect at his New Mexico site, which is destroyed by a wind as weak as 1 m s-1.…”

Diurnal variation of surface currents at a tropical station

“…The conductivity shows higher values during night time than those during day time. The relatively higher conductivity during night is caused by the increased rate of ionization because of trapping of radioactive gases in the stable and stratified atmosphere (Crozier, 1965). Our observations show that the space charge density is positive on most of the days; however, negative space charge density is also observed during night time on some days due to reverse electrode effect, as shown in Figs.…”

An atmospheric electrical method to determine the eddy diffusion coefficient

“…Since space charge density has steep gradients close to ground surface during calm periods at night-time, its measurements only at three levels may not be enough for accurate estimation of its average values in the lowest 1-2 m during such periods. Hence no attempt has been made to evaluate the mixing parameter with the data obtained by Crozier (1965) and Kamra (1982) during such periods. Further, as shown by Pawar and Kamra (2000), the Faraday cage measurements of space charge are reliable only in the well-mixed atmosphere.…”

“…It also displays values of mixing parameter estimated from the bulk aerodynamic method and from Tuomi's formula (1982) for the average meteorological conditions prevailing during different experimental periods. In these experiments, electric field is obtained at the earth's surface, and space charge is measured either with the filtration apparatus installed at two or three levels in the lowest 1-2 m (Crozier 1965;Kamra 1982), or with a Faraday cage with its centre at a height of either 1.5 m from water surface (Hoppel and Gathman 1972) or 1.8 m above ground (Pawar and Kamra 2000). Since space charge density has steep gradients close to ground surface during calm periods at night-time, its measurements only at three levels may not be enough for accurate estimation of its average values in the lowest 1-2 m during such periods.…”