Effect of Urban Aerosol on Potential Gradient Measurements
J C Matthews1, M D Wright1, H G Silva2 and D E Shallcross1
1ACRG, School of Chemistry, Cantock’s Close, Bristol, BS8 1TS, UK
2University of Évora, IIFA, Palácio do Vimioso, Largo Marquês de Marialva, 7002-554, Évora, Portugal
The atmospheric potential gradient (PG) is caused by thunderstorm activity charging the ionosphere causing a current to flow back to ground through the weakly ionised atmosphere. The conductivity of the atmosphere is dependent on the concentration of atmospheric ions, created by cosmic rays and terrestrial radiation, and lost to recombination and attachment to aerosol. Enhanced aerosol concentration can deplete ions and hence increase the magnitude of potential gradient. Measurements of PG in an urban and a rural site have been compared and differences in the time series between the two have been attributed to higher aerosol concentration within the city.