Comparative measurements of the atmospheric electric space charge density made with the filtration and Faraday cage techniques

Close-to-ground measurements of the atmospheric space charge density simult aneously made with the direct filtration and Faraday cage techniques are re ported. The data obtained on fair-weather days show that the measured value s from the two techniques are small and agree with each other within the li mits of experimental error during windy and turbulent conditions in the aft ernoon hours, but are; large and vastly different, both in magnitude and po larity, during the calm and stable conditions at nighttime. The disagreemen t between the data obtained from the two techniques is explained due to the nonfulfillment of the requirement of maintenance of the entire Faraday cag e in a region of uniform space charge density. It is concluded that the sel ection of a measuring technique for space charge in a study should be based on the requirements of the problem to be studied. (C) 2000 Elsevier Scienc e B.V. All rights reserved.