First results of fair-weather atmospheric electricity measurements in Northeast India

Abstract

During the month of March 2006, a short campaign was conducted to measure fair-weather atmospheric electricity parameters in Tripura, Northeast India (23.50°N, 91.25°E). The campaign was the first of its kind in this region of the globe. The main objective of the campaign was to char-acterize the diurnal variation of three parameters namely vertical potential gradient (E), vertical air-earth current density (J z ) and atmospheric electrical conductivity (σ) in fair-weather condi-tions. The diurnal variation of E and J z over sixteen fair-weather days shows two distinct maxima around 14 UT and 20 UT and a minimum around 03 UT. The average vertical potential gradient is found to be 108V·m -1 and air-earth current density 1.85pA·m -2. The average bipolar atmospheric electrical conductivity at the ground level is found to be 19.6fS·m -1. An excellent positive corre-lation between E and J z is found, with a correlation coefficient of 0.96. A comparative study with Carnegie universal variation shows 70% correlation with observed variation of vertical potential gradient during the period of the campaign. The results are discussed in view of difficulty as well as possibility of getting global signatures in atmospheric electricity measurements made from tropical land stations. © Indian Academy of Sciences.