Diurnal variation of surface currents at a tropical station

The surface measurements of different atmospheric electrical and meteorological parameters made at a tropical station were analyzed, to study their diurnal variation pattern with specific emphasis on convection current and the meteorological conditions responsible for its generation. The analysis shows that most of the time the displacement current is very small. The convection current is positive for most of the time of the day indicating transport of negative charge to the earth by convection. In spite of very low winds during night, the convection current is found to be more during night than during day. Large space charge density gradient near the earth's surface during stable and stratified atmosphere at night may be a reason for large convection current during that time. This study demonstrates that eddy diffusion during day time and large space charge gradient during night time are responsible for generation of convection current at this location.