Response of surface boundary layer parameters during the formation of thunderstorms over Cochin

In the present study we made a detailed analysis of the surface ABL parameters associated with three thunderstorms that occurred over Cochin during pre-monsoon season. The high-resolution sonic anemometer data can provide microscale evolution of the surface boundary layer processes. The parameters studied are momentum flux, sensible heat flux, Turbulent Kinetic Energy (TKE), friction velocity and variance of u, v, w, T. Momentum flux anomalously increases from 0.1 N m−2 to 1 N m−2 during the occurrence of thunderstorm. Correspondingly, sensible heat flux decreases anomalously to a value of −200 W m−2 from 10 W m−2. TKE increases abruptly to 3 m2 s−2 from 0.5 m2 s−2 during convective activity. Friction velocity also changes abruptly to 1 m s−1 from 0.1 m s−1. The thermodynamic parameters and stability indices were investigated prior to the occurrence of thunderstorms and found that the atmospheric characteristics were conducive for the formation of convective activity.