Role of wind shear, temperature lapse rate, and aerosol in assessment of atmospheric condition

Abstract

The near-surface environment of the earth remains either in calm or in a turbulent state as per the kinetic force acts, which encourage the growth of disturbance in the atmospheric fluid. In a stable condition, mixing of the air particles at different heights reduces the overall vertical variability of the air particles in the atmosphere while unstable atmospheric condition produces the minimum shear that leads to convective situation and promotes the mixing of its composition. To analyse these types of atmospheric conditions, here two basic parameters temperature lapse rate and aerosol optical depth (AOD), has been taken into consideration. Along with these parameters, a model named hybrid single particle lagrangian integrated trajectory (HYSPLIT) has been utilised to track the air parcel or wind flow pattern. The observations were made over Guwahati (26°N, 92°E), NE region of India. It has been determined from the observations that the wind shear (WS) follows a seasonal pattern. On certain days, the shear is higher than that of the normal condition. In this context, parameters temperature lapse rate and AOD along with WS has been observed and examined to analyse the stability of the atmosphere. It is observed that on the day of high WS value, high AOD and slow decrease of temperature per km (vertically with height) shows a completely different pattern than the normal one.