M.Tech. Thesis:

Title: Investigation of Atmospheric Boundary Layer Characteristics for Different Aerosol Absorptions:  An Observational and Modeling Approach

Abstract: Atmospheric boundary layer (ABL) over the land is directly influenced by and rapidly responds to diurnal cycle of solar radiation. Aerosols interact directly with the evolution of the ABL by scattering and absorbing solar radiation. The scattering and absorption of aerosols reduces the solar radiation reaching the surface, inhibiting the sensible heat flux and evaporation and inducing feedbacks in the surface through various parameters such as ABL stratification, RH, etc. Thus aerosol plays a vital role in the evolution of ABL through the interaction between land and atmosphere. This inspired us for a detailed study on the impact of aerosols in the evolution of ABL.

This study investigates the impacts of tropospheric aerosols on the evolution of the ABL over Anand (22 35' N, 72 55'), Gujarat, a tropical semi-arid site in Western Indian region. In this study, we used a one-dimensional planetary boundary layer model (OSU 1-D PBL), developed at Oregon state University to simulate the interactions of the ABL, vegetation and soil. In this, PBL model is coupled with an active two layer soil model and a primitive plant canopy model. The oversimplified radiation scheme of the OSU 1-D PBL model is replaced with Santa Barbara Discrete Ordinate Radiative Transfer (SBDART) model, to include the radiative effects of scattering and absorbing aerosol types. We used Land surface processes experiment (LASPEX) data sets obtained at Anand, in the OSU 1-D PBL model and studied the effect of aerosols on the evolution of the PBL height, sensible and latent heat fluxes etc. during different months. The results indicate that the (positive / negative) effect is more in the case of absorbing aerosols than scattering aerosols.