The role of radiation in the nocturnal boundary layer : the origin of the lifted temperature minimum

Abstract

The nocturnal boundary layer(NBL) that develops over land is important in weather forecasting, climate modeling and in the dispersion of pollutants. Physical transport mechanisms such as radiation and turbulence play a strong role in the formation and evolution of the NBL as characterized by the vertical temperature profile above the ground. Characterizing radiation and its interaction with other transport processes(such as turbulence, advection, subsidence etc.), and the effect of these interactions on the thermal structure of the NBL, is not yet fully understood. In this thesis, we mainly address the issue of frequency parameterization in modeling radiation over a surface with arbitrary emissivity and varying directional characteristics. Further, we discuss in detail, the implication of this issue with regard to the origin of a specific micrometeorological phenomenon called the Ramdas layer; a phenomenon that concerns the radiation-driven non-monotonic vertical distribution of temperature in the lowest decimeters of air on calm clear nights.