ASSESSMENT OF MONTHLY CHANGES IN THE HEIGHT OF ATMOSPHERIC BOUNDARY LAYER WITH RESPECT TO SURFACE SOIL MOISTURE CONDITION

Abstract

The Earth’s surface is the bottom boundary of the Atmosphere. The portion of the atmosphere most affected by that boundary is called the Atmospheric Boundary Layer (ABL)orBoundary Layerin short. The thickness of the boundary layer is quite variablein space and time. Normally, it is 1.0to2.0 km thick, i.e., occupying the bottom 10 to 20% of the troposphere. Overall, it can range from tens of meters to 4 km or more. The thickness of boundary layer is quite variable in space and time.In the Troposphere closest to the ground, the atmospheric boundary layer is about 1km width and forms the layer where atmosphere feels contact with ground surface, land or sea. Location of the ABL with respect to the atmosphere and earth surface is given in Figure 1. The surface-air interaction occurs in two primary forms: mechanical and thermal. Mechanical contact arises from the friction exerted by the wind against the ground surface, the friction causes the wind to be sheared and creates turbulence. Thermal (convective) turbulence is induced by the vertical distribution of temperature: the earth surface is heated by solar radiation during daytime, cooled during night time.