Effects of Surface Roughness Length on the Atmospheric Circulation in a Tidally-Locked Planet

Abstract

With the advent of advanced observational techniques in characterizing exoplanetary atmospheres, it has become necessary to model the general circulation dynamics of these atmospheres- taking into account their spectroscopically identified composition, external forcing, orbital dynamics etc. to enable inverse modelling of the planetary conditions and their underlying physics. Capturing the nuances of atmospheres and forcings that are alien to planets in our solar system would shed more light into the more generalized physical pro cesses that governed the formation of our planetary system, the Earth and its atmosphere. Hence exoplanetary sciences could provide us with a way to understand our own past, and possibly our future. Many projects have been undertaken by people working in this field to resolve the effect of each parameter such as orbital distance, rotation rate, stellar insolation, cloud distribution, etc. in shaping the atmospheric circulation of exoplanets and how they may be interpreted from observational data. For the purpose of this thesis, we have identified a research gap in resolving the effect of surface roughness length on the atmospheric dynamics of a tidally locked exoplanet. Surface roughness being a reasonable representative variable of terrain, we hope this simple thesis project could contribute towards more advanced studies that may help in quantifying the effect of surface friction and terrain on observable atmospheric features. The scope of this project- in the context of atmospheric science- is limited to under standing how the planetary boundary layer functions, how variations in the surface roughness length changes the circulation, and how such changes are propagated through the atmosphere via eddies.