Venus as an Exoplanet: I. An Initial Exploration of the 3-D Energy Balance for a CO2 Exoplanetary Atmosphere Around an M-Dwarf Star

Abstract

A 3-D GCM simulates middle and upper atmospheric effects of energy balance and dynamics for a Venus-type exoplanet orbiting GJ 436.2. Increasing stellar EUV/UV fluxes for decreasing planet-star distances produce increasing zonal wind, thermospheric temperature, and conductive cooling. 3. Energy balance sensitivity study shows that (a) a ±30% change in the NIR heating profile only incrementally changes the thermal structure above 10 -5 mbar, and virtually no change below 10 -5 mbar, and (b) doubling and quadrupling the NIR heating profile produces significant changes in dynamics and temperature throughout the range of atmospheric pressures considered. 4. CO2 15-μm cooling is a strong thermostat regulating dayside temperatures due to cooling enhancement via collisions of O and CO2.