# Atmospheric Heat Redistribution and Collapse on Tidally Locked Rocky Planets

 Title: Atmospheric Heat Redistribution and Collapse on Tidally Locked Rocky Planets Author: Wordsworth, Robin Citation: Wordsworth, Robin. 2015. “Atmospheric Heat Redistribution and Collapse on Tidally Locked Rocky Planets.” The Astrophysical Journal 806 (2) (June 17): 180. doi:10.1088/0004-637x/806/2/180. http://dx.doi.org/10.1088/0004-637X/806/2/180. Full Text & Related Files: 1412.5575v1.pdf (1.082Mb; PDF) Abstract: Atmospheric collapse is likely to be of fundamental importance to tidally locked rocky exoplanets, but it remains understudied. Here, general results on the heat transport and stability of tidally locked terrestrial-type atmospheres are reported. First, the problem is modeled with an idealized three-dimensional (3D) general circulation model (GCM) with gray gas radiative transfer. It is shown that over a wide range of parameters that the atmospheric boundary layer, rather than the large-scale circulation, is the key to understanding the planetary energy balance. Through a scaling analysis of the interhemispheric energy transfer, theoretical expressions for the day–night temperature difference and surface wind speed are created that reproduce the GCM results without tuning. Next, the GCM is used with correlated-k radiative transfer to study heat transport for two real gases $$CO_2$$ and CO). For $$CO_2$$, empirical formulae for the collapse pressure as a function of planetary mass and stellar flux are produced, and critical pressures for atmospheric collapse at Earth's stellar flux are obtained that are around five times higher (0.14 bar) than previous gray gas estimates. These results provide constraints on atmospheric stability that will aid in future interpretations of observations and exoplanet habitability modeling. Published Version: doi:10.1088/0004-637X/806/2/180 Other Sources: https://arxiv.org/abs/1412.5575 Terms of Use: This article is made available under the terms and conditions applicable to Open Access Policy Articles, as set forth at http://nrs.harvard.edu/urn-3:HUL.InstRepos:dash.current.terms-of-use#OAP Citable link to this page: http://nrs.harvard.edu/urn-3:HUL.InstRepos:27846316 Downloads of this work: