Stratospheric Temperatures and Water Loss from Moist Greenhouse Atmospheres of Earth-like Planets

A radiative-convective climate model is used to calculate stratospheric temperatures and water vapor concentrations for ozone-free atmospheres warmer than that of modern Earth.

Cold, dry stratospheres are predicted at low surface temperatures, in agreement with recent 3-D calculations. However, at surface temperatures above 350 K, the stratosphere warms and water vapor becomes a major upper atmospheric constituent, allowing water to be lost by photodissociation and hydrogen escape. Hence, a ‘moist greenhouse’ explanation for loss of water from Venus, or some exoplanet receiving a comparable amount of stellar radiation, remains a viable hypothesis. Temperatures in the upper parts of such atmospheres are well below those estimated for a gray atmosphere, and this factor should be taken into account when performing ‘inverse’ climate calculations to determine habitable zone boundaries using 1-D models.

James F. Kasting, Howard Chen (BU), Ravi Kumar Kopparapu
(Submitted on 13 Oct 2015)

Comments: 4 Pages, 4 Figures, Accepted to the Astrophysical Journal Letters
Subjects: Earth and Planetary Astrophysics (astro-ph.EP)
Cite as: arXiv:1510.03527 [astro-ph.EP] (or arXiv:1510.03527v1 [astro-ph.EP] for this version)
Submission history
From: Howard Chen
[v1] Tue, 13 Oct 2015 04:09:12 GMT (180kb,D)
http://arxiv.org/abs/1510.03527