47 research outputs found
A New 2D Energy Balance Model For Simulating the Climates of Rapidly- and Slowly-Rotating Terrestrial Planets
Energy balance models (EBMs), alongside radiative-convective climate models
(RCMs) and global climate models (GCMs), are useful tools for simulating
planetary climates. Historically, planetary and exoplanetary EBMs have solely
been 1D latitudinally-dependent models with no longitudinal dependence, until
the study of Okuya et al., which focused on simulating synchronously-rotating
planets. Following the work of Okuya et al., I have designed the first 2D EBM
(PlaHab) that can simulate N2-CO2-H2O-H2 atmospheres of both rapidly-rotating
and synchronously-rotating planets, including Mars, Earth, and exoplanets
located within their circumstellar habitable zones. PlaHab includes physics for
both water and CO2 condensation. Regional topography can be incorporated. Here,
I have specifically applied PlaHab to investigate present Earth, early Mars,
TRAPPIST-1e and Proxima Centauri b, representing examples of habitable (and
potentially habitable) worlds in our solar system and beyond. I compare my EBM
results against those of other 1D and 3D models, including those of the recent
Trappist-1 Habitable Atmosphere (THAI) comparison project. Overall, EBM results
are consistent with those of other 1D and 3D models although inconsistencies
among all models continue to be related to the treatment of clouds and other
known differences between EBMs and GCMs, including heat transport
parameterizations. Although two-dimensional EBMs are a relatively new entry in
the study of planetary/exoplanetary climates, their ease-of-use, speed,
flexibility, wide applicability, and greater complexity (relative to 1D
models), may indicate an ideal combination for the modeling of planetary and
exoplanetary atmospheres alike.Comment: Accepted into The Planetary Science Journal (35 pages, 12 Figures, 4
Tables
A more comprehensive habitable zone for finding life on other planets
The habitable zone (HZ) is the circular region around a star(s) where
standing bodies of water could exist on the surface of a rocky planet. Space
missions employ the HZ to select promising targets for follow-up habitability
assessment. The classical HZ definition assumes that the most important
greenhouse gases for habitable planets orbiting main-sequence stars are CO2 and
H2O. Although the classical HZ is an effective navigational tool, recent HZ
formulations demonstrate that it cannot thoroughly capture the diversity of
habitable exoplanets. Here, I review the planetary and stellar processes
considered in both classical and newer HZ formulations. Supplementing the
classical HZ with additional considerations from these newer formulations
improves our capability to filter out worlds that are unlikely to host life.
Such improved HZ tools will be necessary for current and upcoming missions
aiming to detect and characterize potentially habitable exoplanets.Comment: Published in Geosciences. Invited review for the "Planetary Evolution
and Search for Life on Habitable Planets" Special Issue (58 pages, 15
Figures, 1 Table). Fixed a typo in Table 1 and updated acknowledgements (was
not fixed in v2). http://www.mdpi.com/2076-3263/8/8/280/ht