Thermal phases of earth-like planets: Estimating thermal inertia from eccentricity, obliquity, and diurnal forcing
ABSTRACT In order to understand the climate on terrestrial planets orbiting nearby Sun-like stars, one would like to know their thermal inertia. We use a global climate model to simulate the thermal phase variations of Earth analogs and test whether these data could distinguish between planets with...
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ftciteseerx:oai:CiteSeerX.psu:10.1.1.1090.5567 2023-05-15T18:18:51+02:00 Thermal phases of earth-like planets: Estimating thermal inertia from eccentricity, obliquity, and diurnal forcing Nicolas B Cowan Aiko Voigt Dorian S Abbot The Pennsylvania State University CiteSeerX Archives 2012 application/pdf http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.1090.5567 http://geosci.uchicago.edu/%7Eabbot/files/PAPERS/cowan-et-al-12b.pdf en eng http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.1090.5567 http://geosci.uchicago.edu/%7Eabbot/files/PAPERS/cowan-et-al-12b.pdf Metadata may be used without restrictions as long as the oai identifier remains attached to it. http://geosci.uchicago.edu/%7Eabbot/files/PAPERS/cowan-et-al-12b.pdf text 2012 ftciteseerx 2020-05-24T00:23:18Z ABSTRACT In order to understand the climate on terrestrial planets orbiting nearby Sun-like stars, one would like to know their thermal inertia. We use a global climate model to simulate the thermal phase variations of Earth analogs and test whether these data could distinguish between planets with different heat storage and heat transport characteristics. In particular, we consider a temperate climate with polar ice caps (like the modern Earth) and a snowball state where the oceans are globally covered in ice. We first quantitatively study the periodic radiative forcing from, and climatic response to, rotation, obliquity, and eccentricity. Orbital eccentricity and seasonal changes in albedo cause variations in the global-mean absorbed flux. The responses of the two climates to these global seasons indicate that the temperate planet has 3× the bulk heat capacity of the snowball planet due to the presence of liquid water oceans. The obliquity seasons in the temperate simulation are weaker than one would expect based on thermal inertia alone; this is due to cross-equatorial oceanic and atmospheric energy transport. Thermal inertia and cross-equatorial heat transport have qualitatively different effects on obliquity seasons, insofar as heat transport tends to reduce seasonal amplitude without inducing a phase lag. For an Earth-like planet, however, this effect is masked by the mixing of signals from low thermal inertia regions (sea ice and land) with that from high thermal inertia regions (oceans), which also produces a damped response with small phase lag. We then simulate thermal light curves as they would appear to a high-contrast imaging mission (TPF-I/Darwin). In order of importance to the present simulations, which use modern-Earth orbital parameters, the three drivers of thermal phase variations are (1) obliquity seasons, (2) diurnal cycle, and (3) global seasons. Obliquity seasons are the dominant source of phase variations for most viewing angles. A pole-on observer would measure peak-to-trough amplitudes ... Text Sea ice Unknown |
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English |
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ABSTRACT In order to understand the climate on terrestrial planets orbiting nearby Sun-like stars, one would like to know their thermal inertia. We use a global climate model to simulate the thermal phase variations of Earth analogs and test whether these data could distinguish between planets with different heat storage and heat transport characteristics. In particular, we consider a temperate climate with polar ice caps (like the modern Earth) and a snowball state where the oceans are globally covered in ice. We first quantitatively study the periodic radiative forcing from, and climatic response to, rotation, obliquity, and eccentricity. Orbital eccentricity and seasonal changes in albedo cause variations in the global-mean absorbed flux. The responses of the two climates to these global seasons indicate that the temperate planet has 3× the bulk heat capacity of the snowball planet due to the presence of liquid water oceans. The obliquity seasons in the temperate simulation are weaker than one would expect based on thermal inertia alone; this is due to cross-equatorial oceanic and atmospheric energy transport. Thermal inertia and cross-equatorial heat transport have qualitatively different effects on obliquity seasons, insofar as heat transport tends to reduce seasonal amplitude without inducing a phase lag. For an Earth-like planet, however, this effect is masked by the mixing of signals from low thermal inertia regions (sea ice and land) with that from high thermal inertia regions (oceans), which also produces a damped response with small phase lag. We then simulate thermal light curves as they would appear to a high-contrast imaging mission (TPF-I/Darwin). In order of importance to the present simulations, which use modern-Earth orbital parameters, the three drivers of thermal phase variations are (1) obliquity seasons, (2) diurnal cycle, and (3) global seasons. Obliquity seasons are the dominant source of phase variations for most viewing angles. A pole-on observer would measure peak-to-trough amplitudes ... |
author2 |
The Pennsylvania State University CiteSeerX Archives |
format |
Text |
author |
Nicolas B Cowan Aiko Voigt Dorian S Abbot |
spellingShingle |
Nicolas B Cowan Aiko Voigt Dorian S Abbot Thermal phases of earth-like planets: Estimating thermal inertia from eccentricity, obliquity, and diurnal forcing |
author_facet |
Nicolas B Cowan Aiko Voigt Dorian S Abbot |
author_sort |
Nicolas B Cowan |
title |
Thermal phases of earth-like planets: Estimating thermal inertia from eccentricity, obliquity, and diurnal forcing |
title_short |
Thermal phases of earth-like planets: Estimating thermal inertia from eccentricity, obliquity, and diurnal forcing |
title_full |
Thermal phases of earth-like planets: Estimating thermal inertia from eccentricity, obliquity, and diurnal forcing |
title_fullStr |
Thermal phases of earth-like planets: Estimating thermal inertia from eccentricity, obliquity, and diurnal forcing |
title_full_unstemmed |
Thermal phases of earth-like planets: Estimating thermal inertia from eccentricity, obliquity, and diurnal forcing |
title_sort |
thermal phases of earth-like planets: estimating thermal inertia from eccentricity, obliquity, and diurnal forcing |
publishDate |
2012 |
url |
http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.1090.5567 http://geosci.uchicago.edu/%7Eabbot/files/PAPERS/cowan-et-al-12b.pdf |
genre |
Sea ice |
genre_facet |
Sea ice |
op_source |
http://geosci.uchicago.edu/%7Eabbot/files/PAPERS/cowan-et-al-12b.pdf |
op_relation |
http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.1090.5567 http://geosci.uchicago.edu/%7Eabbot/files/PAPERS/cowan-et-al-12b.pdf |
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Metadata may be used without restrictions as long as the oai identifier remains attached to it. |
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1766195593780133888 |