Earth as an Exoplanet. I. Time Variable Thermal Emission Using Spatially Resolved Moderate Imaging Spectroradiometer Data
Among the more than 4000 exoplanets known today, some terrestrial planets have been detected in the so-called habitable zone of their host stars and their number is expected to increase in the near future, energizing a drive to understand and interpret the eagerly awaited wealth of data to identify...
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ftunivzuerich:oai:www.zora.uzh.ch:200185 2024-10-13T14:03:10+00:00 Earth as an Exoplanet. I. Time Variable Thermal Emission Using Spatially Resolved Moderate Imaging Spectroradiometer Data Mettler, Jean-Noël Quanz, Sascha P Helled, Ravit 2020-11-05 https://www.zora.uzh.ch/id/eprint/200185/ https://www.zora.uzh.ch/200185 eng eng IOP Publishing https://www.zora.uzh.ch/200185 doi:10.3847/1538-3881/abbc15 urn:issn:0004-6256 info:eu-repo/semantics/closedAccess Mettler, Jean-Noël; Quanz, Sascha P; Helled, Ravit (2020). Earth as an Exoplanet. I. Time Variable Thermal Emission Using Spatially Resolved Moderate Imaging Spectroradiometer Data. Astronomical Journal, 160(6):246. Institute for Computational Science 530 Physics Space and Planetary Science Astronomy and Astrophysics Journal Article NonPeerReviewed info:eu-repo/semantics/article 2020 ftunivzuerich https://doi.org/10.3847/1538-3881/abbc15 2024-09-25T00:59:12Z Among the more than 4000 exoplanets known today, some terrestrial planets have been detected in the so-called habitable zone of their host stars and their number is expected to increase in the near future, energizing a drive to understand and interpret the eagerly awaited wealth of data to identify signs of life beyond our solar system. So far, Earth remains the best and only example of a habitable (and inhabited) world. Although, it seems extremely unlikely that any other exoplanets will be true Earth twins, it is important to explore and understand the full range of spectral signatures and variability of Earth in order to inform the design of future instruments and missions, and understand their diagnostic power as well as potential limitations. In this work we use Earth observation data collected by the MODIS instrument aboard the Aqua satellite. The complete data set comprises 15 years of thermal emission observations in the 3.66–14.40 μm range for five different locations on Earth (Amazon Rainforest, Antarctica, Arctic, Indian Ocean, and the Sahara Desert). We then determine flux levels and variations as a function of wavelength and surface type (i.e., climate zone and surface thermal properties) and investigate whether periodic signals indicating Earth's tilted rotation axis can be detected. Our findings suggest that (1) viewing geometry plays an important role when thermal emission data is analyzed as Earth's spectrum varies by a factor of three and more depending on the dominant surface type underneath; (2) typically strong absorption bands from CO2 (15 μm) and O3 (9.65 μm) are significantly less pronounced and partially absent in data from the polar regions implying that estimating correct abundance levels for these molecules might be challenging in these cases; and (3) the time-resolved thermal emission spectrum encodes information about seasons/planetary obliquity, but the significance depends on the viewing geometry and spectral band considered. Article in Journal/Newspaper Antarc* Antarctica Arctic University of Zurich (UZH): ZORA (Zurich Open Repository and Archive Arctic Indian The Astronomical Journal 160 6 246 |
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Open Polar |
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University of Zurich (UZH): ZORA (Zurich Open Repository and Archive |
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ftunivzuerich |
language |
English |
topic |
Institute for Computational Science 530 Physics Space and Planetary Science Astronomy and Astrophysics |
spellingShingle |
Institute for Computational Science 530 Physics Space and Planetary Science Astronomy and Astrophysics Mettler, Jean-Noël Quanz, Sascha P Helled, Ravit Earth as an Exoplanet. I. Time Variable Thermal Emission Using Spatially Resolved Moderate Imaging Spectroradiometer Data |
topic_facet |
Institute for Computational Science 530 Physics Space and Planetary Science Astronomy and Astrophysics |
description |
Among the more than 4000 exoplanets known today, some terrestrial planets have been detected in the so-called habitable zone of their host stars and their number is expected to increase in the near future, energizing a drive to understand and interpret the eagerly awaited wealth of data to identify signs of life beyond our solar system. So far, Earth remains the best and only example of a habitable (and inhabited) world. Although, it seems extremely unlikely that any other exoplanets will be true Earth twins, it is important to explore and understand the full range of spectral signatures and variability of Earth in order to inform the design of future instruments and missions, and understand their diagnostic power as well as potential limitations. In this work we use Earth observation data collected by the MODIS instrument aboard the Aqua satellite. The complete data set comprises 15 years of thermal emission observations in the 3.66–14.40 μm range for five different locations on Earth (Amazon Rainforest, Antarctica, Arctic, Indian Ocean, and the Sahara Desert). We then determine flux levels and variations as a function of wavelength and surface type (i.e., climate zone and surface thermal properties) and investigate whether periodic signals indicating Earth's tilted rotation axis can be detected. Our findings suggest that (1) viewing geometry plays an important role when thermal emission data is analyzed as Earth's spectrum varies by a factor of three and more depending on the dominant surface type underneath; (2) typically strong absorption bands from CO2 (15 μm) and O3 (9.65 μm) are significantly less pronounced and partially absent in data from the polar regions implying that estimating correct abundance levels for these molecules might be challenging in these cases; and (3) the time-resolved thermal emission spectrum encodes information about seasons/planetary obliquity, but the significance depends on the viewing geometry and spectral band considered. |
format |
Article in Journal/Newspaper |
author |
Mettler, Jean-Noël Quanz, Sascha P Helled, Ravit |
author_facet |
Mettler, Jean-Noël Quanz, Sascha P Helled, Ravit |
author_sort |
Mettler, Jean-Noël |
title |
Earth as an Exoplanet. I. Time Variable Thermal Emission Using Spatially Resolved Moderate Imaging Spectroradiometer Data |
title_short |
Earth as an Exoplanet. I. Time Variable Thermal Emission Using Spatially Resolved Moderate Imaging Spectroradiometer Data |
title_full |
Earth as an Exoplanet. I. Time Variable Thermal Emission Using Spatially Resolved Moderate Imaging Spectroradiometer Data |
title_fullStr |
Earth as an Exoplanet. I. Time Variable Thermal Emission Using Spatially Resolved Moderate Imaging Spectroradiometer Data |
title_full_unstemmed |
Earth as an Exoplanet. I. Time Variable Thermal Emission Using Spatially Resolved Moderate Imaging Spectroradiometer Data |
title_sort |
earth as an exoplanet. i. time variable thermal emission using spatially resolved moderate imaging spectroradiometer data |
publisher |
IOP Publishing |
publishDate |
2020 |
url |
https://www.zora.uzh.ch/id/eprint/200185/ https://www.zora.uzh.ch/200185 |
geographic |
Arctic Indian |
geographic_facet |
Arctic Indian |
genre |
Antarc* Antarctica Arctic |
genre_facet |
Antarc* Antarctica Arctic |
op_source |
Mettler, Jean-Noël; Quanz, Sascha P; Helled, Ravit (2020). Earth as an Exoplanet. I. Time Variable Thermal Emission Using Spatially Resolved Moderate Imaging Spectroradiometer Data. Astronomical Journal, 160(6):246. |
op_relation |
https://www.zora.uzh.ch/200185 doi:10.3847/1538-3881/abbc15 urn:issn:0004-6256 |
op_rights |
info:eu-repo/semantics/closedAccess |
op_doi |
https://doi.org/10.3847/1538-3881/abbc15 |
container_title |
The Astronomical Journal |
container_volume |
160 |
container_issue |
6 |
container_start_page |
246 |
_version_ |
1812819587640590336 |