Thermophysical Properties of the North Polar Residual Cap using Mars Global Surveyor Thermal Emission Spectrometer
Using derived temperatures from thermal-infrared instruments aboard orbiting spacecraft, we constrain the thermophysical properties, in the upper few meters, of the north polar residual cap of Mars. In line with previous authors we test a homogeneous thermal model (i.e., depth-independent thermal pr...
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Online Access: | http://hdl.handle.net/10150/633496 https://doi.org/10.1029/2018je005786 |
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ftunivarizona:oai:repository.arizona.edu:10150/633496 2023-05-15T16:38:24+02:00 Thermophysical Properties of the North Polar Residual Cap using Mars Global Surveyor Thermal Emission Spectrometer Bapst, J. Byrne, S. Bandfield, J. L. Hayne, P. O. Univ Arizona, Lunar & Planetary Lab 2019-05 http://hdl.handle.net/10150/633496 https://doi.org/10.1029/2018je005786 en eng AMER GEOPHYSICAL UNION Bapst, J., Byrne, S., Bandfield, J. L., & Hayne, P. O. ( 2019). Thermophysical properties of the north polar residual cap using Mars Global Surveyor Thermal Emission Spectrometer. Journal of Geophysical Research: Planets, 124, 1315– 1330. 2169-9097 doi:10.1029/2018je005786 http://hdl.handle.net/10150/633496 2169-9100 JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS ©2019. American Geophysical Union. All Rights Reserved. Mars polar ice climate thermophysics accumulation Article 2019 ftunivarizona https://doi.org/10.1029/2018je005786 2020-06-14T08:17:40Z Using derived temperatures from thermal-infrared instruments aboard orbiting spacecraft, we constrain the thermophysical properties, in the upper few meters, of the north polar residual cap of Mars. In line with previous authors we test a homogeneous thermal model (i.e., depth-independent thermal properties), simulating water ice of varying porosity against observed temperatures. We find that high thermal inertia (>1,000Jm(-2)K(-1)s(1/2) or <40% porosity) provides the best fit for most of the residual cap. Additionally, we test the observed data against models with depth-dependent thermal properties. Models tested converge on similar solutions: we find extensive regions of low surface thermal inertia consistent with a porous layer at the surface (>40% porosity) that densifies with depth into a zero-porosity ice layer at shallow depths (<0.5m). We interpret this as evidence of recent water ice accumulation. Our results along the edge of the residual cap imply that denser (<40% porosity) ice is present at the surface and coincides with lower albedo. These results suggest that older ice is undergoing exhumation along much of the residual cap margin. The results support recent water ice accumulation having occurred over specific regions, while ablation dominates in others. Plain Language Summary The polar regions of Mars host kilometer-thick stacks of water ice that have been built up over millions of years. At the north pole today, the top of this ice deposit is interacting with the Martian atmosphere. Whether or not ice at the surface is fluffy (like snow) or dense (like an ice slab) can provide useful information about the polar ice cap and recent climate. Multiple years of surface temperature measurements have been acquired by instruments aboard spacecraft in orbit around Mars. By comparing these values with temperature simulations, we can narrow down the type of ice near the surface. Our results show that the type of ice varies across the polar cap. Some regions appear to be a snow-like surface where the polar cap may be growing. Other regions, most notably along the edge of the polar cap, show denser ice that is likely older. The nature of the ice tells us about the current climate and how these kilometer-thick ice deposits form. Mars Data Analysis Program [NNX15AM62G] 6 month embargo; first published: 09 April 2019 This item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at repository@u.library.arizona.edu. Article in Journal/Newspaper Ice cap North Pole The University of Arizona: UA Campus Repository North Pole Journal of Geophysical Research: Planets |
institution |
Open Polar |
collection |
The University of Arizona: UA Campus Repository |
op_collection_id |
ftunivarizona |
language |
English |
topic |
Mars polar ice climate thermophysics accumulation |
spellingShingle |
Mars polar ice climate thermophysics accumulation Bapst, J. Byrne, S. Bandfield, J. L. Hayne, P. O. Thermophysical Properties of the North Polar Residual Cap using Mars Global Surveyor Thermal Emission Spectrometer |
topic_facet |
Mars polar ice climate thermophysics accumulation |
description |
Using derived temperatures from thermal-infrared instruments aboard orbiting spacecraft, we constrain the thermophysical properties, in the upper few meters, of the north polar residual cap of Mars. In line with previous authors we test a homogeneous thermal model (i.e., depth-independent thermal properties), simulating water ice of varying porosity against observed temperatures. We find that high thermal inertia (>1,000Jm(-2)K(-1)s(1/2) or <40% porosity) provides the best fit for most of the residual cap. Additionally, we test the observed data against models with depth-dependent thermal properties. Models tested converge on similar solutions: we find extensive regions of low surface thermal inertia consistent with a porous layer at the surface (>40% porosity) that densifies with depth into a zero-porosity ice layer at shallow depths (<0.5m). We interpret this as evidence of recent water ice accumulation. Our results along the edge of the residual cap imply that denser (<40% porosity) ice is present at the surface and coincides with lower albedo. These results suggest that older ice is undergoing exhumation along much of the residual cap margin. The results support recent water ice accumulation having occurred over specific regions, while ablation dominates in others. Plain Language Summary The polar regions of Mars host kilometer-thick stacks of water ice that have been built up over millions of years. At the north pole today, the top of this ice deposit is interacting with the Martian atmosphere. Whether or not ice at the surface is fluffy (like snow) or dense (like an ice slab) can provide useful information about the polar ice cap and recent climate. Multiple years of surface temperature measurements have been acquired by instruments aboard spacecraft in orbit around Mars. By comparing these values with temperature simulations, we can narrow down the type of ice near the surface. Our results show that the type of ice varies across the polar cap. Some regions appear to be a snow-like surface where the polar cap may be growing. Other regions, most notably along the edge of the polar cap, show denser ice that is likely older. The nature of the ice tells us about the current climate and how these kilometer-thick ice deposits form. Mars Data Analysis Program [NNX15AM62G] 6 month embargo; first published: 09 April 2019 This item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at repository@u.library.arizona.edu. |
author2 |
Univ Arizona, Lunar & Planetary Lab |
format |
Article in Journal/Newspaper |
author |
Bapst, J. Byrne, S. Bandfield, J. L. Hayne, P. O. |
author_facet |
Bapst, J. Byrne, S. Bandfield, J. L. Hayne, P. O. |
author_sort |
Bapst, J. |
title |
Thermophysical Properties of the North Polar Residual Cap using Mars Global Surveyor Thermal Emission Spectrometer |
title_short |
Thermophysical Properties of the North Polar Residual Cap using Mars Global Surveyor Thermal Emission Spectrometer |
title_full |
Thermophysical Properties of the North Polar Residual Cap using Mars Global Surveyor Thermal Emission Spectrometer |
title_fullStr |
Thermophysical Properties of the North Polar Residual Cap using Mars Global Surveyor Thermal Emission Spectrometer |
title_full_unstemmed |
Thermophysical Properties of the North Polar Residual Cap using Mars Global Surveyor Thermal Emission Spectrometer |
title_sort |
thermophysical properties of the north polar residual cap using mars global surveyor thermal emission spectrometer |
publisher |
AMER GEOPHYSICAL UNION |
publishDate |
2019 |
url |
http://hdl.handle.net/10150/633496 https://doi.org/10.1029/2018je005786 |
geographic |
North Pole |
geographic_facet |
North Pole |
genre |
Ice cap North Pole |
genre_facet |
Ice cap North Pole |
op_relation |
Bapst, J., Byrne, S., Bandfield, J. L., & Hayne, P. O. ( 2019). Thermophysical properties of the north polar residual cap using Mars Global Surveyor Thermal Emission Spectrometer. Journal of Geophysical Research: Planets, 124, 1315– 1330. 2169-9097 doi:10.1029/2018je005786 http://hdl.handle.net/10150/633496 2169-9100 JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS |
op_rights |
©2019. American Geophysical Union. All Rights Reserved. |
op_doi |
https://doi.org/10.1029/2018je005786 |
container_title |
Journal of Geophysical Research: Planets |
_version_ |
1766028678236471296 |