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Mapping the seasonal variability of Titan’s upper atmospheric gases using ALMAWe present a study of the impact of seasonal effects on the spatial distribution of Titan’s atmospheric gases HNC, CH3CN, and HC3N over a timescale of less than a Titan month (9 Earth months). These molecules are synthesized primarily in the upper and middle atmosphere as a result of CH4 and N2 photochemistry, and are redistributed around Titan’s globe as a result of diffusion and zonal and meridional circulation. With observations from the Atacama Large Millimeter/submillimeter Array (ALMA) obtained in August 2016 [1] and May 2017 [2], we produced high-resolution, spectrally and spatially resolved maps of the emission from these gases. These observations are contemporaneous with the end of the Cassini mission (around the time of the northern summer solstice), allowing for studies of seasonal variations in Titan’s organic chemistry through analysis of the production, destruction, and transport of complex molecules. We observed a strong reduction of 41% ± 4% in the HC3N flux coming from the north pole, while CH3CN and HNC remained relatively stable (within errors) over the 9 month period of our observations. In the south pole, CH3CN presented a 31% ± 10% increase, while HNC saw a reduction of 20% ± 8%, and HC3N remained fairly stable (within errors). The HNC emission comes primarily from the highest (thermospheric) altitudes, and is distributed more uniformly about Titan’s limb than HC3N and CH3CN; the latter two molecules show strong polar enhancements due to meridional circulation. The steep decline in the HC3N north polar concentration is consistent its short photochemical lifetime (compared to HNC and CH3CN), combined with a reduction in meridional transport of gases produced at lower latitudes, towards the northern (summer) pole. The loss of emission of HC3N in the northern hemisphere is also consistent with the breakdown of Titan’s northern polar vortex during the onset of the northern summer, leading to a loss of confinement of these species [3].
Document ID
20210020419
Acquisition Source
Goddard Space Flight Center
Document Type
Presentation
Authors
Emmanuel Garcia-Berrios
(Catholic University of America Washington D.C., District of Columbia, United States)
Martin A. Cordiner
(Catholic University of America Washington D.C., District of Columbia, United States)
Conor A. Nixon
(Goddard Space Flight Center Greenbelt, Maryland, United States)
Alexander E. Thelen
(UNIVERSITIES SPACE RESEARCH ASSOCIATION Columbia, Maryland, United States)
Steven B. Charnley
(Goddard Space Flight Center Greenbelt, Maryland, United States)
Date Acquired
August 11, 2021
Subject Category
Space Sciences (General)
Astronomy
Meeting Information
Meeting: Titan Through Time 5
Location: Boulder, CO
Country: US
Start Date: August 10, 2021
End Date: August 12, 2021
Sponsors: National Aeronautics and Space Administration
Funding Number(s)
WBS: 811073.02.03.04.56
WBS: 202844.02.01.04.35
WBS: 811073.02.12.04.40
Distribution Limits
Public
Copyright
Portions of document may include copyright protected material.
Technical Review
Single Expert
Keywords
Titan

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