Regional patterns of extreme precipitation on Titan consistent with observed alluvial fan distribution

Abstract

Geomorphic features typically associated with extreme rainfall events in terrestrial settings, including extensive fluvial features and alluvial fans, have been detected on Titan’s surface. Methane flow from precipitation on Titan can transport sediments and potentially erode the icy bedrock, but averaged precipitation rates from prior global-scale modelling are too low by at least an order of magnitude to initiate sediment transport of observed grain sizes at low latitudes. Here, we quantify the regional magnitude, frequency and variability of extreme rainfall events from simulations of present-day Titan, with a general circulation model coupled to a land model partially covered by wetlands reservoirs that can capture Titan’s regionally varying hydroclimate. We find that the most extreme storms tend to occur in the mid-latitudes, where observed alluvial fans are most concentrated. Storms capable of sediment transport and erosion occur at all latitudes in our simulations, consistent with the observed global coverage of fluvial features. Our results demonstrate the influential role of extreme precipitation in shaping Titan’s surface. We therefore suggest that, similarly to Earth but differently from Mars, active geomorphic work may be ongoing in the present climate on Titan.

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Figure 1: Seasonal methane precipitation.
Figure 2: Titan’s precipitation statistics.
Figure 3: Rainfall compared to alluvial fans.

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Acknowledgements

This work was supported by NASA Cassini Data Analysis and Participating Scientists (CDAPS) Program grant NNX16AI44G. We are grateful to E. Turtle and the Cassini ISS team for sharing unpublished cloud observation data to include in our figures.

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S.P.F. conducted the simulations, performed the data analysis, prepared figures, and wrote the bulk of the manuscript. All co-authors contributed guidance to the analysis and assisted with writing the manuscript. The model used was developed in previous work by J.M.L.

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Correspondence to S. P. Faulk.

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The authors declare no competing financial interests.

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Faulk, S., Mitchell, J., Moon, S. et al. Regional patterns of extreme precipitation on Titan consistent with observed alluvial fan distribution. Nature Geosci 10, 827–831 (2017). https://doi.org/10.1038/ngeo3043

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