Using raindrops to constrain past atmospheric density

dc.contributor.authorKavanagh, Lucas
dc.contributor.authorGoldblatt, Colin
dc.date.accessioned2016-08-25T17:36:18Z
dc.date.available2017-01-15T12:22:05Z
dc.date.copyright2015en_US
dc.date.issued2015-03
dc.description.abstractThere exists a dearth of constraints on the physical properties of the early Earth atmosphere. The Som palaeopycnometry method estimates an upper limit on ancient atmospheric density based on the size of lithified raindrop imprints preserved in ancient strata, with the assumption that the largest imprint was made by the largest possible raindrop. Using this technique Som et al. (2012) proposed a constraint on Archean atmospheric density of less than View the MathML source 2.3 kgm−3. Applying this method to modern raindrop imprints, the upper bound on surface density produced is View the MathML source 0.9 kgm−3, lower than the actual value of View the MathML source 1.2 kgm−3, refuting the method. We propose several changes to the method, the most important of which is increasing the maximum possible drop size from 6.8 to 10 mm6.8 to 10 mm to be consistent with new large datasets of raindrop observations. With these changes, our upper bound on modern surface density becomes View the MathML source 2.7 kgm−3, a valid limit. The upper bound on Archean atmospheric density is then revised to View the MathML source 11.1 kgm−3. In general, we find that raindrop imprint size distribution depends much more strongly on rainfall rate than atmospheric density, which translates into large errors. At best, the precision of raindrop palaeopycnometry will be a factor of a few to an order of magnitude.en_US
dc.description.reviewstatusRevieweden_US
dc.description.scholarlevelFacultyen_US
dc.description.sponsorshipThe authors would like to thank Sanjoy Som, David Catling, and Roger 375 Buick for their discussion regarding their work as well as Kevin Zahnle for his general consultation and advice. The parsivel disdrometer data was obtained from the NASA Global Hydrology Resource Center (GHRC) DAAC, Huntsville, AL. http://ghrc.nsstc.nasa.gov/. Financial support was provided by a University of Victoria Jamie Cassels Undergraduate Research Award to L.K. and by a 380 NSERC Discovery Grant and University of Victoria Professional Development funds to C.G.en_US
dc.identifier.citationKavanagh, L. & Goldblatt, C. (2015). Using raindrops to constrain past atmospheric density. Earth and Planetary Science Letters, 413, 51-58.en_US
dc.identifier.urihttp://dx.doi.org/10.1016/j.epsl.2014.12.032
dc.identifier.urihttp://hdl.handle.net/1828/7480
dc.language.isoenen_US
dc.publisherEarth and Planetary Science Lettersen_US
dc.rightsAttribution-NonCommercial-NoDerivs 2.5 Canada*
dc.rights.urihttp://creativecommons.org/licenses/by-nc-nd/2.5/ca/*
dc.subjectpalaeobarometryen_US
dc.subjectraindropsen_US
dc.subjectArcheanen_US
dc.subjectpressureen_US
dc.subjectdensityen_US
dc.subjectfaint young Sunen_US
dc.titleUsing raindrops to constrain past atmospheric densityen_US
dc.typePostprinten_US

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