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Atmosphere to surface profiles of water-vapor isotopes and meteorological conditions over the northeast Greenland ice sheet
  • +8
  • Kevin Rozmiarek,
  • Laura J. Dietrich,
  • Bruce Vaughn,
  • Michael Town,
  • Bradley R Markle,
  • Valerie Morris,
  • Hans Christian Steen-Larsen,
  • Xavier Fettweis,
  • Chloe Brashear,
  • Hayley Bennett,
  • Tyler R. Jones
Kevin Rozmiarek
University of Colorado, Boulder

Corresponding Author:[email protected]

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Laura J. Dietrich
Geophysical Institute, University of Bergen, and Bjerknes Centre for Climate Research
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Bruce Vaughn
University of Colorado Boulder
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Michael Town
University of Bergen
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Bradley R Markle
University of Colorado
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Valerie Morris
University of Colorado Boulder
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Hans Christian Steen-Larsen
University of Bergen
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Xavier Fettweis
University of Liège
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Chloe Brashear
Institute for Marine and Atmospheric Research, Utrecht University
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Hayley Bennett
University of Colorado, Boulder
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Tyler R. Jones
University of Colorado Boulder
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Abstract

On polar ice sheets, water vapor interacts with surface snow, and through the exchange of water molecules, imprints an isotopic climate signal into the ice sheet. This exchange is not well understood due to sparse observations in the atmosphere. There are currently no published vertical profiles of water isotopes above ice sheets that span the planetary boundary layer and portions of the free troposphere. Here, we present a novel dataset of water-vapor isotopes ( δ18O , δD, dxs) and meteorological variables taken by fixed-wing uncrewed aircraft on the northeast Greenland Ice Sheet (GIS). During June-July (2022), we collected 105 profiles of water-vapor isotopes and meteorological variables up to 1500 m above ground level. Concurrently, surface snow samples were collected at 12-hour intervals, allowing connection to surface-snow processes. We pair observations with modeling output from a regional climate model as well as an atmospheric transport and water-isotope distillation model. Climate model output of mean temperature and specific humidity agrees well with observations, with a mean difference of +0.095 °C and -0.043 g/kg (-2.91 %), respectively. We find evidence that along an air parcel pathway, the distillation model is not removing enough water prior to onsite arrival. Below the mean temperature inversion (~200m), water-isotope observations indicate a kinetic fractionating process, likely the result of mixing sublimated vapor from the ice sheet surface along with an unknown fraction of katabatic wind vapor. Modeled dxs does not agree well with observations, a result that requires substantial future analysis of kinetic fractionation processes along the entire moisture pathway.
19 Oct 2024Submitted to ESS Open Archive
20 Oct 2024Published in ESS Open Archive