Post-depositional modication on seasonal and 1 interannual timescales resets the deuterium excess 2 signals in summer snow layers in Greenland

Abstract

Deuterium-excess (d) decreases up to 5 o /oo in near-surface snow during some summers at EastGRIP, likely due to net sublimation.• After one-to-two years in the snowpack, the peak d shifts from Autumn snow layers towards Summer snow layers.• Isotope-gradient diusion explains some but not all of the d seasonality changes in the near-surface snow.

Snow‐Atmosphere Humidity Exchange at the Ice Sheet Surface Alters Annual Mean Climate Signals in Ice Core Records

“…We evaluate the model performance using three average snowpack isotope profiles obtained in 2017, 2018, and 2019 (Town et al., 2023) in Figure 2. In the control simulation with no fractionation of the surface snow, δ 18 O has a positive bias of 3.0 [2.3–3.7] ‰(square brackets show the bias range for the three individual snow profiles in 2017, 2018, and 2019, Figure 2a).…”

“…The performance of the SNOWISO model is evaluated against averaged isotopic profiles of the upper 1 m of the snowpack across several years at the EGRIP site (original dataset: Behrens et al., 2023, processed data used in this study: Town et al., 2023). In 2017, 24 snowpack cores were obtained at four independent sites on eight sample days.…”

“…In 2019, 25 cores were obtained at five sites on five sample days. For each year, all individual 1‐m snowpack isotopic profiles were aligned using the on‐site temperature record and averaged (Town et al., 2023), providing three average isotopic records for 2017, 2018, and 2019.…”

“…Snow core data are available on PANGEA (Town et al., 2023). The firn core data are available in Vallelonga (2014).…”