Post-depositional Processes Alter the Seasonal and Multi-decadal Water Isotopic Records in Antarctic Snow and Firn

Post-depositional processes alter the water stable isotopic signal recorded in the snow and firn. However, the processes involved in the formation of the seasonal cycle in the snow surface remain poorly constrained. It is also uncertain to what extent post-depositional processes influence the mean and variability of the multi-decadal isotopic signal at low accumulation sites. Here we simulate the isotopic signal in the snow surface and in a 30-year (1994–2024) snow core at Dome C in East Antarctica. We argue that mixing new precipitation with the snow in a surface layer needs to be considered through an effective mixing depth. Using an effective mixing depth of 4 cm allows to simulate the observed mean post-depositional alteration of the snow surface. Considering vapor exchange improves the representation of both the observed amplitude of the seasonal cycle and the observed monthly mean variability in the snow surface isotopic signal (δ18O and d-excess) over five years. In addition, we show that vapor exchange leads to a decrease in the δ18O inter-annual variability (−11 %) and an increase in the d-excess inter-annual variability (+33 %) in a 30-year snow core. Our results highlight that (i) isotopic fractionation during surface vapor exchange in combination with mixing at the surface are key drivers of the isotopic signal in the snow surface, (ii) surface vapor exchange alters the mean and variability in multi-decadal isotopic records at Dome C, and (iii) precipitation intermittency modulates the magnitude of the impact of vapor exchange on the snow core isotopic profiles. Supplementary Material File (1046710_0_merged_1758016478.pdf) - Download - 5.35 MB File (post_depositional_processes_alters_the_seasonal_and_multi_decadal_water_isotopic_records_in_antarctic_snow_and_firn.pdf) - Download - 5.35 MB File (supporting_information___post_depositional_processes_alters_the_seasonal_and_multi_decadal_water_isotopic_records_in_antarctic_snow_and_firn.pdf) - Download - 3.69 MB Information & Authors Information Version history Copyright This work is licensed under a Non Exclusive No Reuse License.

Authors Metrics & Citations Metrics Article Usage 142views 139downloads Citations Download citation Inès Ollivier, Hans Christian Steen-Larsen, Laura J. Dietrich, et al. Post-depositional Processes Alter the Seasonal and Multi-decadal Water Isotopic Records in Antarctic Snow and Firn. Authorea. 08 October 2025. DOI: https://doi.org/10.22541/au.175994561.12898624/v1 DOI: https://doi.org/10.22541/au.175994561.12898624/v1 If you have the appropriate software installed, you can download article citation data to the citation manager of your choice. Simply select your manager software from the list below and click Download. For more information or tips please see 'Downloading to a citation manager' in the Help menu.