Preprints
https://doi.org/10.5194/egusphere-2023-1054
https://doi.org/10.5194/egusphere-2023-1054
14 Jun 2023
 | 14 Jun 2023

An inverse model to correct for the effects of post-depositional processing on ice-core nitrate and its isotopes: model framework and applications at Summit, Greenland and Dome C, Antarctica

Zhuang Jiang, Becky Alexander, Joel Savarino, and Lei Geng

Abstract. Comprehensive evaluation of the effects of post-depositional processing is a prerequisite for appropriately interpreting ice-core records of nitrate concentration and isotopes. In this study, we developed an inverse model that uses archived snow/ice-core nitrate signals to reconstruct primary nitrate flux and its isotopes (δ15N and Δ17O). The model was then applied to two polar sites, Summit, Greenland and Dome C, Antarctica using measured snowpack nitrate concentration and isotope profiles in the top few meters. At Summit, the model successfully reproduced the observed atmospheric 15δN(NO3) and Δ17O(NO3) and their seasonality. The model was also able to reasonably reproduce the observed snowpack nitrate profiles at Dome C as well as the skin layer and atmospheric δ15N(NO3) and Δ17O(NO3) at the annual scale. The calculated Fpri at Summit was 6.9 × 10-6 kgN m2 a-1 and the calculated Δ17O(NO3) of Fpri is consistent with atmospheric observations in the northern hemisphere. However, the calculated 15δN(NO3) of Fpri displays an opposite seasonal pattern to atmospheric observations in the northern mid-latitudes, but is consistent with observations in two Arctic coastal sites. The calculated Fpri at Dome C varies from 1.5 to 2.2 × 10-6 kgN m-2 a-1, with δ15N(NO3) of Fpri varying from 6.2 to 29.3 ‰ and Δ17O(NO3) of Fpri varying from 48.8 to 52.6 ‰. The calculated Fpri at Dome C is close to previous estimated stratospheric denitrification flux in Antarctica, and the high δ15N(NO3) and Δ17O(NO3) of Fpri at Dome C also point towards the dominate role of stratospheric origin of primary nitrate to Dome C.

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Journal article(s) based on this preprint

25 Apr 2024
An inverse model to correct for the effects of post-depositional processing on ice-core nitrate and its isotopes: model framework and applications at Summit, Greenland, and Dome C, Antarctica
Zhuang Jiang, Becky Alexander, Joel Savarino, and Lei Geng
Atmos. Chem. Phys., 24, 4895–4914, https://doi.org/10.5194/acp-24-4895-2024,https://doi.org/10.5194/acp-24-4895-2024, 2024
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The requested preprint has a corresponding peer-reviewed final revised paper. You are encouraged to refer to the final revised version.

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Ice-core nitrate could track the past atmospheric NOx and oxidant level, but its interpretation...
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