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

• Published in: Atmospheric Chemistry and Physics
• Main Authors: Jiang, Zhuang, Alexander, Becky, Savarino, Joel, Geng, Lei
• Format: Text
• Language: English
• Published: 2024
• Subjects: Greenland; Antarc*; Antarctica; ice core
• Online Access: https://doi.org/10.5194/acp-24-4895-2024; https://acp.copernicus.org/articles/24/4895/2024/

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 (i.e., the deposition flux of nitrate to surface snow that originates from long-range transport or stratospheric input) and its isotopes ( δ 15 N and Δ 17 O). 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 δ 15 N(NO 3 - <svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="9pt" height="16pt" class="svg-formula" dspmath="mathimg" md5hash="0723f17b5be9fc41c36a5585631feb47"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="acp-24-4895-2024-ie00001.svg" width="9pt" height="16pt" src="acp-24-4895-2024-ie00001.png"/> </svg:svg> ) and Δ 17 O(NO 3 - <svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="9pt" height="16pt" class="svg-formula" dspmath="mathimg" md5hash="a6a4c5911a740e8377438efb607d4b86"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="acp-24-4895-2024-ie00002.svg" width="9pt" height="16pt" src="acp-24-4895-2024-ie00002.png"/> </svg:svg> ) 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 δ 15 N(NO 3 - <svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="9pt" height="16pt" class="svg-formula" dspmath="mathimg" md5hash="7de8959157e6c258409d4c11688ca166"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="acp-24-4895-2024-ie00003.svg" width="9pt" height="16pt" src="acp-24-4895-2024-ie00003.png"/> </svg:svg> ) and Δ 17 O(NO 3 - <svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="9pt" ...