A model framework on atmosphere-snow water vapor exchange and the associated isotope effects at Dome Argus, Antarctica: part I the diurnal changes
Ice-core water isotopes contain valuable information on past climate changes. However, such information can be altered by post-depositional processing after snow deposition. Atmosphere-snow water vapor exchange is one of such processes, but its influence remains poorly constrained. Here we construct...
| Main Authors: | , , , , , |
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| Format: | Text |
| Language: | English |
| Published: |
2023
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| Subjects: | |
| Online Access: | https://doi.org/10.5194/tc-2023-76 https://tc.copernicus.org/preprints/tc-2023-76/ |
| Summary: | Ice-core water isotopes contain valuable information on past climate changes. However, such information can be altered by post-depositional processing after snow deposition. Atmosphere-snow water vapor exchange is one of such processes, but its influence remains poorly constrained. Here we constructed a box model to quantify the atmosphere-snow water vapor exchange fluxes and the associated isotope effects at sites with low snow accumulation rate where the effects of atmosphere-snow water vapor exchange are suspected to be large. The model reproduced the observed diurnal variations of δ 18 O, δD, and d-excess in water vapor at Dome C, East Antarctica. According to the same model framework, we found that under summer clear-sky conditions atmosphere-snow water vapor exchange at Dome A can cause diurnal variations in atmospheric water vapor δ 18 O and δD by 8.2±0.3 ‰ and 54.4±1.2 ‰, with corresponding diurnal variations in surface snow δ 18 O and δD by 0.11±0.01 ‰ and 0.62±0.01 ‰, respectively. The modeled results under summer cloudy conditions display similar patterns to those under clear-sky conditions but with smaller magnitudes of diurnal variations. After 24-hour simulation, snow water isotopes were enriched under both cloudy and clear-sky conditions. Under winter conditions at Dome A, the model indicates there are no diurnal cycles in atmospheric and surface snow water isotopes can be caused by atmosphere-snow vapor exchange, but the model predicts more or less depletions in snow δ 18 O and δD in the period of 24-hour simulation, opposite to the results under summer conditions. If the modeled snow isotope enrichments in summer and depletions in winter represent general situations at Dome C, this likely suggests the air-snow vapor exchange tends to enlarge snow water isotope seasonality, but the annual net effect would be small due to the offsetting of effects in summer and winter. This remains to be explored in the future. |
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