The origin of present-day Antarctic precipitation from surface snow deuterium excess data

• Published in: Journal of Geophysical Research
• Main Authors: Ciais, P., White, J., Jouzel, J., Petit, J.
• Other Authors: Laboratoire de Modélisation du Climat et de l'Environnement (LMCE)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 1995
• Subjects: [SDU.OCEAN]Sciences of the Universe [physics]/Ocean; Atmosphere; [SDU.ENVI]Sciences of the Universe [physics]/Continental interfaces; environment; Antarctic; South Pole; The Antarctic; Adelie Land; Antarc*; South pole
• Online Access: https://hal.archives-ouvertes.fr/hal-02923793; https://hal.archives-ouvertes.fr/hal-02923793/document; https://hal.archives-ouvertes.fr/hal-02923793/file/ark%20_67375_WNG-2D4CKK9L-D.pdf; https://doi.org/10.1029/95JD01169

International audience The deuterium excess (d) is defined as a linear combination of the D/H and •80/•60 ratios in natural waters. We present an interpretation of deuterium excess data in surface Antarctic snow, using an isotopic model to derive information on the origin of present-day Antarctic precipitation. The data come from near the coast (D47, Adelie Land) and from inland (south pole, 1000 km from the sea). The one-dimensional isotopic model belongs to the Rayleigh family but fully accounts for mixed cloud processes between 0øC and-30øC. Modeling d in polar snowfalls meets the problem of a large sensitivity to the saturation conditions prevailing at snow formation. Therefore we decided to tune the saturation in the model in order to yield realistic mean d values, but we use the seasonal phase of d versus/5, which is less sensitive to the saturation conditions, as an independent validation of the model predictions. Both inland and near the coast, our model can simulate the observed phase between d and/5 in snow with moisture of subtropical origin (40ø-20øS). Although we do not treat specifically storm precipitation near the coast, this study indicates that the observed phase between d and/5 brings up a new validation of isotopic models. It supports a distant vapor source for large-scale precipitation delivered to the Antarctic continent.