Publication Abstracts

Hu et al. 2018

Hu, J., J. Emile-Geay, J. Nusbaumer, and D. Noone, 2018: Impact of convective activity on precipitation δ18O in isotope-enabled general circulation models. J. Geophys. Res. Atmos., 123, no. 23, 13595-13610, doi:10.1029/2018JD029187.

The δ18O signal preserved in paleo-archives is widely used to reconstruct past climate conditions. In many speleothems, this signal is classically interpreted via the "amount effect". However, recent work has shown that precipitation δ18O (δ18OP) is greatly influenced by convective processes distinct from precipitation amount, and new observations indicate that δ18OP is negatively correlated with the fraction of stratiform precipitation. Isotope-enabled climate models have emerged as a key interpretive tool in water isotope systematics, and it is thus important to determine to what extent they can reproduce these relationships. Here, seven isotope-enabled models, including the state-of-the-art model iCAM5, are evaluated to see whether they can simulate the impact of convective activity on δ18OP in observations. The results show that, of these models, only iCAM5 can simulate the observed anticorrelation between stratiform fraction and δ18OP. Furthermore, while all models can simulate the observed relationship between outgoing longwave radiation and δ18OP, different models achieve this via different mechanisms — some getting the right answer for the wrong reasons. Because iCAM5 appears in various metrics to correctly simulate δ18OP variability, we use it to examine longstanding interpretations of δ18OP over Asia. We find that the contribution of convective processes is very site-dependent, with local processes accounting for a very small amount of variance at the sites of most Chinese cave records (speleothems). The residual is attributed to source and transport effects. Our results imply that state-of-the-art models like iCAM5 can and should be used to guide the interpretation of δ18OP-based proxies.

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BibTeX Citation

  author={Hu, J. and Emile-Geay, J. and Nusbaumer, J. and Noone, D.},
  title={Impact of convective activity on precipitation δ18O in isotope-enabled general circulation models},
  journal={Journal of Geophysical Research: Atmospheres},

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RIS Citation

ID  - hu02200w
AU  - Hu, J.
AU  - Emile-Geay, J.
AU  - Nusbaumer, J.
AU  - Noone, D.
PY  - 2018
TI  - Impact of convective activity on precipitation δ18O in isotope-enabled general circulation models
JA  - J. Geophys. Res. Atmos.
JO  - Journal of Geophysical Research: Atmospheres
VL  - 123
IS  - 23
SP  - 13595
EP  - 13610
DO  - 10.1029/2018JD029187
ER  -

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