Stable water isotopes in HadCM3: The isotopic signature of ENSO and the tropical amount effect
Stable water isotopes have been added to the full hydrological cycle of the HadCM3 coupled atmosphere-ocean GCM. Simulations of D18O in precipitation and at the ocean surface compare well with observations for the present day climate. The model has been used to investigate the isotopic anomalies associated with ENSO; it is found that the anomalous D18O in precipitation is correlated with the anomalous precipitation amount in accordance with the “amount effect”. The El Nino D18O anomaly at the ocean surface is largest in coastal regions due to the mixing of ocean water and the more depleted runoff from the land surface. Coral D18O anomalies were estimated, using an established empirical relationship, and generally reflect ocean surface D18O anomalies in coastal regions and sea surface temperatures away from the coast. The spatial relationship between tropical precipitation and D18O was investigated for the El Nino anomaly simulated by HadCM3. Weighting the El Nino precipitation anomaly by the precipitation amount at each gridbox gave a large increase in the spatial correlation between tropical precipitation and D18O. This improvement was most apparent over land points and between 10 and 20 degrees of latitude.
Journal of Geophysical Research, 114, (D04111)
http://www.agu.org/pubs/crossref/2009/2008JD010825.shtml
tindall2008.pdf