The possible role that tropical Pacific SST's played in driving global hydroclimate during the Medieval period is addressed. Fossil coral records from Palmyra are used to derive tropical Pacific SST's for the period from 1320 to 1462 A.D. and shows overall colder conditions as well as extended multidecadal La Niña-like states. The reconstructed SST's are used to force a 16 member ensemble of atmosphere GCM simulations, each with different initial conditions, with the atmosphere coupled to a mixed layer ocean outside of the tropical Pacific. Model results are verified against paleoclimatic proxy data from around the world. The model results are used to argue that the tropical Pacific played an active role in driving North American megadroughts and that these megadroughts are part of a global hydroclimate regime linked to persistent La Niña-like conditions in the tropical Pacific, though it is possible that SST anomalies in other basins also played a role.
AGU Fall Meeting Abstracts
- Pub Date:
- December 2007
- 4220 Coral reef systems (4916);
- 4255 Numerical modeling (0545;
- 4504 Air/sea interactions (0312;
- 4900 PALEOCEANOGRAPHY (0473;