MODELING LAST INTERGLACIAL AND LAST GLACIAL MAXIMUM HYDROCLIMATE IN THE NEOTROPICS WITH A FOCUS ON THE BASIN OF MEXICO

We used two models from the Paleoclimate Modeling Intercomparison Project Phase 4 (PMIP4) and Coupled Model Intercomparison Project Phase 6 (CMIP6) to analyze hydroclimate anomalies (relative to 1850 CE) and underlying ocean-atmosphere circulation patterns in the Neotropics during the Last Interglacial (LIG; ~127,000 years ago) and Last Glacial Maximum (LGM; ~21,000 years ago). The models used are MIROC-ES2L and AWI-ESM-1-1-LR, and the analyzed variables include precipitation, evaporation, air temperature, sea surface temperature, wind speed and wind direction for the LIG (lig127k), LGM (lgm) and pre-industrial control (piControl) experiments. The climate anomalies were computed for annual and seasonal monthly (NDJF and MJJA) means by calculating the difference between the paleo-experiment and the pre-industrial control values. In addition, the differences between the LIG and LGM climate variable anomalies (LIG minus LGM) were computed to assess the influence of different boundary conditions on hydroclimate and ocean-atmosphere circulation during the two time periods.

The model results were compared to sediment records from Lake Chalco developed as part of the MexiDrill: Basin of Mexico Drilling Program. Lithology and X-ray fluorescence (XRF) analysis of the recovered sediments appear to indicate a warm and dry LIG, and a wet and cold LGM which is somewhat inconsistent with model results for the Basin of Mexico region and Central America in general. Future work will include comparing results from the model analysis to records from Lake Junín, Lake Titicaca, Lake Petén and the Valles Caldera in order to further assess the veracity of the model reconstructions of climate in the Neotropics during the LIG and LGM.