Collaborative Research: Past and Present Climatic Controls on the Stable Isotope Composition of Precipitation at Low Latitude Proxy Sites

University Of Massachusetts Amherst, Amherst MA

Investigators

Abstract

This award helps build upon the researchers' previously NSF-funded research on the climatic controls on stable water isotopes (i.e., delta 18-Oxygen, delta Deuterium) in precipitation at low latitude proxy sites. The researchers' main scientific goal is to evaluate the controls on stable isotope variability at various low latitude ice core locations (i.e., Tropical Andes, Tibet, Himalaya) in the modern world and in the past. This will help to resolve some of the controversy surrounding the interpretation of paleoclimate records derived from tropical ice cores. Specific research goals include: -- investigating the modern climatic controls such as temperature, precipitation volume effect, moisture source variability and atmospheric circulation on stable isotopes at tropical ice core sites and analyzing the influence of climate modes such as El Nino-Southern Oscillation (ENSO) or Asian monsoon intensity on stable isotope variability, -- analyzing the influence of changed orbital parameters (mid-Holocene conditions) upon stable isotope distribution and potential climatic controls related to tropical ice cores, -- investigating the effect of Last Glacial Maximum (LGM) boundary conditions upon low latitude stable isotope distribution by prescribing new and more realistic reconstructions of glacial tropical sea surface temperature (SST) data, -- exploring the use of the Deuterium excess in tropical ice cores as an additional climate proxy for improved reconstructions of tropical oceanic conditions, and -- performing model evaluation by comparing the simulated results with the available proxy data and with International Atomic Energy - Global Network of Isotopes in Precipitation (IAEA-GNIP) and National Center for Environmental Prediction - National Center for Atmospheric Research (NCEP-NCAR) reanalysis data for the modern experiments. All experiments will be based on the GISS II (4 degrees latitude x 5 degrees longitude, with new improved topographic control over the Andes) model and the European Center-Hamburg ECHAM-4 (T30 and T106 spectral resolution) models. This research will provide improved understanding of paleoclimatic records that are used to help understand natural climate variability compared to anthropogenic influences on climate. The data and model output resulting from this research will be made available to the wider scientific community through the World Data Center-A for Paleoclimatology.