Generalized view of source-region effects on δD and deuterium excess of ice-sheet precipitation

Abstract

AbstractIt is generally recognized at present that ice-core deuterium excess measurements are potentially useful for reconstructions of vapor source-region temperature and humidity history, and that such measurements provide a method for correcting isotopic paleothermometers for effects of source temperature variations. Here we use a zonally averaged vapor-transport and isotopic-distillation model to show that deuterium excess of precipitation on the ice sheets is sensitive to a wide variety of source-region climate changes in addition to those changes of temperature and humidity that affect the composition of evaporate. Moreover, it is demonstrated that this wide variety of source-region changes all cause anticorrelated changes in deuterium excess with δD and δ18O over the ice sheets, suggesting that deuteriu 14m excess is a generally more useful tool for correcting isotopic thermometers than is currently recognized.