MODELING CLIMATE CONSTRAINTS ON THE FORMATION OF PLUVIAL LAKE BONNEVILLE IN THE GREAT BASIN, USA

Understanding how precipitation patterns will change in terrestrial areas in the future is a major unanswered question in climate change modeling. Specifically, reliable data on terrestrial paleo-precipitation allows climate modelers to validate their models before applying them to future climate scenarios. This study uses a water-balance model to constrain the relative changes in late Pleistocene precipitation required to sustain pluvial Lake Bonneville during the late Last Glacial Maximum (LGM). Lake Bonneville was the largest of the Great Basin pluvial lakes, with a maximum surface area exceeding 50,000 km², more than 10 times the size of modern Great Salt Lake and roughly the same size as modern Lake Michigan. To constrain past precipitation, we first assessed which combination of evaporative models and potential evaporation parameterizations best fit observed data for weather stations in the Great Basin.

The potential evaporation parameterizationdeveloped by Condom et al. (2004) best fits evaporation data in the Lake Bonneville basin from March-November. This selected evaporation model will be used in conjunction with the Condom et al. (2004) water-balance model to reconstruct paleoclimate conditions in the Bonneville basin at various relative highstands of Lake Bonneville during the late LGM.