Modeling the Pluvial Lakes of the Great Basin During the Last Glacial Maximum

Download or read book Modeling the Pluvial Lakes of the Great Basin During the Last Glacial Maximum written by Susanne M. Clement and published by . This book was released on 2005 with total page 268 pages. Available in PDF, EPUB and Kindle. Book excerpt: This study calibrated two new versions of the Local Climate Model version 2 (LCM-2A and LCM-2B) and were used to compute gridded solution of mean monthly maximum daily temperature (TMAX) and the monthly total of the natural log of daily precipitation (LnP) for three large lake systems in the Great Basin: Lahontan, Bonneville and the Owens River domains. The boundary conditions used in this study represented modern (a control scenario) and the Last Glacial Maximum (LGM) approximately 21,000 years ago (LGM scenario). Results of a sensitivity analysis suggested that LCM-2A and LCM-2B are sensitive to LGM scenario 500 mbar wind directions computed using Community Climate Model (CCM1) wind fields. As an alternative LCM scenario wind directions were computed using CCM1 control solutions and the computed wind speed was adjusted to reflect 21 ka wind speed. Using this method LGM climate solutions yielded TMAX departures of - 2.1 °C for the Lahontan region, -2.6 °C for the Owens River domain and -0.3 °C for Bonneville domain. Modeled precipitation was 2.2 times higher in Lake Lahontan, 1.7 times higher in the Owens River domain and 2.4 greater in Lake Bonneville. These solutions are consistent with published LGM climate reconstructions for the Great Basin. The Surface Hydrology Model (SHM) was used to compute annual surface runoff for each solution domain. The solutions of the SHM suggest LGM runoff was 4 times higher than control in the Bonneville domain, 5 times higher in the Owens River domain, 9.5 times greater in the Lahontan domain. The Pluvial Lakes Model (PLM) was used to compute lake system geometry for in equilibrium annual runoff. LGM solutions suggest that the lakes formed in the Lahontan and Owens River domains were under estimated when compared to reconstructed lake geometries based on geologic evidence. LGM solutions of the PLM for the Bonneville domain underestimate the size of the lake in the Great Salt Lake subbasin. The results of this dissertation suggest there is reason to believe that the three largest lake systems may not have responded synchronously to a climate forced by a southerly displaced polar jet stream.