Authors: Wei Zhang, Grace Affram and Hongping Gu – Utah State University
Title: Modeling the Great Salt Lake with VIC and WRF-Lake
Abstract: The Great Salt Lake (GSL) is a shallow terminal lake located in Northern Utah, the United States. Over the years the water extent of the GSL has undergone substantial reduction due to water diversions and a changing climate – in particular rising temperatures. However, the potential impacts of the shrinking GSL water body on the local hydroclimate system is poorly understood. In this study, we utilized the Weather Research and Forecasting model version 4.2 coupled with a lake model to simulate a series of high-resolution numerical experiments; these experiments aimed to assess the effect of varying lake areal extents on a storm. The results revealed a systematic decline in the quantity of precipitation over the GSL and downwind regions with declining areal coverage. In the event of complete disappearance, the regional average precipitation would experience an approximate 50% reduction relative to its 2004 base lake extent; this decrease is principally attributed to a diminished water vapor flux and moist static energy (MSE) above the lake. The research underscores the consequences of a shrinking GSL, not just for precipitation delivery downstream but that of a negative feedback loop within the hydroclimatic system of the GSL basin, i.e., water flow reductions into the basin. Using VIC, we simulated the snowpack under the present and future climate scenarios (1-5 degree warming) and found an earlier snowmelt and decreasing spring runoff into the Great Salt Lake.