A slab model of the Great Salt Lake for regional climate simulation

Abstract

A slab lake model was developed for the Great Salt Lake (GSL) and coupled to a regional climate model to enable better evaluation of regional effects of projected climate change. The GSL is hypersaline with an area of approximately 4400 km2, and its notable shallowness (the deeper sections average 6.5-9 m at current lake levels) renders it highly sensitive to climate change. A time-independent (constant) effective mixing depth of approximately 5 m was determined for the GSL by numerically optimizing model-observation agreement, and improvement gained using a time-dependent effective mixing depth assumption was smaller than the uncertainty in the satellite-based observations. The slab model with constant effective mixing depth accounted for more than 97% of the variance in satellite-based observations of GSL surface temperature for years 2001 through 2003. Using a lake surface temperature climatology in place of the lake model resulted in annual mean near-surface air temperature differences that were small (∼10-2 K) away from the lake, but differences in annual precipitation downstream reached 3 cm (4.5%) mainly because of enhanced turbulent heat fluxes off the lake during spring. When subjected to a range of pseudo global warming scenarios, the annual mean lake surface temperature increased by 0.8 C per degree of air temperature increase. Key Points Great Salt Lake represented as slab model coupled to regional climate model Framework accounts for 97% of variance in observed lake surface temperature Shallowness renders lake highly sensitive to projected air temperature changes