Introduction
As reviewed by Adrian et al. (2009), a variety of physical, biological, and chemical properties of lakes
respond to anthropogenic climate change, modulated by both regional atmospheric forcing and
individual lake physics (e.g., large or small, deep or shallow). A resurgence of interest in understanding
these responses has occurred in recent years (e.g., Fang and Stephan 1999; Austin and Colman 2007;
Sahoo and Schladow 2008; Schneider et al. 2009; Schneider and Hook 2010; Sahoo et al. 2012). As
discussed by MacKay et al. 2009, improved high-resolution coupling between lake and atmospheric
climate models is necessary to further our understanding of future lake systems response to climate
change. In this study, we explore coupling a very simple slab lake model [SLM] to the shallow, terminal
Great Salt Lake.
Study Limitations
There are two major limitations to this study :
1) The assumption of constant lake depth and area
A major limitation of this study is that the formulation of the lake as a slab of constant depth (tuned to
the deep water buoy location in center of lake). We did not incorporate a bathymetric analysis into this
work. In reality, about half of the lake surface is much shallower, and consequently the findings of this
study would not be applicable at those locations (For example, the low-frequency oscillations seen in
the simple slab model (k < 11) with effective depths > 5 m is physically applicable to those portions of
the lake where the lake depth is greater than 5 m).
In the sensitivity simulations to lake depth and climate change, the areal extent of the lake is not
changed. The variation in total lake surface area between historically low and high lake levels is
significant, but the feedbacks between lake size and atmospheric response are not included in this
simple model.
2) The simple slab model does not incorporate complex spatiotemporal variations in salinity and water
clarity.
The mixing dynamics in the GSL are complicated by the presence of vertical gradients in salinity (dense
brine layers near the bottom below around 7 m in depth, freshwater lenses near the surface) and
extreme seasonal variations in the effective penetration of sunlight into the water column (Crosman and
Horel 2009). The impact of these variations on the effective depth, mixing, and the vertical transfer of
heat into and out of the GSL are not known and cannot be modeled in a simple slab model, but may
explain why the findings in Fig. 7 and 8 oppose the general consensus in the GSL lake community that
the lake mixes to greater depths in the Fall than in the Spring.
In addition, while the deepest bottom water brine layers within the lake mix-out once per year (Beisner
et al. 2009), the shallower regions likely completely mix much more frequently, i.e, every few weeks or
months. In the spring months during snowmelt runoff, freshwater lenses forming on top of the water
column act to inhibit mixing (as fresh water is less dense that saline water).
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