Novel, direct observations of ice on Lake Superior during the high ice coverage of winter 2013–2014

Abstract

During the 2013-2014 winter, the Lake Superior basin experienced record low air temperatures and record high ice cover. We present observations from three subsurface moorings which provided a novel view of the ice cover during this extreme winter. Each mooring carried a set of thermistors, and two sites had ADCPs, providing a rare glimpse into the subsurface characteristics and behavior of a large, partially ice-covered lake, including ice drift velocity, keel size and abundance, surface gravity wave suppression, and the remobilization of ice crystals from below the ice sheet. Ice drift velocities were well-correlated with nearby wind velocities, with ice speeds approximately 4% of the wind speed and 20° to the right of the wind direction. Passing ice keels displaced the top subsurface float at the western mooring to depths of 6 m on a regular basis, and up to 11 m during one event. Anomalously large signal return strength at two ADCPs occurred sporadically at roughly the same time at two geographically separate locations,

Climate projection of Lake Superior under a future warming scenario

“…The eastern side is where ice accumulates in the model during the 1990s (Fig. 4e) as a result of westerly winds blowing ice in that direction, a phenomenon that is consistent with observations (Titze and Austin, 2016). The model projects hardly any ice in the open waters of Lake Superior in the mid-century.…”

High‐Frequency Observations of Temperature and Dissolved Oxygen Reveal Under‐Ice Convection in a Large Lake

“…High‐latitude lakes that freeze for lengthy periods in winter constitute close to 50% of all lakes worldwide (Verpoorter et al, ). If research on lakes was done just based upon the frequency of their occurrence, one might expect that the dynamics of frozen lakes would dominate the literature, but the dynamics of water under the ice is relatively rarely studied due to challenges of field work (Titze & Austin, ). Water temperatures of lakes are amongst the most rapidly changing aquatic systems worldwide (O'Reilly et al, ).…”

Mixing, stratification, and plankton under lake‐ice during winter in a large lake: Implications for spring dissolved oxygen levels

“…These potentially lead to a longer summer stratified period with decreased water quality and oxygen content (Stainsby et al 2011;Li et al 2018). However, there are few studies on winter conditions in lakes compared to the summer open water conditions (Hampton et al 2015), mainly due to the complex logistical efforts required for winter field work (Titze and Austin 2016;Block et al 2019). Although some studies pointed out that in large, deep lakes, winter production of oxygen can be high under the ice (Twiss et al 2012;Hampton et al 2017), the role of under-ice convection on algal blooms and DO production remains elusive (Pernica et al 2017).…”