Turbulent convection in Antarctic Subglacial Lakes

Abstract: Trapped beneath the Antarctic ice sheet lie over 400 subglacial lakes, which are considered to be extreme, isolated, yet viable habitats for microbial life. The physical conditions within subglacial lakes are critical to evaluating how and where life may best exist. In this talk, I will demonstrate that Earth’s geothermal flux provides efficient stirring of Antarctic subglacial lake water. I will show that most lakes are in a regime of vigorous turbulent vertical convection, enabling suspension of spherical particulates with diameters up to 36 micrometers. Thus, dynamic flows support efficient mixing of nutrient- and oxygen-enriched meltwater derived from the overlying ice, which is essential for biome support within the water column. I will show that a stable layer isolates the well-mixed bulk from the ice-water interface in lakes beneath a thin (<3.166 kilometers) ice cover, because of the nonlinear equation of state of water. I will discuss how relaxing the approximations that the current theory relies on (flat ice-water ceiling) might change the predictions, as well as the implications of this work for future lake exploration.

atmospheric sciencescryosphere sciencesocean sciences

Audience: researchers in the discipline

BAS Polar Oceans Seminar