Newswise \u2014 Georgia Tech researchers have developed a mathematical formula to predict the size of lakes that form on melting ice sheets \u2014 discovering their depth and span are linked to the topography of the ice sheet itself.\u00a0<\/p>\n
The team leveraged physics, model simulations, and satellite imagery to develop simple mathematical equations that can easily be integrated into existing climate models. It\u2019s a first-of-it\u2019s-kind tool that is already improving climate models.<\/p>\n
\u201cMelt lakes play an important role in ice sheet stability, but previously, there were no constraints on what we would expect their maximum size to be in Antarctica,\u201d says study lead\u00a0Danielle Grau<\/a>, a Ph.D. student in the\u00a0School of Earth and Atmospheric Sciences<\/a>. \u201cI was intrigued by the idea of quantifying how much of a role we could expect them to play in the future.\u201d<\/p>\n The paper, \u201cPredicting mean depth and area fraction of Antarctic supraglacial melt lakes with physics-based parameterizations<\/a>,\u201d was published in\u00a0Nature Communications. In addition to Grau, the research team includes School of Earth and Atmospheric Sciences Professor\u00a0Alexander Robel<\/a>, who is Grau\u2019s advisor, and\u00a0Azeez Hussain (PHYS 2025).<\/p>\n Their predictions show that the majority of these lakes will be less than a meter deep and span up to 40% of the ice sheet surface area.<\/p>\n \u201cMany models don\u2019t include any data about lakes on the surface of ice sheets, while others simulate these melt lakes growing until the ice collapses,\u201d Robel says. \u201cOur results show that the reality is somewhere in between \u2014 and that the maximum size of these lakes can be predicted using these new equations. This gives us real, concrete numbers to use in climate models.\u201d<\/p>\n From summer project to satellite discovery\u00a0<\/p>\n Grau\u00a0first\u00a0started working on the project as an undergraduate student when she applied for a\u00a0Summer Research Experiences for Undergraduates program<\/a> hosted by the School of Earth and Atmospheric Sciences.<\/p>\n Inspired by\u00a0terrestrial lake research<\/a>, Grau and Robel investigated the \u201cself-affinity\u201d of the Antarctic ice sheet \u2014 a property associated with surface roughness across various scales. For example, a landscape like Badlands National Park, with many rolling hills of a wide range of sizes, would have a different self-affinity than a flat prairie with three large volcanoes.<\/p>\n \u201cA previous study had used this property to predict the size of terrestrial lakes and ponds, and we were curious if we could use a similar approach for supraglacial lakes in Antarctica,\u201d Grau says. \u201cEstablishing that the Antarctic ice sheet also has this property was the first step in pursuing this research in more depth.\u201d\u00a0<\/p>\n The mathematics of melt<\/p>\n Grau continued the investigation as a Ph.D. student in Robel\u2019s lab. Together, they unraveled the physics of how meltwater moves across the ice surface, designing a \u2018glacier in a computer\u2019 that mimics meltwater accumulation and movement across various topographies.<\/p>\n \u201cWe designed an algorithm and integrated it into a model that the\u00a0GT Ice & Climate Group<\/a> has used in the past,\u201d Grau says. \u201cFrom that, we were able to see how lakes would form on different surfaces across thousands of scenarios. This was the foundation for the mathematical equations I developed, which can predict the lake depth and lake surface area based on the self-affinity property.\u201d<\/p>\n To check their results, Grau enlisted the help of Hussain \u2014 then an undergraduate in the\u00a0School of Physics<\/a> \u2014 to examine satellite data from the\u00a0Landsat satellite program<\/a> (which captures detailed photography of the Earth\u2019s surface from space) to measure existing supraglacial lakes and surface topography.\u00a0<\/p>\n \u201cIt was exciting to see how our predictions lined up with what we were seeing in the satellite imagery,\u201d Robel explains. \u201cThis shows that our solution is a concrete avenue for climate models to realistically incorporate supraglacial lakes.\u201d<\/p>\n Grau is already working to incorporate the team\u2019s equations into an atmospheric model used by NASA in addition to an ice sheet model developed by the NASA Jet Propulsion Laboratory and Dartmouth College.\u00a0<\/p>\n \u201cBy turning complicated models and satellite data into simple predictive equations, we\u2019re giving climate models a new lens to see the future,\u201d she says. \u201cIt\u2019s a small piece of the puzzle,\u00a0 but one that helps us understand how ice sheets respond to a warming world.\u201d<\/p>\n Funding: NASA Modeling, Analysis, and Prediction Program<\/p>\n