I study the atmospheric drivers of melting on the Larsen C ice shelf on the Antarctic Peninsula. I use a numerical weather prediction model, automatic weather station data, aircraft observations and other available monitoring data to understand processes in this poorly understood region.

Increasing our knowledge of the atmosphere in Antarctica is critically important because polar change has global implications for sea level rise. Antarctica contains enough ice to raise sea levels by 58 m worldwide. While much of the Antarctic ice sheet is currently stable, certain parts, such as West Antarctica and the Antarctic Peninsula, are changing rapidly. Larsen C is located in one of the most rapidly warming regions on Earth. The ice shelf is the largest remaining on the peninsula, and it holds back enough glacial ice to raise global sea levels by several tens of cm alone. However, the area is changing fast: since 1947, more than half of the ice shelves around the peninsula have receded, thinned or disappeared entirely, including Larsen C’s two nearest neighbours, Larsen A and B. Now, Larsen C is beginning to show signs of instability that were observed over Larsen A and B before their collapse, making studying the mechanisms of this atmospherically-driven melt an urgent task.

My previous work has looked at dynamical factors contributing to melt. Our recently published paper (Kuipers Munneke et al., 2018) demonstrates for the first time that Larsen C is melting in the depths of Antarctic winter, in the absence of sunlight. This wintertime melt is driven by ‘foehn’ winds generated by air flowing over the steep peninsula mountains, and bringing warm, dry air to the surface. That air is so hot and dry that it can melt the ice even when typical temperatures are as low as -25°C. Ensuring that models can capture this phenomenon requires that the vertical structure of the atmosphere is modelled accurately, something I am presently working on.

The main focus of my current work is the effect of cloud microphysics on the surface energy balance of the ice shelf. The surface energy balance tells us about the amount of energy that enters the ice surface, and therefore how much energy is available to cause melting. Clouds can impact this considerably because they influence how much solar radiation reaches the surface, and how much outgoing terrestrial radiation can escape. The exact way that clouds alter these energy flows is complex, and depends on cloud properties, or microphysics – things like the water/ice contents, size, shape and number of cloud particles. Unfortunately, our understanding of Antarctic clouds is limited and we have few direct microphysical observations. However, clouds are the largest source of uncertainty in global climate projections. That is why I am trying to compare what data we do have with model output to see if we can improve the way we model clouds and their effects on polar climate. If we can be confident that models accurately simulate clouds, we can increase our confidence in projections of future climate change.

The next stage of my research will be to develop a climatology of Larsen C. Without having a baseline, or knowing which conditions are ‘normal’, it is difficult to quantify change. My aim is to develop the first high resolution model climatology of the region, once we understand better the limitations of the model in Antarctica, and have improved its representation of critical atmospheric properties like boundary layer structure and cloud microphysics.