др Предраг Поповић

29. априла 2022.

У оквиру семинара Центра за изучавање комплексних система Института за физику у Београду, у четвртак, 05. маја 2022. године у 14 часова путем Zoom платформе, др Предраг Поповић (Институт за физику Земље у Паризу), одржаће предавање:

Critical percolation threshold controls Arctic sea ice melt pond evolution


Arctic sea ice covers a vast area of nearly 15 million square kilometers at its peak annual extent. However, in recent years, it has been rapidly disappearing at a rate underestimated by most climate models. A likely reason for this underestimate are processes on scales smaller than tens of kilometers, which the large-scale models cannot resolve. One such small-scale process that contributes to the disappearance of the Arctic ice are meter-sized melt ponds that form on the ice’s surface during summer and absorb significant amounts of solar radiation. During the summer, these ponds evolve in a complicated manner that we do not yet fully understand. In this talk, we will show how the critical point of a connectivity transition – the percolation threshold – controls the melt pond evolution. The ponds evolve by draining through large holes that open over the summer on the ice’s surface so that above the percolation threshold, they can drain easily, while below the threshold, their drainage is impaired. In this way, the percolation threshold is an approximate upper bound on the pond coverage fraction. In fact, in a manner typical for critical phenomena, pond drainage is universal. This universality enables us to write an equation for their evolution below the threshold that compares well with field and satellite observations over most of the summer. Our work, thus, might help resolve some of the uncertainty present in the large-scale climate models and help better predict the fate of the Arctic ice.

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Meeting ID: 845 0021 3601
Passcode: 019682