Title: Land-atmosphere feedbacks and climate change predictions for dune-laden deserts
Speaker: Andrew Gunn
Department of Earth & Environmental Science, University of Pennsylvania
Abstract: Dune fields are regions of Earth's terrestrial surface where loose sand has been blown into patterned topography by wind. The regional climate is often dry, hot and windy—conditions conducive to sand erosion—with large amplitude daily and seasonal cycles. The coupling between this unique pair of Earth components, the dune-field surface and atmosphere, results in some interesting dynamics that play out at the system spatial-scale, and over a range of temporal scales. In this seminar I will discuss two specific land-atmosphere feedbacks that we have identified with a combination of fieldwork at White Sands Dune Field, global atmospheric reanalysis and theoretical arguments. One is
a spatial disequilibrium resulting from dune roughness impinging on atmospheric winds, and the other is a temporal disequilibrium in atmospheric boundary layer stability due to low surface heat capacity. I will also show predictions for dune-field activity from the new CMIP6 future climate change scenarios. Implications for dune-field evolution will be put forward for all three topics.
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