Self-Aggregation of convection, cyclogenesis and climate change

Friday, December 16, 2016 - 08:00
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This project aims at improving our understanding of atmospheric deep convection and its spatial organization. Organized convection, for instance, squall lines or tropical cyclones, with their associated clouds, strong precipitation and winds, can cause severe material damage and can be deadly. The organization of clouds is ubiquitous in the tropics, but is not well understood. One particular type of convective organization in idealized simulations that has received attention recently is the self-aggregation of convection, taking the form of cloud clusters, or tropical cyclones in the presence of rotation.

The processes leading to self-aggregation in idealized simulations are believed to play an important role in cyclogenesis, but the conditions that favor self-aggregation are still unclear. We investigate in detail the physical process responsible for the aggregation, and how aggregation couples to a large-scale circulation. It has been recently suggested that the self-aggregated state could be the preferred stable equilibrium of tropical convection under warm sea-surface temperatures. With changing climate, the tropics could switch to this self-aggregated state. Given the large changes in large-scale properties accompanying self-aggregation, this has important implications for climate sensitivity. The sensitivity of self-aggregation to temperature, and vice versa, will be discussed.

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