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Modelled suppression of boundary-layer clouds by plants in a CO2-rich atmosphere

Due to a campus closure on 9/12/13, this talk was canceled and will be rescheduled.

, Wageningen, Netherlands

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Thursday, September 12, 2013 - 2:00pm

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ECCR 257

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I will present and discuss a conceptual modelling framework that can facilitate the understanding of the interactions between land processes and atmospheric boundary layer dynamics/chemistry at diurnal scales. This framework has been successful applied to the interpretation of field experiments, but also to identify the non-linear relations that occur at larger spatial and temporal scales. I will then discuss in depth the link between shallow cumulus clouds and vegetation exchange of water and carbon dioxide.

Cumulus clouds in the atmospheric boundary layer are characterized by their turbulent nature and play a key role in the hydrologic cycle, in the onset of severe weather by thunderstorms, and in modulating the Earth's reflectivity and climate. How these clouds respond to climate change, in particular over land, and how they interact with the carbon cycle is poorly understood. It is expected that as a consequence of rising atmospheric CO2 the plant stomata will close leading to lower latent heat fluxes and higher sensible heat fluxes.

During the presentation, I will show that this causes a decline in boundary layer cloud formation in middle latitudes. This could be partly counteracted by the greater ability of a warmer atmosphere to take up water and by a growth in biomass due to CO2 fertilization. Our results are based on a new soil-water-atmosphere-plant model supported by comprehensive observational evidence, from which we identify the dominant atmospheric responses to plant physiological processes. They emphasize the intricate connection between biological and physical aspects of the climate system and the relevance of short-term and small-scale processes in establishing this connection.