Issues with convection. What is a useful framework beyond bulk models of large N, non-interacting, scale-separated, equilibrium systems
Seminar Room 1, Newton Institute
AbstractThe representation of cumulus clouds presents some notoriously stubborn problems in climate modelling. The starting point for our representations is the well-known Arakawa and Schubert (1974) system which describes interactions of cloud types ("plumes") with their environment. In some ways, this system has become brutally simplified: in applications, generally only a single "bulk" cloud type is considered, there are assumed to be very many clouds present, and an equilibrium between convection and forcing is assumed to be rapidly reached. In other ways, the system has become greatly complicated: the description of a plume is much more "sophisticated". In this talk, I want to consider what might be learnt from almost the opposite perspective: i.e., keep the plume description brutally simple, but take seriously the implications of issues like finite cloud number (leading naturally to important stochastic effects), competitive communities of cloud types (leading to a proposed relation for the co-existence of shallow and deep convection) and prognostic effects (leading to questions about how far equilibrium thinking holds).
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