School Colloquia Series - Steven Sherwood - Self-agreggation in radiative-convective equilibrium and its link to extreme rain increases in a warming atmosphere
Tuesday 30th May 2017
Old Main Building, Room 150
Speaker: Professor Steven Sherwood, ARC Laureate Fellow | Deputy Director, Climate Change Research Centre, UNSW
Abstract: Traditional views of moist radiative-convective equilibrium, where a uniform wet surface is heated (e.g. by the sun) while the atmosphere above it is cooled and a convective heat transfer occurs (mainly by latent heat transport), have assumed that the resulting convection would always be statistically homogeneous and steady and produces a well-defined time-averaged mean state. However, recent high-resolution modeling studies have shown that such convection can sometimes spontaneously self-aggregate into highly organised and persistent structures that significantly change the time-averaged state. This is a type of hysteresis or quasi-phase-change in what was thought to be a conceptually simple system. Most studies have found that the tendency toward self-aggregation strengthens in warmer equilibrium states and therefore should respond to global warming, in ways that could feed back on the warming. This talk will review work on convective self-aggregregation and argue that the phenomenon is unlikely to represent a big uncertainty in global warming itself, but may play an important role in understanding how warming will affect extreme rainfall events.