Title: Transient monsoon dynamics

Abstract
Monsoons are major features of the general circulation of Earth’s atmosphere during solstice seasons, projecting strongly onto the zonal mean Hadley circulation and containing much of the total global moist convective activity. Like most large-scale circulations, monsoons vary on a broad range of subseasonal time scales. Monsoons are unusual, however, in that even the basic dynamics of these transients are poorly understood. In this talk I review the subseasonal variability of monsoon circulations: the abrupt onset of summer flow, the 30-60 day variability that produces “active” and “break” episodes, and the synoptic scale vortices that produce most continental precipitation in nearly all monsoon regions. I devote the most time to discussion of these synoptic vortices, which have been studied little over the past 30 years, and show that previous theories for their mechanisms of growth and propagation are inconsistent with observations. Motivated by the overall prominence of monsoon transients, I close by discussing how well the time-mean monsoon strength can be obtained from specification of the time-mean boundary conditions and forcings.

Speaker's website: http://people.earth.yale.edu/profile/william-boos/about