Monsoon depressions: Mechanisms and trends of high-impact storms at the edge of Earth's tropics
Much of the rain that falls in the monsoon circulations that dominate the climate of Earth's tropics is delivered by transient, propagating atmospheric vortices. These storms are neither typhoons nor classical extratropical baroclinic waves, but another type of phenomenon that has remained poorly understood despite their role in generating catastrophic flooding in land inhabited by billions of people. In this talk I focus on these vortices in South Asia, where they are called monsoon depressions; I present new theory for their genesis and growth, as well as their propagation and dynamical structure. I discuss historical trends in the frequency of monsoon depressions, projections for how the extreme rainfall that they produce will change over this century, and short-term operational predictions of monsoon depression activity.
