What controls moisture above the clouds?
CAOS postdoctoral research scientist Martin Jucker (now at the University of New South Wales) and professor Ed Gerber explored the moisture circulation of the stratosphere, using a new model of intermediate complexity to help bridge the gap between theory and comprehensive atmosphere models. In a recent study published in the Journal of Climate, they developed a Model of a idealized Moist Atmosphere (MiMA) to explore the tropical tropopause layer, which regulates the moisture content of the stratosphere.
While there is very little water in the stratosphere (just a few parts per million), radiative transfer exhibits a logarithmic dependence on greenhouse gas concentration. Thus a tiny change in stratospheric water vapor in absolute terms can impact global mean surface temperature Note that this logarithmic dependence on greenhouse gas concentration is fortunate for us in terms of carbon dioxide; we’d be in a great deal more in trouble if surface temperature depended linearly on carbon dioxide concentrations, as our emissions continue to increase exponentially.
Martin felt that MiMA deserved a trailer; atmospheric physics seem more exciting when set to music!