Unit Affiliation: Ocean and Climate Physics, Lamont-Doherty Earth Observatory (LDEO)
This project investigates fundamental questions in tropical climate dynamics through the development and use of idealized models. Simple models are of interest because the chains of cause and effect are less intricate than in sophisticated climate and atmospheric circulation models. The project has two components, the firsts of which is an investigation of the interaction of extratropical baroclinic eddies (essentially frontal weather system) with the Hadley circulation (i.e. the large-scale overturning circulations in the tropics) and the intertropical convergence zones (ITCZs, or zones of enhanced cloudiness and rainfall near the equator). The influence of extratropical eddies on the trade winds and the zonally averaged tropical rainfall distribution will be a primary focus of the research. The second component of the research involves development of methodology for applying the weak temperature gradient (WTG) approximation to single column models (SCM) of the atmosphere. The WTG approximation is a simple representation of the fact that tropical atmospheric temperatures are horizontally homogeneous because of the geostrophic adjustment process, and work conducted here will advance understanding of the implications of the approximation for the behavior of SCMs and the observed tropical atmosphere. In particular, the extent to which the SCM can mimic the dependence of precipitation (a key SCM output) on tropical sea surface temperature, surface wind speed, and horizontal moisture advection in a state-of-the-art climate model. In addition to advancing the science of tropical climate dynamics, the project has broader impacts through the training and education of a graduate student and a postdoctoral research associate. In addition, source code for software developed over the course of the project will be made available online for the use of the research community.