CAREER: The Effect of Latent Heating on the Hadley Circulation

University Of Washington, Seattle WA

Investigators

Abstract

The Hadley circulation is a dominant feature of the climate system. Its strength and extent are connected to the distribution of clouds, water vapor, precipitation, surface winds, and ocean currents throughout the tropics and subtropics. Despite the primary role of latent heating in driving the Hadley circulation, most previous theoretical work has used dry models. The research goals of this project are to test theories for the Hadley circulation using a hierarchy of general circulation models, with particular focus on an idealized moist model that uses simplified parameterizations and allows for large parameter variations and ease of interpretation and reproducibility of results. The importance of physical effects, such as eddy fluxes of moisture, heat, and momentum in modifying the zonally symmetric theories in the past will be investigated. Simulations with a range of prescribed ocean heat fluxes (both symmetric about the equator and centered off-equator), with zonally asymmetric boundary conditions, with changes to the height of the tropopause, and with changes to the convective parameterization will be performed in order to investigate how these different factors and processes affect the Hadley circulation. Simulations with an idealized coupled ocean-atmosphere model will also be performed. The hierarchy of models is chosen to isolate individual physical effects in models of maximal simplicity first, then add in different effects systematically, and then compare with more comprehensive models. The educational goals of this project are to inform high school students, undergraduates, and the general public about the importance of condensation as a source of heat in the atmosphere. At the high-school level, this will be accomplished with a series of laboratory experiments with students from two different climate zones. The students will measure the effect of condensation on the outside of cooled drink cans on raising the temperature of the liquid therein, and will compare data between the two sites. The Principal Investigator (PI) will visit the site in central Washington State, which has a high percentage of minority and low-income students, to give presentations about the effects of condensation on the atmosphere. In addition to the outreach experiments, educational and research goals will be integrated by using undergraduate and graduate research assistants in the project and by presenting research results and concepts to the general public in the form of essays.