A Climate Process Team will be assembled to develop parameterizations of gravity current entrainment for inclusion in ocean general circulation models. A better representation of overflow processes in climate models is crucial to better capture the variability of the thermohaline circulation, including abrupt climate change. First, entrainment in observations and process studies will be closely examined and the derived knowledge will be used to develop new parameterizations of entrainment. Several recent observational programs have examined the entrainment in overflow gravity currents, and many recent laboratory and numerical process studies have elucidated a variety of physical processes contributing to entrainment. Several possible formalisms for including such processes into climate models have been developed. For both isopycnal and z-coordinate Ocean General Circulation Models (OGCM), preliminary parameterizations of gravity currents exist which can be modified to better incorporate new understanding of the physics of entrainment. The new parameterizations will be implemented and evaluated in three classes of OGCMs.
Broader impacts of the proposed activity: Gravity current entrainment is an important component of the ocean climate circulation, and this study will enhance our understanding of this process and its role in the climate. This study will enhance links between modeling centers and academic institutions; provide concrete products in the form of new parameterizations which can be used by the whole climate modeling community; benefit society by enabling more reliable predictions of climate variability; promote interdisciplinary training through funding of 2 post-docs; disseminate results through annual workshops involving the larger community; promote underrepresented groups (female coordinating PI).