Collaborative Research: Exploring the Role of Internal Wave Generation in Gravity Currents

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Entrainment in dense oceanic gravity currents has been studied intensively in the past owing to its importance for the oceanic overturning circulation. These studies contain only little examination of the actual processes that produce the entrainment, and have historically not been linked the generation of internal gravity waves (IGWs) with gravity current flows. This contrasts many atmospheric studies of atmospheric down slope wind flows in which IGW generation has been found to be an essential process and responsible for a significant amount of momentum transfer. In oceanic overflows, few historical observations capture the scales necessary to detect internal wave generation.However, based on a reanalysis of the limited available data, at least some overflows have a vertical structure and range of temporal scales conducive to IGW generation. We hypothesize that IGW generation represents a momentum sink in the Mediterranean Outflow (Med Outflow). The project will examine the presence, characteristics, and dynamic role of IGWs in the Med Outflow in collaboration with Spanish scientists. Two short-term moorings and intensive shipboard LADCP/CTD surveys are planed to explore the IGW structure and to examine if it is likely to be important for gravity current dynamics and entrainment. This study offers a strategic opportunity to initiate an international, European-American collaboration.