Scale Dependent Air-Sea Mechanical Coupling and Eddy-Killing
Shikhar Rai, PhD Qualifying Exam, Advised by Professor Hussein Aluie
Thursday, December 22, 2022
Meeting ID: 910 9228 4882
Wind is the main source of kinetic energy maintaining the global oceanic circulation. But winds can also extract kinetic energy from the ocean by a process called “eddy-killing.” A systematic scale analysis of the wind forcing is necessary to disentangle eddy killing from the wind driven circulation. Using a new coarse graining method, we scan the entire range of scales resolved by satellites and in model. This allows us to determine for the first time the length-scales over which eddy-killing operates and its magnitude. We also show that significant spurious eddy killing arises from resolution mismatch between the winds and ocean currents, which is often the case in climate and ocean models. We provide a simple recipe to fix such exaggerated eddy killing, which shows very good agreement with observations. In addition to its implications to ocean modeling, our work has important bearing on the longstanding problem of energy pathways to dissipation in the ocean.