TRR 181 Seminar "Moored internal tide energy fluxes in a tidal beam"
The TRR 181 seminar is held every other week in the semester and as announced during semester break. The locations of the seminar changes between the three TRR181 locations, but is broadcastet online for all members of the TRR.
The TRR 181 seminar is held by Jonas Löb (University of Bremen, PhD in W2) on April 25, 11 am at Universität Hamburg, Bundesstr. 53, ground floor, room 22/23.
Abstract
Low mode internal tides in the ocean are generated by interaction between barotropic tides and seafloor topography. They are crucial for interior mixing and for the oceanic energy pathways, since they carry a large portion of the energy of the entire internal wave field. Energy flux is an important diagnostic quantity for ocean models because its divergence identifies sources and sinks. The aim of this work is to investigate how realistic global datasets capture M2 energy fluxes in an energetic tidal beam compared with mooring measurements. For this we combined 10 months of mooring data with output from a 1/10° global ocean tide and circulation model forced with the complete lunisolar tidal potential and the 6 hourly NCEP reanalysis and internal tide energy fluxes based on satellite altimetry.
The moored internal tide energy flux shows a strong spring-neap variability coupled with the barotropic forcing. During the observation period a distinct surface eddy damped the energy flux in the first and second mode in the semidiurnal component, while a deep eddy (highest velocities at 2000m) reduced the energy flux mainly in the second mode. Removing time periods where mesoscale interactions occur from the mean flux calculations, results in a good agreement of energy flux in observations and model. Energy fluxes calculated from satellite altimetry seem to underestimate the total energy flux inside the tidal beam due to spatial and temporal averaging.