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Energy Flux Observations in an Internal Tide Beam in the Eastern North Atlantic
Author(s) -
Köhler Janna,
Walter Maren,
Mertens Christian,
Stiehler Jan,
Li Zhuhua,
Zhao Zhongxiang,
Storch JinSong,
Rhein Monika
Publication year - 2019
Publication title -
journal of geophysical research: oceans
Language(s) - English
Resource type - Journals
eISSN - 2169-9291
pISSN - 2169-9275
DOI - 10.1029/2019jc015156
Subject(s) - internal wave , internal tide , dissipation , energy flux , altimeter , geology , tidal power , range (aeronautics) , flux (metallurgy) , geodesy , stratification (seeds) , turbulence kinetic energy , climatology , turbulence , atmospheric sciences , geophysics , environmental science , oceanography , meteorology , physics , seed dormancy , ecology , materials science , germination , botany , astronomy , dormancy , biology , metallurgy , composite material , thermodynamics
Low‐mode internal waves propagate over large distances and provide energy for turbulent mixing when they break far from their generation sites. A realistic representation of the oceanic energy cycle in ocean and climate models requires a consistent implementation of their generation, propagation, and dissipation. Here we combine the long‐term mean energy flux from satellite altimetry with results from a 1/10° global ocean general circulation model that resolves the low modes of internal waves and in situ observations of stratification and horizontal currents to study energy flux and dissipation along a 1000 km internal tide beam in the eastern North Atlantic. Internal wave fluxes were estimated from twelve 36‐ to 48‐hr stations in along‐ and across‐beam direction to resolve both the inertial period and tidal cycle. The observed internal tide energy fluxes range from 5.9 kW m −1 near the generation sites to 0.5 kW m −1 at distant stations. Estimates of energy dissipation come from both finestructure and upper ocean microstructure profiles and range, vertically integrated, from 0.5 to 3.3 mW m −2 along the beam. Overall, the in situ observations confirm the internal tide pattern derived from satellite altimetry, but the in situ energy fluxes are more variable and decrease less monotonically along the beam. Internal tides in the model propagate over shorter distances compared to results from altimetry and in situ measurements, but more spatial details close the main generation sites are resolved.