Moored Mixing Measurements

Our conception, development and deployment of instruments capable of measuring turbulence or mixing on oceanographic moorings has led to long time series at various locations in Pacific, Atlantic and Indian Oceans. Several technical papers (at bottom) describe the measurement in detail, show how different turbulence subranges can be used for quantitative estimation and how the moored turbulence estimates are consistent with more traditional profiling measurements.

Resultant long time series show seasonal and monsoon mixing cycles in the Bay of Bengal and how turbulence is rapidly suppressed by freshwater buoyancy there. Measurements on NOAA moorings in the equatorial Pacific have shown the detailed structure and turbulence generated by shear instabilities formed in the strongly sheared and stratified upper equatorial current system. On longer time scales, these measurements have also shown  mixing’s role in tropical instability waves, the annual cycle of SST and in ESNO phase changes. The Figure shown below is adapted from (a) Moum et al., 2013, (b) Warner and Moum, 2019.

Science Papers

Narrowband high-frequency oscillations at the equator. Part I: Interpretation as shear instabilities. J. Phys. Oceanogr, 41, 397-411,, 2011 (J.N. Moum, J.D. Nash and W.D. Smyth).

Narrowband high-frequency oscillations at the equator. Part II: Properties of shear instabilities, J. Phys. Oceanogr, 41, 412-428, doi:, 2011, (W.D. Smyth, J.N. Moum and J.D. Nash).

Modulation of equatorial turbulence by a tropical instability wave, J. Geophys. Res., 117, C10009, doi:, 2012 (R. Inoue, R.-C. Lien and J.N. Moum).

Seasonal sea surface cooling in the equatorial Pacific cold tongue controlled by ocean mixing. Nature, 500, 64-67, doi:, 2013 (J.N. Moum, A. Perlin, J.D. Nash and M.J. McPhaden). [News & Views: Unequal equinoxes]

Monsoon mixing cycles in the Bay of Bengal: A year-long subsurface mixing record, Oceanography, 29(2):158–169,, 2016 (S.J. Warner, J. Becherer, K. Pujiana, E.L. Shroyer, M. Ravichandran, V.P. Thangaprakash and J.N. Moum).

Ocean feedback to pulses of the Madden–Julian Oscillation in the equatorial Indian Ocean, Nature Commun. 7, 13203, doi:, 2016 (J.N. Moum. K. Pujiana, R-C. Lien and W.D. Smyth).

Variations of equatorial shear, stratification, and turbulence within a tropical instability wave cycle, J. Geophys. Res. Oceans., 124, 1858– 1875, doi:, 2019 (R. Inoue, R-C. Lien, J.N. Moum, R.C. Perez and M.C. Gregg).

Seasonality and buoyancy suppression of turbulence in the Bay of Bengal, Geophys. Res. Lett., 46, 4346– 4355, doi:, 2019 (R. Thakur, E.L. Shroyer, R. Govindarajan, J.T. Farrar, R.A. Weller and J.N. Moum).

Feedback of mixing to ENSO phase change, Geophys. Res. Lett., 46, 13920– 13927, doi:, 2019 (S.J. Warner and J.N. Moum).  AGU Editor’s Highlight.

The seasonal cycle of upper ocean mixing at 8N in the Bay of Bengal, J. Phys. Oceanogr.50(2), 323-342, doi:, 2020 (D.A. Cherian, E.L. Shroyer, H. Wijesekera and J.N. Moum).

Technical Papers

Mixing measurements on an equatorial ocean mooring, J. Atmos. and Oceanic Tech., 26, 317-336, doi:, 2009 (J.N. Moum and J.D. Nash).

Inertial-convective subrange estimates of thermal variance dissipation rate from moored temperature measurements. J.Atmos. Oceanic Technol., 27, 1950-1959, doi:, 2010 (Y. Zhang and J.N. Moum).

Comparison of Thermal Variance Dissipation Rates from Moored and Profiling Instruments at the Equator, J. Atmos. Oceanic Technol., 29, 1347–1362, doi:, 2012 (A. Perlin and J. N. Moum).

Ocean speed and turbulence measurements using pitot-static tubes on moorings, J. Atmos. Oceanic Technol., 32, 1400-1413, doi:, 2015 (J.N. Moum).

An Efficient Scheme for Onboard Reduction of Moored χpod Data, J. Atmos. Oceanic Technol., 34, 2533-2546, doi:, 2017 (J. Becherer and J.N. Moum).