Global calculation of the internal M2-tide generation with a horizontal direction (mode 1)

This dataset represents the barotropic-to-baroclinic energy transfer of the M2-tide’s first mode in the global ocean. The method is based on linear theory and, for the first time, resolves the horizontal direction of the modal internal tide generation without resorting to WKBJ-scaling (see Pollmann et al., 2019: Resolving the horizontal direction of internal tide generation, Journal of Fluid Dynamics). By construction, the conversion field is positive definite and hence ready to use in tidal mixing parameterizations.
Supercritical slopes, where linear theory breaks down, are masked in the calculations. The details of the calculations and the analysis of the results is described in the manuscript „Resolving the horizontal direction of internal tide generation: Global application for the M2-tide’s first mode“, Pollmann and Nycander, under revision at Journal of Physical Oceanography. Please refer to this publication when using this data set.


The data set includes:

a) the anisotropic barotropic-to-baroclinic energy flux Fphi (W/rad) at a horizontal resolution of 0.5°x0.5° and with 1000 directions in wavenumber angle space. The angle phi is zero in eastward direction, 90° in northward direction etc.

b) the total conversion Conv (W/m^2), obtained by scaling the energy flux Fphi by the effective patch area pi*rG^2 and integrating over all angular points. Each value of Conv and Fphi is representative of a circular patch with a radius of 2.5*rG, whose center is located on the 0.5°x0.5° horizontal grid. The tidal currents (from TPXO9.1; Egbert and Erofeeva, 2002), the stratification (from Gouretski and Koltermann, 2004) and hence wavenumbers and phase velocities, and the topography (SRTM30+; Becker et al., 2009) from the entire patch contribute to the estimates of Fphi and Conv given at the respective patch center.

c) the standard deviation of the two-dimensional Gaussian taper, rG, which is applied to the high-resolution topography (SRTM30+) in each patch to ensure a smooth decrease toward the patch average at the patch boundary.

d) the bottom depth based on SRTM30+.

e) the mask that excludes steep continental slopes and shelves, deep ocean trenches and shallow seas from the calculations, based on the geomorphology data of Harris et al., 2014, at 0.5° and 1/120° resolution.


Physical oceanography


tides, internal waves, ocean mixing, supercritical slopes


10 MoNetCDFProcessed data
Mode-1 M2-tide generation
589 MoNetCDFProcessed data
How to cite
Pollmann Friederike, Nycander Jonas (2022). Global calculation of the internal M2-tide generation with a horizontal direction (mode 1). SEANOE.

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