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

Date 2022-10-27
Author(s) Pollmann FriederikeORCID1, Nycander JonasORCID2
Affiliation(s) 1 : Universität Hamburg, Institut für Meereskunde, 20146 Hamburg, Germany
2 : Dept. of Meteorology, Stockholm University, Stockholm, Sweden
DOI 10.17882/92304
Publisher SEANOE
Keyword(s) tides, internal waves, ocean mixing, supercritical slopes

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.

Licence CC0
Acknowledgements A contribution to the project W4 of the Collaborative Research Centre TRR 181 ``Energy Transfers in Atmosphere and Ocean'' funded by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) - Projektnummer 274762653.
File Size Format Processing Access
Mask 10 MB NC, NetCDF Processed data Open access
Mode-1 M2-tide generation 589 MB NC, NetCDF Processed data Open access
Top of the page

How to cite 

Pollmann Friederike, Nycander Jonas (2022). Global calculation of the internal M2-tide generation with a horizontal direction (mode 1). SEANOE.