ZHAO30yr: model errors and geographic mask
In the internal tide model ZHAO30yr (https://doi.org/10.6084/m9.figshare.28078523.v1), model errors are estimated using background internal tides. Background internal tides are extracted from the same altimetry data following the same procedure but using tidal periods slightly different from the eight principal constituents. In other words, model errors are indicated by internal tide signals where internal tides do not exist. In principle, model errors are determined by the given altimetry data and the mapping technique used to extract internal tides. Background internal tides do not vary much over the narrow semidiurnal or diurnal frequency bands. ZHAO30yr estimates errors in semidiurnal internal tides using 12.3373 hours (M2 minus 5 minutes) and in diurnal internal tides using 23.8511 hours (K1 minus 5 minutes). Both mode-1 and mode-2 internal tides are estimated for the semidiurnal and diurnal constituents. A geographic mask is provided. In most of the global ocean, model errors are very low. On a global average, the model errors in all semidiurnal and diurnal constituents are lower than 1 mm. In regions of extremely high mesoscale eddies, the semidiurnal errors are dominantly larger than 1 mm due to mesoscale contamination. These regions include the Kuroshio extension region, the Gulf Stream, the East Australian Current, and so on. These regions are highlighted by black contours.
In this folder, there are 4 files for model errors of different baroclinic modes and different frequencies, as indicated by file names (ZHAO30yr-V1-MD1-K1-error, ZHAO30yr-V1-MD2-K1-error, ZHAO30yr-V1-MD1-M2-error, and ZHAO30yr-V1-MD2-M2-error). Each file contains a 5-wave summed 1-degree smoothed SSH amplitude error map and 5 decomposed waves (amplitude, phase, and direction) at each grid point. ZHAO30yr_mask gives the geographic mask for regions fouled by mesoscale contamination.
