IGPP and AOML bottom pressure measurements at four MODE stations constitute a unique set of deep-sea tidal measurements (although deployed for other purposes). A response analysis relative to a Bermuda reference has been optimized with regard to the number of complex weights and the makeup of gravitational and radiational inputs. Duplicate instrumentation on EDIE capsule gave 32.067, 2.5° 32.074, 2.6° for M2 amplitude (cm) and Greenwich epoch, thus attesting the reality of measured small station differences (order 1 cm, 1°). M2 tidal currents (calculated from the M2 surface and bottom slopes) have u and v speeds of 0.5 and 0.8 em s−1, respectively, in rough agreement (both amplitude and phase) with preliminary estimates from current measurements. M2 and K1 tides are in accord with sonic existing cotidal and co-range charts. M2 tides are a fraction of equilibrium magnitude, whereas M4, M5 and M6 (typically 0.07, 0.05, O.03 cm) vastly exceed equilibrium values. Presumably these overtides are generated by nonlinear coupling in the world's shallow basins, from where they radiate into the global oceans to attain a level where radiative and dissipative processes are somehow balanced.
Journal of Physical Oceanography
American Meteorological Society
Digital Object Identifier (DOI)
Zetler, B., W. Munk, H. Mofjeld, W. Brown and F. Dormer. 1975. MODE tides. Physical Oceanography 5:430-441.