Measured Temperature [°C] Computed Temperature [°C] Besides many plausibility tests, the model MACH3 was verified with the FLEX76 data set. During the Fladengrund Experiment in the year 1976, the temporal evolution of the seasonal thermal stratification was measured at a certain geographical point over a period of three months (upper figure). By prescribing wind and heat fluxes and starting with an homogeneous temperature distribution, an hindcast of the thermal stratification has been calculated with the one-dimensional model version MACH1 at the same geographical point (lower figure). In this calculation, all transport processes have been neglected, and only the vertical heat transfer due to the wind- and tide-induced turbulence has been considered. The result is outstanding and surpasses by far all previously performed simulations with other models: even the evolution of the second thermocline in 50m depth due to the short storm event at day 135 is reproduced in time and space almost identically.