Left axis: variations of the 50 mbar zonally and time-averaged zonal wind at the equator with N_y. The blue squares correspond to the models with a zonal resolution N_x = 128, the red circle shows model LowRes, and the black plusses show the results of the models with a meridional resolution N_y = 65 and varying number of cells in the zonal direction. Right axis (green stars): variations of the amplitude of the high-frequency fluctuations of the zonally averaged zonal wind fluctuations (see text for details on its calculation) with N_y for the series of models with N_x = 128.