GSWM Sample Output: April Meridional Diurnal Tide

Return to GSWM page
Apr Mer Diurnal: Lat v. Lon
Animation cycles three times (three solar days). [ESC] to stop, Reload to replay.

Contour plot of the meridional (northward) diurnal tide in April at 100km altitude as a function of latitude, longitude, and local time. Dashed lines and blue colors indicate southward winds.

This view shows that the migrating tide does not change with longitude, but repeats the same pattern at each longitude over time (alternatively, it changes in time exactly the same way at each longitude). The tide propagates westward.

The phase of the tide differs by 12 hours across the equator, so the maxima in opposite hemispheres at a given altitude and time occur in the opposite directions. Contrast this with the altitude vs. latitude view of the diurnal zonal tide (April case), or compare it with the altitude vs. latitude plot for diurnal meridional winds in January.

The "top view" at 100km of the semidiurnal meridional winds show the two cycles of the semidiurnal tide, as opposed to the single cycle shown here, with stronger amplitudes near the poles.