From measurements taken over the tropical Pacific Ocean, reported in Diurnal and Semidiurnal Variations of the Surface Wind Field over the
Tropical Pacific Ocean (Deser and Smith, 1997), observe that
The observed semidiurnal near-surface wind variations
are dynamically consistent with the zonally averaged
semidiurnal pressure field, which is forced by
the atmospheric thermal tide in the stratosphere and
This 'thermal tide' is further explained in the paper Diurnal and semidiurnal variations in global wind and divergence fields (Dai and Deser, 1999), which state that solar heating and regional forcings play a major role in the pressure variations.
The article Solar Semidiurnal Tides in the Troposphere: Detection of Radar Profilers (Whiteman and Bian, 1996), state that the variation is far more pronounced in the tropics than at mid-latitudes and beyond. The authors confirm that the semi-diurnal oscillation is indeed a solar tide, as their periodicity
is an exact harmonic of the solar period
But from their observations deduce that the pressure variations are solar tides wind perturbations in the troposphere.
The authors also state that there are similarities between the solar tides and the lunar tides on the ocean, in that they both cause a "tidal bulge" on opposites of the planet and minima in between.