Do mesogranules exist?

Applying spatial and temporal averaging techniques to several long sequences of Dopplergrams obtained at the solar disk center and near the limb, we confirmed the persistent supergranule velocity pattern. After excluding the 5-min oscillation and supergranule velocity fields from the disk center Doppler data, we find that the velocity structure shows a typical scale of 7 Mm, consistent with the scale of mesogranules found by November, Toomre, and Gebbie (1981) and November et al. (1982). However, this velocity pattern does not show properties of the cellular convection. It is not coherent for more than one hour, the period during which the raw Doppler images are averaged to remove the 5-min oscillation. Furthermore, we did not find convection patterns in the scale of mesogranules from the Doppler data obtained near the solar limb. We propose that the mesogranule velocity structure found by November et al. might be the uncorrected part of the 5-min oscillation and granule velocity.