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Meridional flow is thought to play a very important role in the dynamics ofthe solar convection zone; however, because of its relatively small amplitude,precisely measuring it poses a significant challenge. Here we present acomplete time-distance helioseismic analysis of about two years of ground-basedGONG Doppler data to retrieve the meridional circulation profile for modestlatitudes, in an attempt to corroborate results from other studies. We use anempirical correction to the travel times due to an unknown center-to-limbsystematic effect. The helioseismic inversion procedure is first tested andreasonably validated on artificial data from a large-scale numericalsimulation, followed by a test to broadly recover the solar differentialrotation found from global seismology.  From GONG data, we measure poleward photospheric flows at all latitudes withproperties that are comparable with earlier studies, and a shallow equatorwardflow about $65$\,Mm beneath the surface, in agreement with recent findings fromHMI data. No strong evidence of multiple circulation cells in depth norlatitude is found, yet the whole phase space has not yet been explored. Testsof mass flux conservation are then carried out on the inferred GONG and HMIflows and compared to a fiducial numerical baseline from models, and we findthat the continuity equation is poorly satisfied.  While the two disparate data sets do give similar results for about the outer$15\%$ of the interior radius, the total inverted circulation pattern appearsto be unphysical in terms of mass conservation when interpreted over modesttime scales. We can likely attribute this to both the influence of realizationnoise and subtle effects in the data and measurement procedure.

Meridional Flow in the Solar Convection Zone II: Helioseismic Inversions of GONG Data