Inflows Around Active Regions Explain Solar Cycle Scale Variations in Photospheric Meridional Flow During Cycle 24

Using time distance local helioseismology flow maps within 1 Mm of the solar photosphere, we detect inflows into active regions that vary in magnitude as a function of active region sizes. We show that these inflows, averaged over several hundred active regions, stretch out as far as 20 degrees away from active region centroids. We also show that most of the solar cycle scale variation of meridional flow during solar cycle 24 was a consequence of these inflows into active regions. If Active Region neighborhoods are ignored, the solar cycle scale variation in background meridional flow diminishes to the level of uncertainty in the data. This implies that the background photospheric meridional flow, which is a proxy for the return meridional flow deep in the solar interior, did not significantly change during solar cycle 24. This is an important constraint for solar dynamo and surface flux transport models.