Solar meridional circulation is an axisymmetric flow system, extending from the equator to the poles (\(\sim \)20 m/s at the surface, \(\approx \)1% of the mean solar rotation rate), plunging inwards and subsequently completing the circuit in the interior through an equatorward return flow and a radially outward flow back up to the surface. This article reviews the profound role that meridional circulation plays in maintaining global dynamics and regulating large-scale solar magnetism. Because it is relatively weak in comparison to differential rotation (\(\sim \)300 m/s, \(\approx \)7% of the mean solar rotation rate) and owing to numerous systematical errors, accurate surface measurements were only first made in 1978 and initial inferences of interior meridional circulation were obtained using helioseismology two decades later. However, systematical biases have made it very challenging to reliably recover flow in the deep interior. Despite numerous advances that have served to improve the accuracy of inferences, the location of the return flow and the full extent of the circulation are still open problems. This article follows the historical developments and summarises contemporary advances that have led to modern inferences of surface and interior meridional flow.

太阳经向环流是一个轴对称的流动系统，从赤道延伸到两极（地表\(\sim \) 20 m/s，\(\约 \) 1% 的太阳平均自转率），向内和随后通过向赤道的回流和径向向外的流回到地面完成内部的回路。本文回顾了经向环流在维持全球动态和调节大尺度太阳磁力方面的深远作用。因为它与差速旋转相比相对较弱（\(\sim \) 300 m/s, \(\approx \)7% 的平均太阳自转率），并且由于许多系统误差，直到 1978 年才首次进行准确的地表测量，并且在 20 年后使用日震学获得了内部经向环流的初步推论。然而，系统性偏差使得可靠地恢复内部深处的流动变得非常具有挑战性。尽管有许多进步有助于提高推断的准确性，但回流的位置和循环的全部范围仍然是悬而未决的问题。本文跟踪历史发展并总结导致现代推论表面和内部经向流的当代进展。