By modulating the distribution of heat, precipitation and moisture, the Hadley cell holds large climate impacts at low and subtropical latitudes. Here we show that the interannual variability of the annual mean Hadley cell strength is ~ 30% less in the Northern Hemisphere than in the Southern Hemisphere. Using a hierarchy of ocean coupling experiments, we find that the smaller variability in the Northern Hemisphere stems from dynamic ocean coupling, which has opposite effects on the variability of the Hadley cell in the Southern and Northern Hemispheres; it acts to increase the variability in the Southern Hemisphere, which is inversely linked to equatorial upwelling, and reduce the variability in the Northern Hemisphere, which shows a direct relation with the subtropical wind-driven overturning circulation. The important role of ocean coupling in modulating the tropical circulation suggests that further investigation should be carried out to better understand the climate impacts of ocean-atmosphere coupling at low latitudes.

通过调节热量、降水和水分的分布，哈德利单元在低纬度和亚热带地区具有巨大的气候影响。在这里，我们表明，北半球的年平均 Hadley 细胞强度的年际变化比南半球低约 30%。使用海洋耦合实验的层次结构，我们发现北半球较小的变异性源于动态海洋耦合，这对南半球和北半球哈德利细胞的变异性具有相反的影响；它的作用是增加与赤道上升流成反比的南半球的变率，并减少与副热带风驱动的翻转环流直接相关的北半球的变率。