Southern Hemisphere (SH) storminess has increased in the satellite era and recent work suggests comprehensive climate models significantly underestimate the trend. Here, we revisit this reanalysis-model trend discrepancy to better understand the mechanisms underlie it. A comprehensive like-for-like analysis shows reanalysis trends exhibit large uncertainty, and coupled climate model simulations exhibit weaker trends than most but not all reanalyses. However, simulations with prescribed sea surface temperature (SST) exhibit significantly greater storminess trends, particularly in the South Pacific, implying SST trend discrepancies in coupled simulations impact storminess trends. Using pacemaker simulations that correct Southern Ocean and tropical east Pacific SST trend discrepancies, we show that storminess trends in coupled simulations are underestimated because they do not capture the enhanced storminess resulting from Southern Ocean cooling and La-Nina-like teleconnection trends. Our findings emphasize large reanalysis uncertainty in SH circulation trends and the impact of regional SST trend discrepancies on circulation trends.

南半球 （SH） 风暴在卫星时代有所增加，最近的研究表明，综合气候模型明显低估了这一趋势。在这里，我们重新审视了这种再分析模型趋势差异，以更好地了解其背后的机制。全面的同类分析表明，再分析趋势表现出较大的不确定性，耦合气候模式模拟表现出比大多数但不是全部重新分析更弱的趋势。然而，使用指定海面温度 （SST） 的模拟显示出明显更大的风暴趋势，尤其是在南太平洋，这意味着耦合模拟中的 SST 趋势差异会影响风暴趋势。使用校正南大洋和热带东太平洋 SST 趋势差异的起搏器模拟，我们表明耦合模拟中的风暴趋势被低估了，因为它们没有捕捉到南大洋冷却和类似拉尼娜的遥相关趋势导致的增强风暴。我们的研究结果强调了 SH 流通趋势中较大的再分析不确定性以及区域 SST 趋势差异对流通趋势的影响。