Key Laboratory of Meteorological Disaster, Ministry of Education/Joint International Research Laboratory of Climate and Environment Change/Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters, Nanjing University of Information Science and Technology, Nanjing, China.
Earth System Modeling Center, Nanjing University of Information Science and Technology, Nanjing, China.
Nat Commun. 2021 Nov 22;12(1):6787. doi: 10.1038/s41467-021-27030-z.
How anthropogenic forcing could change tropical cyclones (TCs) is a keen societal concern owing to its significant socio-economic impacts. However, a global picture of the anthropogenic aerosol effect on TCs has not yet emerged. Here we show that anthropogenic aerosol emission can reduce northern hemisphere (NH) TCs but increase southern hemisphere (SH) TCs primarily through altering vertical wind shear and mid-tropospheric upward motion in the TC formation zones. These circulation changes are driven by anthropogenic aerosol-induced NH-cooler-than-SH and NH-increased versus SH-decreased meridional (equator to mid-latitudes) temperature gradients. The cooler NH produces a low-level southward cross-equatorial transport of moist static energy, weakening the NH ascent in the TC formation zones; meanwhile, the increased meridional temperature gradients strengthen vertical wind shear, reducing NH TC genesis. The opposite is true for the SH. The results may help to constrain the models' uncertainty in the future TC projection. Reduction of anthropogenic aerosol emission may increase the NH TCs threat.
人为强迫如何改变热带气旋（TCs）是一个社会热点问题，因为它会带来重大的社会经济影响。然而，目前还没有出现人为气溶胶对 TCs 影响的全球图景。本文表明，人为气溶胶排放可以减少北半球（NH）的 TCs，但会增加南半球（SH）的 TCs，主要是通过改变 TCs 形成区的垂直风切变和中层向上运动。这些环流变化是由人为气溶胶引起的 NH 比 SH 更冷以及 NH 增加而 SH 减少的经向（赤道到中纬度）温度梯度驱动的。较冷的 NH 产生了一个低水平的向南跨赤道输送的湿静力能量，从而削弱了 TCs 形成区的 NH 上升；同时，增加的经向温度梯度加强了垂直风切变，减少了 NH TCs 的生成。对于 SH 来说则正好相反。研究结果可能有助于限制未来 TCs 预测模型的不确定性。减少人为气溶胶排放可能会增加 NH TCs 的威胁。
