The relative amount of scattering and absorbing aerosols is essential in determining the aerosol radiative and climate effects. Using reanalysis datasets and climate simulations, here, we show that changes in the relative amount of scattering and absorbing aerosols in the Northern Hemisphere (NH) high latitudes, manifested as long-term decreasing trends in aerosol single-scattering albedo (SSA), have played an important role in driving the widening and weakening trends of the NH Hadley circulation (HC) since the early 1980s. Decreasing SSA in the NH middle and high latitudes can notably warm the troposphere there, thus reducing the equator-to-pole temperature gradient, increasing static stability in mid-latitude regions, and leading to the widening and weakening trends of NH HC. Further analysis of the Coupled Model Intercomparison Project Phase 6 (CMIP6) aerosol forcing–only simulations also supports the importance of SSA trends in perturbing NH HC through the above mechanism.

中文翻译：

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散射和吸收气溶胶的分数变化有助于北半球哈德莱环流扩张


散射和吸收气溶胶的相对量对于确定气溶胶辐射和气候效应至关重要。使用再分析数据集和气候模拟，我们在这里表明，北半球 （NH） 高纬度地区散射和吸收气溶胶相对量的变化，表现为气溶胶单散射反照率 （SSA） 的长期下降趋势，自 1980 年代初以来在推动 NH 哈德莱环流 （HC） 的扩大和减弱趋势中发挥了重要作用。NH 中高纬度地区 SSA 的减少可以显着使那里的对流层变暖，从而减少赤道到两极的温度梯度，增加中纬度地区的静态稳定性，并导致 NH HC 的扩大和减弱趋势。对耦合模式比较计划第 6 阶段 （CMIP6） 仅气溶胶强迫模拟的进一步分析也支持 SSA 趋势在通过上述机制扰动 NH HC 中的重要性。