Marine low clouds are one of the greatest sources of uncertainty for climate projection. We present an observed climatology of cloud albedo susceptibility to cloud droplet number concentration perturbations (S₀) with changing sea surface temperature (SST) and estimated inversion strength for single-layer warm clouds over the North Atlantic Ocean, using eight years of satellite and reanalysis data. The key findings are that SST has a dominant control on S₀ in the presence of co-varying synoptic conditions and aerosol perturbations. Regions conducive to aerosol-induced darkening (brightening) clouds occur with high (low) local SST. Higher SST significantly hastens cloud-top evaporation with increasing aerosol loading, by accelerating entrainment and facilitating entrainment drying. In a global-warming-like scenario where aerosol loading is reduced, less cloud darkening is expected, mainly as a result of reduced entrainment drying. Our results imply a less positive low-cloud liquid water path feedback in a warmer climate with decreasing aerosol loading.

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关于海面温度对气溶胶引起的海洋云变亮的重要性以及对未来变暖气候中云反馈的影响

海洋低云是气候预测的最大不确定性来源之一。我们使用八年的卫星和再分析，展示了观测到的云反照率对云滴数浓度扰动 ( S ₀ ) 随海面温度 (SST) 变化的气候学和北大西洋单层暖云的估计逆温强度数据。主要发现是 SST 对S ₀有显性控制在存在共同变化的天气条件和气溶胶扰动的情况下。有利于气溶胶引起的变暗（变亮）云的区域出现在高（低）局部海温下。较高的 SST 通过加速夹带和促进夹带干燥，随着气溶胶载荷的增加显着加速云顶蒸发。在气溶胶负荷减少的类似全球变暖的情景中，预计云变暗会减少，主要是由于夹带干燥减少。我们的结果表明，在气溶胶载荷减少的温暖气候中，低云液态水路径反馈的积极性较低。