Sulfate aerosols are typically the dominant source of cloud condensation nuclei (CCN) over remote oceans and their abundance is thought to be the dominating factor in determining oceanic cloud brightness. Their activation into cloud droplets depends on dynamics (i.e. vertical updrafts) and competition with other potential CCN sources for the condensing water. We present new experimental results from the remote Southern Ocean illustrating that, for a given updraft, the peak supersaturation reached in cloud, and consequently the number of droplets activated on sulfate nuclei, is strongly but inversely proportional to the concentration of sea-salt activated despite a 10-fold lower abundance. Greater sea-spray nuclei availability mostly suppresses sulfate aerosol activation leading to an overall decrease in cloud droplet concentrations; however, for high vertical updrafts and low sulfate aerosol availability, increased sea-spray can augment cloud droplet concentrations. This newly identified effect where sea-salt nuclei indirectly controls sulfate nuclei activation into cloud droplets could potentially lead to changes in the albedo of marine boundary layer clouds by as much as 30%.

硫酸盐气溶胶通常是偏远海洋上云凝结核（CCN）的主要来源，并且它们的丰度被认为是确定海洋云白度的主要因素。它们被激活成云滴取决于动力学（即垂直上升气流）以及与其他潜在的CCN源争夺冷凝水的能力。我们提供了来自偏远南部海洋的新实验结果，该结果表明，对于给定的上升气流，云中达到了峰值过饱和，因此，在硫酸盐核上活化的液滴数量与活化的海盐浓度强烈但成反比，尽管低10倍的丰度。更大的海雾核可用性主要抑制了硫酸盐气溶胶的活化，从而导致总体上云滴浓度的降低。然而，对于高垂直上升气流和低水平的硫酸盐气溶胶，增加海浪可以增加云滴浓度。这种新近确定的效应，即海盐核间接控制硫酸盐核活化成云滴的作用，有可能导致海洋边界层云的反照率变化多达30％。