Stability-dependent increases in liquid water with droplet number in the Arctic

Abstract. The effects of aerosols on cloud microphysical properties are a large source uncertainty when assessing anthropogenic climate change. aerosol–cloud relationship is particularly unclear in high-latitude polar regions due to limited number observations. Cloud liquid water path (LWP) an important control radiative properties, the Arctic, where clouds play central role surface energy budget. Therefore, understanding how may alter LWP important, especially as aerosol sources such industry and shipping move further north warming Arctic. Using satellite data, this work investigates Arctic over open ocean by considering between droplet concentration (Nd) LWP, component aerosol–LWP relationship. response Nd varies significantly across region, with increases observed at very high latitudes multiple datasets, positive signal most strongly during summer months. This result contrast negative typically seen global studies previous showing little aerosols. lower tropospheric stability (LTS) was found be spatial variations response, influencing sign magnitude Nd–LWP relationship, high-stability environments. influence humidity varied depending stability, impact low LTS but strong LTS. mean state does not dominate despite non-linearities As sensitivity changed from moving high- low-LTS environments, shows evidence temperature-dependent indirect effect. Additionally, LWP–LTS changes Nd, generating aerosol-dependent feedback. projected decrease boundary layer become more polluted future these results show that produce paths. shift unstable environments implies adjustments enhancing Twomey effect 8 % offsetting it around 40 %, having potential consequences for sea ice extent.