Natural marine cloud brightening in the Southern Ocean

[摘要] The number of cloud droplets per unit volume ( N d ) is afundamentally important property of marine boundary layer (MBL) liquidclouds that, at constant liquid water path, exerts considerable controls onalbedo. Past work has shown that regional N d has a direct correlation tomarine primary productivity (PP) because of the role of seasonally varying,biogenically derived precursor gases in modulating secondary aerosolproperties. These linkages are thought to be observable over the high-latitude oceans, where strong seasonal variability in aerosol and meteorologycovary in mostly pristine environments. Here, we examine N d variabilityderived from 5 years of MODIS Level 2-derived cloud properties in a broadregion of the summer eastern Southern Ocean and adjacent marginal seas. Wedemonstrate latitudinal, longitudinal and temporal gradients in N d thatare strongly correlated with the passage of air masses over high-PP watersthat are mostly concentrated along the Antarctic Shelf poleward of60 ∘  S. We find that the albedo of MBL clouds in the latitudessouth of 60 ∘  S is significantly higher than similar liquid water path (LWP) cloudsnorth of this latitude.

[学科分类] 医学（综合）