Cloud fraction mediates the aerosol optical depth - cloud top height relationship

Journal article

The observed strong link between aerosol optical depth (τ) and cloud top pressure (p_top) has frequently been interpreted as the invigoration of convective clouds by aerosol, with increased τ being strongly correlated with decreases in p_top (increases in cloud top height). A strong correlation between τ and cloud fraction (f_c) has also been observed. Using satellite-retrieved data, here we show that p_top is also strongly correlated to f_c, and when combined with the strong sensitivity between f_c and τ, a large proportion of the relationship between p_top and τcan be reconstructed. Given the uncertainties about the influence of aerosol-cloud interactions on the τ-f_c relationship, this suggests that a large fraction of the τ-p_top correlation may not be due to aerosol effects. Influences such as aerosol humidification and meteorology play an important role and should therefore be considered in studies of aerosol-cloud interactions.

Authors: Gryspeerdt, E; Stier, P; Grandey, B

• Publication status: Published
• Peer review status: Peer reviewed
• Publisher: Blackwell Publishing Ltd
• Journal: Geophysical Research Letters
• Volume: 41
• Issue: 10
• Pages: 3622-3627
• Publication date: 2014-05-19
• DOI: 10.1002/2014GL059524
• EISSN: 1944-8007
• ISSN: 0094-8276
• Language: English
• Keywords: aerosol-cloud interactions; aerosol
• Subjects: Atmospheric, Oceanic, and Planetary physics; Environment