Quantifying the aerosol effect on droplet size distribution at
cloud-top
不同粒径气溶胶对云的影响
A major debate refers to the relative importance of aerosol composition against size distribution and total number concentration (McFiggans et al., 2006). Several studies suggest that accurate measures of aerosol size and number concentration are more
important to obtain a relatively accurate description of cloud droplet populations (Feingold, 2003; Dusek et al., 2006; Ervens
et al., 2007; Gunthe et al., 2009; Rose et al., 2010; Reutter et al., 2009).
不同自然条件下的影响不一样的
However, they show that w/Na, or supersaturation-based regimes, cannot fully predict the compositional dependence of CCN activity, it also varies significantly as a function of r¯a.It is remarkable that for small aerosols (r¯a < 0.06 µm), composition affects CCN activity even in the aerosol-limited regime.
For instance, Feingold (2003) showed that the influence of aerosol parameters over the droplet effective radius (re) varies as a function of aerosol loading. Under clean condition, re is mostly determined by the liquid water content and the aerosol number concentration (Na), with decreasing dependence on the aerosol size distribution, aerosol composition and vertical velocity (w).
Because they belong to the “aerosol35 limited regime", characterized by strong updrafts and a low aerosol background concentration (Reutter et al., 2009), Amazonian clouds are found to be very sensitive to aerosols (Andreae et al., 2004; Braga et al., 2017; Cecchini et al., 2017; Fan et al., 2018;
Reid et al., 1999).
中国的情况大为不同，背景气溶胶浓度很高