Scavenging calculation

Particles are scavenged by cloud droplets in the cloud, and by falling raindrops below the cloud. The change in concentration C is described by the exponential relation C=C0 exp (- λt)

\lambda _{icp}=\frac{4.2\times 10^{-7} E_{c}\cdot P}{d_{d}}

In-cloud scavenging

\lambda _{bcp}=\frac{4.2\times 10^{-7} E_{c}\cdot P}{d_{d}}

Below-cloud scavenging

The in-cloud scavenging coefficient λicp and below-cloud scavenging coefficient λbcp depend on
dd drop diameter
Ec collection efficiency for precipitating cloud droplets
Ep collection efficiency for particles
P precipitation rate in mm/hr (at ground level)




The net change of concentration can be calculated straightforwardly when using these parameterizations. However,  the collection efficiencies themselves are a function of droplet size and particle size distribution.

Used in 





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Visit the NanoFASE Library for abstracts of deliverable reports.

Seinfeld, J. H., & Pandis, S. N. (2016). Atmospheric Chemistry and Physics, Wiley-Inter Science, Chapter 20 pp 856-859.





Astrid Manders

TNO, Netherlands