## deposition velocity

in atmospheric chemistry
https://doi.org/10.1351/goldbook.D01602
The ratio of flux density (often given in units of $$\text{g}\ \text{cm}^{-2}\ \text{s}^{-1}$$) of a substance at a sink surface to its concentration in the atmosphere (corresponding units of $$\text{g}\ \text{cm}^{-3}$$). While the units of this ratio are clearly those of velocity (in this case $$\text{cm}\ \text{s}^{-1}$$), the ratio is not a flow velocity in the normal sense of the word.
Source:
PAC, 1990, 62, 2167. (Glossary of atmospheric chemistry terms (Recommendations 1990)) on page 2184 [Terms] [Paper]