Measurements and Approximations for Submicron‐Aerosol Size Distribution Functions

Results of field measurements taken in the near‐Caspian (2002, 2003, 2007, 2009, 2010, 2011, 2013, 2014, 2016 years) and near‐Aral sea (1998) deserts under the conditions of weak winds (almost in the absence of saltation processes) and strong heating of the land surface are given. These results show that the fine mineral dust aerosol (0.1–1 μm) considerably contributes to the total aerosol content of the atmospheric surface layer under such conditions. The scaling of daytime mean size d distribution at a height of 2 m is approximated by dependence d−μ, where μ changes from 4 to 6 for different years of measurements, in contrary to the law d−2 for fraction d>1μm. Different compositions of aerosol particles at 0.11μm from African deserts, which were processed using different methods, on the whole, support some invariance the product of the area of aerosol fragments and their number that is the consequence of theory for brittle materials fragmentation. However, if there is a sufficient amount of smaller particles (0.01–1.0 μm) in the composition of desert dust removals, the number of particle is extremely increased compared to this invariance law. We construct some simple model based on the processes of particle integration and disintegration. Key Points Results of field measurements taken in the near‐Caspian and near‐Aral sea deserts under the conditions of weak winds and strong heating of the land surface are given The results show that the fine mineral dust aerosol (0.01–1.0 μm) considerably exceed in number particle fractions with sizes d > 1 μm The simplest distribution approximations are given based on the Kolmogorov direct differential equation