Preliminary results of atmospheric aerosols measurements over chad rainfall impact on particles quantitative study

This paper studies the vertical distribution of atmospheric aerosols by concentrations and mid-volume diameters over three localities in a band of land situated likely inthe middle of Chad, namely N’djaména in the western, Abéché in the centre and Amdjarass in the eastern parts of the country. The measurements were made in the program OPEN with the use of aircraft and appropriate instruments presented in the text. This experiment took place from 2011 to 2012. It precised our knowledge on the vertical distribution of aerosols in the atmosphere. Notably, they are more concentrated near the earth surface and decrease with the height increasing. They are encountered till almost altitude 6000 m. With regard to their mid-volume diameters, various sizes particlesare observed in the troposphere till altitude around 5000 m. Their mid volume diameters vary from 0.2 to 0.8 μ m. Upper height 5000 m particles with mid diameters from 0.2 to0.5μm are most encountered, particularly during the rainy season. This vertical distribution is the consequence of the rainfall impact on the aerosols. The quantification of the washing effect of rain on atmospheric particles indicated that this phenomenon is intense near the desert.