AN ANALYTICAL STUDY ABOUT THE RATIO BETWEEN PARTICLE MASS LOADING ANDEXTINCTION - APPLICATION TO DESERT DUST AEROSOLS

Here the goal is to study the behaviour of the ratio between aerosol m ass loading M and extinction tau(a)(lambda) at a given wavelength, gen erally at 0.55 mu m. The simple ratio M/tau(a) is currently applied in aerosol studies to estimate total vertical mass aerosol content, but this ratio shows a strong variability. Obviously the M/tau(a) ratio is dependent on the aerosol size distribution model so we have carried o ut a theoretical analysis to observe this dependence. Two functions we re selected, the Junge and the lognormal function. By means of their c umulative values the M/tau(a) ratio is evaluated as a function of aero sol parameters. The results clearly show the dependence and variabilit y of the M/tau(a) on the aerosol size distribution model and parameter s. An additional problem is analysed in the case of the Junge function due to the dependence of this function on the limits r(1) and r(2) Of the size distribution. The study is applied to current desert aerosol models together with a real experiment, carried out in Senegal, Afric a. (C) 1997 Elsevier Science Ltd.