WRF-Chem simulates excessive dust in North Africa（dust_opt=3）

[Pengwen Fu]

I am using WRF-Chem 3.8 dust_opt=3 or dust_opt=4 to simulate dust in North Africa for the month of January 2015, and I am able to achieve a total dust of 30,000ug/m3 by dividing the dust into five bins. I would like to know if I have to modify the emission factors etc. to match the real observation?