FIT EQUATIONS FOR f(RH)

The parameter f(RH) describes scattering as a function of relative humidity. We define f(RH) as the ratio of scattering at 85% RH to scattering at 40% RH:

f(RH)=bsp(85)/bsp(40)

We have two equations we use to describe how scattering changes with humidity. These equations are fitted to measurements of scattering at different humidity made by our humidigraph system (currently at SGP and KOS). The fits are then used to determine the value of f(RH). The 2 parameter fit is more commonly used, however the 3 parameter fit appears to work better with deliquescent-type aerosols.

2 parameter fit

bsp(RH%)/bsp(~40%)=a*[1-(RH%/100)]^-b

3 parameter fit

bsp(RH%)/bsp(~40%)=a[1+b(RH%/100)^c]