The description of DTW (cloud chemistry timestep) in AQCHEM

CMAQ
1

Hi everyone,

Recently I am reading aqchem.F. I notice the description of DTW (cloud chemistry timestep) in aqchem.F:

DTW( 1 ) = -0.05D0 * MIN( TH2O2, TSIV ) / DSIVDT( 1 )
DTW( 2 ) = -0.01D0 * MIN( TO3, TSIV ) / DSIVDT( 2 )
DTW( 3 ) = -0.1D0 * TSIV / DSIVDT( 3 )
DTW( 4 ) = -0.1D0 * MIN( TMHP, TSIV ) / DSIVDT( 4 )
DTW( 5 ) = -0.1D0 * MIN( TPAA, TSIV ) / DSIVDT( 5 )

I wonder why the coefficients multiplied in each of the expressions are different.
Much appreciated for your answer!