The aerosol weighting function NetCDF variables are:
weight_type (dimensionless integer): the type of the weighting function, with 0 = invalid weight, 1 = no weight ( ), 2 = power weight ( ), 3 = MFA weight ( )
weight_exponent (dimensionless): the exponent for the power weight_type, set to -3 for the MFA weight_type, and zero otherwise