Transform OC from biogenic sources to POM
CONV_OCawb_POMAn object of class numeric of length 1.
Kanakidou, M., Seinfeld, J.H., Pandis, S.N., Barnes, I., Dentener, F.J., Facchini, M.C., Dingenen, R.V., Ervens, B., Nenes, A.N.C.J.S.E., Nielsen, C.J. and Swietlicki, E., 2005. Organic aerosol and global climate modelling: a review. Atmospheric Chemistry and Physics, 5(4), pp.1053-1123.