2-DIMENSIONAL MODELING OF SOME CFC REPLACEMENT COMPOUNDS

The Cambridge 2-D Eulerian model has been used to study the potential atmospheric distributions and lifetimes of a number of CFC replacement compounds and their degradation products. The study has focused on HF C 134a and HCFCs 123, 141b and 142b and the major products formed by t heir atmospheric degradation. The loss of these compounds and their pr oducts by hydroxyl radical attack, photolysis and in-cloud hydrolysis have been investigated. The study has shown that HCFCs 141b and 142b h ave sufficiently long lifetimes to enter the stratosphere in significa nt quantities, where degradation leads to an increase in the total str atospheric chlorine concentration. The study has also highlighted area s where further experimental work would be valuable, in particular cha racterisation of the product channels for the degradation reactions an d determination of the removal rates of the products in the aqueous ph ase.