Interactive comment on “A new formulation of equivalent effective stratospheric chlorine (EESC)” by P. A. Newman et al

The present paper (Newman et al.,) reports on a new formulation of the equivalent effective stratospheric chlorine (EESC), and attempts to forecast the EESC for the coming decades. Notwithstanding that such a study could make a very valuable contribution to prognose the future threat of the ozone layer by halogens, it largely fails to calibrate the forecast with past and present field data. As argued in more detail below, this is most important to assess the EESC of stratospheric bromine, for which 25 % is known to come from other sources than CH3Br and the halons (e.g., Dorf et al., 2006). Also, since the calculation of EESC involves parameters such as ages of stratospheric air masses (and their age distribution) and fractional release factors (fi) for the species under consideration, a robust approach would need to calibrate the model result with