Corrigendum to "Influence of Giant CCN on warm rain processes in the ECHAM5 GCM" published in Atmos. Chem. Phys., 8, 2949–2963, 2008

Abstract

In the simulations for the paper “Influence of Giant CCN on warm rain processes in the ECHAM5 GCM” by Rebekka Posselt and Ulrike Lohmann (Atmos. Chem. Phys., 8, 2949‐2963, 2008) we discovered that the pre-industrial (PI) simulations included only the effect of pre-industrial sulphate. All other emissions were by mistake present-day (PD). Thus, the reported values for the aerosol indirect effect (AIE) have to be corrected and the conclusions regarding the effect of the giant cloud condensation nuclei (GCCN) on the AIE change slightly. The present-day simulations are correct and thus the conclusions regarding this part are not affected. The corrected figures (Figs. 11, 12, 13) and table (Table 5) appear below. In most cases only the numbers change but the explanation remain the same. Cases where the effect of GCCN on anthropogenic aerosols also changes are discussed below. The changes of the zonal mean GCCN concentration as well as GCCN fraction from the pre-industrial to present-day climate are shown in Fig. 11. The GCCN concentration increases between 45 S and 60 N. Below and above these latitudes the GCCN concentrations are decreasing. These changes are mostly caused by the changes in the 10 m wind speed from pre-industrial to present-day climate as shown in Fig. 12. Most obvious changes are visible in the Southern Hemisphere, where the 10 m wind speed increases between 30 S and 45 S but decreases between 45 S and 60 S. In the Northern Hemisphere the 10m wind speed is slightly increasing. The changes in the annual global and zonal means from pre-industrial to present-day climate are shown in Table 5 and Fig. 13. The increase in total cloud cover (TCC) from PI to PD decreases with an increasing amount of GCCN from 0.43 for CTL30 to 0.4 and 0.33 for simulations GCCN10 and GCCN5, respectively. Main changes are visible in the Northern Hemisphere in analogy to the changes in total water path (TWP) and the cloud drop number concentration (Nl) of the original paper. The decreasing TCC differences results in reduced changes in the shortwave (SW) radiation budget depending on whether and how many GCCN are present. The implementation of the prognostic rain scheme reduces the SW total anthropogenic effect by 0.29 W m 2 in CTL30 and by 0.39 W m 2 in CTL10 as compared to 2 W m 2 reported by Lohmann et al. (2007) for the standard ECHAM5-HAM. In case of the simulation GCCN10 the GCCN number is not yet large enough to cause considerable changes in the SW radiation globally but in simulation GCCN5 the GCCN lead to further reduction in the SW radiation by 0.28 W m 2 . As in