Corrigendum to "First direct observation of the atmospheric CO2 year-to-year increase from space" published in Atmos. Chem. Phys., 7, 4249–4256, 2007

M. Buchwitz, O. Schneising, J. P. Burrows, H. Bovensmann, M. Reuter, J. Notholt
2007 Atmospheric Chemistry and Physics  
After the ACPD open review process and after our manuscript Buchwitz et al. (2007) , entitled "First direct observation of the atmospheric CO 2 year-to-year increase from space", appeared in ACP, we have received some relevant private communications, which we would now like to address. In summary, we conclude that we would like to refer readers of our manuscript to information given in three other manuscripts not cited in Buchwitz et al. (2007) , namely Chédin et al. (2002 Chédin et al. ( ,
more » ... édin et al. ( , 2003 and Strow et al. (2006) . We also conclude that the title of our paper now appears somewhat general and not sufficiently specific to atmospheric CO 2 columns. In our manuscript we report that the CO 2 annual increase has been observed indirectly already by Aumann et al. (2005) by analying AIRS brightness temperatures in the thermal infrared (TIR) spectral region. We have used the term indirectly because Aumann et al. (2005) is not focussing on CO 2 retrieval but on the sensitivity of AIRS temperature measurements to CO 2 variability, including CO 2 trends. We were not aware of results shown in other relevant manuscripts also discussing mid tropospheric CO 2 trends using satellite measurements in the TIR spectral region, namely Chédin et al. (2002 , 2003 ) using HIRS and Strow et al. (2006 using AIRS. In the following we would like to shortly discuss the results presented in these manuscripts focussing on aspects related to the interpretation of the title of our manuscript. As written in Chédin et al. (2002) the TIR radiances in the CO 2 absorption bands "mostly depend on the temperature of the atmosphere but also on the CO 2 concentration". In contrast, our results are based on absorption spectroscopy in the near-infrared (NIR) spectral region using reflected solar radiation, which primarily depends on CO 2 and only weakly depends on temperature. Because of this the NIR CO 2 retrievals may be characterized as more direct but we used di-
doi:10.5194/acp-7-5341-2007 fatcat:4otgsuh7rzgipgm3gl76xhedwy