The authors have adressed most issues raised by the reviewers. There are a few points where I suggest some additional clarification:

* The new Figure 9 needs some explanation. Please explain more carefully what the surface residence time is and how it is calculated.

Reviewer #2 questioned the usefulness of figure 6-8. In general it seems to me that the main message of these two figures is now condensed in Figure 9. I suggest to consider either leaving out figures 6-8 or explaining them a little more. Right now they are presented and very little discussion is actually given to the figures.

The answer to the remark of reviewer #2 regarding the seasonality of the UTLS is not satisfactory. I suggest to at least discuss the difference in seasonality between stratosphere and troposphere and point out that this will influence the column but not the ground measurments, procifing a further possible shift in seasonality. I think that the magnitude of the possible effect can be discussed without the need for a large model study.

The change suggested by the author on p. 15. l 27 regarding the non-exploitation of the vertical resolution of the FTIR data is misleading, as it may suggest that the FTIR has a good vertical resolution which was just not exploited. Please merge the old and the new statement, explaining that vertical resolution is poor and was therefore not exploited.

Most remaiing questions have been clarified.

There are two issues, where I would like to see some improvements.

The first one is the description of the residence time. Please be a little more explicit on what this represents. It is then o.k. to refer to Henne et al. for the way it was calculated.

The second point is the phase shift with respect to the stratosphere. The reason for the phase shift in the stratosphere is not a shift in the seasonal cycle between the tropics and mid latitudes in the troposphere. The different phase of the seasonal cycle in the lower stratosphere is caused by a time lag for tropospheric air to reach that area. I suggest to quantitatively mention that the seasonal cycle in the lower stratosphere is shifted with respect to the troposphere, that this will influence the column and the seasonal cycle of the column, but not the ground based measurements and that this should be explored more closely in future studies. Modelling the seasonal cycle of CO2 in the lower stratosphere is far from trivial, so it is plausible that a quantitative assessment of this effect is beyond the scope of this study.