I agree with Referee #1, Point 1. I see that you have answered to that in your response. However, your response is more a listing of results and not an easy-to-read guide to the main goal and results of the paper. More importantly, you have indicated no related changes in the manuscript. Therefore, I would request you to make related changes to that in the manuscript as follows:

1. Reword Introduction:
- make page 3 line 1 ("In this paper ...") - page 3 line 21 an own paragraph which should be reworded in a way to make clear in an easy to read/understand way what the main goals of the paper are.

2. Try also to improve the wording of the Conclusions to become even more readable and highlight/guide more easily to the most important ones among your results.

Thank you in advance.

Sincerely,
Ralf Sussmann

Dear authors,

thank you for clarifying the wording in Introduction and Conclusions, which have been improved indeed.

One final request for your consideration: In doing the reading for my Editor Review, I realized that you make a long statement about GPS PWV from mountain regions (- as also mentioned by Referee #1). We had analyzed and described this effect of a high bias at mountain sites already in 2002/2003 in my group for the Zugspitze GPS, and you might consider and make reference to our results (which are confirmed by your findings):

Sussmann, R. and Camy-Peyret, C.: Ground-Truthing Center
Zugspitze, Germany for AIRS/IASI Validation, Phase I Report,
EUMETSAT, 2002, 18 pp., http://www.imk-ifu.kit.edu/
downloads/AIRSVAL_Phase_I_Report.pdf, 2002.

Sussmann, R. and Camy-Peyret, C.: Ground-Truthing Center
Zugspitze, Germany for AIRS/IASI Validation, Phase II Report,
EUMETSAT, 2003, 15 pp., http://www.imk-ifu.kit.edu/
downloads/AIRSVAL_Phase_II_Report.pdf, 2003.

Finally, thank you for your revisions and congratulations to an interesting paper.

Sincerely,
Ralf Sussmann