MS: “P.J. Crutzen – interactions with friends and colleagues” by R. Müller et al.

The present manuscript is yet another biographical description of P. J. Crutzen which complements previous texts. P. J. Crutzen was a brilliant scientist of the late 20st century and beyond. He has advanced atmospheric sciences in a manifold of its facets like hardly anyone before. He therefore deserves preserving memories and biographical annotations.

P.J. Crutzen worked on all compartments of the atmosphere with a focus on the understanding of the origins of human induced impact on the atmosphere and on climate. He not only was the first to pin down scientific explanations on a number of yet unknown issues such as the significance of the NOx cycle in stratospheric ozone depletion, the origin of the ozone hole over Antarctica, the role of biomass burning and aerosols in tropospheric chemistry and the aspect of a “nuclear winter” after an assumed nuclear war and others.

Being an inquisitive person he also inspired students and colleagues in different institutions in the US, Germany and beyond. In this aspect his kind hearted and humorous personality was a real asset and made him an empathic partner in any discussion.

The present manuscript is a collection of short summaries of experiences and impressions by a number of colleagues who have collaborated with PJC as students and colleagues. The MS starts with a brief history of his early life written largely by his wife and children and extended to include a brief survey of the different institutions in which he has worked.

The major part of the MS is devoted to individual anecdotes written by Lennart Bengtsson, John Birks, John Burrows, Ruprecht Jaenicke, Richard Stolarski and Rolf Müller. In general, all anecdotes are informative and enlightening. However, they are somewhat out of balance in length and details of information.

The most informative section is the one by John Burrows, who was a post-doc with PJC in Mainz and later benefited from his endeavour as science manager in promoting remote sensing a new tool in atmospheric observation with the result that JB built a formidable career as a leading scientist in this field after his appointment at the University of Bremen.

The section by Ruprecht Jaenicke is equally of importance because he highlights – among other things- the difficulties that PJC experienced with his appointment as a director of a conventional MPI institution in Germany including the disrespect that he faced by the faculty of the University of Mainz. The relation between the two only remedied after PJC received the Nobel prize in 1995.

Rich Stolarski describes some important discussions that he had with PJC on the potentiality that chlorine chemistry increases stratospheric ozone rather than depleting it as commonly accepted at that time. However, he also notes some imperfection of PJC in pointing out to us his sloppiness in writing computer codes with seemingly irrational annotations. Note by the reviewer: In aspects of adhering to the bureaucracy of German administrators in writing grant applications – such as in the special research areas of the “Deutsche Forschungsgemeinschaft” PJC was not the

Rolf Müller describes his experience with PJC as a Ph.D. student in Mainz with hints towards PJCs impatience in seeing the students generating new results. The experience with science talks on such crazy days like “Weiberfastnacht” is legendary.

As mentioned above the different sections are out of balance. I believe that the manuscript would have benefited a lot from one of the authors acting as an editor. Moreover, it is not clear why some anecdotes have subheadings and others do not. This could be more uniform.

A final comment from the reviewer regarding the Arabba conference in the dolomites  in 1977, which was organized by Karlheinz Becker from Wuppertal and which was mentioned here by John Burrows. The current reviewer attended this conference also. In his view this was one of the most exciting events in early atmospheric science, combining intellectual and social activities, and with PJC as the rising star of atmospheric chemical issues and especially admired by us, the younger generation in the field. It well deserves mentioning in these biographical notes on PJC.