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Interview of Hans Hinzpeter by Hans von Storch and Klaus Fraedrich on 1995 Spring, Niels Bohr Library & Archives, American Institute of Physics, College Park, MD USA, www.aip.org/history-programs/niels-bohr-library/oral-histories/35176
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In this interview Hans Hinzpeter discusses topics such as: how he got into meteorology; Potsdam Observatory; radiation measurement; Institute of Marine Sciences in Kiel; International Association of Meteorology and Atmospheric Physics (IAMAP); Howard Georgi; Meterological Institute at the University of Hamburg; University of California, Los Angeles; maritime meteorology; Max Planck Institute for Meterology; atmospheric physics; cloud-radiation interaction; climate models; climate research; satellites; Klaus Hasselmann; result of carbon dioxide on climate change; Ed Lorenz; boundary layer clouds; Centre for Marine and Atmospheric Sciences; Joeseph Smagorinsky; Han Ertel; Albert Defant; Julius Bartels.
Mr. Hinzpeter, on 31st January 1996 you will turn 75. You have been dedicating yourself to meteorology already as a young man and have thus witnessed crucial developments in this science. What were your first impressions?
I joined the air force during the war when I had just entered the job market and was a young meteorologist. Precise formulation was necessary to give useful advice. A typical forecast of a front was: Approaching cirrus will reach the airfield at 13 o’clock, at 16 o’clock the lower level of the clouds will have sunk to 3000 metres and at 17 o’clock it will start raining. Such a prognosis was based on insufficient data and partly also on questionable methods. Nevertheless, I found that challenging, and the need to formulate accurately as very beneficial in forcing one to think precisely. I came across also other predictions for larger areas and longer periods. Inevitably, these were less accurate and would have misled me into vague thinking. Having become acquainted also with other branches of meteorology, however, I was disappointed by the prevailing, mostly non-reproducible forecasts, especially since even eminent meteorologists considered weather forecasting to exhibit more the character of an art than an exact science. Therefore, I wanted to study physics after the war, and had saved the necessary money. After the war, however, the occupying powers cleared all bank accounts, and so I could not carry out my intention. I had to earn money. First I worked as an assistant teacher at a grammar school. After several unsuccessful applications I finally managed to find employment in the radiation research division of the Meteorological Observatory Potsdam.
After all, that was very different from the meteorology you knew and from what you were presumably taught during your studies?
That is certainly true. The Potsdam Observatory and especially Mr. Feußner, the head of radiation research, had a good international reputation, and during these years I learnt a lot about the experimental technique of radiation measurement, but also about radiative transport — Chandrasekhar’s book "Radiative Transfer" was published in 1950. In general, Potsdam had a very favorable scientific climate at that time, if one disregards the political constraints. The Geomagnetic Institute, the Geodetic Institute and the Astrophysical Institute were on the same grounds, so that there were quite a number of inspiring colloquia, not only on meteorology. There were many young scientists at the institutes. After the years of war, everyone was striving to do scientific work as independently as possible. It was a very pleasant time.
Nevertheless, you went to Dresden. How did this come about?
I cannot really tell. When you enjoy science, you work, you are interested in all kinds of new questions, and you do not think about what today one would call a career. Then, I was asked whether I wanted to take over the management of the observatory in Wahnsdorf near Dresden. I went there because I was tempted by the greater independence. A disadvantage was the larger distance to West Berlin, to which we still could go unhindered in those days. But at the same time there was a larger distance from the office in Potsdam, which was more politically biased. I had to adapt to new tasks at the institute in Wahndorf, since the work there included not only radiation observations but also air-chemical analyses of the natural and artificial radioactivity of the air. It was the time of the H-bomb tests, and we were concerned with the retention time of natural radioactivity in the atmosphere and the spectrum of the hot particles originating from H-bomb tests. In addition, the observatory operated an air chemical measurement network which monitored, among other things, the variation of the near-surface ozone concentration… In those days, I thought this was rather uninteresting and should better be the task of a hygienic institute. Today these observations belong to the longest series of ozone observations and have a very topical scientific value. Although a reasonable political climate prevailed at the observatory itself, the general situation at that time had deteriorated. It was the period of the “peasant clearance”, when even the last small farmers were forced into the agricultural cooperatives. The directors of institutes were also supposed to visit peasants and subject them to moral pressure. Even though I could avoid that, the general situation had become quite unpleasant.
You then transferred to the Institute of Marine Sciences in Kiel which is, after all, a completely different field of activity. What was your reason?
Through my work on radiation, I had been able to become acquainted with Fritz Möller, a professor in Munich, originally from Thüringen in East Germany, who was very open minded towards young scientists in the GDR. He nominated me for election into the IAMAP International Radiation Commission, which gave me the opportunity to participate in conferences in western countries. In the beginning of August 1961 I went to a meeting of the Ozone Commission in Arosa and afterwards to a meeting of the Radiation Commission in Vienna. During this time the GDR erected the Wall. Not without some scruples, I decided to stay in the west, which was possible only because my family was in Freiburg in the west at that time. Through my radiation research, I already had developed some relation to marine research. At the beginning of the fifties, Mr. Georgi from Hamburg paid us a visit in Potsdam, in order to compare his radiation instruments with the standards in Potsdam. Georgi had overwintered in “Eismitte” during Wegener’s Greenland expedition, and thanks to this experience he had been able to establish good relations with the French Greenland expedition. He asked me whether I would join a French expedition to Greenland. I accepted enthusiastically, the French approved, but the Danish Ministry of Greenland refused a visa. At that time the International Geophysical Year was being prepared, and in a shipyard in Rostock the research vessel “Lomonossow” was being built for the Soviet Union. Probably provoked by the failure to participate in the Greenland expedition, the administration of the (East-German) Meteorological Office achieved a participation of GDR scientists in maritime expeditions of the “Lomonossow”. That way, in 1958 I became a participant in a 4 months expedition in the North Atlantic. Apart from measurements of the radiation and energy budgets I mainly dealt with diurnal temperature variations and their explanation by the divergence of shortwave and long-wave radiation fluxes. Such an expedition is also marked by months of monotony, because the sea looks the same everywhere, and the measurements gain their value by constant repetition. Thus, I also had gained some — admittedly small — understanding of maritime meteorology. I encountered favorable conditions in Kiel. Succeeding Mr. Wüst, Mr. Dietrich had become director of the Marine Research Institute, and on that occasion a division for maritime meteorology had been established, headed by the young Defant, the son of Albert Defant. I acted as assistant in this division, which meant adapting again to new conditions, but at least I could work again. However, the change from being the director of an institute to an assistantship was not always easy for me.
You made a new start in Kiel, while in Hamburg there was the Meteorological Institute which had been dealing successfully with issues of maritime meteorology for many years. Was this not a difficult situation?
Yes and no. We began new in Kiel and did not have any equipment at first. However, everyone at the Hamburg institute provided excellent support. Nevertheless, I was looking for a field of activity which was not already covered in Hamburg. Based on my experience gained on the expeditions, I decided to study the viscous boundary layers at the air-sea-interface, and its impact on temperature variation at the water surface, and to determine the divergence of long-wave radiation near the water surface. Afterwards I obtained my Habilitation with the results of this work. During that time I participated in two expeditions, the Indian Ocean Expedition and the Trade Wind expedition in the Atlantic. After that I spent almost a year at the Meteorological Institute of UCLA. I gave lectures there following a prescribed concept, but, in doing so, I learnt a lot.
Yet, you were soon to change institution and field of activity again. Why was that?
I was very happy in Kiel, but the situation — I had become senior assistant in the meantime — could not satisfy me in the long run, after my independent position in Dresden. When I was offered to head a small, but independent institute in Freiburg, I accepted the call. As I had come into contact with turbulence during my work in Kiel, in Freiburg I wanted to examine turbulent transports above forests and the interaction between the turbulence field and the forest. For this purpose, we set up a research station above a young spruce forest in the Rhein meadows. As I spent only two years there, and the Trade Wind experiment I mentioned took place during that time, I failed to really complete the planned study. The only achievement was the development of an instrument for measuring the turbulent heat flux. In my measurements of the profiles of wind, temperature and heat flux, the impact of the very small heat capacity of the fir needles surprised me. When the sky as almost clear and the sun was high, the heat flux was, of course directed upwards. However, when a small cumulus veiled the sun, the direction of the heat flux abruptly reversed, only to immediately change its direction again when the sky cleared. When I accepted an offer by the Meteorological Institute at Mainz University, I knew that they had already a strong group dealing with atmospheric radiation, and that this subject was also covered at other German universities. On the other hand, the question of turbulence and its impact on the processes in the boundary layer had not been treated in detail in the Federal Republic. Therefore, I built up a small group in Mainz dealing especially with processes in boundary layers. I myself worked on the damping of turbulence by long-wave radiation. Because of my participation in several maritime expeditions, Mr. Brocks [Professor of Meteorology in Hamburg] asked me to join GATE (the GARP [Global Atmospheric Research Program] Tropical Atlantic Experiment) and help in its preparation. After the death of Mr. Brocks I became responsible for the international cooperation of the three vessels participating in the experiment. Thus I became involved in management. Among my tasks was to set up a German group in the international steering centre in Dakar and later to organize the analysis of this very large experiment. An attempt to call me to Munich University failed, because at that time I had spent only two years in Mainz, and the Ministry in Mainz did not agree to the change. But after having stayed in Mainz for five years, I could then accept an offer by the University of Hamburg. Hamburg had a very strong group working on maritime meteorology, which was internationally well-known for its very accurate experimental studies. It was also supported by a large Collaborative Research Centre, so that the financial conditions were attractive. At first, this group had also been supported by a Fraunhofer Institute, which was later closed and partially taken over by the new Max Planck Institute for Meteorology in Hamburg. This offered great future prospects; so I went to Hamburg and stayed there until I received emeritus status. Following Mr. Hasselmann, I became speaker of the Collaborative Research Centre. In spite of the favourable conditions in Hamburg, it was not easy for me to leave the very inspiring scientific environment in Mainz.
Did you get engaged into scientific management even more strongly then?
This is certainly true. During that time I was managing director of the university institute and director of the Max Planck Institute in the division Atmospheric Physics, as well as speaker of the Collaborative Research Centre. After Mr. Möller had received emeritus status, I had also taken on the chair of the German GARP Committee. But another function was added. I had noticed, already back in Kiel, a significant difference in the style of communication among meteorologists and oceanographers in Germany. The personal exchange of ideas between meteorologists was limited to the conversation between tenured professors at the meetings of the scientific advisory board of the weather service twice a year. The Priority Programme of the oceanographic community, in contrast, enabled the integration of all scientists in the scientific exchange of ideas. Because of the increased involvement of meteorologists in international programmes, it became possible to establish a Senate Commission on Atmospheric Sciences with the German Research Foundation DGF, which had quite a positive influence on the development of meteorology in Germany. As initiator I had to take the chair of this commission, too. Today, however, through the greatly increased funding of climate research through the Federal Ministry for Research and Technology BMFT, the significance of the DFG for climate research has been strongly reduced.
You still remained active after receiving emeritus status. How did that come about?
After I became emeritus I wanted to concentrate on the issue of cloud-radiation interaction. We had dealt theoretically, and also as in the framework of larger experiments, with the development of clouds in the boundary layer. The problem is not satisfactorily solved, “however” for application in climate models. But then, totally unexpected by me, there suddenly came the opportunity for the reunification of the GDR and the Federal Republic. I had grown up in a unified Germany, and for me the division of Germany had been a disaster. The reunification was very fortunate for me. When at the age of 70 I was asked to participate in evaluating and re-establishing scientific institutes in the former GDR, I gladly accepted the challenge, probably also because, due to my past, I thought I could understand the situation of the people there better than someone who had grown up in the west. I cooperated in the evaluation of the observatories of the Meteorological Service and of university and academy institutes, which pursued environmental research in the broader sense. The result were proposals to found the Institute of Atmospheric Physics, the Baltic Sea Research Institute, and the Institute of Tropospheric Research. I am still a member of advisory boards and boards of trustees of these institutes. It is still interesting and I hope I am still able to help. However, as I am not chairman of these boards, the work load is relatively light. Unfortunately, I was unable to secure my former observatory near Dresden, because its profile was inconsistent with the functions of a weather service according to the weather service law of the Federal Republic. During the establishment of the Institute of Atmospheric Physics in Kühlungsborn, I worked as founding director until April 1993. The main work, however, was done by Professor Schmitz.
What was the procedure with such an evaluation and re-establishment?
Among other things, the Scientific Council had formed a group to visit and evaluate institutes working in the field of environmental research. The members and especially the chairman of the group were very objective and anxious to understand the difficult situation of those to be evaluated. I perfectly understood that GDR citizens, who had arranged their lives in the GDR, after having heard from the Federal Republic for many years that the GDR was not to be destabilized. We therefore limited ourselves to evaluating the scientific potential and did not ask for party affiliation and the like. Nevertheless, our task was difficult. We had only one day to visit and evaluate an institute with 100 employees. Part of the decision was to determine how many scientists and technicians should belong to an institution which should be re-founded. This number was always smaller than that in the former GDR institute. Sometimes we felt this task was unacceptable, and many asked themselves whether they should cooperate. We finally told ourselves that if we withdrew, others would take our place who would not make it better. I think, however, that we solved the problem reasonably well, in spite of the need to finish the process by June 1991. The number of re-foundations proposed by the different evaluation groups was undoubtedly larger than the financial bounds set by the politics. The resolution of this problem was left to the Scientific Council, which included the chairmen of the evaluation groups. After the evaluations were concluded, I heard nothing further about the matter until in August 1991, when I was invited to participate in the Founding Committee for the Baltic Sea Research Institute. In October 1991, the state ministries in charge and the BMFT asked me to chair the Founding Committees for the Institute of Tropospheric Research in Leipzig and the Institute of Atmospheric Physics in Kühlungsborn. In the short time from mid-October until shortly before Christmas, we had to establish the institute in Kühlungsborn, to advertise the positions, to evaluate and decide upon the applications, and to fix the budget, including the salaries. This was quite a strange period. Other hard decisions also had to be made. According to the Scientific Council’s recommendations, 10% of the scientific positions should be reserved for applicants from the west, and 20% of all positions should be filled only temporarily, in order to leave some freedom in appointment for the directors who were to be elected in the future. Further important decisions had to be made with the goal of achieving a reasonable age structure. The institute was finally founded, but other interests also entered.
Were these also of a party-political kind?
In a certain sense, yes. The State of Mecklenburg was quite formal in this respect. It wanted to ensure that scientists who had been dismissed from the university for party-political reasons would not find a position in the newly founded non-university research centres. Therefore the performance of every single applicant during the last 30 years had to be assessed. Rules were established for which sanctions were to be imposed. The rules were very formal. For instance, a former party secretary had either to be barred from managerial functions for several years or to be removed from the institute. In the case of a smaller institute with, e.g., only 10 party members, of course, everyone had once been party secretary. As founding director you automatically belonged to the honour commission which had to assess the behaviour of the institute’s members. That was an unpleasant time. Other states acted in a less formal way. A different style of working prevailed in the GDR.
In what way did that affect the re-foundations of the institutes?
In the scientific field, I hardly noticed any difference in the way of working. Of course, there were institutes of different quality. But let me come back to the institute in Kühlungsborn. During the crucial years 1990 and 1991 a wide range of good manuscripts was published by the scientists of the institute, to a large part in American journals, although this time was certainly very irksome for the members of the institute, who had to adapt to the new extended bureaucracy.
You were also concerned with the observatories of the GDR’s Meteorological Service. Can you comment on that?
Before World War I and partly still after World War II, the observatories Lindenberg and Potsdam had a very high international reputation. I was against closing both or even one of them, and I was committed to preserve them and to equip them with modern instrumentation. They were finally maintained, thanks to the head of the environmental evaluation group. As I had been working in Potsdam until 1958, I met many familiar colleagues again. This happened totally without prejudice, perhaps because I had grown up in the original unified Germany and thus had neither a West German nor an East German identity.
You took part in initializing fundamental climate research. How do you judge the significance of the models for climate science?
The climate models have developed from the weather prediction models via general circulation models. As I said, I was disappointed by the rules and methods of forecasting weather in the forties, and that is why I wanted to study physics. I have since seen an extraordinary improvement in the development of numerical weather forecasting. Even if numerical predictions were not better than the classical ones, they were superior, because of their reproducibility — or at least their improved reproducibility. I was quite impressed by Smagorinski’s work, which was published in 1964. It mainly provided a synthetic climatology. Although, of course, if the water surface temperature is given, the result must be more or less correct. It was clear that it would need to be coupled to an ocean model. It took, however, nearly another 30 years to overcome the inherent difficulties of doing so. Another event impressed me very much. The first satellite film was shown at the IUGG Conference in Helsinki. It was a camera film shot from a non-stabilised satellite. The pictures taken from the irregularly swaying satellite were confusing. But suddenly the spiral cloud picture of a large low pressure area could be discerned. Though it was possible to construct such a picture from ground observations, this image was quite convincing. The following developments produced an important tool for medium-term weather forecast and for the assessment of the radiation budget. When later five geostationary and two polar circulating satellites were planned, I became concerned that one central office would be created to collect the data necessary for a global weather forecast, and thus only one centre for the forecast for all regions of the world would emerge. This was a very theoretical idea. I similarly thought it would be sufficient to collect all necessary meteorologists in one place, and to provide forecasts for all places in the world from there. This was at least premature, because even if numerical forecasts are reproducible, the predictions themselves have not yet reached that stage. The conclusions a meteorologist draws from the fields of wind, temperature and pressure will be different for the islands in the North Sea and for the Alpine foothills. Experience gathered on site still plays an important role. Further progress in Model Output Statistics, however, will gradually reduce the importance of experience.
You also addressed the issue of satellite development, a field that should be of special interest to you who comes from radiation research. Can you tell us anything more about that?
I think remote sensing possibilities are not nearly exhausted. So far, for reasons of energy supply, almost exclusively passive remote sensing methods are used on satellites. Profiles of temperature and water vapor are deduced from spectral measurements in the CO2 band and the water vapour bands. For this purpose, integrals must be inverted, in which the relevant matrices are very badly conditioned This is still very unsatisfactory today, so that methods of active remote sensing will no doubt be more used in the future. For example, the profile of backscatter yields estimates of aerosol layers, which are almost always correlated with changes in the temperature gradient. That alone could improve the present methods. Adding line width and Doppler shift, the profiles of temperature and wind would become even better, independent of cloud occurrence. This requires a larger energy source on the satellite, but with the active radar used on the ERS 1, this possibility has been demonstrated. Perhaps I should insert a word on the importance of geostationary satellites. The images obtained in the visual range replace many-hours of lecturing on climatology and general circulation. A series of such images clearly illustrates the variability of the circulation. I am more cautious about the possibility of deriving fluxes at the ocean-atmosphere interface from satellite data. Many parameterizations enter here. Relevant is not whether one can obtain high skill in determining the fluxes averaged over all oceans. This is not difficult, because most of the area is represented by subtropical seas, where there is hardly any weather but only climate. In general, it should always be checked to what extent the fluxes gained by satellite are better than the fluxes calculated on the basis of other data — clouds, geostrophic wind, classical determination of water temperature.
Can we get back to the models again?
Climate models, as well as their builders, face more difficult challenges than weather forecast models. The latter can be examined and, if necessary, improved every day in different weather situations on the basis of daily comparisons of prediction and reality. The climate models are much more complex; verifiable predictions are impossible. One can verify only the simulation of the global temperature change observed during the last 130 years. For many issues, however, the change in precipitation rates is more important than the temperature. This applies also to my somewhat cautious assessment of predictions based on changes in carbon dioxide concentration. In my view the problem of cloud formation and dispersal has not yet been solved satisfactorily in climate models. Nevertheless, the further development of climate models is necessary, because they are the only possibility to improve our knowledge. With the help of such models we have greatly improved our understanding of climate, especially regarding the role of the ocean. However, we also learnt that there may be quasi-periodic variations with periods of several hundred years in the ocean. Their amplitude and phases are unknown for the present and are an uncertainty factor in climate forecasts.
What do you think of the significance of atmospheric trace gases in general?
I have thoroughly changed my views on that during the past 20 years. We now know of a whole series of trace gases which are of similar importance as CO2 regarding the reinforcement of the greenhouse effect. They must be considered in the models. Another trace substance is aerosol particles which might partly compensate the greenhouse effect. The increase of condensation nuclei can lead to a change in the cloud drop spectrum, to a larger number of drops, and thus to an increased reflectivity in some types of clouds. At least over the oceans, an increased number of aerosol particles alone without clouds — would cause a similar effect. It is difficult to extract the impact of, e.g., the altered concentration of a trace substance from the results obtained with a very complex climate model. In view of this great complexity the development of simple, transparent models should not be neglected. In the former GDR, for example, simpler models were generated which could more easily be used to gain basic insights.
Climate impact research is presently much called for. How do you see this?
This research should have been intensified already 15 years ago. Unfortunately, there was nobody who focused on it the way Mr. Hasselmann focused on climate research. It was often said that it was necessary to wait until the models could produce reliable results on the impact of an increase in CO2 on climate change in, e.g., Bavaria. I never shared this opinion. I always considered it advisable to specify plausible scenarios for precipitation and temperature and to establish the resultant impact on plant growth, harvests, etc. However, this is not yet a description of atmosphere/biosphere interaction. Presently, studies of the cycles of matter related to the biosphere are developing, so that climate impact research can be expected to expand in this direction.
Since when have you been dealing with climate issues? Were you not a meteorologist earlier and have become a climate researcher only recently?
If you define meteorologist as weather forecaster, I can understand your question. However, for me the term meteorologist includes climate researcher. At the beginning, I said that I had been disappointed by the qualitative methods of synoptic meteorology. If I had gone to the weather service, I would have tried to work in the climate division, because they work with quantitative methods there and thus obtain reproducible statements. Especially with modern statistical methods interesting problems can be studied. Of course, this is not directly related to climate models. But climate research is more than climate modeling. I do not see myself as a climate researcher. My colleagues and I have examined the development of boundary layer clouds with the aid of experiments as well as with models. The results, of course, were also of significance for climate models. I took part in developing the logistics of fundamental climate research. Based on my experience in the field of marine research, where the research vessel “Meteor” was administered by a governmental institution and was at the scientists’ disposal during 50% of its operating time, I was in favour of providing and operating the necessary large-capacity computer by a governmental institution, so that the scientists would not be burdened with the associated logistic questions. However, a different and by today’s standards better way was chosen. In addition, I have always been of the opinion that the task of fundamental climate research is to examine climate variations and to separate between system immanent components and components caused by modified boundary conditions. Among the basic insights, which were not linked to climate models, was that of Mr. Hasselmann, showing that a white noise atmosphere induces red noise in the thermally inert ocean. Mr. Mikolajewicz then showed numerically that in an Atlantic model forced by white noise quasi-periodic variations of the circulation of several hundred years emerge. We do not know, however, in which phase the ocean is presently in.
What do you think will be the most interesting developments in the next 10 years?
I can only make assumptions here. The climate models’ development was made possible by computers with increasing capacities. In future, parallel computers will become more important, and that will allow further models advancements. The presently still unsatisfactory performance with respect to small regions will be improved, and the correct integration of further trace gases as well as the gas exchange between biosphere and atmosphere will be taken into account. Keeping in mind, how significant the development of computer technology —, which could not be foreseen 20 years ago has been, for climate modeling, I am cautious with prognoses.
Are there other works which made a special impression on you?
There was certainly the work of Ed. Lorenz. Initially I saw its relevance mostly for the limits of weather forecasting. The additional fundamental meaning I perceived only later.
We want to ask a question concerning scientific policy. How do you judge such institutions as, e.g., the IPCC?
I have to restrain myself, because I cannot really judge this. It is an institution for advising the UNO, i.e., acting in the political arena. In the Federal Republic, climate research is supported by the BMFT. I always see in such a situation the danger that a certain policy is supported, and results are interpreted, according to the governing ideology. But I want to be careful and not judge anything.
I once was requested to comment on the issue of a possible intensification of storms and their implications for the insurance industry. We climatologists find ourselves in a different role than 20 years ago. The public is interested in the results of our work, and this changes our self-image. Did you have similar experiences?
Climatologists had to submit statements and reports in the past, too. Today, many of them are asked for statements for which they have to rely on climate predictions. In addition, radio and TV journalists address this question to a much larger extent than before. In these cases it is essential to unemotionally describe the obtained results as well as their limitations and uncertainties.
Did you act in public yourself? Did you give interviews concerning these problems?
I always watched climate research with great interest, but that does not qualify me as a climate researcher. As I said, we dealt with boundary layer clouds, and also with remote sensing. Therefore, I always referred people who asked me for an interview to other, more competent persons. From my point of view, advice to politicians must be limited to the presentation of our knowledge, the obtained results, and the uncertainty those are afflicted with. The politician, not the scientist, must make decisions on the basis of this information. As information is never complete, and the estimations for the future are afflicted with uncertainty, these decisions may, of course, be wrong. Otherwise they would not be decisions. In my opinion, the development of the automobile is a good example. If 100 years ago the proposal had been made to develop a means of transportation, designed to increase individual mobility and thus individual freedom, this proposal would have been welcomed enthusiastically. If, however, the proposal would have included an increase of the number of deaths on the road, we may imagine what would have happened to this proposal in an emotionally stirred time like today. Nowadays, we lose the inhabitants of a medium-sized town to traffic each year, and we live with that. In addition, the politician must also balance causes and prioritize. Do I spend several billions on a flight to the moon, or do I use this money for social purposes?
Is it good for science that there are so many questions related to applications, and that science partly turns into project science, so that the sponsoring institutions only support basic research as far as it is necessary?
This question cannot simply be answered yes or no. When a discipline is sponsored with large sums, and there is a large public interest in its object of research, there is a certain pressure for justification. This pressure strongly depends on public interest. In addition, the term basic research is a little vague. It is often used to describe pure research, which is an important feature of our western culture and the results of which are, in our experience, often used for applied research many years later. Of course, the BMFT must apply other criteria in research funding than, e.g., the DFG or the Max Planck Society. I somewhat regret that the DFG has lost some of its importance for our field.
How would you compare German research funding to that in other countries?
Some other countries invest more into research, although less so in our field. A serious disadvantage for our country is the animosity against science which prevails in public discussions and, in a large part, in public opinion. It is concerning that too few people clearly oppose this animosity with strong statements. What will become of the Centre for Marine and Atmospheric Sciences ZMAW?
I do not know. I initiated it some time ago, and Mr. Sündermann has promoted it energetically. Its realization was then delayed for a long time, and now funds are scarce everywhere. The ZMAW represents an institutionalised cooperation between the geoscience institutes of the University of Hamburg and the Max Planck Institute of Meteorology. The ZMAW was created in [???] to combine and strengthen Hamburg's existing expertise in marine, climate and earth system research. One problem was perhaps that I wanted it to be a centre at the university, taking the Kiel Institute of Marine Sciences as an example. This met with opposition.
What is your opinion on the democratization of the universities? As a managing director of the university’s Meteorological Institute you were re-elected every two years. Were there also voices of dissent?
Oh yes, every time! Once, there were four votes for me, including my own, and four votes against me. The election was repeated twice, and the final result was one abstention and three votes against me. I had not consulted all panels regarding the acquisition of the mainframe computer. I have never fully understood the reasons for the democratization. There may have been disciplines where a tenured professor, hovering high above all others, issued instructions without allowing discussions. I do not think that this was the case in our discipline or, e. g., in physics. Whatever the structure, clear decision-making processes and responsibilities are necessary. When a panel votes, perhaps even by secret ballot, nobody can be held accountable.
Can research be effective in an institute customized to a single person?
The Max Planck Society works on this principle, and largely with success. When the director makes a decision, it is based on the best possible information which he has obtained in discussions within and outside the institute. Of course, this includes conversations with younger scientists from which scientific initiative and innovations are expected. Elections at universities have become pure issues of power, which are also politically influenced. This is not good for scientific quality. The opinion expressed by an eminent politician that an increase in the number of students is associated with a lowering of their qualifications, and that therefore the university should reduce its standards, is very dangerous for the university. As you can see, I do not understand what democratization is, but perhaps you can teach me.
Where do you seek advice, and where do you find competent colleagues for a discussion, when a decision is necessary?
Democratization or not, this is always the essential problem. Only experience and insight into human nature help.
There is the famous fundamental theorem by Hinzpeter, saying that the number of good students is constant. Would you still say so today?
Yes, because I think that the corresponding distribution function of the characteristics of a sufficiently large group changes very slowly.
Is Humboldt’s ideal of the unity of research and teaching still valid in a time when very large institutes are created?
I still deem it correct, even if it is hard to achieve today. When a professor must give lectures for eight hours a week, and he continuously reworks his lectures, so that they correspond to the actual state of science, this requires much time. When science develops as quickly as it does today, this means that he cannot dedicate himself sufficiently to research. The professors’ strong involvement in teaching will hardly change, so that I advocate all the more that the institutes associated with the universities, in particular the Max-Planck Institute or Blue List Institutes, also participate in teaching. They can give a few, challenging lectures, and thereby attract and win the best students. But we must clearly distinguish here between students before and after their pre-diploma. Before the pre-diploma, the main emphasis must be on mathematics and physics, because without good basic knowledge in these fields studying meteorology makes little sense.
You were always talking about meteorology and did not mention oceanography. Is that just a habit?
I was talking about the study of meteorology. The same is valid for oceanography. Anyhow, both curricula are nearly identical before the pre-diploma. Afterwards there are major differences. In oceanography it is more important to take the boundaries into account and the linearized equations — wave solutions — play a larger role. In meteorology the phase transformations of water vapor and radiation are more important, but ocean and atmosphere share the same basic physics.
Do you think that exercises are necessary and useful? It seems artificial when the student knows that there is a solution to the task, while in a diploma project he does not know whether there is a right way and a solution. There are many students who do well in the exercises but fail in their diploma thesis.
I think that exercises and tests are necessary. The students see whether they master the tools of the trade, and they learn to analyze a scientific problem. I do not know the present conditions, but when I came to Hamburg, grades for exercises and tests had been abolished in the frame of democratization and reforms, and hardly anybody was allowed to fail. I consider it discouraging for good and ambitious students, when a very good achievement is formally not rated any differently than a just adequate performance. After the pre-diploma, students can be led to science, e. g., as student assistants. During this phase the exercises should be challenging enough that the students will approach their diploma problem thesis with self-confidence. Again it is important to call on scientists from institutes outside the universities for teaching. Especially good younger ones should be encouraged to obtain their Habilitation.
Did you enjoy teaching, and were your lectures good?
The latter question must be answered by others. I did not enjoy lectures very much, but I liked the cooperation with diploma students and doctorate students.
You wrote a book on radiation.
Together with Mr. Foitzik, I wrote it in 1953. It was published in 1958 and was already then outdated. German publications on radiation issues were unsatisfactory at that time, because there were no clear definitions of the different radiation quantities. Then I read Chandrasekhar’s book, which was published in 1950, and partly translated it for me, and I felt relieved by the clear definitions. I also learnt that many questions regarding “remote sensing” had already been treated by astrophysicists. The astrophysicists could work with a satellite moving around the sun and had developed the instruments to explore the sun. The meteorologists face the difficulty that, contrary to astrophysics, they deal with complicated band structures. In addition, on their small artificial satellite they cannot operate with as elaborate instruments as an astrophysical observatory.
Can your scientific life be divided into phases; some specific for you and others typical for any scientist striving upwards in the hierarchy?
I think I already mentioned this at the beginning. There are a number of specific phases. To begin with, the collapse of unified Germany. Then a normal phase began. I worked at a scientific institute, and without any initiative on my part I then became the director of another institute. In those times I was requested to give lectures at the University of Leipzig. If you like to express it that way, I moved up in the hierarchy. The next phase is specific for me. The GDR built the Wall while I was abroad. I did not go back, but started from the beginning again as an assistant at the University of Kiel. It was certainly not normal to begin as an assistant at more than 40 years of age. My further path was professional advancement in the academic hierarchy. I received my Habilitation in Kiel, became the director of a small university institute, then went to Mainz as a tenured professor, and after five years as a tenured professor to the University of Hamburg, and a little later I was appointed director at the Max Planck Institute. Especially considering my advanced age, this was partly due to the lucky circumstance that there were chairs to be filled.
You were pushed more and more firmly into scientific organization and thus removed from detailed research issues. Is that normal?
This is surely not normal. During the preparation of the GATE Experiment I was a kind of assistant to Mr. Brocks. After his death I had to take over the organization of the German contribution, which was the largest, with three vessels. When Mr. Möller retired after a stroke, I took the chair of the German GARP Committee. As it seemed to me that meteorology was insufficiently represented in the DFG, the Senate Commission on Atmospheric Sciences was established at the DFG. I then went into many other commission and councils. I hope I have acted not only in my interests, but also in the interests of meteorology. Funding by the DFG was of great importance for our science, especially for establishing Priority Programs which brought the young scientists from different meteorological institutes together. In many respects, this was more important for meteorology than a large Collaborative Research Centre. In the sum, the development of meteorology was good, especially comparing it to the time 35 ago when only tenured professors met twice a year.
I see a certain analogy to thematic priorities in the research projects of the European Union, where scientists of different countries are brought together. When someone has finished a PhD and has graduated, it is an enormous satisfaction to observe that the graduate now shows much more self-confidence, and has gained personal stature.
This is true. Mr. Geiger once jokingly remarked, when a non-PhD is asked something he does not know, he answers: "I do not know"; the PhD answers: "That is not of interest to me." Such justifiable pride of the PhDs can also be observed in students who have successfully worked out not too simple exercises or tests.
Were there any events which made a particular impression on you?
After the war, we were isolated from international science. When I was about 27, I considered it a great scientific experience when Rossby accepted Ertel’s invitation to visit Berlin as the first prominent scientist. He gave a convincing, wonderfully precise talk on the derivation of Rossby waves. I already commented on Smagorinski’s, Lorenz’ and Hasselmann’s works. Smagorinski’s work satisfied me because it was published at a time when also graduated meteorologists still believed that meteorology was too complicated to be solved with differential equations. "To my right, there is Ertel, Leibniz is above. I am a mediocrity and do not really belong here."
Which role did climate variations play for your understanding in earlier years?
Already as a student, I was unsatisfied with the proposition that climate should be defined as a mean state over a period of 30 years. The efforts to explain all observed variations as periodical were also disturbing — because none of these were statistically verified. I saw the main task of modern climate research in establishing the DFG’s Priority Program to distinguish between internal fluctuations and climate variations caused by altered boundary conditions and to verify these findings with the help of climate models. This included, e.g., modeling the Little Ice Age. Now, quasi-periodic variations emerging in climate models have become more likely.
Were there any teachers who served as a model for you?
Three teachers left a lasting impression on me: Ertel, Albert Defant and Julius Bartels. Ertel gave didactically excellent lectures. Actually, they were didactically too good. He let the subject matter seem very easy, but the students did not always understand everything so that they ran the risk of not reworking, and thus the things they heard did not stick in their minds. Defants’ lectures were an excellent combination of the theory of oceanic processes with observations, and thus always enthralling. Bartels impressed me as a personality who confidently knew his stuff. But, he was less interested in good didactics.
One final question: If once more you had the choice, would you become a meteorologist again?
When I started my studies, nobody could suspect what a fascinating development meteorology would undergo. Today I am glad I could witness it. Anyway, I do not regret having chosen this discipline. A second time, however, I would chose the path via the study of physics.
 See also the interview with Klaus Wyrtki in this volume. Professor Wyrtki earned his doctorate under the supervision of Professor Wüst in Kiel
 A traditional degree in German academic life. Usually received a few years after the doctorate-degree, it formally qualifies for professor positions. There have been attempts to abandon the Habilitation, but it seem deeply rooted in the academic system, and young scientists still apply for the degree in the hope of improving their chances when searching professor positions.
 See interview in this volume with Klaus Hasselmann, who speaks about this process in more detail
 Deutsche Forschungsgemeinschaft
 Bundesministerium für Forschung und Technology
 The interview was taped in 1995
 Zentrum für Marine und Atmosphärische Wissenschaften in Hamburg
 "Blaue Liste Institute" of what is nowadays called Leibniz-Gemeinschaft
 Berlin Wall, erected in 1961