Dr. Ferenc Ligetvári, Minister for Environment of Republic of Hungary,

Dr. Yadowsun Boodhoo, President of WMO Commission for Climatology,

Dear Participants,

Ladies and Gentlemen,

This is the third time that the Hungarian Meteorological Service hosts this Homogenization Seminar. The focus of the meeting has now been extended to include data quality issues, which is a closely related field.

Since the last Seminar, we can notice both advantageous and unfavourable processes. We can be pleased that homogenization as a task is gaining broader acceptance, and one can find less and less data series analysis that does not mention whether the data it used had been homogenized. We can be less satisfied by the fact that papers without mentioing the issue keep appearing at respected scientific forums. It has not been widely accepted that the results of homogenization depend on the applied methods. Some researcher who use the methods of this community might not be able to tell which method he used. These questions must be addressed if we want to acheive data series intercomparability.

It is indeed a development, that certain well-known and general inhomogeneities became individual topics of successful international conferences. On the other hand, methods are still not adequately compared. Large internatinal databases are being developed and planned, which aim at serving increasing number of users, but most of the times the quality requirements or controlling procedures are not exactly formulated.

Scientist can welcome that the focus of this Seminar has been extended from the very specific though highly important homogenization, and now incorporates the more general and data quality control and requirements in climatological databases. This extention has been discussed in detail with the Commision for Climatology of WMO, and its Working Group on Climate Change Detection and reflects their suggestions.

The WMO measurement recommendations and handbooks are widely known. It is also widely known that several station do not fulfil entirely these requirements, simply because with the population growth it is increasingly difficult to find appropriate places where micrometeorological influences are small. Meteorologists should therefore make practical comporomises, and obtain data while accepting that external constraints originating from the not optimal conditions influence these measurements and modify the obtained data. Data quality control should address these problems as well.

The frequency of control and calibration of instruments and sensors are defined and strictly imposed. But are we aware of the external influences, how the human activity in the neighbourhood of an automatic station lead to data modifications? And if human activity indeed modify our observations, how can we perceive and correct? These questions are still not adequately answewed.

With technological development and the increasing value of human environment, meteorological and climatological knowledge is becoming increasingly valuable and incorporation into everyday use and decision making is becoming a general practice. Therefore, inhomogenities and unreliable data can induce severe losses. These underline the importance of this meeting and the discussions between and after the presentation during the following days.

Let me take this opportunity to emphasize, that efficient work can only be achieved if it is successfully combined with entertainment and recreation. Let me draw your attention, especially those who are visiting Hungary for the first time, to the beauties of Hungary, especially Budapest. Beyond work, please enjoy your stay in Hungary, so when you return home, you could say that I have attended a highly beneficial Seminar at a beautiful place.

Finally, I would like to wish you success with your work, and a beneficial meeting here at the Hungarian Meteorological Service.

Thank you for your attention.