t tituu ch Ins orologis Koninklijk Nederlands Mete 1999 - 2000 - 1999 Biennial Scientific Report Scientific Biennial climate research and seismology department seismology and research climate climate research and seismology department Biennial Scientific Report 1999-2000 Contents Preface Introduction Recent highlights Palaeoseismology: in search of large earthquakes 13 Sensing the forest: a micro-meteorological study 23 Dances with waves: the knmi wave follower 35 New ways of observing clouds: a tour along satellite based and ground based remote sensing techniques 51 South meets north over Suriname: ozone observations in Paramaribo 65 Current projects Predictability Research 77 Oceanographic Research 93 Atmospheric Composition Research 107 Atmospheric Research 127 Climate Analysis 154 Seismology 162 National and international policy related activities 174 Model support 177 2 Appendices The web site 183 Externally funded projects 186 Theses 190 Acronyms 191 Organisational scheme 200 List of employees 1999-2000 202 How to reach us 206 3 4 Preface • Two important events mark the activities of knmi’s Climate Research and Seismology Department in the years 1999 and 2000. In 1999 an international Review Board reviewed the research of the Department. It was concluded that the quality and productivity of the research meet high international standards. Of course I am proud of this result. The important public task of knmi regarding climate change was emphasised by contributions of the Department to various reports and meetings. The recent report of the Intergovernmental Panel on Climate Change underlines the impact of research on public awareness of environmental problems and climate change. It also underlines the necessity of national and international co-operation in research to realise progress in climate research. Our scientific work is firmly embedded in international programmes and networks. In this third biennial report of the Climate Research and Seismology Department an overview of the results and some highlights of experimental research in 1999 and 2000 are presented. Prof. Dr. Joost de Jong Director knmi 5 Preface 6 Introduction • knmi’s research programme is a balanced combination of experimental, modelling and theoretical research, covering a wide range of aspects of the climate system. The central theme of this third Biennial Scientific Report of knmi’s Science Department is our experimental research. Five articles highlight various experimental and observational studies and facilities. Together they emphasise the importance of this aspect of knmi’s climate research. Bernard Dost and Läslo Evers describe a project aiming at improving the assessment of seismic risks by the Seismology Division’s work on ‘unearthing’ palaeoseismic information. Fred Bosveld reviews research on the micrometeorology of a forest and its interaction with the free atmosphere, contributing to a better understanding of the role of forests in the climate system. The Oceanographic Research Division has a long tradition in research of the microscale aspects of air/sea interaction. Cor Jacobs and co-workers present the first promising results obtained with a wave-following device that has been tested and will be deployed from the platform Noordwijk off the Dutch North Sea coast. The greatest uncertainty in future projections of climate probably arises from clouds and their interactions with radiation, as is reaffirmed by the Third Assessment Report of the Intergovernmental Panel on Climate Change 7 Introduction (ipcc). André van Lammeren and his colleagues describe their work on simultaneous ground based and satellite detection and observation of many relevant cloud characteristics. To further extend and improve this work, a cloud radar has been purchased during the reporting period, which will be installed in the course of 2001. The tropics are almost void of upper-air ozone stations. The recent establishment of such a station in Paramaribo, Surinam, with generous financial support from the Netherlands Organisation for Scientific Research, was greeted with enthusiasm by the research community. Paul Fortuin and his colleagues report in the last highlight on the technical aspects of this station and on the first results. In addition to these highlights, all Divisions present their progress during the past two years, followed by an overview of our national and international policy related activities. The final chapter describes the work of the model support group. At the end of 1999 an international Review Board reviewed the productivity and quality of our research. The Board concluded that our research has been very productive and has reached a high quality level by international standards. Of course the Board made some critical comments, some of which have already led to the implementation of proposed changes. We are working on a Research Strategy for the forthcoming years, in which the Board’s suggestions for improvement will be taken into account. 8 Introduction knmi’s Research Department is the largest climate research group in the Netherlands. It is vital for the Department to have access to young scientists and to funding offered by the National Science Foundation and by national programmes. It is therefore essential to maintain excellent relations with universities with a climate research related curriculum. We offer research opportunities at graduate and post-graduate level and encourage part-time professorships of knmi staff at Dutch universities. This policy has been fruit- ful. Three Heads of Divisions became part-time professor during the reporting period: Hennie Kelder at the Technical University of Eindhoven, Theo Opsteegh and Gerbrand Komen at the University of Utrecht. Bert Holtslag moved to Wageningen as a full-time professor. Many projects are carried out in co-operation with these universities. One of the Department’s public tasks is its close involvement in ipcc. We represent the Netherlands on the Panel and in Working Group I. Moreover, knmi scientists contributed to ipcc’s Third Assessment Report as lead author, contributors or reviewers. A substantial part of our scientific output was assessed by ipcc. A pleasant working environment stimulates productivity: in 2000 Climate Research moved back to the refurbished east wing of knmi’s premises and our Seismology division moved to their great satisfaction into the beautifully restored old Villa, knmi’s former Headquarter since 1897. Unfortunately the hall with its beautiful stairs, which figured so prominently on the cover of the previous Biennial Reports, fell victim to this restoration. 9 Introduction The Ministry of Transport, Public Works and Water Management, of which knmi is an Agency, funds our work in the first place. Additional funding is obtained from various funding agencies listed in an Appendix. I hope that this Report is convincing evidence that we made efficient, productive and grateful use of all funding provided. Dr. Fons Baede Head of Climate Research and Seismology Department 10 Introduction Recent highlights Palaeoseismology: inPalaeoseismology search of large earthquakes Palaeoseismological research along the Roer Valley Graben by Bernard Dost and Läslo Evers Introduction • The Netherlands is generally regarded a low seismicity area. This means that large earthquakes are rare, but not necessarily absent. Seismic hazard analysis for the Netherlands and immediate surroundings is based on the historical occurrence of seismicity in the region. Unfortunately, the historical catalogue is limited in time and moreover the magnitude of most events before 1960 is poorly known. Instrumental observations started around 1900 and it was not before 1935 that Richter designed a magnitude scale that was accepted and generally used. However, even though we have only access to a catalogue of events over a limited time frame, a statistical analysis of the historical dataset enables a hazard estimation 1). In this analysis, based on Poisson statistics, a reference return period of earthquakes of 475 years is adopted, corresponding to an exceedence probability of 10% in 50 years. The south-eastern part of the Netherlands shows the strongest hazard, related to the Roer Valley Graben (rvg). There is interest from the (re)-insurance companies considering the economic importance of the region. Calculations of the potential losses for a hypothetical earthquake of magnitude 6.4 near Cologne at 10 km depth amounts to a loss of 55 billion us $ 2). Fortunately there are methods to extend the observation period. One way is to use written historical data, though the interpretation will not always be easy. In some cases, like a reported historic event in the Northern part of the Netherlands in 1262 3), earthquake phenomena are reported in combination with strong winds and the association of three reported 13 Recent highlights phenomena with an earthquake is doubtful. The help of a historian is indispensable for the evaluation of the written sources. In this way the observational period can be extended from 100 years to approximately 700 years. Looking at an even longer timescale, palaeoseismology, the study of prehistoric earthquakes, may add additional information. Looking in detail at the near surface geology of large faults, a search is made for traces of movements at the surface (surface rupture) that may be interpreted as being caused by large earthquakes. There is a strong indication of surface rupture for 3 events in the last 30.000 years The Roer Valley Graben is the main active tectonic