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Das Weltklimaproblem - eine Herausforderung auch an die Verantwortung in der Wissenschaft
(2002)
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Christian-Dietrich Schönwiese
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Klimafaktor Mensch - ein Indizienbeweis
(2000)
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Christian-Dietrich Schönwiese
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Grad-Wanderung im Treibhaus
(2001)
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Christian-Dietrich Schönwiese
- Die Zunahme der Konzentration von CO2 und anderen „Treibhausgasen“ in der Atmosphäre ist unzweifelhaft, und ebenso unzweifelhaft reagiert das Klima darauf. Christian-Dietrich Schönwiese, Professor für Meteorologische Umweltforschung und Klimatologie an der Universität Frankfurt am Main, sieht dringenden politischen Handlungsbedarf und plädiert gleichzeitig dafür, die Debatte rund um den Klimaschutz zu versachlichen.
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Die Klimadebatte : Zwischen Katastrophe und Verharmlosung
(1997)
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Christian-Dietrich Schönwiese
- Die öffentliche Klimadebatte scheint sich zu verselbständigen. Abgehoben von den Erkenntnissen der Fachwissenschaftler reden die einen von der "Klimakatastrophe", die uns demnächst mit voller Wucht treffen wird, wenn wir nicht sofort alles ganz anders machen; Panik ist ihnen das rechte Mittel, Aufmerksamkeit zu erregen. Die anderen sehen im "Klimaschwindel" einen Vorwand für Forschungsgelder und zusätzliche Steuerbelastung der Wirtschaft; ihre Strategie ist Verwirrung und Verharmlosung. Mit der Fixierung auf solche Extrempositionen werden wir den Herausforderungen der Zukunft sicherlich nicht gerecht. Höchste Zeit für eine Versachlichung und für einen klärenden Beitrag zum Verwirrspiel "Klima".
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Secular change of extreme monthly precipitation in Europe
(2003)
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Christian-Dietrich Schönwiese
Jürgen Grieser
Silke Trömel
- Temporal changes in the occurrence of extreme events in time series of observed precipitation are investigated. The analysis is based on a European gridded data set and a German station-based data set of recent monthly totals (1896=1899–1995=1998). Two approaches are used. First, values above certain defined thresholds are counted for the first and second halves of the observation period. In the second step time series components, such as trends, are removed to obtain a deeper insight into the causes of the observed changes. As an example, this technique is applied to the time series of the German station Eppenrod. It arises that most of the events concern extreme wet months whose frequency has significantly increased in winter. Whereas on the European scale the other seasons also show this increase, especially in autumn, in Germany an insignificant decrease in the summer and autumn seasons is found. Moreover it is demonstrated that the increase of extreme wet months is reflected in a systematic increase in the variance and the Weibull probability density function parameters, respectively.
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Statistical time series decomposition into significant components and application to European temperature
(2002)
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Jürgen Grieser
Silke Trömel
Christian-Dietrich Schönwiese
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Quark Matter 99 summary: hadronic signals
(1999)
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Reinhard Stock
- I review the new data presented at QM99. The main emphasis is placed on the CERN SPS hadron production systematics concluding that the boundary between a partonic and a hadronic phase has now been located at $T=180 \pm10\:MeV$ and $\epsilon \approx 1 \:GeV$ per $fm^3$.
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The parton to hadron phase transition observed in Pb+Pb collisions at 158 GeV per nucleon
(1999)
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Reinhard Stock
- Hadronic yields and yield ratios observed in Pb+Pb collisions at the SPS energy of 158 GeV per nucleon are known to resemble a thermal equilibrium population at T=180 +/- 10 MeV, also observed in elementary e+ + e- to hadron data at LEP. We argue that this is the universal consequence of the QCD parton to hadron phase transition populating the maximum entropy state. This state is shown to survive the hadronic rescattering and expansion phase, freezing in right after hadronization due to the very rapid longitudinal and transverse expansion that is inferred from Bose-Einstein pion correlation analysis of central Pb+Pb collisions.
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Simulation of global temperature variations and signal detection studies using neural networks
(1998)
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Andreas Walter
Michael Denhard
Christian-Dietrich Schönwiese
- The concept of neural network models (NNM) is a statistical strategy which can be used if a superposition of any forcing mechanisms leads to any effects and if a sufficient related observational data base is available. In comparison to multiple regression analysis (MRA), the main advantages are that NNM is an appropriate tool also in the case of non-linear cause-effect relations and that interactions of the forcing mechanisms are allowed. In comparison to more sophisticated methods like general circulation models (GCM), the main advantage is that details of the physical background like feedbacks can be unknown. Neural networks learn from observations which reflect feedbacks implicitly. The disadvantage, of course, is that the physical background is neglected. In addition, the results prove to be sensitively dependent from the network architecture like the number of hidden neurons or the initialisation of learning parameters. We used a supervised backpropagation network (BPN) with three neuron layers, an unsupervised Kohonen network (KHN) and a combination of both called counterpropagation network (CPN). These concepts are tested in respect to their ability to simulate the observed global as well as hemispheric mean surface air temperature annual variations 1874 - 1993 if parameter time series of the following forcing mechanisms are incorporated : equivalent CO2 concentrations, tropospheric sulfate aerosol concentrations (both anthropogenic), volcanism, solar activity, and ENSO (all natural). It arises that in this way up to 83% of the observed temperature variance can be explained, significantly more than by MRA. The implication of the North Atlantic Oscillation does not improve these results. On a global average, the greenhouse gas (GHG) signal so far is assessed to be 0.9 - 1.3 K (warming), the sulfate signal 0.2 - 0.4 K (cooling), results which are in close similarity to the GCM findings published in the recent IPCC Report. The related signals of the natural forcing mechanisms considered cover amplitudes of 0.1 - 0.3 K. Our best NNM estimate of the GHG doubling signal amounts to 2.1K, equilibrium, or 1.7 K, transient, respectively.
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Ursachen der Lufttemperaturvariationen in Deutschland 1865 - 1997
(1999)
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Andreas Walter
Christian-Dietrich Schönwiese
