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- ItemLong-term trends in the ionospheric E and F1 regions(Göttingen : Copernicus, 2008) Bremer, J.Ground based ionosonde measurements are the most essential source of information about long-term variations in the ionospheric E and F1 regions. Data of such observations have been derived at many different ionospheric stations all over the world some for more than 50 years. The standard parameters foE, h'E, and foF1 are used for trend analyses in this paper. Two main problems have to be considered in these analyses. Firstly, the data series have to be homogeneous, i.e. the observations should not be disturbed by artificial steps due to technical reasons or changes in the evaluation algorithm. Secondly, the strong solar and geomagnetic influences upon the ionospheric data have carefully to be removed by an appropriate regression analysis. Otherwise the small trends in the different ionospheric parameters cannot be detected. The trends derived at individual stations differ markedly, however their dependence on geographic or geomagnetic latitude is only small. Nevertheless, the mean global trends estimated from the trends at the different stations show some general behaviour (positive trends in foE and foF1, negative trend in h'E) which can at least qualitatively be explained by an increasing atmospheric greenhouse effect (increase of CO2 content and other greenhouse gases) and decreasing ozone values. The positive foE trend is also in qualitative agreement with rocket mass spectrometer observations of ion densities in the E region. First indications could be found that the changing ozone trend at mid-latitudes (before about 1979, between 1979 until 1995, and after about 1995) modifies the estimated mean foE trend.
- ItemClassification and clustering: models, software and applications(Berlin : Weierstraß-Institut für Angewandte Analysis und Stochastik, 2009) Mucha, Hans-Joachim; Ritter, GunterWe are pleased to present the report on the 30th Fall Meeting of the working group ``Data Analysis and Numerical Classification'' (AG-DANK) of the German Classification Society. The meeting took place at the Weierstrass Institute for Applied Analysis and Stochastics (WIAS), Berlin, from Friday Nov. 14 till Saturday Nov. 15, 2008. Already 12 years ago, WIAS had hosted a traditional Fall Meeting with special focus on classification and multivariate graphics (Mucha and Bock, 1996). This time, the special topics were stability of clustering and classification, mixture decomposition, visualization, and statistical software.
- ItemSimilarities and differences in polar mesosphere summer echoes observed in the Arctic and Antarctica(München : European Geopyhsical Union, 2008) Latteck, R.; Singer, W.; Morris, R.J.; Hocking, W.K.; Murphy, D.J.; Holdsworth, D.A.; Swarnalingam, N.Polar Mesosphere Summer Echoes (PMSE) have been observed in the high latitudes of the Northern and Southern Hemisphere for several years using VHF radars located at Andenes/Norway (69° N, 16° E), Resolute Bay/Canada (75° N, 95° W), and Davis/Antarctica (69° S, 78° E). The VHF radars at the three sites were calibrated using the same methods (noise source and delayed transmitting signal) and identical equipment. Volume reflectivity was derived from the calibrated echo power and the characteristics of the seasonal variation of PMSE were estimated at the sites for the years 2004 to 2007. The largest peak volume reflectivity of about 2×10−9 m−1 was observed at Andenes compared with their counterparts at Davis (~4×10−11 m−1) and Resolute Bay (~6×10−12 m−1). The peak of the PMSE height distribution is 85.6 km at Davis which is about 1 km higher than at Andenes. At Resolute Bay the height distribution peaks at about 85 km but only a few layers were found below 84 km. The mean PMSE occurrence rate is 83% at Andenes, 38% at Davis with larger variability and only 18% at Resolute Bay (in late summer). The duration of the PMSE season varies at Andenes from 104 to 113 days and at Davis from 88 to 93 days. In general the PMSE seasons starts about 5 days later at Davis and ends about 10 days earlier compared to Andenes. In all three seasons the PMSE occurrence suddenly drops to a much lower level at Davis about 32 days after solstice whereas the PMSE season decays smoothly at Andenes. The duration of the PMSE season at Andenes and Davis is highly correlated with the presence of equatorward directed winds, the observed differences in PMSE occurrence are related to the mesospheric temperatures at both sites.
- ItemEmerging pattern of global change in the upper atmosphere and ionosphere(München : European Geopyhsical Union, 2008) Laštovička, J.; Akmaev, R.A.; Beig, G.; Bremer, J.; Emmert, J.T.; Jacobi, C.; Jarvis, M.J.; Nedoluha, G.; Portnyagin, Yu. I.In the upper atmosphere, greenhouse gases produce a cooling effect, instead of a warming effect. Increases in greenhouse gas concentrations are expected to induce substantial changes in the mesosphere, thermosphere, and ionosphere, including a thermal contraction of these layers. In this article we construct for the first time a pattern of the observed long-term global change in the upper atmosphere, based on trend studies of various parameters. The picture we obtain is qualitative, and contains several gaps and a few discrepancies, but the overall pattern of observed long-term changes throughout the upper atmosphere is consistent with model predictions of the effect of greenhouse gas increases. Together with the large body of lower atmospheric trend research, our synthesis indicates that anthropogenic emissions of greenhouse gases are affecting the atmosphere at nearly all altitudes between ground and space.
- ItemGeometrie(Zürich : EMS Publ. House, 2006) Burago, Yuri; Pinkall, UlrichThe program covered a wide range of new developments in geometry. To name some of them, we mention the topics “Metric space geometry in the style of Alexandrov/Gromov”, “Polyhedra with prescribed metric”, “Willmore surfaces”, “Constant mean curvature surfaces in three-dimensional Lie groups”. The official program consisted of 21 lectures and included four lectures by V. Schroeder (Zürich) and S. Buyalo (Sankt-Petersburg) on “Asymptotic geometry of Gromov hyperbolic spaces”.
- ItemPDE and Materials(Zürich : EMS Publ. House, 2006) James, Richard D.; Müller, StefanThis meeting brought together a carefully selected group of mathematicians, physicists, material scientists and engineers to discuss and review the impact of modern mathematical methods on the understanding of material behaviour and the design of new materials. A key issue is that the material behaviour is determined by physical processes at many different spatial and temporal scales which cannot be simulataneously resolved by brute force computation. Central themes of the meeting were (spatial) microstructures, the relation between atomistic and continuum models, the treatment of multiple temporal scales, and the influence of randomness and the use of methods from statistical mechanics.
- ItemCoagulation and Fragmentation Models(Zürich : EMS Publ. House, 2007) Norris, James; Wagner, WolfgangAnalysis of coagulation and fragmentation is crucial to understanding many processes of scientific and industrial importance. In recent years this has led to intensified research activities in the areas of differential equations, probability theory, and combinatorics. The purpose of the workshop was to bring together people from these different areas working on various aspects of coagulation and fragmentation. We believe that the insights resulting from the interactions which have been stimulated that week should lead to further advances both in the development of mathematical techniques and in new applications.
- ItemSingularities(Zürich : EMS Publ. House, 2009) van Straten, Duco; Vassiliev, Victor A.Local/global Singularity Theory is concerned with the local/global structure of maps and spaces that occur in differential topology or theory of algebraic or analytic varieties. It uses methods from algebra, topology, algebraic geometry and multi-variable complex analysis.
- ItemSingularities(Zürich : EMS Publ. House, 2006) van Straten, Duco; Vassiliev, Victor A.noindent This is the report of the Oberwolfach Workshop on singularity theory held in september 2006. Singularity theory is concerned with the local structure of maps and spaces that occur in many situations in mathematics. It uses methods from algebra, topology and algebraic geometry for their study.
- ItemGeometry and Arithmetic around Hypergeometric Functions(Zürich : EMS Publ. House, 2008) Yoshida, Masaaki; Wolfart, Jürgen[no abstract available]