View More View Less
  • 1 Department of Applied of Environmental Geology, Eötvös Loránd University H-1117 Budapest, Pázmány Péter sétány 1/C, Hungary
  • 2 Geological Institute of Hungary H-1143 Budapest, Stefánia út 14, Hungary
  • 3 Institute of Nuclear Research of the Hungarian Academy of Sciences H-4026 Debrecen, Bem tér 18/C, Hungary
  • 4 Institute of Methodology, Budapest Business School H-1054 Budapest, Alkotmány u. 9-11, Hungary
Restricted access

The time-series ofδ18O values measured weekly in Lake Balaton gave a chance to estimate the period time. To do this, we used a recently worked-out psd estimation method, the Lomb-Scargle periodogram (Lomb 1976, Press et al. 1992), in which the type of distribution can be given exactly to the power values, so confidence interval can be calculated. The result, however, is only a characteristic mean value of the time-interval examined, so the changes of the period-time were examined by demodulation. The essence of the method is that the process (time-series) is let through a filter that is permeable at merely one frequency, all the other frequency components are filtered out, so the difference from the mean period time can be placed in time. We also examined to what extent the water samples coming from one bay of Lake Balaton are representative of the whole lake. Hierarchical clustering was carried out on the hydrobiological and hydrochemical parameters of water samples coming from ten sites of Lake Balaton to determine the similar sampling sites. After the clustering, part of the sampling sites fell into different groups in the examined 16 sampling times. So the groups were marked in all the 16 sampling times with a code that shows to which group that actual sampling site belongs. In this way, each sampling site was placed in a 16-dimension space. Thus, another clustering became possible, so the grouping related to the given time period could be determined. The result was checked by statistical calculations.

  • Longo G, D'Argenio B, Ferreri V, Iorio M 1994: Spec. Publs Int. Ass. Sediment, 19, 77-85.

    () 19 Spec. Publs Int. Ass. Sediment : 77 -85.

  • Cserny T 2002: Földtani Közlöny (in Hungarian), 132, 193-213.

    () 132 Földtani Közlöny (in Hungarian) : 193.

  • Cserny T, Hertelendi E, Tarján S 1995: Acta Geol. Hung., 38, 355-376.

    () 38 Acta Geol. Hung. : 355 -376.

  • Lomb N R 1976: Astronomical and Space Science, 39, 447-462.

    () 39 Astronomical and Space Science : 447 -462.

  • Press W H, Teukolsky S A, Vetterling W T, Flannery B P 1992: Numerical recipes in C: The art of scientific computing. Cambridge University Press, 2nd ed.

  • Cserny T 2000: Environmental geological investigation of the sediments of Lake Balaton. Integrated interpretation of the data of the complex geological investigation of the Lake Balaton. Final report of the Hungarian Scientific Research Fund (OTKA) T 022371 project (in Hungarian), Geological Institute of Hungary