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Integrating spatio-temporal information in environmental monitoring data: a visualization approach applied to moss data
KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering.
2005 (English)In: Science of the Total Environment, ISSN 0048-9697, E-ISSN 1879-1026, Vol. 347, no 1-3, 1-20 p.Article in journal (Refereed) Published
Abstract [en]

Large-scale environmental monitoring data being sparse and collected on irregular grids, which may differ from year to year, are difficult to analyse and present. The traditional techniques from statistics and Geographic Information Systems (GIS) may not be useful given the often relatively small sample size combined with varying sampling density. In this study, the freeware visualization package XmdvTool was used for integration and exploration of monitoring data from three surveys of terrestrial mosses. Data on contents of Cu, Ni, Pb, V and Zn in mosses within an area of 300×300 km in southern Sweden, sampled in 1985 (177 samples), 1990 (156 samples) and 1995 (188 samples), were integrated and visualized using parallel coordinate and scatterplot display techniques. Several interesting findings about multi-element composition of samples, as well as changing temporal trends in the relations of five metals were made during interactive visual discovery. Visualization techniques for high-dimensional data may have limitations considering, for example, number of variables, ranges of data values, and spatial scales. Nevertheless, interactive data manipulation tools encourage the process of visual exploration, and the unique way of integrating spatial, temporal and multi-element components of moss data provided visual insights that are not possible to gain with traditional analysis tools.

Place, publisher, year, edition, pages
2005. Vol. 347, no 1-3, 1-20 p.
Keyword [en]
Moss survey; Environmental monitoring; Multi-element data; Visualization
National Category
Engineering and Technology
URN: urn:nbn:se:kth:diva-5029DOI: 10.1016/j.scitotenv.2004.12.054ISI: 000231553400001ScopusID: 2-s2.0-23444446919OAI: diva2:7636
QC 20100609Available from: 2005-04-18 Created: 2005-04-18 Last updated: 2011-11-08Bibliographically approved
In thesis
1. Visualization, integration and analysis of multi-element geochemical data
Open this publication in new window or tab >>Visualization, integration and analysis of multi-element geochemical data
2005 (English)Doctoral thesis, comprehensive summary (Other scientific)
Abstract [en]

generated large databases containing information on the concentrations of chemical elements in rocks, surface sediments and biogeochemical materials. Regional geochemical data being imprecise, multivariate, spatially auto-correlated and non-normally distributed pose specific problems to the choice of data analysis methods. Commonly several methods are combined, and the choice of techniques depends on the characteristics of data as well as the purpose of study. One critical issue is dealing with extreme data values (or outliers) in the initial stages of analysis. Another common problem is that integrated analysis of several geochemical datasets is not possible without interpolating the point data into surfaces. Finally, separation of anthropogenic influences from natural geochemical background in the surface materials is an issue of great importance for environmental studies.

This study describes an approach to address the above-mentioned problems by a flexible combination and use of GIS and multivariate statistical techniques with high-dimensional visualization. Dynamically linked parallel coordinate and scatterplot matrix display techniques allow simultaneous presentation of spatial, multi-element and qualitative information components of geochemical data. The plots not only display data in multi-dimensional space, but also allow detailed inspection of the data with interactive multi-dimensional brushing tools. The results of the study indicate that these simple high-dimensional visualization techniques can successfully complement the traditional statistical and GIS analysis in all steps of data processing, from data description and outlier identification through data integration, analysis, validation, and presentation of results. The outcomes of the study include: a visual procedure towards intelligent data cleaning where potentially significant information in very high element concentrations is preserved, methods for integration and visual analysis of geochemical datasets collected in different grids, estimation of geochemical baseline concentrations of trace metals in till geochemistry of southeastern Sweden, use of multi-element spatial fingerprints to trace natural geochemical patterns in biogeochemistry, and a new graphical approach to present multi-element geochemical data summaries and results from numerical analysis.

Place, publisher, year, edition, pages
Stockholm: KTH, 2005
Trita-LWR. PHD, ISSN 1650-8602 ; 1018
Earth sciences, GIS, interactive visualization, glacial till, biogeochemistry, metals, southeastern Sweden, Geovetenskap
National Category
Earth and Related Environmental Sciences
urn:nbn:se:kth:diva-169 (URN)91-7178-014-9 (ISBN)
Public defence
2005-04-21, Kollegiesalen, Valhallavägen 79, Stockholm, 10:00
QC 20100609Available from: 2005-04-18 Created: 2005-04-18 Last updated: 2010-06-09Bibliographically approved

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