GFZ ISDC - PORTAL TO GEOSCIENTIFIC DATA, INFORMATION AND KNOWLEDGE

The GFZ Information System and Data Center (ISDC) portal is integrating important data management services for satellite missions like CHAMP, GRACE and TerraSAR-X as well as for geodetic projects like Global Geodetic Project (GGP) and GPS data reprocessing (GPS-PDR) [1], [2], [3], [4], [5]. The main components of the ISDC portal system are the portal framework, a content management system, the user and product management as well as detailed monitoring and statistics software. The new ISDC product philosophy describes the usage of parent and data child DIF XML documents [6], [7], [8] for the documentation of product type and data product specific metadata.

The entrance to the main functions and features of the new ISDC portal (http://isdc.gfz-potsdam.de), realized by a three-tiered graphical user interface (GUI) is shown in figure 1.  The portal frame work is based on the open source software PostNuke. In addition to the portal frame and standard components, like user registration, content management and a user forum, most of the components are developed by the ISDC team.

Figure 1: GFZ ISDC Portal - GUI

At present the ISDC is managing almost 300 different product types covering various geoscience domains, like geodesy, geophysics as well as atmosphere and ionosphere physics. One third of these product types are accessible by public users and user groups. The other product types are used for operational, restricted and internal use only. More than 11 terra byte and 18 millions data products are long-term stored at the ISDC product archive and online accessible via the ISDC online product archive. The current number of 1760 international users and user groups has been increasing exponentially since the start of the new ISDC portal in March 2006. Beside Germany, most of the users and user groups are from China, followed by United States, India and Japan.

The ISDC is supporting almost all parts of a scientific data product lifecycle management. Due to the standardized ISDC product philosophy, almost 300 different product types can be managed by an uniform process. As mentioned already, all product types are described by standardized parent DIF (NASA's Directory Interchange Format for the Global Change Master Directory GCMD) metadata documents (figure 2) [6], [7], [8]. This means, all product type dependent information, like entry id (unique identifier), entry title, parameters (science keywords), topic category, data center, summary, personnel, instrument, quality as well as the temporal and spatial coverage of the whole data set are recorded in parent DIF files. In order to deal with data products (single data files) of a specific product type, a further development of the DIF standards was necessary. In addition to the “old” ISDC metadata standards, the product dependent metadata of all new ISDC product types are stored in separate data (file) only related child DIF metadata documents. Detailed information about the new ISDC product philosophy based on XML structures are given in the “DIF Metadata and Handling at the GFZ ISDC” paper [8]. The data input and output management, is realized by ISDC data pumps, which are not only designed for the transfer of data but also for the import of information to the ISDC product catalog (figure 2). In order to keep ISDC data and information sustainable, science driven data review processes are necessary, which are unfortunately not realized by now.

Figure 2: Extended ISDC product philosophy

For the improvement of the interoperability of the ISDC catalog, which consists of information about product types and data products, the usage of standardized Service Oriented Architecture (SOA) driven concepts is useful. XML as representation language for the documentation of ISDC product type and data product dependent metadata, provides a smooth opportunity for the transformation of metadata documents from one standard to another one. Especially the transformation from ISDC DIF to OGC/ISO 19115 standard compliant metadata and the usage of the open source software “deegree” (http://www.deegree.org) [9], [10], [11] provides the capability for an OGC compliant CSW 2.0 catalog service.

Most of the ISDC interfaces are based on committee driven standards and techniques. In addition, there are a lot of community driven activities and developments, which are composing the interactive Web 2.0.  Recently the ISDC team is studying such Web 2.0 techniques, like tagging and social navigation for the usage at the ISDC, and appropriate user interfaces are in development already. The combination of Web 2.0 techniques and semantic web languages, like OWL and SKOS is offering new ways for the representation of data, information and knowledge stored at the ISDC. Detailed information about the ISDC research status of semantic web technologies are given at the “Semantic web technologies for value added services at the GFZ ISDC” [12].

References

Deegree Project: http://www.deegree.org

Global Change Master Directory: http://gcmd.nasa.gov/

XML & XSLT: www.w3.org/TR/xslt , http://selfhtml.org/

PostNuke: http://postnuke.com/

[1] Reigber Ch., Schwintzer P., Lühr H., Massmann F.-H., Galas R., Ritschel B.: CHAMP Mission Science Data System Operation and Generation of Scientific Products, GEOTECHNOLOGIEN Science Report, Observation of System Earth from Space, Status Seminar, Bavarian State Mapping Agency (BLVA), Munich, 12-13 June 2003, 129-131

[2] Flechtner F., Ackermann Ch., Meixner H., Meyer U., Neumayer K.-H., Ritschel B., Schmidt, A., Schmidt R., Zhu S., Reigber Ch.: Development of the GRACE Science Data System, GEOTECHNOLOGIEN Science Report, Observation of System Earth from Space,Status Seminar, Bavarian State Mapping Agency (BLVA), Munich, 12-13 June 2003,48-50

[3] Ritschel B., Behrends K., Braune St., Freiberg S., Kopischke R., Palm H., Schmidt A.: CHAMP/GRACE-Information System and Data Center (ISDC) - The User Interfaces for Scientific Products of the CHAMP and GRACE Mission, GEOTECHNOLOGIEN Science Report, Observation of System Earth from Space,Status Seminar, Bavarian State Mapping Agency (BLVA), Munich, 12-13 June 2003, 132-133

[4] Ritschel, B., Bruhns, Ch., Burgess, Ph., Freiberg, S., Gericke, L., Kase, St., Kopischke, R., Loos, St., Lowisch, St., Palm, H.: The integration of CHAMP and GRACE products as well as associated scientific services in the new ISDC portal, GEOTECHNOLOGIEN Science Report, Observation of System Earth from Space, Status Seminar, Oberpfaffenhofen 2006

[5] Ritschel, B., Mende, V., Palm, H., Kopischke, R.,Bruhns, Ch.,Gericke, L., Freiberg, S. ISDC Services: Data Management, Catalog Interoperability and International Cooperation

[6] V.Mende, B. Ritschel, H. Palm, L. Gericke, S. Freiberg.: ISDC Metadata Management, GEOTECHNOLOGIEN Science Report, Observation of System Earth from Space, Status Seminar, München 2007

[7] Ritschel,B., Bruhns, C:, Kopischke R., Mende V., Palm H., Freiberg S., Gericke L., The ISDC concept for long-term sustainability of geoscience data and information, PV 2007 Conference, Symposiums-Proceeding, Oberpfaffenhofen 2007

[8] Mende, V., Ritschel, B., Freiberg, S., Palm, H., Gericke, L. DIF Metadata and Handling at the GFZ ISDC, GeoInformatics (Potsdam 2008)

[9] Braune, S., Czegka, W., Klump, J., Palm, H., Ritschel, B., Lochter, F. A. (2003): Anwendungen ISO-19115-konformer Metadaten in in Katalogsystemen aus dem Bereich umwelt- und geowissenschaftlicher Geofachdaten. - Zeitschrift für Geologische Wissenschaften, 31,1, 37-44

[10] Voges, U., Senkler, K. (2005): OpenGIS® Catalogue Services Specification 2.0 - ISO19115/ISO19119 Application Profile for CSW 2.0.; OpenGIS Consortium, Wayland, Massachusetts

[11] Burgess, Ph., Palm, H., Ritschel, B., Bruhns, Ch., Freiberg, S., Gericke, L., Kase, St., Kopischke, R., Loos, St., Lowisch, St.: Implementing modern data dissemination concepts in the ISDC Portal, GEOTECHNOLOGIEN Science Report, Observation of System Earth from Space, Status Seminar, Oberpfaffenhofen 2006

[12] Ritschel, B., Mende, V., Pfeiffer, S., Freiberg, S. Semantic web technologies for value added services at the GFZ ISDC, GeoInformatics (Potsdam 2008)