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A Virtual Observatory for Space Weather? R.D. Bentley (UCL/MSSL) Chris Harvey (CDPP) Second European Space Weather Workshop ESTEC, 18 November 2005
Virtual Observatories • Virtual Observatories (VOs) are the modern way of exploiting and sharing data • Each VO provides information, data and services to a particular scientific community. • The need for VOs has evolved as desire to address cross-disciplinary science problems has grown • The evolution of VOs powered by rapid changes in hardware and expanding capabilities in Information Technologies • Data sets stored anywhere in the world can be included • Volumes growing, not practical for a single site to hold all data • Communities have well established ways of handing the data • Expertise can stay at main archive of dataset • Services can be used to find, manipulate and stage the data • Need processing and storage resources
Requirements for Implementing a VO • Resources (data archives, processing, modelling, etc.) prepared to collaborate at some level • active participation most beneficial • contribution to standards, willingness to deploy them. • A system able to handle: • data centres, etc. that can only participate at minimum level • manpower, etc. to make changes may be limited • data that are not fully compliant • data and metadata translators used to adapt the data • this is the case of practically all existing data centres • Note, not all VOs adopt same policy here... • An organization capable of harmoniously supervising: • Definition of standards for metadata • Proposal of new standards for future data • Deployment over a scattered community
The importance of metadata • Several scientific communities have started building Virtual Observatories. In Europe, these include : • Astrophysical Virtual Observatory (AVO) – the first and most firmly established, with strong trans-Atlantic connections (through IVOA) • European Grid of Solar Observations – this is operational works with related VOs in the US • These organizations coordinate existing data archives to create virtual observatories – they do no operate the archives. • Key to operation of a VO is metadata - data that describes data. • Allows heterogenous data to be used together • Minimizes the need to change existing systems • Facilitates interoperability
Data Models and Dictionaries • A data model is a set of terms and their relationships that capture the essential concepts of a given domain. • A data dictionary provides the terms. • The data models and dictionary help define necessary metadata and the contents of registries. They serve two purposes: • To find the desired data or services • For this purpose a dictionary is essential, so that standard terms (keywords) have standard meanings. • Precision of search result depends upon precision of the request. • To understand data. Here it must be possible to : • read each physical record and reconstitute the sequence of numbers • know what each number represents: time, data parameter, support parameter, ... • exploit the data: units, coordinate system, ..., of each parameter must be known • Ontologies are now being developed to describe data models
SPASE, Space Physics Archive Search & Extract • A collaborative effort to define metadata dictionary for space plasma and solar metadata between: • NASA / National Space Science Data Center • Planetary Data System - UCLA Plasma Physics Interactions Node • CNRS / CNES Plasma Physics Data Centre (CDPP) • Rutherford Appleton Laboratory • Southwest Research Institute • Johns Hopkins University Applied Physics Laboratory • many other US and Japanese groups. Endorsed by a Charter (2003) and supported by NASA (since 2004) • Recent plenary meeting JHU/APL, 02 – 04 November 2005 • V0.99.8 was issued on 18 Nov 2005, hopefully V1.0 approved shortly • XML descriptions of several data sets have been prepared. • EGSO used SPASE as input when defining its data model for solar and heliospheric data
EGSO System Architecture http://www.egso.org
EGSO Search Capability • Hierarchy of registries and catalogues allow optimization of the search and minimize the burden on the resource providers • Static and Dynamic Search Registries, Unified Observing Catalogue, Data Registry, etc. • Registries etc. follow concepts set out in EGSO Data Model • This type of structure is not unique to solar physics, or EGSO • Data Archives are interfaced through adaptor modules • HTTP, FTP, Web Services, CGI… • Stand-alone servers (the Special Providers) maintain key metadata • Solar Event Catalogue (SEC), Solar Feature Catalogue (SFC), Unified Observing Catalogue (UOC), Database of Solar Observatories (DSO)… • Relational databases behind Web Service interface (SOAP+XML) • Hides management of metadata from main system • Available to other VOs, etc. to use (SEC used by AstroGrid and VSPO)
Data Archives accessed by EGSO CoSEC is used by EGSO to provide some resources, including data processing (TRACE), and is regarded by CoSEC as a resource. Many interfaces supported: V: VSO Web Service; H, HTTP; F: FTP, D: using database
SEC Special Provider Architecture WSDL (Web Service Definition Language) document describes the application programming interface (API) and can be used by standard software to generate the required interface code. This was used this week by VSPO in order to provide access to the EGSO Solar Event Catalogue. .
Existing relevant Virtual Observatories Solar & Heliospheric: EGSO, European Grid of Solar Observations (UCL; was EC FP5/IST) VSO, Virtual Solar Observatory (NSO+GSFC; NASA) VHO, Virtual Heliospheric Observatory (GSFC; NASA) VSTO, Virtual Solar Terrestrial Observatory (HAO; NSF) VSPO, Virtual Space Physics Observatory (GSFC; NASA) CoSEC, Collaborative Sun-Earth Connector (LMSAL; NASA) Geophysical: VMSO, Virtual Magnetospheric Observatories(LWS Eng.?; NASA) ViRBO, Virtual Radiation Belt Observatory(U. Colorado; NSF?) VITMO, Virtual Ionosphere, Thermosphere & Mesosphere Obs.(JHU/APL; white paper?) VGMO, Virtual Global Magnetic Observatory(U. Michigan NSF & NASA) Generally not involved with IVOA (International Virtual Observatory Alliance) Solar physics has an advantage in that it has a well developed analysis environment based around IDL – SolarSoft. This software tree has branches for dozens of instruments, is mastered from GSFC and is used by groups around the world. EGSO, VSO, CoSEC and VSPO have regular telecons to ensure interoperability. There is also an IAU Working Group on “International Data Access” for solar and heliospheric data
Some European Resources CAA, Cluster Active Archive, an ESA contribution to the “International Living With a Star” program. (Beta-testing now) • Covers only space plasma physics • It’s metadata dictionary is based upon SPASE CDPP, Centre de Données de la Physique des Plasmas • Adopting SPASE dictionary. WDC, World Data Centres (RAL…) DIAS, European DIgital upper Atmosphere Server (DIAS) SWENET, supports SDAs in ESA Space Weather Initiative Solar-B Data Centre, will provide European access to Solar-B data Database & Modelling Server, (Heyndericks) Other modelling, (Cargill, etc.) etc… Most of the relevant Virtual Observatories are in the US – funded by NASA and NSF – however, they are still important components
Tying things together • Resources appear disparate, but making them work together not necessarily impossible or difficult • A lot of the ground work has been done on defining data models that could be extended and adapted • SPASE, EGSO Data Model, etc. • A single data model to fit all available resources is not realistic and could never be agreed by the different communities • Ontologies are the way to integrate the communities’ contributions • Data model/ontology for each community, with over-spanning data model/ontology that ties everything together • A limited set of interface protocols need to be adopted • Grid: Web Services, Grid Services, P2P; FTP, HTTP+PHP… • Structured messages (XML/VOTable) rather than simple ASCII • We must not get hung up about file types…
Conclusions • We have a rich and diverse set of resources that are relevant to Space Weather and that could be made interoperable • Many resources are available in Europe, but to facilitate science all resources globally should be considered for inclusion • A Virtual Observatory for Space Weather would allow us to integrate data services, processing and modeling into a tool to support the community • Already some discussions in the communities on a related VO for the whole Solar System. • All solar system down to “ionosphere” of all planet (=>EuroPlaNet) • Main difference is immediacy of access to data and models • Two proposals submitted under FP6 (CASSIS coordination action; Eu-SSVO under NEST); COST Action being considered • In way we have been discussing it, a Space Weather VO would a special case of Eu-SSVO centred on the Earth • However, to support for manned planetary exploration we would need to consider the wider view