FACILITATION OF SATELLITE DATA EXCHANGE UNDER WMO WIS

Transcription

1 CGMS40 EUMWP15 Prepared by EUMETSAT Agenda Item: WGIV/6 Discussed in WGIV FACILITATION OF SATELLITE DATA EXCHANGE UNDER WMO WIS The WMO Information System (WIS) has reached a stage where users can discover and access in near and non real time operational products made available by the different WIS centres. A stronger involvement from Satellite operators is recommended to improve the visibility and availability of satellite products in WIS. This paper addresses some aspects of the WIS that are particularly relevant from a Satellite operator (DCPC) point of view and enumerates different areas of potential improvements. The WIS discovery services rely on product descriptions contained in standardised metadata records and the metadata records for satellite data is one of the necessary aspects for improvement in order to provide meaningful and consistent discovery results to the users. Another aspect is to promote the utilization of the communication links between the WIS centres for data exchange as well as the integration and further strengthening of satellite operators data dissemination systems in WIS to provide users improved access to satellite data. A working organisation between a to be setup CGMS task team and the related WMO Expert Teams is recommended to address and coordinate those aspects in a generic way. Action/Recommendation proposed: Take note of the data provision and data exchange features of WIS; To create a CGMSWMO Task Force Team on Metadata implementation for satellite data to provide consolidated views/advice on the metadata definition.

2 CGMS40 EUMWP15 Facilitation of satellite data exchange under WMO WIS 1 INTRODUCTION During 2012, the first main components of the newly built WMO Information System (WIS) have been declared operational. The infrastructure is now in a stage where users can discover and access datasets. Satellite operators are encouraged to increase promoting the access to their satellite data in WIS. This document provides a short introduction to WIS and discusses how the visibility of satellite data could be improved by creating consolidated metadata recommendations from a group of satellite metadata experts and how data provision to and data exchange within WIS can be addressed in general. A way forward is also proposed to allow Satellite operators providing consistent metadata for all satellite products. 2 WIS, THE NEW WMO DATA EXCHANGE PLATFORM For more than a decade, the world has entered in datacentric era where the volume of data produced has increased exponentially. It has become crucial to easily find and access relevant datasets for all economical main sectors. It is certainly true for the meteorological community and the developed WMO Information System (WIS) is the WMO response to these challenging changes. The WIS is an emerging infrastructure designed to provide powerful data discovery and data delivery services. It has been engineered to let data providers easily publish and exchange data in near realtime and non realtime fashion. It also allows users to easily discover datasets and get access to the data. 2.1 WIS Infrastructure Organisation The WIS services are provided by the WMO Members implementing three types of WIS centres: Global Information System Centres (GISCs), Data Collection or Production Centres (DCPCs), National Centres (NCs). GISCs serve as a collection and distribution centres in their area of responsibility and they are the WIS access points for general users. Via their data discovery and data retrieval services, users can discover and get hold of meteorological realtime or archived datasets. DCPCs are centres that operate under a WMO or related international programme and/or Regional Association. They may have a national role but they are primarily focused on international or global activities. They are connected to the GISCs and are responsible for the collection or generation of sets of data, forecast products, processed or valueadded information, and/or for providing archiving services. NCs are also a categorization of existing centres within WMO or national programmes. Although they may have some international role, their focus is primarily on national activities. This includes collection and distribution of data and creation of products and services on a national basis, NCs also coordinate or authorize the use of the WIS by national users, under the authority of the respective Permanent Representative with WMO.

3 CGMS40 EUMWP15 The terms NC, DCPC and GISC are used for describing the necessary functions, not actual organizational entities. There may be organizations, such as NMHSs, which combine all three functions within their structure. Satellite operators are typically expected to take the role of a DCPC in the WIS architecture. More information regarding the WIS can be found in the referenced Manual on WMO Information System (1) and the WIS in a nutshell documents (2). 2.2 WIS infrastructure built on standards The WIS infrastructure has been defined on standards recognised by international standardisation bodies. It is built on reference architectures for data discovery and data delivery to allow all WMO members an easy integration with the WIS. Because of such a reference architecture, each WMO member can be fully compliant to the defined interfaces but nevertheless implement their own WIS infrastructure node with off the shelf components. Those can also be developed and integrated by industry and/or further developed to build WIS services tailored to their own needs. The WIS data retrieval services provide an immediate support to all WMO data representation and formats and allow an easy integration of new and future data formats. The WIS data discovery services rely on the definition for each dataset, of metadata information based on ISO and OGC metadata discovery standards (ISO19115 and ISO19139). These ISO metadata discovery standards that are used in most of the existing Geographic Information Systems (GIS) services have been chosen to ease the interoperability with other communities and to facilitate the creation of discovery metadata using off the shelf tools. 2.3 DCPC key functions To be nominated as a DCPC in the WIS, an organisation needs to demonstrate to CBS the ability to provide WIS services in compliance with the DCPC functions and responsibilities as defined in the Manual on WIS. Amongst the required functions, two key ones are discussed within this paper: A DCPC shall exchange with its associated GISC, metadata describing its datasets made available via the WIS. Metadata records are used by the GISCs to create the WIS catalogue of products as well as building powerful discovery services around this catalogue. Having good discovery services is essential to help users easily finding Satellite datasets and it is therefore crucial for Satellite operators to provide the most accurate and adapted description of their datasets in the metadata records. DCPCs are also obligated to provide to their associated GISC, products intended for global exchange. The GISC to GISC data exchange mechanism

4 CGMS40 EUMWP15 will then insure that all GISCs from all WMO regions have a copy of all data intended for global exchange ENHANCING THE VISIBILITY OF SATELLITE DATA IN THE WIS Advantages of the WIS to a DCPC The WIS has many advantages for a DCPC. The WIS builds on powerful discovery services such as a productbased search engine and a browsable product categorization. The discovery services create their search index from a product catalogue which is updated in realtime. When a DCPC updates its product metadata records with its associated GISC, the WIS insures that they are synchronized on all GISCs and that any WIS user can discover DCPC products intended for global and nonglobal exchange. The WIS discovery services are openly available to any user and from any GISC centre. This means that the WIS infrastructure is open to a very large community and therefore will improve the visibility of all DCPCs products as well as promoting the organisations providing these relevant products. The WIS has also been built on standards to easily interoperate with the infrastructures from other communities, thus with the potential to again largely increasing the visibility of satellite data. Finally, the WIS includes also the usage of open internet technologies such that users can easily and securely get hold of DCPCs data intended from global exchange directly from their associated GISCs. GISCs are required to provide services for delivering global exchange data in near real time DCPC data provision and data exchange DCPCs are required to provide all data intended for global exchange to their associated GISC. GISCs are then required to synchronise all products intended for global exchange and via the GISC to GISC cache synchronisation, these products are propagated in near real time across all GISCs and therefore being made available to users in all WMO regions. Through this mechanism users can access via their local GISCs in near realtime globally exchanged products. This particular GISC function removes the need for DCPCs to provide such data directly to users outside their area of responsibility. Other products, not intended for global exchange, will continue to be served by DCPCs directly. For DCPCs the data provision to users in their area of responsibility is a WIS function and Satellite providers are encouraged to continue strengthening the development of their own data delivery mechanisms to provide the best possible service. In particular, Satellite providers are invited to also consider including broadcast systems to support the ongoing implementation of WMO IGDDS. The interoperability between satellite broadcast systems should be emphasised in this context in order to facilitate easier bilateral data exchange between Satellite operators and therefore provide an easier access to the data for all users in all WMO regions Improving the WIS metadata for satellite operators

5 CGMS40 EUMWP15 The following paragraph relates the EUMETSAT experience and potential issues encountered while establishing its DCPC infrastructure with respect to the WIS metadata. The WIS metadata is built on the ISO19115 standard which defines the conceptual model for describing any geospatial information as well as ISO19139 which defines how to encode all the ISO concepts in XML. These ISO standards define object constructs to express lists, ranges, dates, geometrical shapes, etc on a map. The ISO standard is a very large and complex model designed to define GIS metadata for all domains like for instance cartography and meteorology. Fortunately, the ISO metadata standard permits to define profiles that restrict the standard scope to a certain domain. WMO has defined over the years a dedicated meteorology profile called the WMO Core Profile. The WMO Core Profile currently in version 1.2 narrows down the number of constructs that can be used to express different concepts but there are still multiple ways to express for instance, airplane or buoy weather observations. This makes it difficult to build a very meaningful user s search experience. WMO via dedicated expert teams is currently trying to develop best practices and guidance documents to define metadata in each sub domains and therefore avoid creating a very disparate set of metadata very difficult to index. For the satellite observation sub domain, the metadata structure is usually being defined by members from the forecast or technical (IT) teams of the different Met Services. These WMO team members do not necessarily have the right understanding regarding satellite data to create relevant metadata best practices. In this sense, the WMO Core Profile in its current version is meteocentric as it has been tailored to properly define station observations, forecast data but not precisely satellite data. For example, it would be interesting to have the search engine being able to index some information related the level of processing (Level0, Level1, Level2) for satellite data. The categorisation information used to create the browsing by category could also contain this information. In addition the satellite metadata records should embed more information regarding the involved instrument, the timeliness of the data and its distribution means. Finally guidelines could be developed to create homogenous and consistent satellite metadata amongst the different satellite data providers in order to provide a coherent search experience to the WIS users. It would also beneficial for the WIS community to increase the participation from the Satellite community in the standardisation process and the associated formalising instances in order to build the best dedicated WMO Core Profile metadata records for satellite data. Another issue for Meteorology Satellite data providers is to be at the boundaries between the meteorology and earth observation satellite communities. This might result in having different requirements regarding the metadata definition for these diverse communities. For example the EUMETSAT Product Navigator that provides discovery and data retrieval services is also required to be compliant to the HMA (Heterogeneous Missions Accessibility) requirements. Both, HMA and WIS, are based on the ISO19115/ISO19139 standards but were developed at different speeds with a slightly different orientation regarding the metadata definition. As a consequence, 2 different ISO versions and definitions are used in EUMETSAT to describe the same metadata with different extensions, keywords, categorisation, etc.

6 CGMS40 EUMWP15 A tool has therefore been built to generate WMO Core Profile compliant metadata from the EUMETSAT Product Navigator metadata, however ideally there should be no need to maintain two variants of the same data description and the standard describing the metadata should be aligned such that different communities can be addressed. It is proposed that the satellite providers exchange their experiences on this topic with the aim to achieve a common view that might be beneficial to other DCPCs also. Therefore it is proposed to follow the same approach as the one established in the data codes and formats area. A CGMSWMO Task Force Team on Metadata implementation for satellite data could be created to facilitate the integration of Satellite operators within the WIS infrastructure. This task force team could provide Satellite operators relevant and consolidated view/advices. 4 CONCLUSIONS The WIS infrastructure is a good opportunity for Satellite operators to reach new user communities, find new audiences, provide access to data, promote their products and provide more visibility for their organisation. Making the integration into WIS a success for Satellite operators is not only to make operational use of the data delivery and data exchange features that WIS provides but also to define appropriate ISO19115/19139 metadata records that address the satellite communities specifics. Creating a consistent and coherent search experience for all satellite data is key to the success of the WIS and for this reason, the definition of metadata records for satellite data should follow some to be defined guidelines which are agreed amongst the different satellite data providers. To address those issues and to provide consolidated views and advices, a CGMS WMO Task Force Team on metadata implementation for satellite data could be created. The same approach has been applied to the Data domain with the creation of the CGMSWMO Task Force on Satellite Data Codes (TFSDC) and has proven to be very successful REFERENCES Manual on WMO Information System [ftp://ftp.wmo.int/documents/mediapublic/publications/manual%20on%20wmo%20inf ormation%20system_wmo_no_1060/1060_manual_on_wis_en.pdf] WIS in a nutshell [