The WMO Information System (WIS) acts as a one-stop shop for all activities related to data management.Users with access privileges can easily find and retrieve all the weather, climate and water data and products they need in one place. Data and products that are of worldwide interest remain available in the 24-hour GISC cache. Authorized users can gain immediate access to data without waiting for requests to be routed through various GTS hubs before the data can be delivered. Furthermore, they can easily modify their data subscription and maintain their discovery metadata as needed.
WIS enables discovery of authoritative meteorological and hydrological data and supports the collection of data and its exchange between WMO Centres and their users. The "WIS Catalogue" describes the data and products available across WMO. Data and products are registered with the WIS by submitting a metadata record to the WIS Catalogue that describes the content, structure and access mechanisms for the associated data or product.
The majority of data and products published through WIS are provided as files and made available via FTP servers or distributed using the Global Telecommunication System (GTS) for exchange between collaborating Centres. However, the Web is increasingly used to publish data on WIS.
- WIS Centres responsible for publishing data are designated either as a National Centre (NC) or a Data Collection and Production Centre (DCPC). The Centres are similar but the latter are affiliated with a WMO Programme rather than a national activity.
- Global Information System Centres (GISC) are networks hubs that maintain synchronized copies of the WIS Catalogue, provide a portal to search the WIS Catalogue, maintain a cache of data and products for near-real-time exchange between operational centres and offer mechanisms to download or subscribe to data and products within the cache. It is important to note that this "global cache" represents a very small subset of the data that is discoverable on WIS.
WIS Centres must be approved by the Permanent Representative to WMO of the country (or 'Member') within which the Centre is located. Furthermore, GISCs and DCPCs are required to demonstrate through independent audit their capability to meet the relevant WMO technical regulations. These constraints ensure that WIS remains an authoritative source of meteorological and hydrological data. The list of approved WIS Centres is published in Appendix B of the Manual on WIS (WMO-No. 1060): Approved WIS Centres.
To publish your data on the WIS, you must do so through a registered WIS Centre. The primary requirement to publish your data or product on WIS is to provide to the WIS Catalogue a metadata record that describes your data or product and how to access it. The arrangements to achieve this will vary between centres, but many offer a Web-based user interface for entering metadata to the WIS Catalogue removing the need for data publishers to work directly with XML.
Once your data are registered in the WIS Catalogue, your data may be accessed directly from FTP or Web servers hosted by your institution; for example, using a THREDDS Data Server.
However, if you are intending to routinely publish data (e.g. for real-time observations to be assimilated into operational weather prediction models) it may be pertinent, or even necessary, to distribute that data to other WMO centres through the WIS. Again, this must be achieved through a registered WIS Centre. The exact mechanism(s) used to pass your data to the affiliated centre for onward transmission will vary, but will typically options include direct dissemination from satellite data collection platforms, FTP / SFTP and email. One mechanism that your affiliated WIS Centre may use to distribute the information is the part of WIS known as the Global Telecommunication System (GTS). The GTS is the communications network operated by national meteorological and hydrological services (NMHS) and collaborating organisations for routine collection and dissemination of time- and operation-critical data and products. Relevant technical regulations are published in the Manual on the GTS (WMO-No. 386) . Technically, the GTS uses pre-arranged agreements to route files (e.g. the data and products) between Centres using the File Transfer Protocol (FTP) and Secure FTP (SFTP). It has been the mainstay of operational data exchange in WMO for decades. It is robust and resilient but band-width constrained as it uses high-availability dedicated links and network clouds to ensure a guaranteed quality of service. In some circumstances, the Internet may be used as an underlying technology for components of the GTS (e.g. when acceptable levels of service and adequate security measures are provided in a cost-effective manner) - particularly for less time-critical requirements and for distribution of larger volumes of data.