- It had to be possible to perform monitoring and (some remote) maintenance of all sensors and systems from any site, using some network architecture; - Standard, proven, but modern, technology should be used to ensure the expected life cycle of approximately 10 years. - Meteorological users had to be able to access systems at any location in the Netherlands meteorological network and generate meteorological reports for any site, at any other site.
In 2000, the KNMI started a project to implement a fully automated meteorological network of observation and airport systems. This network consists of
- 20 fully automated observation stations, - 6 airports - A central acquisition and data processing site at the KNMI headquarters in de Bilt.
The KNMI and the supplier, Almos Systems (selected after an international tender procedure) have selected a TCP/IP network supporting a client/server architecture, in which all processing and distribution of data is done at one central site. All automated stations are contacted via ISDN or Ethernet at least once every 10 minutes and all data is collected at the central system. The central system performs all calculations and produces SYNOPs observation reports on 'whole hours' and sends them to the MSS for dissemination. Copies of all data are sent to another system where it is made available for all user in the KNMI Network.
All six airports have their own database servers, which are connected via a WAN link to the central system in De Bilt. These servers supply data to the central system in De Bilt to be used for the SYNOP, but most of the data is used locally at the airport itself. Observers and meteorologists at the airports have graphical presentation systems for monitoring the weather and preparing meteorological reports (e.g. METARs). These presentation systems and other clients in the network, can contact any of the database servers located at any of the airports or in De Bilt. This network configuration allows for any sensor or system, throughout the Netherlands, to be monitored from any client for purposes of maintenance, for example. It also enables an observer to prepare a meteorological report for any airport from any of these presentation systems, as long as it is connected to the KNMI-WAN. The client software contains modules for meteorological users (observers, meteorologists), for maintenance monitoring and generating alarms, for remote control of the servers and software distribution, etc. Access to the systems is protected by username and password, and specific functions for certain users or technicians are also protected by the application of passwords.
All systems are built on Windows 2000 Professional, or Server, operating systems. All servers have ‘hot standby’ machines, and some other facilities to achieve high availability have been implemented. All computers and network component are standard ‘of the shelf’ products and can be replaced or upgraded easily during the system’s life cycle, which is expected to be approximately 10 years.
A detailed description of the systems and their functionality will be given in our presentation.