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The Hong Kong Observatory Computer System and Its Applications

Introduction:

The Hong Kong Observatorys use of computers dates back to 1968 when the Observatory used the computer resources at the Government Data Processing Division to prepare the climatological summaries of Meteorological Results. Thereafter, with the development of the Global Telecommunication System (GTS) of the World Meteorological Organization (WMO), point-to-point regional telecommunication circuits between Hong Kong, Macao, Beijing and Tokyo were established. It was thus necessary for the Observatory to acquire its own computer system to process the vast amount of meteorological data for operational and climatological use.

Computer Systems:

The first computer system in the Observatory, an IBM minicomputer system, was acquired in 1973. The year also marked the establishment of the computer division in the Observatory. Subsequently, two Data General Eclipse computers replaced the IBM system in July 1978. Towards the end of 1982, enhancements were made to enable connection with additional workstations, graphic terminals and plotters. The Eclipse computers were replaced by a MV15000 computer in 1989.

In 1987, the Observatory acquired two MV20000 computers to cater for the need of new projects, which included automation of weather chart plotting, automatic dissemination of weather information through the local telecommunication network, numerical weather prediction, storm surge and wave modelling.

The need for faster computers grew as more sophisticated atmospheric and oceanographic models were introduced to the Observatory. In 1991, two IBM RS/6000 540 POWER servers were commissioned to meet the increasing demand for computing power.

In 1994, the MV20000 and MV15000 computers were replaced by a UNIX-based computer system, which comprised two RS/6000 590 servers. In 1995, a RS/6000 C20 server was installed. In the ensuing years, a number of UNIX based computers were deployed to serve as front-end data reception, storage servers, and to provide intranet services including domain name service, time service and web service. One SGI Power Challenge and two SGI Origin 2000 were installed in 1997 and 1998 respectively for the detection of windshear and turbulence. Two SUN E450 servers were subsequently installed in 1998 for the development and operation of a weather nowcasting system. A supercomputer, CRAY SV1, was acquired in 1999 to support the operations of a high resolution numerical weather prediction model to provide guidance in short range forecasting.

The Observatory embarked on a server consolidation project in 2000. An IBM SP server cluster was acquired to replace many aged computer servers. The server cluster was subsequently enhanced with more nodes to support meteorological data processing, database operation, testing of windshear/turbulence algorithm, and processing aircraft downlink data. The server cluster was configured to provide high availability services and a load sharing facility. An IBM p690 Regatta computer was acquired in 2003 to replace the SUN E450 servers and to support the implementation and operations of weather nowcasting activities.

Servers in the Observatory Headquarters are interconnected by a Fast Ethernet backbone network while computers located at out-post offices are linked to the network at the Headquarters by means of ATM or Frame Relay circuits. Dedicated circuits and ISDN links are used for data exchange with other centres while asynchronous communication lines are used for collection of data from local observation networks. Dissemination of weather information to the public and special users is automatically done through network and facsimile with the Observatorys Meteorological Information Dissemination System (MINDS).

Applications:

Listed below are some applications running on the Observatory's computer systems:-

  1. Data Acquisition and Message Switching: The Hong Kong Observatory acquires worldwide meteorological data mainly through the Global Telecommunications System (GTS). The department currently has three point-to-point regional meteorological circuits: Hong Kong-Tokyo, Hong Kong-Beijing and Hong Kong-Macao, which were established in 1969, 1975 and 1999 respectively for exchange of weather data. These links were incrementally upgraded or implemented in the past decade to cater for the increase in data volume. To take advantage of the advance in information technology many meteorological data such as numerical weather prediction products from overseas meteorological centres, is now gathered via the Internet. Aerodrome weather reports and forecasts are received from the Aeronautical Fixed Telecommunication Network (AFTN). These information are processed by the computer system to generate products supporting operations of forecasting offices. Upper-air data from the DigiCORA system at King's Park Radiosonde Station, winds data at different heights above the ground measured by the wind profilers, real-time signals from automatic rainfall stations as well as automatic weather stations are regularly received by the computer system.

     

  2. Data Processing and Presentation: The GTS data are decoded and checked at fixed time intervals. Objective analyses are then carried out for data at various standard pressure levels to produce grid point values. Routine charts showing observed, analyzed or forecast fields of various meteorological parameters, such as divergence, vorticity, pressure and temperature changes, and rainfall amounts are generated and posted onto the Observatory's Intranet for use by forecasters. Flight level winds, temperatures and other information for aviation uses are produced by the computer system at Airport Meteorological Office (AMO) and issued to airlines as flight documentation. Graphical terminals at AMO and Central Forecasting Office (CFO) are commonly used by the forecasters to analyse the meteorological conditions and prepare forecast bulletins and warnings..

     

  3. Tropical Cyclone Forecasting: When a tropical cyclone is centered within Hong Kong's area of responsibility for issuing warnings for shipping, objective forecasts of tropical cyclone movement are computed. When tropical cyclone warning signals are issued, charts of predicted tides using numerical models are produced.

     

  4. Numerical Modelling, Nowcasting and Statistical Analysis: Using numerical weather prediction models operated by the Hong Kong Observatory and other advanced weather centres, forecasts of various meteorological elements are computed and presented to forecasters. The Observatorys Rainstorm Nowcasting System makes use of radar and raingauge data to track the movement of rainstorm and predict every 6 minutes local rainfall distribution trends within the next one to three hours. Besides rainfall forecast, the Nowcasting System also produces specialized forecast products to alert forecasters the probability of the occurrence of landslip over the territory in inclement weather. The computer system also performs statistical analysis of data, estimates of rainfall amounts and return periods for occurrences of heavy rain, strong winds, tide heights, storm surges and earthquakes, etc.

     

  5. Automated Weather Chart Plotting: Weather charts showing reported observations from surface and upper-air stations in the region are automatically plotted by computers.

     

  6. Internet Web Service: Starting from March 1996, information about the Observatory and real-time weather information is made available to the public through the Internet. The Observatorys website (https://www.hko.gov.hk and https://www.weather.gov.hk) provides real-time weather information, warnings and forecasts for the public as well as the marine and aviation communities. Seismological, astronomical and tidal information, ultraviolet index, press releases, educational resources, information on radiation monitoring and time services are also available to meet different needs of the public.

     

  7. Database and Data Archiving: All past data received by the computers are archived on magnetic tapes and other electronic media. Relational databases are also used to store and process weather information to support decision making, forecast operations and research activities.