Reprint 472

Expert Group Meeting on Internet Applications

For Agrometeorological Products

Washington DC, USA, 6-9 May 2002

Use of Web Server for International Exchange

of Public Forecasts and Warnings

of National Meteorological Services via the Internet

Dr H K Lam

Director of the Hong Kong Observatory

Permanent Representative of Hong Kong, China with WMO

Vice-President of WMO Regional Association II (Asia)

Tel: (852) 2926 8221

Fax: (852) 2721 6557

Telex: 54777 GEOPH HX

E-mail: dhko@hko.gov.hk

Abstract

Tasked by the Commission for Basic Systems (CBS), Hong Kong

Observatory (HKO), Hong Kong, China is taking the lead in the development of two

WMO-sponsored pilot websites, viz World Weather Information Service (WWIS)

and Severe Weather Information Centre (SWIC). This paper focuses on the technical

considerations in the development of the two pilot websites and their implementation

requirements.

The existing system setup of the two websites will be covered. Key factors

that are essential to the successful implementation and operation of a common

website for international exchange of public forecasts and warnings of National

Meteorological Services (NMSs) via Internet will also be discussed.

1. Introduction

Weather information is a much sought-after commodity – by the traveling

public, by the international media, etc. The rapidly expanding Internet with a

diversity of weather information from a wide array of information service providers

often bewilders the users and leads many governments to question the amount of

resources required to support National Meteorological Services (NMSs). WMO

Members, especially those from developing countries, have expressed concern on the

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impact of non-professionals on the public recognition of the weather services

provided by National Meteorological Services [1].

The meteorological community needs a collective official voice to

counteract the many spurious sources of weather information over the Internet. An

authentic and authoritative source of weather information on the web with the

backing of WMO Members will be a strategic step in elevating the public weather

services operated by NMSs to the international arena, enhancing the profile and

visibility of NMSs, leading to an appreciation that official and reliable forecasts come

from those who operate a highly regulated network of weather observations under the

auspices of WMO.

The Commission for Basic Systems (CBS) embraced these ideas and tasked

Hong Kong, China to take the lead in the development of two WMO-sponsored pilot

websites, viz World Weather Information Service (WWIS) and Severe Weather

Information Centre (SWIC).

The objectives for establishing the two websites are:

i. To develop a methodology for the international exchange of public forecasts

and warnings issued by NMSs via the Internet;

ii. To provide a centralized source of official weather information on the

Internet;

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iii. To encourage the international media and the public to make good use of

official weather information provided by NMSs; and

iv. To enhance the visibility of NMSs, especially those of developing countries,

so as to strengthen the public recognition of the weather services they

provide.

The websites are to be easily accessible and user-friendly to the public and

media. Collated information would also be used to generate an integrated set of

weather information for dissemination to the media, the public and back to the NMSs.

2. Recent Developments

The CBS Public Weather Services Expert Team on Warning and Forecast

Exchange Issues developed in July 2000 an initial framework for the exchange of city

forecasts among WMO Members. The addresses of the websites are: WWIS –

www.worldweather.org (Fig. 1) and SWIC – severe.worldweather.org or

typhoon.worldweather.org (Fig. 2). The WWIS website is being implemented in a

phased manner. In Phase I of the project, the website provides climatological

information for selected cities as well as links to the websites operated by the official

meteorological services of WMO Members. This phase is currently under

operational trial. Phase II will include city forecasts a few days ahead. City forecasts

are being added to the website as they become available. Phase II of the website will

undergo operational trial at the end of 2002. The SWIC website deals with severe

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weather warnings issued by Members. In the first instance, the website now covers

warnings of tropical cyclones in the western North Pacific provided by members of

the ESCAP/WMO Typhoon Committee. The website is also under operational trial

[2]. Both sites are currently operated in English only.

3. System Requirements

To meet the objectives of the pilot projects, a system to support the operation

of the websites needs to satisfy the following requirements:

i. Providing an appropriate resource management system to handle the

numerous weather information items supplied by WMO Members;

ii. Providing a high availability and reliability platform with automatic fail-over

and load-balancing features;

iii. Having sufficient storage capacity, system memory and computing power to

generate and manage the large number of web pages inside the two websites;

and

iv. Supporting a diversity of communication methods to facilitate exchange of

up-to-date weather information by WMO Members.

These requirements are to ensure that the system can provide a reliable and

capable platform for the exchange of public weather forecasts and warnings issued by

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NMSs. The diversity of communication methods would hopefully encourage all

WMO Members, including developing countries, to participate in the pilot projects.

4. System Configuration

A schematic diagram of the system is given in Figure 3. The web servers

and the backend processing system are part of a server farm which also hosts other

websites operated by the Hong Kong Observatory (HKO). To maintain high

availability and reliability, the server farm has automatic data backup facilities and

secondary power supplies. The system’s backend is connected to the Hong Kong

Observatory’s main computer system with a dedicated T1 (1.54 Mbps) leased line.

The front-end connection to the Internet backbone has a maximum capacity of 60

Mbps. Both connections are protected by firewalls as well as other system security

tools.

Two identical web servers forming a cluster are used to host the contents of

the two websites. They can simultaneously handle about 5,000 requests. The

resilience of the web servers is achieved by a pair of load balancers that constantly

monitor the serviceability of the servers and automatically divert traffic where the

situation warrants. To ensure data integrity across the web servers, web pages of the

websites are stored on a Network Attached Storage (NAS) device which is a high

availability data storage device and has automatic data backup capability.

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5. Content Management

The pilot websites are implemented based on a data-centric model. The web

contents are generated and updated based on the information stored in a relational

database management system (RDBMS), which is implemented in a two-tier fashion.

The “master” database is located at the Hong Kong Observatory’s main database

server. The “slave” database resides on the server farm. Data synchronization

between the “master” and “slave” database is achieved by using automatic data

replication. With this arrangement, the database is accessible by web applications

while a high security level for the data source can be maintained in the “master”

database at the same time.

In developing the content management software, open source system

development tools are used for better portability of the software. A combination of

Java Server Page (JSP), Java Database Connectivity (JDBC) and Perl module is

employed to manage the web contents. Backend processes are set up to regularly

monitor data updating in the RDBMS and, if necessary, update web pages

automatically by fetching data from the RDBMS using JDBC.

6. Weather Information Exchange Mechanism

In view of the diversity of capabilities and practices among WMO Members,

it would be important to allow a matching variety of communication means to

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facilitate the exchange of public forecasts and warnings in both coded and plain text

format. A system to receive and process information submitted by Members utilizing

a number of means is now under development. An array of communication methods

[3], including FTP, e-mail and web-form through the Internet in addition to sending

messages over the conventional GTS and AFTN, will be available for this purpose.

For example, the web-form (Figure 5) is a web interface to assist users in preparing

and submitting their forecasts manually. Users could choose the forecast periods,

weather elements and temperatures from pull-down menus. Upon confirmation, the

software residing on the HKO server would automatically process the message and

post the forecasts onto the pilot website.

A schematic diagram illustrating the workflow of weather information

exchange is depicted in Figure 4. A dedicated server is set up to receive forecasts via

FTP, e-mail and the tailor-made web-form. A software decoder is implemented to

automatically process and check the validity of the forecast bulletins submitted by the

participants. Deviations from the recommended format will be flagged to allow

manual intervention.

Forecasts submitted will be converted in eXtensible Markup Language

(XML). Using XML for information archival has the following advantages:

i. XML, a recommendation endorsed by the World Wide Consortium

(www.w3c.org), is now widely in use in the Internet community. Numerous

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tools, either commercial software or freeware, for processing XML data are

readily available. XML data can be easily converted into other format.

ii. XML is a highly extensible format. It is easy to incorporate new types of

information into the XML data structure.

In the near future, the XML data processing system will be used to support the web

server as an information distribution agent to allow Members to retrieve forecasts

available on the server via FTP for their own national applications.

For severe weather warnings and advisories, information is gathered

primarily from Members’ websites. A metafile format has been designed so as to

allow participating Members to decide the range of information to be presented in the

SWIC website. Metafiles created by participating Members in their websites are

fetched routinely by the data processing system and the corresponding web pages are

updated according to the contents in the metafiles. As a secondary channel, the

system is also capable of processing and posting onto the website warnings and

advisories available on the GTS.

7. Resources for Developing and Maintaining the Pilot Websites

Apart from technical considerations, a crucial factor for the successful

implementation is the availability of resources to support the setting up, the

continuous development and the day-to-day operation of the web servers. Hong

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Kong, China fully supports the concept of international exchange by Internet and

commits itself to providing the necessary resources required to run the pilot projects.

A summary of resources contributed by Hong Kong, China is in Annex I.

Human resources are second to none as the key element for success. A

project team has been set up in HKO to oversee liaison, system design and product

development. Two computer programmers are specifically assigned to handle the

numerous tasks on data processing and automation. It is likely that a number of staff

will still be required to maintain and update the system upon the full implementation

of the servers.

8. Observations to Date

The two pilot projects so far have demonstrated some success in using web

servers for international exchange of public forecasts and warnings of NMSs via the

Internet. By the end of April 2002, climatological information of 514 cities from 149

Members is included in the WWIS website. 25 participating Members are submitting

forecast bulletins either through GTS or e-mail to WWIS. Forecasts for more than

100 cities from these Members are now available in the website (Fig. 6). The

availability of e-mail submissions has made possible for some developing countries

to contribute to the pilot project.

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Visit statistics is a good measure to gauge the popularity of the websites.

By the end of March 2002, a total of about 300,000 page visits to the two websites

were recorded since their operational trial (Annex II). This is an encouraging sign

that the websites would grow to become a good means to promote Members’

visibility in the Internet community.

In the course of consulting participating Members regarding the

recommended form for the exchange of forecasts, language has emerged as a

potential issue. The pilot project is conducted in English. In order to encourage the

participation of Members whose native languages are not English, it would be

advantageous to strengthen the system to support the reception of information and the

generation of web pages in different languages.

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References

1. World Meteorological Organization 1999: Abridged Final Report with

Resolutions, Thirtheenth World Meteorological Congress. WMO-No. 902,

38.

2. World Meteorological Organization, 2001: Hong Kong Observatory and

WMO launch Trial Web Site WWW.WORLDWEATHER.ORG. Press release,

14 December 2001.

3. World Meteorological Organization, 2001: Weather on the Internet and

Other New Technologies. WMO/TD No. 1084.

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Figure 1: The World Weather Information Service website

Figure 2: The Severe Weather Information Centre website

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Figure 3: A schematic diagram of the system configuration

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Figure 4: Schematic diagram of the forecast collection and distribution system.

Figure 5: Web-form under development for Members to prepare and submit

weather forecasts to the WWIS website.

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Figure 6: Number of city forecasts available in the WWIS website from December 2001 to April 2002

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ANNEX I Summary of the resources for the development and management of the two pilot websites

(past and projected)

Manpower (Man-Month) Up to Dec. 2001 2002 2003

SWIC 12 12 8

WWIS 26 42 22

Total 38 54 30

Other Resources (US Dollars) Up to Dec. 2001 2002 2003

SWIC 1,400 7,600 7,300

WWIS 5,000 24,800 15,200

Total 6,400 32,400 22,500

SWIC – Severe Weather Information Center WWIS – World Weather Information Service Remarks (1) Estimates based on the assumption that no major change in scope would occur after operational trial. (2) “Other resources” include web hosting services and development software / hardware. (3) The recurrent cost for 2004 onwards for web hosting services is estimated to be around US$20,000 annually.

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ANNEX II

Visitor statistics of the two WMO pilot websites Monthly page visits to the SWIC and WWIS website since the operational trial: (SWIC: September 2001, WWIS: December 2001)

0

10,000

20,000

30,000

40,000

50,000

60,000

70,000

Sep 2001 Oct 2001 Nov 2001 Dec 2001 Jan 2002 Feb 2002 Mar 2002

Month

Pag

e V

isit

s

SWIC WWIS

Total and average daily page visits of SWIC and WWIS websites (up to 31 March 2002)

SWIC WWIS

Total page visits 87,000 214,000

Average daily page visits 300 1,800

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