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Previous  Fig 7: display of in situ radiological data measured by the survey vehicle  Fig 8:Display of in situ wind and temperature measurement from the portable automatic weather station (denoted by CBRN in the map) also provides spatial data analysis tools, so that user can retrieve the number of lightning strokes occurring in a selected area of interest over a period of time. For data sharing the same GIS platform, the development of new value- added products is much simplified. A good example is the overlaying of radar images onto lightning data which enables user to appreciate which rain area bears lightning activities and which does not (Figure 6). Moreover, a film loop can be activated to track the movement of lightning alongside rain areas for assessing how the lightning develops or decays as the rain progresses.  Fig 9: Combined GIS and mobile technology providing in situ weather service USE OF GIS AND LBS IN EMERGENCY RESPONSE In the event of a radiological emergency, a custom-fitted van with radiological measuring equipment on board is deployed to measure the background radiation level over the territory. To allow the decision maker at the Observatory headquarters to make an overall assessment of the situation and give appropriate commands to the survey team on the van, he/she has to be kept informed of the radiation level at every point along the survey route instantly. This is achieved by transmitting realtime radiological data measured en route automatically to the headquarters using wireless communication and displaying the track of the van and the measurement results in front of the decision maker, with the aid of sophisticated GIS tool as shown by the example in Figure 7. Besides the above, the measurement of weather information in the event of a nuclear, chemical or biological attack is another example of the Observatory's location-specific service. Since the attack can take place at any part of the territory, a portable automatic weather station is deployed to the affected site so that in situ wind and temperature information can be collected for identifying the area of downwind hazard. With the combination of mobile, GPS and GIS technology, weather information of the affected location can be displayed together with data of other fixed weather stations on a map (Figure 8) for analysis by the emergency response personnel of the Observatory and other operation departments. LOOKING AHEAD If we would just imagine, there are even more possibilities of using GIS and LBS to enhance public weather services. Once numerical weather prediction becomes more and more reliable, location-specific weather forecasts with fine time resolution, say less than an hour, may be provided to members of the public, facilitating them to make intelligent weatherrelated and location-specific decisions for themselves. For example, imagine someone caught in a rainstorm while travelling. If this person could use a mobile device to obtain information on when the rain will stop (Figure 9), he could make a decision as to whether he should proceed or seek a temporary shelter. Another possibility of applying LBS is the provision of location-specific weather warning to the public, especially when there is no territory-wide warning in force but localised hazard may exist. For example, when there is a tropical cyclone in the vicinity of Hong Kong but winds generally over Hong Kong are not strong except for a certain region of the territory. If people in that region can obtain alert of the strong winds through mobile devices (Figure 10), it would on the one hand ensure safety of the public and at the same time minimises disruption to normal life caused by the issuance of warnings of higher winds.  Fig 10: Alert of local strong winds to individuals Information technologies such as GIS and LBS advance rapidly and give us a lot of convenience in service delivery. Nowadays, many commercial GIS and LBS platforms are increasingly affordable. With the development of interoperability standards, software with GIS and LBS features conforming to these standards is now highly portable. All these serve to expedite the Observatory's development of GIS and LBS applications for the public. The Observatory will continue to make good use of the technologies and at the same time enhance the content of the service itself, in terms of accuracy, diversity and usefulness of the weather information. There is no doubt therefore that GIS and LBS will become more and more widely used and will increasingly aid the mitigation of disasters caused by severe weather. REFERENCES Lam, C.Y. & Lee, L.S. (2006), "GIS Applications in Weather and Geophysical Services in Hong Kong", Atmospheric Front (November), ESRI, pp. 8-10. Lee, L.S. (2007), "GIS and LBS Applications in the Delivery of Weather and Geophysical Services in Hong Kong". Presented at the 4th International Symposium on LBS and TeleCartography, Hong Kong, China, 8-10 November 2007. (Available at www.weather.gov.hk/publica/reprint/r733.pdf) Page 1 of 1
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