Wed, Jul 30, 2008 - Page 8 News List

Accurate forecasting takes money

By Kao Chia-Chuen 高家俊

The public criticized the Central Weather Bureau earlier this month for the lack of warning about unexpectedly heavy rains brought by Tropical Storm Kalmaegi. Local media then embarrassed the bureau by quoting Japanese and US typhoon forecasts rather than the bureau’s ahead of Typhoon Fung-wong on Monday. But the bureau is facing its own difficulties.

Any computer program that predicts natural environmental changes cannot perform calculations without data. It can only predict future changes based on the input of environmental parameters at a given point in time. The accuracy of such parameters is crucial to final predictions. When a typhoon hits Taiwan, the program needs data from when the typhoon was over water to calculate its structure when it makes landfall. But budget constraints have long left the bureau without equipment at sea. All of its equipment is on land, leaving the sea beyond the bureau’s grasp.

Taiwan has radar and satellite receiving stations to monitor typhoons. But indirect measurements gained from electric waves are highly uncertain and can only be fully used with the help of data collected at sea. In recent years, the bureau occasionally took the risk of sending aircraft into the radius of typhoons to collect data at sea, which was then used to complement radar and satellite data. However, for rapidly changing typhoon structures, this method is not very effective without constant observation at sea.

This is the difficulty the weather bureau is facing today. Since Taiwan is unable to collect environmental data at sea, the bureau has come under fire.

We urgently need to build observation stations to help forecast typhoons at sea. The government could deploy automated observation stations along common typhoon routes to measure the environmental parameters 24 hours and 6 hours before a typhoon makes landfall and then use this data with computer programs to improve calculations. The bureau could then use this information to adjust its radar and satellite data on an hourly basis. This is the only way to have accurate typhoon forecasts.

Flooding and landslides cause billions of dollars in economic losses annually in Taiwan, not to mention loss of lives. Typhoons are the main cause of these natural disasters. Although improving the accuracy of typhoon forecasts may not prevent all losses, more accurate typhoon forecasts could help protect lives and ease concerns.

Hopefully, the government will do something to improve the accuracy of Taiwan’s typhoon forecasts soon.

Kao Chia-chuen is a professor at National Cheng Kung University’s Department of Hydraulic and Ocean Engineering.


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