Precise Typhoon Prediction and Tracking Made Possible by NTU’s Functionally Enhanced Data Buoys
 
Jul 14, 2019
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For the first time in history, two functionally improved data buoys have successfully recorded air and sea variables along the path of a super typhoon. NTU’s marine research and technical team at the Institute of Oceanography, with the solid support of the Ministry of Science and Technology and Central Weather Bureau, has developed and deployed weather buoys for accurate typhoon prediction. The unprecedented field research was the first of its kind to be conducted and completed by a local team at NTU. The related research paper was published in the April 2019 issue of Nature Communications, and the research findings will be translated into computer programs, representing a major milestone in the precise and timely prediction of typhoons.

Typhoons that strike the Philippines, Taiwan, China, Korea, and Japan threaten the nearly one billion people living in coastal areas. Using observations to provide in situ data for the weather forecast center, advance knowledge of air-sea exchanges during extremely strong winds, and thus increase the accuracy of the typhoon forecasts is crucial to giving timely warnings to the public for disaster mitigation.

As early as the 1970s, scientists had found that a warmer sea surface generally provides more energy for typhoon development. The window to determining whether the water surface is warm enough to generate sufficient energy to produce a typhoon is as short as 10 hours. Scientists have struggled with the problem of insufficient data to grasp the needed temperature change. Now, the two NTU buoys have provided answers by revealing how air and sea interact at critical moments. This important cross-disciplinary study thus contributes significantly to timely warning, accurate forecasting, and improved disaster mitigation with respect to typhoons.

The two NTU buoys survived Super Typhoon Nepartak in 2016. The data captured along the typhoon’s path showed that sea surface temperature dropped 1.5°C in the four hours prior to the arrival of the typhoon eye. The intensity of Nepartak was, however, not affected by the temperature drop. After analyzing the data in detail, the researchers reached beyond the sea surface and identified more factors concerning the growth of a typhoon; for example, the sea current velocity in this case. The time-lapse cameras and current meters on the buoys captured the images and the data of a super typhoon, marking an unprecedented advancement in typhoon tracking. These results showed that during the four critical hours, while warm water was brought from the sea surface to the typhoon, the typhoon was also pushing the sea surface forward, speeding up currents at the top. This generated large and small vortexes in the ocean, as the currents at the bottom could not keep up with the upper currents. Icy cold sea water was thus brought up, cooling down the heat feeding the typhoon, depleting its strength.

Accurate typhoon forecasting requires more than a full understanding of the physical interaction between air and sea. It also needs constant feeds of atmospheric and oceanic in situ data into computer models, as well as regular verifications and modifications. Technical developments and satellite remote sensing have contributed significantly to the accurate prediction of typhoon direction. However, the forecast of typhoon intensity remains a challenge because there are insufficient observations of sea-air exchanges. On the one hand, sending research vessels or instruments to the deep blue sea to await typhoons or chase typhoons is like sending mice to attach a bell to a cat— an impossible mission. On the other hand, if we could deploy anchored buoys in selected areas to “wait for” typhoons, measure and assess the key metrics with advanced sensors, and rapidly transmit the data to land-based labs for forecasting and analysis, it would be far safer and more effective. Unfortunately, buoys that can precisely measure oceanic weather conditions and deliver data rapidly are not yet commercially available. Merchandising the buoys and their deployment services may be the next step to take.

Since 2015, the two buoys have documented the changes in weather at sea during 10 typhoon events. The altruistic act of sharing data is a part of the TOMATO (TOwards Multiple Arrays for Typhoon Observations) framework that deploys weather buoys and underwater gliders in the Northwestern Pacific Ocean. In the future, TOMATO will partner with meteorological organizations and universities in the Philippines to expand the scope and scale of the program. The NTU meteorological buoys will serve as sentinels at the defensive perimeter, protecting the lives and property of people in Taiwan.

Photo caption / Members of the buoy project from NTU’s Institute of Oceanography pose for a group photo on Ocean Researcher I.

SOURCE / National Taiwan University