As the hurricane grows stronger, U.S. scientists suggest adding a superlative to the rating system

Mondo Science Updated on 2024-02-07

BEIJING, Feb. 7 (Xinhua) -- Two U.S. climatologists suggested on Feb. 5 that due to the repeated occurrence of super tropical storms in the past 10 years and the expected frequency in the future, it is recommended that the current tropical storm rating system in the United States be increased to a maximum level of 6.

This photograph, taken on August 8, 2023, shows smoke billowing from the town of Lahaina, Maui County, Hawaii, USA. Xinhua News Agency (photo by Alex Freeman).

Michael Weiner, a climatologist at the Lawrence Berkeley National Laboratory under the U.S. Department of Energy, and Jim Cosin, a hurricane expert at the National Oceanic and Atmospheric Administration, said in an article published in the Proceedings of the National Academy of Sciences that Hurricane Saffir-Simpson should be added to the Hurricane Saffir-Simpson Wind Rating System, a maximum level of 6, to include tropical storms with winds of more than 309 kilometers per hour.

The U.S. typically uses the Saffir-Simpson Wind Scale to assess tropical storm power. According to this rating system, which has been in use for more than 50 years, tropical storms with winds of 252 kilometres per hour or higher are classified as the highest category 5.

They say the current highest level, Level 5, is not enough to describe the power of some super-tropical storms and to serve as a warning to avoid the risks.

Tropical storms have become more powerful in recent years, and it would be an underestimation of the damage these superstorms can cause if the original five-level rating system is still used, Kosin said.

This is a photo taken on October 4, 2022 in Fort Myers, Florida, U.S., of a building damaged by Hurricane Ian. Xinhua News Agency (photo by Rolando López).

Since 2023, only five tropical storms with winds exceeding 309 km/h have been recorded, all of which have occurred in the Pacific Ocean. Tropical storms that have been recorded to have generated in the Atlantic Ocean have not yet broken through this wind speed. However, Weiner and Kosin said that as global warming intensifies, the climate conditions in the Atlantic Ocean are becoming more ripe for such tropical storms.

However, many experts who did not participate in the study believe that the relevant agencies in the United States are unlikely to change the existing assessment system. Researchers interviewed by the Associated Press said the recommendations could give the public the illusion that the damage caused by tropical storms is primarily related to wind speed, when in fact heavy rainfall and flooding caused by tropical storms are a major contributor to the damage.

Jamie Rom, deputy director of the National Hurricane Research Center, said that when warning about the risk of a tropical storm, the center usually warns the public to watch out for disasters such as rising water, high winds, rainfall, tornadoes and jet streams, and does not pay special attention to the specific rating of the tropical storm, which only provides information related to wind speed. He said the top five-level classification system was already able to reflect the "catastrophic damage" caused by strong winds, and it was unclear whether it was necessary to label stronger storms with a higher level.

According to current international practice, tropical storms that form east of the International Date Line are called hurricanes when they reach a certain wind speed, while those that form west of the International Date Line are called typhoons, and those that form in the Indian Ocean and the waters near Australia are called cyclones. (Yuan Yuan).

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