Whenever a tropical cyclone heads toward the southeastern United States, forecasters assign it a name and a category based on the widely used classification system for Atlantic hurricanes. .
But if a similar storm were to sweep westward across the Pacific, there would be no such unified system.
There is variation in how different regions of the world define tropical systems, including hurricanes, depressions, and cyclones. In the Western Pacific, the process is particularly complicated because countries and territories have their own systems for measuring, classifying, and naming tropical cyclones, which they call hurricanes instead of hurricanes.
Clarence Fong, a meteorologist in Macau, a Chinese territory, who works for an intergovernmental committee under the World Meteorological Organization, which coordinates storm warnings across the region, said : “In Asia, it’s a bit complicated in Asia.
Let us explain.
What do tornadoes have in common?
The scientific definition of a tropical cyclone is simple: It is a hurricane, usually about 200 to 500 kilometers (124 to 311 mi) in diameter, that begins over a tropical ocean and produces intense winds, torrential rain, high waves and bad weather. Less powerful storms are called tropical depressions or disturbances.
Another obvious fact: Tropical cyclones are destructive. Experts say that climate change has increased frequency of major tropical cyclonesand the possibility of destruction, because a warmer ocean provides more energy to power them.
But the terms and categories forecasters use for a tornado depend on its location and intensity. And they’re not particularly intuitive.
Number versus word
storm term derived from hurakan, an Arawak word for storm god. It applies to tropical cyclones that have maximum sustained winds of at least 74 miles per hour and form in the North Atlantic, northeastern Pacific, Caribbean Sea or Gulf of Mexico.
Major Hurricane – Category 3, 4 or 5 – with maximum sustained winds of 111 mph or higher above Category five Saffir-Simpson storm wind scalewas developed by American forecasters in the 1970s and has been revised over the years.
But other parts of the world have completely different systemsand guidelines are given at the regional level by separate hurricane committees.
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In the Indian Ocean, for example, three separate classification systems classify hurricanes and tropical depressions using adjectives that change depending on the system’s location. If the equivalent of a medium-range Category 3 storm forming in the western Indian Ocean off the east coast of Africa, it would be a “very strong tropical cyclone”. But if it did form in the Arabian Sea or the Bay of Bengal – both in the northern Indian Ocean – it would be a “super cyclone”, one order of magnitude from an “extremely severe cyclone”.
Why is the western Pacific different?
Then came hurricanes, the term for tropical cyclones that develop in the Pacific Northwest and affect Asia. The word was used as early as the 16th century by European travelers in the East Indies, and it may have etymological origin in Arabic, Chinese, Greek and Urdu.
The basic definition of a hurricane is the same as a hurricane: tropical cyclone with maximum sustained winds of at least 74 mph. But some Asian countries have their own storm classification systems.
For example, China would call a medium-range Category 3 storm a “super typhoon”. Japan would call it a “violence”. And in South Korea, the storm will be “super strong” – a type of storm created two years ago in response to a stronger rate of typhoons in recent years, according to the Korea Meteorological Administration.
Some governments also have unique ways of describing storms to their people. Hong Kong, a Chinese territory, uses a numbered warning system introduced in 1917 of the city’s British colonial government. And since 1963, the Philippines has given local names to storms, a naming system parallel to the one used by the Philippines. other pacific countries and the United States.
Sheilla Reyes, a weather expert at the country’s national meteorological agency, said local names must be proper Philippine nouns that cannot exceed nine letters or three syllables. Some people complain that the system is confusing, she added, but others like it because they find Filipino names easier to remember.
Why isn’t there a standardized system?
The U.S. government has had weather observation sites in Florida since the 1870s, and the National Hurricane Center, established in 1966, has long been the dominant weather agency for countries in the basin. Atlantic. But when the US military establish an agency based in Hawaii to monitor Pacific storms in 1959, many governments in Asia developed their own measurement and monitoring systems.
One result: There is a persistent difference in the “average time period,” the period in which forecasters measure tropical cyclone wind speeds to get results. In the United States, the interval is one minute. In China it’s two minutes. And to many other Asian countries and territories, including Macau and Hong Kong, is 10 minutes.
Those differences affect the strength of a hurricane against civilians. For example, Ms. Reyes said, a hurricane with 150 mph winds for a one-minute period – a “superstorm” by the US definition – would only have winds of 115 mph over a 10-minute period. . That’s part of the reason why the Philippines lowered the threshold for a “super typhoon” last year, to 115 mph from 138 mph.
In the wake of that change, “we were asked at one point why the JTWC was so massive and we weren’t,” Reyes said, referring to the US military. Joint Typhoon Warning Centerbased in Hawaii.
Taoyong Peng, a senior science official for tropical cyclones at the headquarters of the World Meteorological Organization in Geneva, called the difference in wind measurements “very strange”.
Dr Peng, a former principal scientist at the forecasting office in Guangzhou, China, says that WMO has been talking about standardizing the world’s average wind cycle for about 20 years. In 2010, the agency issued guide to convert wind measurements between different systems.
But many countries are used to their own systems, he added, and standardizing weather equipment around the world would be a large and expensive undertaking.
“It’s going to be very, very expensive, and I don’t think WMO can afford it,” he said.
John Yoon contribution report.