Accumulated cyclone energy (ACE) is used by the National Oceanic and Atmospheric Administration and other agencies to express the activity of individual tropical cyclones that are above tropical storm strength and entire tropical cyclone seasons. [29] It is calculated by taking the squares of the estimated maximum sustained velocity of every active tropical storm (wind speed 35 knots or higher) at six-hour intervals. [29] The numbers are usually divided by 10,000 to make them more manageable. The unit of ACE is 10 4 kn 2, and for use as an index the unit is assumed. [29] As well as being squared for ACE, wind speed can also be cubed, which is referred to as the Power Dissipation Index (PDI). [30] Arizona State University (2009-08-12). "Taiwan Rainfall Record Investigation". Archived from the original on 2011-01-02 . Retrieved 2011-03-06.

In addition, the Taiwan Central Weather Bureau has its own scale in Chinese but uses the Typhoon Committee scale in English. [18] North Indian Ocean [ edit ] India Meteorological Department a b c d Fu; etal. (2023). "Historic and Future Perspectives of Storm and Cyclone" (PDF). Advances in Atmospheric Sciences. 40 (3): 450–451. Bibcode: 2023AdAtS..40..447F. doi: 10.1007/s00376-022-2184-1. ISSN 0256-1530. S2CID 253918708. The most active Western Pacific typhoon season was in 1964, [ citation needed] when 39storms of tropical storm strength formed. Only 15 seasons had 30 or more storms developing since reliable records began. The least activity seen in the northwest Pacific Ocean was during the 2010 Pacific typhoon season, when only 14tropical storms and seven typhoons formed. In the Philippines, the most active season, since 1945, for tropical cyclone strikes was 1993 when nineteen tropical cyclones moved through the country. [46] There was only one tropical cyclone that moved through the Philippines in 1958. The 2004 Pacific typhoon season was the busiest for Okinawa since 1957. [47] Within Guangdong in southern China, during the past thousand years, the most active decades for typhoon strikes were the 1660s and 1670s. [48] Tropical cyclones are defined as being warm cored, non-frontal synoptic cyclones, that develop over tropical or subtropical waters, with organized atmospheric convection and have a definite cyclonic surface wind circulation. They are classified by the wind speeds located around the circulation centre and are ranked, by the World Meteorological Organization's Regional Specialized Meteorological Centers on one of five tropical cyclone scales. The scale used for a particular tropical cyclone depends on what basin the system is located in; with for example the Saffir–Simpson hurricane wind scale and the Australian tropical cyclone intensity scales both used in the Western Hemisphere. All of the scales rank tropical cyclones using their maximum sustained winds, which are either observed, measured or estimated using various techniques, over a period between one and ten minutes.A tropical depression is the lowest category that the Japan Meteorological Agency uses and is the term used for a tropical system that has wind speeds not exceeding 33 knots (38mph; 61km/h). [19] A tropical depression is upgraded to a tropical storm should its sustained wind speeds exceed 34 knots (39mph; 63km/h). Tropical storms also receive official names from RSMC Tokyo. [19] Should the storm intensify further and reach sustained wind speeds of 48 knots (55mph; 89km/h) then it will be classified as a severe tropical storm. [19] Once the system's maximum sustained winds reach wind speeds of 64 knots (74mph; 119km/h), the JMA will designate the tropical cyclone as a typhoon—the highest category on its scale. [19] When it comes to hurricanes vs. typhoons, the differences are minimal and the similarities abundant. Find out more about these aggressive weather phenomena by reading more. Due to Typhoon Hagibis, 85 fatalities and 9 missing people were reported at the time of writing (NHK, 2019). EM-DAT. (2019). EM-DAT | The international disasters database. [online] Available at: https://www.emdat.be/index.php [Accessed 24 Oct. 2019]. Hakone town in Kanagawa prefecture (a resort town approximately 90km south-west of Tokyo) was one neighbourhood that experienced severe flooding. Within 24 hours, Hakone received a total of 922.5mm of rainfall, which is the highest volume of rainfall ever recorded in Japan over a 24-hour period (Mori, 2019). It has an estimated return period of greater than 1,500 years based on JBA’s rainfall return period data.

Japan Meteorological Agency (2001-05-25). "Annual Report on Activities of the RSMC Tokyo – Typhoon Center: 2000" (PDF). pp.iii, 11. Archived (PDF) from the original on 2013-12-12 . Retrieved 2011-03-11. RSMC Tokyo-Typhoon Center. "List of names for tropical cyclones adopted by the ESCAP/WMO Typhoon Committee for the western North Pacific and the South China Sea (valid as of 2019)". Japan Meteorological Agency: RSMC Tokyo - Typhoon Center. Japan Meteorological Agency. Archived from the original on January 5, 2021 . Retrieved October 25, 2019.A typhoon is a tropical cyclone that develops between 180° and 100°E in the Northern Hemisphere. [1] This region is referred to as the Northwestern Pacific Basin, [2] accounting for almost one-third of the world's annual tropical cyclones. The term hurricane refers to a tropical cyclone in the northeast Pacific and northern Atlantic. [3] For organizational purposes, the northern Pacific Ocean is divided into three regions: the eastern (North America to 140°W), central (140°W to 180°), and western (180° to 100°E). The Regional Specialized Meteorological Center (RSMC) for tropical cyclone forecasts is in Japan, with other tropical cyclone warning centres for the northwest Pacific in Hawaii (the Joint Typhoon Warning Center), the Philippines, and Hong Kong. Although the RSMC names each system, the main name list itself is coordinated among 18 countries that have territories threatened by typhoons each year. [4] a b c d e "Saffir–Simpson hurricane scale Information". National Hurricane Center. May 24, 2013 . Retrieved November 8, 2015. a b c d Tropical cyclone alerts and warnings summary of procedures within Fiji: 2009–2010 season (PDF) (Report). Fiji Meteorological Service. Archived from the original (PDF) on November 18, 2015 . Retrieved November 7, 2015.

Classifications of Tropical cyclones" (PDF). Hong Kong Observatory. March 18, 2009. Archived from the original (PDF) on March 30, 2012 . Retrieved July 27, 2012. Saola will also bring storm surges to coastal low-lying areas, the Hong Kong Observatory noted, estimating Saola is currently about 440km (270 miles) from the metropolis. A system is designated as a tropical depression or a subtropical depression when it reaches wind speeds above 28 knots (52km/h; 32mph). If a tropical depression reaches wind speeds of 35 knots (65km/h; 40mph) then it will be classified as a moderate tropical storm and assigned a name by either the Sub Regional Center in Mauritius or Madagascar. No matter how strong a subtropical system is in this basin, it is always designated as a subtropical depression. [23] The Chaozhou Chronicle 潮州府志 (1762) recorded 29 expressions for typhoon, including 回南風, 落西風, 蕩西風, 奔龍 and 鐵風篩. As cited in 李荣 (1990). "台风的本字(上)". 方言 (4). ; 李荣 (1991). "台风的本字(中)". 方言 (1). ; 李荣 (1991). "台风的本字(下)". 方言 (2). Hurricanes are classified according to the Saffir-Simpson Hurricane Wind Scale. This scale ranges from categories one to five — with those ranking above three considered major storms posing danger to life, buildings and infrastructure. A category five hurricane has wind speeds that exceed 157 miles per hour.

Typhoon and Tropical Cyclone Seasons in Vietnam". U.S. Embassy & Consulate in Vietnam. 2019-10-29. Archived from the original on 2022-01-07 . Retrieved 2022-01-07. Joint Typhoon Warning Center (2015). 2015 Annual Tropical Cyclone Report: Western Pacific (PDF) (Report). United States Navy, United States Air Force . Retrieved 2016-07-11. [ permanent dead link] More than 110,000 people are taking part in search and rescue operations across Japan, including 27,000 military troops and rescue crews (BBC News, 2019a; BBC News, 2019b). Around 92,000 households remain without power, although more than 360,000 households were originally cut off on Sunday 13 October (BBC News, 2019a; The New York Times, 2019). Around 120,000 households are experiencing water outages (BBC News, 2019a).