1. Typhoon Names

Summary

Typhoons are named after number-based conventions and a list-based convention. The latter convention is more popular in most countries, such as human names for hurricanes, while the former is popular in Japan. Both conventions, however, share the same problem of ambiguity.

Basic Description

We have the following types of naming conventions of the typhoon, the hurricane, and the tropical cyclone (hereafter we call all of them as the typhoon).

  1. Number-based Conventions
  2. List-based Conventions

Number-based Conventions

Number-based conventions are based on the sequential number from the beginning of a typhoon season. For example, Typhoon No. 14 is the 14th typhoon of the typhoon season. This kind of simplified 2-digit convention like "台風 14号" (Typhoon No. 14) is very popular in Japan, often used in the media such as newspaper and television. This name does not the represent the year, because at the time of usage the current year is obvious.

On the other hand, a 4-digit YEAR+NUMBER identification code such as Typhoon 0314, or T0314 for short, is a more preferred convention in technical and professional areas. Japan Meteorological Agency has another official name such as "Heisei 15, Typhoon No. 14" which represents that this is the 14th typhoon of Heisei 15, which is another system of year assigned in relation to the Emperor of Japan. This last convention, however, is only used in official documents of governments. Finally this Website uses another type of number-based conventions, namely 6-digit convention such as Typhoon 200314 because of the problem of periodicity as described below.

The fundamental disadvantage of this convention is that a number is hard to remember. The event-driven convention is hence introduced in special cases; that is, Japan Meteorological Agency gives a special name to the typhoon when it brought severe disasters or when significant meteorological phenomena were observed with it. In this case, the typhoon is usually named after the place or the accident of significance. Although we have eight typhoons with special names, we have not added new typhoons since 1977.

Number-based conventions, however, directly use sequential numbers, so it is sensitive to subsequent changes of orders. Firstly, if you delete a typhoon once registered, the corresponding number becomes a defunct number. For example, you cannot find 195402 and 195410 in the list of typhoons in 1954. Secondly, when the order of birth is changed, names do not change to reflect the actual order. For example, in the list of typhoons in 1990, 199013 is born before 199012, and this inconsistency is caused by the change of birth on later analysis for compiling the official report. Finally, the procedure is also defined for inserting a typhoon in the list. In this case, additional number is given after the decimal point like 200314.1. But there has been no such cases since 1951, and we may not see them in the future.

List-based Conventions

List-based conventions are based on the list of typhoon names defined in advance by the committee of meteorological organizations worldwide. A new name is automatically chosen from the list upon the genesis of a typhoon. The list is defined for each basin and managed by the meteorological organization responsible for the respective basin. For example, Typhoon 200314 has a name "Maemi," which means a cicada or a locust in North Korea, and is an Asian name chosen from the list of typhoon names for the Western North Pacific basin.

The majority of countries in the world seems to prefer list-based conventions to number-based conventions, which are much popular in Japan. The latter conventions have advantage in the explicit representation of the sequential order of the typhoon during the typhoon season, but the disadvantage is the similarity of all names which leads to the difficulty of making distinction. This may be the reason for list-based conventions to be used in many countries worldwide.

The following table summarized, to my knowledge, how typhoons are named in each country. I welcome more detailed information and corrections from people living in those countries (Feedback).

Japan Only number-based convention
Philippines Own list-based convention only used within the country
China Transition from number-based convention to list-based convention?
Korea Primary number-based convention, and secondary list-based convention?
Taiwan List-based convention is more often used?
Vietnam Unique number-based convention only counted around Vietnam with list-based convention
United States Only list-based convention

Why Typhoons (Hurricanes) are Often Named after Women?

The most famous list with the longest history is the list of hurricane names of the Atlantic Ocean. This list contains alphabetically-ordered names from A. On the birth of a new hurricane, a new name is chosen in the alphabetical order. Only female names were used in the beginning, because hurricanes were named after girlfriends or wives of US Army Air Corp and Navy meteorologists. In 1979, however, male names are included in the list from an argument on gender equality (detailed information).

In detail, there are two types of name lists, namely "annual lists" and "perpetual lists." A representative example of "annual lists" can be found in the list of hurricane names in North Atlantic. In this convention, a set of 21 names are chosen (Q, U, X, Y and Z skipped) in an alphabetical order, and it is used for each year always beginning with A. Six sets of them are prepared for six years round, and in six years the list goes back to the first set. This means that names in the last part of the list, such as those starting with V and W, appear only when many hurricanes are born in an year, so those names have seldom been used in history. On the other hand, the annual list is exhausted on the occurrence of more than 21 hurricanes, and Greek alphabets, alpha, beta, gamma, ... follow the annual list of names. The 2005 hurricane was extraordinary active to see the first Greek-alphabet hurricane in record, and at this time the name has proceeded to Alpha, Beta, Gamma, Delta, Epsilon, and Zeta.

A representative example of "perpetual lists" is Asian Names of Typhoons (next section). This convention does not split the list into the annual set of names, so the list is never exhausted. This also means that every name in the list will appear at least once.

(Note 2.3.1) In Eastern North Pacific basin, the list has 24 hurricane names just skipping Q and U. Hence this area has more names compared to 21 names (skipping 5 characters) in the Atlantic basin.

The American-style convention has been applied on typhoon names in the Western North Pacific through 1999. In particular, during the American occupation of Japan through 1951, female names of typhoons were officially used in Japan, so American female names are also well known for typhoons attacked just after the World War II. Famous ones include Typhoon KATHLEEN (194709), Typhoon IONE (194821), Typhoon KITTY (194910), Typhoon JANE (195028) and Typhoon RUTH (195115).

This American-style convention had been used through Typhoon 195302, and after that Japan Meteorological Agency started to use number conventions for domestic typhoon information. In Okinawa prefecture, however, American occupation has continued until 1972, and American-style convention had been in use during that period. Therefore, American female names such as Typhoon SARAH (195914), Typhoon CORA (196618) and Typhoon DELLA (196816) are still widely remembered with the memory of severe disasters.

Asian Names of the Typhoon

Those male and female names have advantage, especially in the United States, to increase familiarity to hurricanes and help people remember the experiences of severe hurricanes. Those American names, however, were relatively unknown to Japanese and Asian people, and this is the motivation of establishing another list of typhoon names called Asian names, which has been in effect since 2000.

The Asian names are list of words submitted to the typhoon committee, consisting of meteorological organizations of 14 countries and regions in the Asia / Pacific, that belongs to Tropical Cyclone Programme, World Meteorological Organization (WMO). This list contains 140 names (= 14 countries times 10 names), which originate in various themes such as animals, plants, and natural phenomena, but there remains no preference to human names. Japan Meteorological Agency, for example, proposed names after constellations. Asian names are sorted according to the alphabetical name of countries, so typhoon names themselves are not arranged in an alphabetical order.

Asian names go worldwide as they are, and soon became popular in countries where list-based conventions has already gained popularity, but in Japan, where typhoon numbers have been used for tens of years, typhoon Asian names are still far from popular. But typhoon Asian names are more and more often noticed by people, especially by Internet users, so we can say that its popularity is gradually increasing. To know the meaning of the Asian name of recent typhoons, please refer to Digital Typhoon: News Weblog.

The same naming convention has been used in Indian Ocean since 2004. India Meteorological Department is in charge of naming cyclones, names were suggested by Bangladesh, India, the Maldives, Myanmar, Oman, Pakistan, Thailand and Sri Lanka, and names are used in the order of alphabetical order of country names. For example, Cyclone SIDR was suggested by Oman, and Cyclone NARGIS was suggested by Pakistan.

(Note 2.4.1) Philippines have its own list of names for tropical cyclones and it is mainly used for domestic news and advisory.

(Note 2.4.2) When a hurricane in the Central North Pacific basin reached the 180 degree line (the International Date Line) from east to west, and enters into the Western North Pacific basin, it starts to be called a typhoon. A new Asian name, however, is not assigned in this case, and the hurricane name is kept as the name of the tropical cyclone. This causes a shift of correspondence between Asian names and typhoon numbers. In recent years, Typhoon 200217 and Typhoon 200224 has changed from a hurricane to a typhoon. Therefore, 142 typhoons had been recorded in the first round of Asian names in spite of 140 Asian names registered in the list.

(Note 2.4.3) If you are not familiar with the word of Asian names, please refer to some of the pronunciation of typhoon names.

Ambiguity Problem

Natural Language Processing of Typhoon Text

One problem with typhoon names is the ambiguity of typhoon names. Some typhoon names had multiple appearances in history, so we need to identify which typhoon is the topic of a text using some hints in the text or background knowledge. This means that a successful natural language processing system of typhoon-related text should resolve the ambiguities of typhoon names, and should solve the problem of "named entity recognition" (or "named entity extraction") that automatically identify a typhoon name as the typhoon in history.

The Problem of Periodicity

This problem is apparent in number-based conventions. If we employ the 4-digit convention, it has an obvious problem of 100 year cycle --- Typhoon 0314 may represent the 14th typhoon of year 2003, or maybe 1903. Well, this 100 year cycle is not a big problem yet, but the offical record of typhoons had started to be compiled since 1951, so we should expect to have the year 2051 problem (at least we have passed the halfway of this periodicity anyway). And, of course, the 2-digit convention like Typhoon No. 14, which is standard in Japan, has the more obvious problem of 1 year cycle. We often encounter cases where we have to disambiguate whether the typhoon No. 14 is the one of the current year (in most cases), or the 14th of 2 years ago, or the 14th of 1970. To avoid such an ambiguity problem, we adopt a 6-digit convention like Typhoon 200314, which does not have a short cycle problem as stated, at least before the year 10000...

On the other hand, list-based conventions also have the same kind of problem because a name is chosen from a circular list, which means that the same name will be "recycled" in the future. For example, on the formation of a new typhoon, we assign a new name from the list of 140 Asian names. This means that after assigning 140 typhoon names, we return to the first name of the list and reuse same names. Studying past cases reveal that we in fact have 15 typhoons with the name FAYE since 1951. Thus the list-based convention cannot avoid the ambiguity problem either.

Typhoon Names May be Retired

To cope with the ambiguity problem, the typhoon name is sometimes "retired," and removed from the list. This case happens when the typhoon has a severe impact on lives or the economy to the level that is remembered for generations after the devastation. Whenever a typhoon has had this level of impact, any country affected by the storm can make a request to the World Meteorological Organization (WMO) that the name of the typhoon be retired to facilitate historic references, legal actions, insurance claim activities, etc. This convention is exactly like a retired number for a famous sports player to keep memory and avoid confusion.

Asian names to be retired are RUSA, VAMEI, IMBUDO, and CHATAAN, and these four names are replaced by NURI, PEIPAH, MOLAVE and MATMO, respectively (Typhoon Committee Annual Review 2003).

The 2005 hurricane season in the Atlantic Basin was the most active hurricane season in history with 27 named storms. Not only the number is large but the impact was also huge, including Hurricane Katrina that struck New Orleans. Due to the extraordinary activity of hurricanes, it was decided that as many as five names -- DENNIS, KATRINA, RITA, STAN, WILMA -- be retired from the list of 2005 hurricane names.

The Nameless Cyclone and No-Name Typhoons

An article from NASA on April 2, 2004 says that we finally had "the nameless cyclone (hurricane)." The story goes that they observed a cyclone in the South Atlantic basin where tropical cyclones have never been observed before. The list of cyclone names for this basin was therefore not prepared so this cyclone could not be named. What is the reason of this rare phenomenon? Is this related to the global climate change of the earth?

(Note) It seems that this hurricane is now called Catarina after the name of the place it made landfall.

In contrast to the nameless cyclone, we had many "no-name typhoons" in Japan. This may not be a problem because number-based conventions are far more popular in Japan, but in any case a no-name typhoon sounds a bit strange. Why do we have a typhoon with such a strange name?

The reason is that, the certifying organization and the naming organization of a typhoon were different before 2000. Namely, in the western north Pacific basin before 2000, when Japan Meteorological Agency (JMA), the certifying organization, declares the birth of a typhoon, while Joint Typhoon Warning Center (JTWC), the naming organization, did not declare the birth of a typhoon, the international name was not assigned even when the typhoon number was increased. The decision of the birth of a typhoon was made by experts in each country, so it frequently happens that a typhoon in Japan is not a typhoon in the USA. This is the case that we had a no-name typhoon.

This site gives a tentative name NO-NAME for those typhoons, and if you search, you get as many as 82 typhoons in the past. But after 2000, Japan Meteorological Agency starts to be in charge of both decision and naming, so we will see no more "no-name" typhoons in the future.

Related Links

Digital Typhoon: News Weblog