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Updated at 03:00 UTC, 20 March 2015
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The roles of the Tokyo VAAC

Volcanic ash can seriously affect air services by causing:
In order to avoid aviation disasters caused by volcanic ash, it is essential to provide related information to airlines, aviation authorities, Meteorological Watch Offices (MWOs) and other relevant organizations. In conjunction with the World Meteorological Organization (WMO), the International Civil Aviation Organization (ICAO) established a framework for the International Airways Volcano Watch initiative in 1993. Under this system, Volcanic Ash Advisory Centers (VAACs) are tasked with monitoring volcanic eruptions and providing information on the extent and movement of volcanic ash clouds as well as outlooks for their regions of responsibility. Within this framework, nine VAACs are designated around the world. In its role as the Tokyo VAAC, the Japan Meteorological Agency (JMA) has been in charge of the East Asia and the Northwest Pacific region since March 1997, providing Volcanic Ash Advisories (VAAs) to the above organizations.

Operation of Tokyo VAAC

Monitoring volcanic ash clouds

Early detection of volcanic eruptions is crucial for VAAC operations. Volcanic activities in Japan are monitored by four JMA Volcanic Observations and Information Centers located in Sapporo, Sendai, Tokyo and Fukuoka. The Tokyo VAAC receives volcanic activity reports from these centers when eruptions or explosions occur in domestically volcanoes. The Tokyo VAAC also receives information on volcanic activities outside Japan from the MWOs within its area of responsibility and relevant organizations such as the Kamchatka Volcanic Eruption Response Team (KVERT), the Philippine Institute of Volcanology and Seismology (PHIVOLCS), the Alaska Volcano Observatory (AVO) and adjacent VAACs. Volcanic eruption reports from pilots from cruising airplanes as well as satellite imagery from the geostationary meteorological satellite and the polar-orbiting satellite are also important sources of information.

Volcanic ash forecasting

Forecasting of volcanic ash movement is essential in deciding optimal flight routes. A volcanic ash transport model developed by the Tokyo VAAC calculates the expected extent and height of volcanic ash clouds 6, 12 and 18 hours ahead based on analysis of satellite imagery and other data using the latest three-dimensional forecast atmospheric data on variables such as wind direction and speed from JMA's global numerical weather prediction system.

Volcanic ash advisory (VAA) issuance

VAACs issue VAAs describing the latest extents of volcanic ash clouds and forecasting their trajectories in both text and graphical form (as defined in ICAO Annex 3) to assist MWOs in preparing SIGMETs on volcanic ash clouds. VAAs are updated as a minimum at six-hour intervals (normally at 00, 06, 12 and 18 UTC) for as long as ash clouds are identified in satellite imagery. If notable changes occur in ash clouds, the VAA is updated as often as needed. In the event that ash cloud extension is identified in satellite imagery, VAG (Volcanic Ash Graphic) and VAGI (Volcanic Ash Graphic for Initial Distribution) information is also issued. VAAs are disseminated to airlines, aviation authorities, MWOs and other related organizations through airport branches of JMA and aviation authorities.

Tokyo VAAC's area of responsibility

Information flow of volcanic ash advisory

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