Environmental Emergency Response Division

Volcanic Ash Charts

Description

Average volcanic ash density prognostic charts for three atmospheric layers corresponding to Canadian air traffic control zones: SFC-FL200, FL250-350, FL350-FL600. The charts are produced by the CANERM model ( CANadian Emergency Response Model ) using the forecasts of the operational Global model based on the 00 UTC or 12 UTC data.

Each chart consists of 6 panels. Each panel presents the average ash density forecast for an atmospheric layer at a specific time. The first chart depicts a 6 and 12 hour prognostic while the second chart depicts an 18 and 24 hour prognostic. Occasionally, CMC may transmit prognostic charts valid at 30-36, 42-48, 54-60 and 66-72 hours.

Times of availability

The charts are ususally available approximately within one hour after the beginning of the execution of CANERM. The results are bases on the last execution of the global model (i.e. 00 UTC or 12 UTC).

Scale

Polar stereographic projection true at 60N. The scale varies according to the area of coverage.

Area of coverage

Different areas of coverage are available depending on the location of the volcano and the forecast time. The areas normally covered are Alaska, Canada, the United States and the Northwest portion of the Pacific.

Depiction

The forecast time, the date and the time of validity as well as the atmospheric layer for which the forecast is valid are indicated above each of the panels. The location of the volcano is indicated by the following symbol.

Solid lines :

Isolines of the forecast of the average volcanic ash density in the atmospheric layer. The isolines are for 10, 100 and 1000 micrograms per cubic meter (µg/m3 which is equivalent to 10E-6 g/m3). Areas between the isolines are enhanced as follows :

• 10-100 µg/m3: Light stippling or blue color
• 100-1000 µg/m3: Dark stippling or green color
• > 1000 µg/m3: No stippling or yellow color

These ranges correpond to LGT, MDT and HVY respectively.

Notes

1. In the lower left corner of the chart, we find the symbol and the name of the volcano; ERUPTION indicates the day, the date and the time of the eruption along with LATITUDE and LONGITUDE. The cycle line is only for internal use at CMC.

2. In the lower right corner of the chart, we find the mention SEE CURRENT SIGMET FOR WARNING AREA - VOIR SIGMET COURANT POUR ZONE D'AVERTISSEMENT.

3. It it important to note that even LGT concentrations constitute a potentiel danger to aviation.

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