Montréal Volcanic Ash Advisory Centre (VAAC)

GOES-WEST AND GOES-EAST SATELLITE IMAGERY

• IR: Channel 4 brightness temperature in kelvin
• 4m5: Channel 4 minus channel 5 brightness temperature difference (''split-window'') in kelvin. Not calculated due to unavailability of 12-micron band on channel 5 for GOES-EAST and GOES-WEST
• VIS: Channel 1 (albedo from 0 to 1)

The volcano of interest is at the centre of the image, which is produced once per hour. For GOES-WEST images, the HOUR (UTC) axis below the volcano name label corresponds to the time at which the data capture begins. This process takes between 15 and 26 minutes. A GOES-W image with HOUR equal to 02 UTC corresponds to a data capture starting at 0200 UTC and ending between 0215 UTC and 0226 UTC. The label on the image itself is given as 0200 UTC. For GOES-EAST images, the actual time at which the data capture begins is 15 minutes earlier than the time indicated on the HOUR (UTC) axis. The data capture process takes between 15 and 26 minutes. A GOES-E image with HOUR equal to 02 UTC corresponds to a data capture starting at 0145 UTC and ending between 0200 UTC and 0211 UTC. The time label on the image itself is 0145 UTC.

AUTOMATIC WATCH / HYPOTHETICAL MODEL RUNS TRAJECTORY MODEL

IMPORTANT INFORMATION:
THESE IMAGES ARE NOT OFFICIAL FORECASTS. THEY ARE PROVIDED FOR GUIDANCE AND PLANNING PURPOSES ONLY AND ARE NOT TO BE USED AS A SUBSTITUTE FOR OFFICIAL INFORMATION. SEE SIGMETs FOR OFFICIAL WARNING INFORMATION.

The trajectories are produced automatically using ''what if'' hypothetical eruption start times that are 2 hours apart. The time at which the trajectories start is given on the HOUR (UTC) axis below the volcano name label.

For start times of 22, 00, 02, 04, 06, and 08 UTC, the forecast wind fields of the GEM GLOBAL 12 UTC model run are used.

For start times of 10, 12, 14, 16, 18, and 20 UTC, the forecast wind fields of the GEM GLOBAL 00 UTC model run are used.

The images show the trajectories normally starting at 3 vertical levels above the volcano. The forecast period covers up to 48 hours from the initial time of the GEM GLOBAL model run that is used.

AUTOMATIC WATCH / HYPOTHETICAL MODEL RUNS
MLDP0 MODEL

IMPORTANT INFORMATION:
THESE IMAGES ARE NOT OFFICIAL FORECASTS. THEY ARE PROVIDED FOR GUIDANCE AND PLANNING PURPOSES ONLY AND ARE NOT TO BE USED AS A SUBSTITUTE FOR OFFICIAL INFORMATION. SEE SIGMETs FOR OFFICIAL WARNING INFORMATION.

The MLDP0 outputs are produced automatically using ''what if'' hypothetical eruption start times that are 3 hours apart. The time at which the run starts is given on the HOUR (UTC) axis below the volcano name label. The forecast period from the start time given by HOUR (UTC) is given on the vertical axis (6, 12, 18, and 24 hours). For example, with HOUR (UTC) equal to 03, the 18-hour forecast will be valid at 21 UTC.

For start times of 00, 03, 06, and 09 UTC, the forecast wind fields of the GEM GLOBAL 12 UTC model run are used.

For start times of 12, 15, 18, and 21 UTC, the forecast wind fields of the GEM GLOBAL 00 UTC model run are used.

The eruption parameters vary from one volcano to another as a function of the information received for each.

The images show the average concentration in microgram per cubic meter for 3 layers expressed in flight levels (in hundreds of feet):

• FL350 - FL600
• FL200 - FL350
• SURFACE TO FL200