Meteosat-9 observes Chilean volcanic eruption.
22 October 2020
04 June 2011
by HansPeter Roesli and Marianne Koenig (EUMETSAT)
EUMETSAT's Meteosat-9 geostationary satellite is one of the systems that observed the eruption of the Puyehuè-Cordón Caulle volcanic complex (PCCVC) in the Chilean Andes. After a major eruption in 1960, PCCVC has remained relatively quiet during the last 50 years. On 4 June 2011, however, PCCVC erupted again, ejecting large amounts of ash and sulphur dioxide (SO2) into the atmosphere. Some observations indicated that the plume initially might have reached up to 17 km height.
The 15-minute Meteosat-9 image sequence (see image and animation below) shows the long volcanic plume meandering across the South Atlantic. On this particular combination of MSG SEVIRI IR channels (the Ash RGB composite), the plume and streaks are coloured in bright yellow, indicating the combined presence of ash and SO2 (ash with no SO2 appears in reddish shades in places, see colour interpretation ).
On their way to the South Indian Ocean, the yellow streaks disappear temporarily under high cloud, a sign that the volcanic material has descended into the upper troposphere. At these levels, one might expect the ash to be slowly dissipated by precipitation. However, some of the ash did not encounter 'bad weather' on its way around the southern hemisphere and therefore remained suspended in the atmosphere, even though it was partially dispersed.
Meteosat-9 Ash RGB Product
Met-9, 09 June 2011, 06:00 UTC
RGB Composite IR12.0–IR10.8, IR10.8–IR8.7, IR10.8
Animation 1 (initial phase of the eruption)
(4 June 20:00–6 June 05:00 UTC)
Animation 2 (volcanic plume reaches the Indian Ocean)
(4 June 20:00–9 June 06:00 UTC)
Animation 3 (new volcanic plume over Argentina)
(10 June 15:00–12 June 23:45 UTC)
The combination of six-hourly images from the three geostationary satellites Meteosat-9, MTSAT-1R and GOES-11 covering the period from 5 June to 1 July shows the plume's complex circumnavigation of the southern hemisphere (see image and animation below). PCCVC continued to have briefer eruptions every now and then (e.g. a major one on 10 June), spewing out ash at irregular intervals.
A close look at the animation and the ash signal on 30 June at 18:00 UTC (see colour bar ) appears to indicate that some ash originating from the initial eruption (on 4-5 June) might have gone around the Earth four times.
It should be noted that the simple split window difference product shown here is quite noisy (note that MSG difference product has the lowest noise), which can be seen in the presence of salt-and-pepper patterns, that to the untrained eye might be misleading. But it has the advantage of giving quite homogeneous images for all three satellites used. Given that we are using geostationary satellites — and here only three of a number of available options — there are blind areas, notably over Antarctica. Looking at the image sequence, it is highly possible that some ash has ended over there.
Meteosat-9, MTSAT-1R and GOES-11 Image Composite
Met-9, MTSAT-1R and GOES-11 image composite, 09 June 2011, 18:00 UTC
Difference of IR split window channels IR11–IR12 (see colour bar )
Background image: MODIS Blue Marble image mosaic of the Earth (source: NASA)
Animation 1 (5 June 12:00–17 June 06:00 UTC)
Animation 2 (5 June 12:00–1 July 06:00 UTC)
Terra MODIS Ash and Truecolour RGB products (4 June 18:50 UTC, source: NASA)
Aqua MODIS sandwich product (5 June 19:36 UTC, source: NASA)
Author: Zdenek Charvat (CHMI): image combination of MODIS band 1 (at 250 m resolution)
and the true colour RGB (RGB bands 1-4-3, at 500 m resolution)
Metop-A AVHRR RGB product (6 June 14:10 UTC, source: SMHI)
Met-9 Dust RGB product (7 June 10:45 UTC)
FY-2D split window difference product (8 June 15:15 UTC, source: CMA)
Images processed by EUMETSAT that show ash and SO2 plumes resulting from volcanic eruptions are published to demonstrate this additional capability of Meteosat Second Generation. The images give a good qualitative impression of the horizontal extent and the movement of ash and SO2 clouds, but do not provide any quantitative measures such as cloud height or concentration.
Higher level products such as total ash loading can be derived from the data, which correspond well with independent measurements. For volcanic ash warning purposes, both the image colour composites and the quantitative products must always be used in combination with other data or model fields.
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