There was a powerful explosive eruption from the Ubinas volcano in Peru on 19 July 2019.
Ubinas is a stratovolcano in the Moquegua Region of southern Peru, 60km east of the city of Arequipa. Part of the Central Volcanic Zone of the Andes, it is 5,672m above sea level. On 19 July a powerful eruption spewed ash 5km high above the mountain, which spread across parts of southern Peru.
In the area around Ubinas, it was reported that nearly 30,000 people were evacuated and airports closed. The plume crossed southern Brazil and reached the Atlantic at 13km high, as a sulphuric gas plume 1,800km long and 270km wide, progressing at a speed of 150km/h. It continued its trip into the Indian Ocean on 22 July (Figure 3).
The animated GOES-16 Dust product sequence (Figure 2) shows the eruption onset shortly before 07:30 UTC, launching gas (green) and ash (red) eastwards.
The stable stratification at the upper limit of the troposphere enables the generation of gravity waves, like the folds of an accordion. Under the gas lines we see the ashes at lower level, propagating almost parallel to the gas, particularly noticeable around 13:30 UTC, as in Figure 1.
Gravity waves are high frequency internal perturbations in the air, generated by buoyancy under vertical stability. In this volcano case, the buoyancy frequency can be estimated from the propagation speed (70km/h) and the crest separation (12km) at around (1/600Hz). Mesoscale convection can lead to wavelengths between 10km and 1,000km, although for convection the lack of a tracer on satellite imagery makes them hard to spot. For the night time, water vapour in the 6µm absorption band often plays that role.
On 1 February 2018 there was short-lived but very powerful eruption from Fuego. The largest eruption on the morning of 1 February was followed by a series of small eruptions during the day. The first eruption was reported to have sent ash at least 6km into the air and was one of the largest in the volcano's history.
A sequence of Ash RGBs from the ABI instrument on GOES-16 shows its evolution during the hours following the first intense blast at about 08:00 UTC. The bright pink ash plume showed quite a complex behaviour under the influence of winds shearing in altitude and time.
After the release of the main plume that, according to CIMSS Satellite Blog , reached up to at least 6km Fuego continued to send a weaker streak (dark blue to magenta on the imagery) in western and south-western directions. In the same time interval a couple of dark-coloured contrails passed over Fuego.
22-23 April, Chile By Michael Grzegorski, Mark Higgins, Jochen Kerkmann, Vesa Nietosvaara and HansPeter Roesli
Southern Chile’s Calbuco volcano unexpectedly erupted for the first time in more than 40 years on 22 April, and then again early on 23 April.
The Meteosat-10 Dust RGB shows the plume from the second eruption, as it headed towards Chile, Argentina and Uruguay at 05:00 UTC on 24 April.
The eruption caused air traffic disruptions with a number of international flights cancelled or delayed. Qantas flight QF27 was five hours into its journey to Santiago when it had to turn back to Sydney.
The Calbuco volcano in southern Chile erupted around 21:03 UTC on 22 April, as can be seen on the GOES-13 visible image from 21:38 UTC (Figure 7) and the infrared animation from 22 April 20:38 UTC to 23 April 13:38 UTC (Figure 8).
There was a second explosive eruption that began some time before the Suomi-NPP VIIRS image from 05:13 UTC (Figure 9). The I-band 5 (11.4µm) minimum brightness temperature within the overshooting top of the second plume was -101°C, which is extraordinary for mid-latitudes and indicates a cloud top height of well above 15km.
The volcanic cloud from the second eruption can also be seen in the VIIRS Ash RGB product (Figure 10) close to the position of the Calbuco volcano in the lower part of the image. The colour (brown) indicates a very thick ash cloud. The cloud from the first pulse is visible more to the north (red and yellow colours), stretching east-west along a deformation zone. The yellow colour indicates the presence of SO2 inside the plume (probably together with the presence of small ash particles).
About one hour later, Aqua MODIS also captured the volcanic plumes (Figure 11). Note that no retrievals are present in the core of the cloud produced by the second explosion due to its large optical depth. The MODIS retrievals show small effective radii in the eastern, and highest portion, of the dispersed cloud (yellow colour in the Ash RGB product, top left) from the first eruption. The relatively small area of larger heights in the western portion of the dispersed cloud are likely an artifact of the unsupervised, near-real time retrieval process.
Unfortunately, the volcanic clouds were located near the edge of the Aqua MODIS morning pass, which means that a CALIPSO overpass above the cloud was not available (CALIPSO and Aqua fly in nearly the same orbit, offset by a few minutes). But the CALIPSO afternoon overpass captured the volcanic plume, the portion of the cloud overpassed by CALIOP was as high as about 17–18km (Figure 12).
A daytime view of the volcanic clouds was provided by Suomi-NPP VIIRS on 23 April at 19:10 UTC (Figures 13 and 14). At this time, the volcanic clouds stretch from the west to the east coast of southern South America.
In the Ash RGB product (Figure 14), most of the cloud, which is getting thinner as it moves away from the Calbuco volcano, is yellow (ash and SO2 mixed), but there is also a larger red area ('pure' ash cloud) and a small cyan-green band close to Santiago ('pure' SO2 cloud with some remaining ash particles).
The presence of SO2 in the yellow and cyan parts of the volcanic cloud is confirmed by GOME-2 (Figure 15) and AIRS (Figure 16) SO2 vertical column products.
Although right on the edge the Meteosat-10 field of view, the volcanic plumes could also be seen on Ash and Airmass RGB imagery (Figures 17 and 18).
The Airmass RGB (Figure 18) is sensitive to high-level sulphur dioxide, because of the WV7.3 band that is used in combination with the WV6.2 in the red component of the RGB. The Ash RGB (Figure 17) is sensitive to both SO2 and ash clouds.
The animations above follow the plume of the Calbuco eruptions across the South Atlantic from 23 to 27 April. The Airmass RGB animation shows the high-level SO2 plume (bright red, gradually fading), as it crosses Argentina, Paraguay, Uruguay and Brazil (it reaches Buenos Aires at around 10:00 UTC on 24 April). In the second part of the animation, when the plume crosses the Atlantic and gets thinner, the colour of the SO2 plume gets 'weaker' (more orange), thus it is more difficult to distinguish it from regions with low upper-level humidity (also orange colour).
The Ash RGB animation shows both the ash (pink to magenta), SO2 (cyan-green) and ash mixed with SO2 (yellow). On its way to the mid Atlantic, the colour turns from mainly yellow to mainly cyan-green, hinting that the ash is falling down, leaving, essentially, only SO2 behind.
The Polar Multi-Sensor aerosol product retrieves aerosol optical depth over sea (Figure 19) and a volcanic ash classification flag (Figure 20, ash pixels marked in red) using GOME and AVHRR on Metop. The transport of the ash over sea can be clearly observed in both products.
The PMAp results are also in a very good agreement with the SO2 observations from GOME showing a strong plume moving eastwards. The operational sulphur dioxide products from GOME-2 Metop-A and -B are produced by the O3M SAF.
4 June-1 July, Chile
By Marianne Koenig and HansPeter Roesli
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 17km height.
The 15-minute Meteosat-9 image sequence (Figure 23) 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 red 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.
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 (Figure 25) shows the plume's complex circumnavigation of the southern hemisphere. PCCVC continued to have briefer eruptions every now and then (eg 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.
2-5 May, Chile
By Jochen Kerkmann and HansPeter Roesli
On 2 May 2008 an old volcanic caldera erupted close to the coastal town of Chaitén in southern Chile. More than 9,000 years after the last eruption, huge amounts of ash and gases were ejected to great heights for several days (activity is ongoing even even months after the first eruption).
With Meteosat-9's sensitivity to ash and SO2 their transport across the Southern Atlantic into the Indian Ocean could be monitored over several days. The hourly Meteosat-9 animation (3 May 06:00 UTC–06 May 09:00 UTC) shows the initial evolution in a sequence of the standard RGB enhancing the presence of ash and SO2. The 3-hourly Meteosat-9 animation (3 May 00:00 UTC–09 May 06:00 UTC) is a longer sequence at lower temporal resolution but spanning three more days and the whole part of the southern hemisphere covered by Meteosat-9.
Three frames taken from the latter animation are used to single out a couple of SO2 signals that tag the general circulation over the area. On frame 1 (4 May 6:00 UTC) the upper red arrow marks a pink-coloured ash plume and the lower red arrow shows the approximate position of a SO2 cloud. The blue arrow points to a second, light green SO2 plume.
Two and a half days later, on frame 2 (6 May 21:00 UTC) the two SO2 clouds of the former frame move over to the longitude of South Africa with the respective trajectories (red arrow now north of blue one). At the same time, over the Argentinean Atlantic coast yet another Chaiten plume (white arrow) is appearing again carrying ash and SO2.
While the SO2, marked with red and blue arrows, appear to merge moving further into the Indian Ocean, on frame 3 (9 May 03:00 UTC) the SO2-part of the Argentina plume has moved on a more southern track (white arrow) than the patches seen before. New ash plumes continue to cover the coast from Argentina to southern Brazil. There are other SO2 patches in the sequence that can be followed.
All in all, the trajectories indicate clearly the meandering circulation, much in contrast to the SO2 tracks over the North Atlantic following the Kasatochi event in August 2008.