FY-2E 0.73 µm visible channel images (click image to play animation)

The Nabro volcano erupted in the northeast Africa country of Eritrea on 12 June 2011. An oblique view using the Chinese FY-2E satellite (positioned over the Equator at 105º East longitude) 0.73 µm visible channel data (above; click image to play animation) showed the volcanic plume streaming northwestward on 13 June (the Nabro volcano is located near the bottom center of the images. Note that the plume became much brighter on the visible images later in the day, due to forward scattering.

A sequence of EUMETSAT Meteosat-9 7.35 µm “water vapor channel” images (below; click image to play animation) was useful for following the leading edge of the volcanic plume (the volcano summit is circled on the first few images of the animation). The plume moved northward over far northeastern Africa, and eventually curved anticyclonically and passed over the northern Arabian Peninsula on 14 June. It then appeared as if the leading edge of the volcanic plume might have eventually become entrained into a conveyor of isentropic ascent, where moisture began to increase (exhibiting a darker blue color on the water vapor images).

Meteosat-9 7.35 µm water vapor channel images (click image to play animation)

GOES-12 0.65 µm visible channel images

An explosive eruption of the Puyehue-Cordón Caulle volcano in Chile occurred on 04 June 2011. GOES-12 0.65 µm visible channel images (above) showed a darker gray ash cloud punching above the meteorological cloud deck around 18:15 UTC, with the ash cloud quickly spreading southeastward and moving over Bariloche, Argentina (station identifier SAZS).

A comparison of GOES-12 3.9 µm shortwave IR and 10.7 µm IR window channel images (below) revealed a pronounced and persistent “hot spot” signature (dark black pixels) at the summit of the volcano on the shortwave IR images — while the long and narrow cold high-altitude volcanic cloud (exhibiting IR brightness temperatures around -60º C, darker red color enhancement) could be seen spreading southeastward for a great distance on the IR window images.

GOES-12 3.9 µm shortwave IR (top) and 10.7 µm IR window (bottom) images

CIMSS activities in the GOES-R Proving Ground include the generation of real-time volcanic ash retrieval products (using Meteosat SEVIRI data as a proxy for GOES-R data), which showed a significant volcanic ash plume emerging over the Atlantic Ocean (below).

SEVIRI volcanic ash retrieval products

Meteosat-9 visible channel images

Meteosat-9 visible channel images (above) showed the volcanic eruption cloud emanating from the Grímsvötn volcano in Iceland on 21 May 2011 (images courtesy of Dave Santek, SSEC). According to the Icelandic Met Office, at 21:00 UTC the eruption plume had risen to an altitude of over 65,000 ft (~20 km). It is interesting to note that the London VAAC reported

EXTREME LIGHTNING ACTIVITY DETECTED BY ATDNET SYSTEM OF UK METOFFICE, 7000 BETWEEN 1900Z AND 0100Z

The volcanic eruption cloud was even apparent on the very edge of GOES-13 (GOES-East) imagery, as can be seen in an animation of visible channel images (below). The oblique viewing angle from this satellite helped to emphasize the large vertical extent of the eruption cloud.

GOES-13 visible channel images

An animation of Meteosat-9 SEVIRI volcanic ash retrieval product 4-panel images (below) indicated that the initial volcanic cloud was ice-dominated (darker red color enhancement on the false color Red/Green/Blue or RGB images in the upper left panel). Around 22:00 UTC, the signal of an SO2 cloud (green color enhancement) began to appear around the northern and northeastern edges of the eruption cloud — very high values of SO2 were subsequently seen moving northward, using data from the OMI instrument.

A more distinct volcanic ash signal (pink color enhancement on the RGB image) became obvious as time progressed along the southern and southeastern edges of the eruption cloud, and by 06:00 UTC on 22 May the retrieved maximum ash height had reached 7.52 km (with the mean volcanic ash particle effective radius at 11.14 µm). Total volcanic ash mass loading had increased to 44.97 kilotons by 06:00 UTC.

Meteosat-9 volcanic ash retrieval 4-panel images

CIMSS participation in GOES-R Proving Ground activities includes the generation of these SEVIRI volcanic ash retrievals, which offers a demonstration of the type of products that will be available for volcanic ash monitoring with the ABI instrument on the future GOES-R satellite.

===== 22 MAY UPDATE =====

Meteosat-9 visible channel images (below; click image to play animation) showed that multiple volcanic eruption clouds were still reaching significant vertical heights, with much of this high-altitude material drifting northward. Another lower-altitude hazy volcanic ash cloud could also be seen spreading out just off the southern coast of Iceland. See the US Air Quality blog for MODIS true color images and OMI SO2 images of the volcanic eruption.

Meteosat-9 visible images (click to play animation)

GOES-11 3.9 µm shortwave IR images (click image to play animation)

A fissure eruption on the Kilauea volcano on the island of Hawaii began on 05 March 2011 — and 3 days later, McIDAS images of GOES-11 3.9 µm shortwave IR data (above; click image to play animation) displayed a prominent “hot spot” (yellow to red enhanced pixels) during the day on 08 March 2011.

GOES-11 0.65 µm visible images (below; click image to play animation) showed the hazy summit plume spreading southwestward during the day. This volcanic plume contained high levels of sulphur dioxide (SO2), as seen on an image of OMI total column SO2 (courtesy of NOAA/NESDIS).

GOES-11 0.65 µm visible images (click image to play animation)

About 3000 miles (4800 km ) to the north, GOES-11 0.65 µm visible images (below; click image to play animation) showed the movement of ice in the Bering Sea west of Alaska. Note that the motion of the ice was toward the northeast early in the animation, but then changed to motion toward the southwest later in the day. Surface winds along with tidal currents in the Bering Sea have an influence on the overall motion of the ice.

GOES-11 0.65 µm visible images (click image to play animation)

The motion of the ice in the Bering Sea could also be seen on a sequence of AWIPS images of POES AVHRR 0.86 µm visible channel data (below).

POES AVHRR 0.86 µm visible images

The POES AVHRR Sea Surface Temperature (SST) product (below) indicated that SST values were in the low to middle 30f F (darker blue color enhancement) in the ice-free water south and west of the ice edge.

POES AVHRR Sea Surface Temperature product

GOES-13 (left) and GOES-12 (right) 3.9 µm shortwave IR images

McIDAS images of GOES-13 and GOES-12 3.9 µm shortwave IR (IR channel 2) data (above) revealed the “hot spot” (yellow to red color enhancement) due to the eruption of the Tungurahua volcano in the South American country of Ecuador on 04 December 2010. The summit of the volcano is located south-southeast of the city of Latacunga (station identifier SELT). According to an ash advisory issued by the Washington DC Volcanic Ash Advisory Center (VAAC), ash was estimated to be extending upward to altitudes about 26,000 feet around this time.

Note that at times there are sight differences in the size and intensity of the volcano hot spot, due to the different viewing angles from the GOES-13 satellite (located at 75º West longitude) and the GOES-12 satellite (located at 60º West longitude). Also note the improved image navigation and registration (INR) with GOES-13, which keeps the volcano hot spot centered at the same location during the image animation.

Meteosat-9 SEVIRI volcanic ash retrieval products

The Icelandic volcano Eyjafjallajökull (which started to become active again in late March 2010) continued to remain active into early May, with another significant plume being observed on 06 May 2010. EUMETSAT Meteosat-9 SEVIRI volcanic ash retrieval products (above) showed a plume streaming southeastward from Iceland, with the maximum ash cloud height reaching 17.27 km. These volcanic ash retrieval products provide a demonstration of the type of products that will be available with the ABI instrument on the GOES-R satellite — they are available in near-realtime on the CIMSS GOES-R Proving Ground site.

A Terra MODIS Red/Green/Blue (RGB) image (using bands 01/04/03) shows the brown ash plume curving southeastward and then southward over the eastern Atlantic Ocean (below).

Terra MODIS RGB image (using bands 01/04/03)

As a result of this most recent volcanic eruption, some airports in Scotland, Northern Ireland and the Irish Republic were closed on 06 May.

===== 07 MAY UPDATE =====

A Terra MODIS RGB image using bands 01/04/03 (below) showed a very long and narrow volcanic plume emanating from Eyjafjallajökull on 07 May.

Terra MODIS RGB image (using bands 01/04/03)

Aqua MODIS Red/Green/Blue (RGB) image

The eruption of the Eyjafjallajökull volcano on southern Iceland continued on 19 April 2010 (in addition, see the previous CIMSS Satellite Blog entries published on 15 April and 21 March). A McIDAS Red/Green/Blue (RGB) image composite using Aqua MODIS channels 01/04/03 (above) revealed yet another large ash plume streaming southward over the North Atlantic Ocean. According to the London Volcanic Ash Advisory Center (VAAC), the ash from this latest eruption was generally confined to 10,000-15,000 feet and lower. With the volcanic ash plume drifting to the south, air traffic in the immediate vicinity of Reykjavik-Keflavik International Airport (station identifier BIKF) was not affected — and after a 5-day shut-down of air traffic across much of Europe, some airports there were finally beginning to allow limited flights to resume.

The corresponding volcanic ash retrieval products (below, courtesy of Mike Pavolonis, NOAA/NESDIS/STAR/CoRP/ASPB) indicated that the total ash loading was 75.82 kilotons, the maximum ash height was 7.37 km, and the mean ash particle effective radius was 3.51 micrometers. Note that these volcanic ash retrieval products are available in near-realtime at this NOAA/NESDIS/STAR/CIMSS site.

MODIS volcanic ash retrieval products

In addition to MODIS instruments on Terra and Aqua, the AVHRR instrument on the NOAA polar orbiters can give information on the state of the eruption. NOAA-19 passed over Iceland at 04:08 UTC 19 April, and NOAA-16 passed over at 09:16 UTC 19 April. What do the two views suggest?

Only the NOAA-16 pass occurred during daylight, and that image, below, centered on the Volcano, shows a plume extending southward from Iceland in the wake of a low pressure system (the cyclonic swirl of clouds in the eastern half of the image) departing to the east.

.

Infrared imagery from 0408 UTC and 0916 UTC today suggest how the ash cloud may be changing with time. The 3.74 micron imagery and the 10.8-micron imagery, below, both show an increase in the area covered by the plume. This suggests an ongoing eruption. The 10.8-micron imagery in particular shows a lengthening of the volcanic plume southward from Iceland. The 3.74 micron imagery is affected by radiation reflected from the Sun. The 0408 UTC image occurred before sunrise. Only radiation emitted by the Earth, or clouds, or ash, is detected by the satellite. Note the warm (dark) spot that colocates with the volcano: brightness temperatures there are 20 K warmer than surrounding pixels. The 0916 UTC occurred during daylight, and as such, solar radiation at 3.74 microns can be reflected off the Earth and detected by the satellite. The sum total of radiation (emitted plus reflected) will always be greater than only the emitted radiation, thus the scene will appear warmer (and in the greyscale enhancement, darker): the “extra” radiation detected by the satellite is interpreted to mean a warmer emitting surface. Note the striking appearance of the plume. It is very dark (warm) because the particles in the plume are highly reflective. At 0916 UTC, the volcano still retains its dark spot presence in the 3.74 micron imagery. The brightness temperature remains about 20 K warmer than at surrounding pixels.

MODIS Red/Green/Blue (RGB) and 3.7 µm shortwave IR images

Eyjafjallajökull continued to erupt on 20 April 2010. An Aqua MODIS Red/Green/Blue (RGB) image (above) showed a thin but well-defined cloud plume (likely a plume of volcanic steam) arcing southeastward, with a hint of a broader volcanic ash plume spreading out southward from the volcano. The corresponding MODIS 3.7 µm shortwave IR image displayed a pronounced “hot spot” (yellow to red color enhancement) associated with the source of the eruption.

An animation of Meteosat-9 volcanic ash retrieval products (below) indicated that the cloud heights decreased rapidly with time (likely a result of relatively large particles), and the ash cloud quickly became undetectable with increasing distance from the source volcano, due to its low optical depth and obstruction by meteorological clouds.

Meteosat-9 volcanic ash retrieval products

Eyjafjallajökull, a now-active volcano in southern Iceland that erupted in late March, has recently erupted again, ejecting significant volcanic ash into the atmosphere. Iceland is at high enough latitudes (between 63 and 66.5 degrees north Latitude) that views from geostationary satellites are not as helpful in diagnosing evolving events such as ash clouds as they would be for lower-latitude events. Meteorologists instead rely on polar orbiters to observe the atmosphere surrounding the eruption.

For example, A Terra overpass yesterday allowed MODIS to image the eruption, shown as a true color composite below.

Ash from volcanoes is a significant aviation hazard if it is drawn into jet turbines. For that reason, all flights at London’s Heathrow (and at other airports throughout northern Europe) have been grounded as of mid-afternoon London time on 15 April. The volcanic ash cloud is visible from satellite. The imagery above shows 10.8- and 12.0-micron imagery from a NOAA-18 pass at 0342 UTC on 15 April. The volcanic plume is visible as colder cloud tops arcing eastward from Iceland towards northern Scotland. The color enhancement in the loop shows that the 12.0-micron image has colder brightness temperatures than the 10.8-micron image. For example, the coldest point (red pixels) just off the coast of Iceland have 12.0-micron brightness temperatures of 212.6 K; 10.8-micron temperatures in that region are closer to 214.5 K. This difference in temperature arises because volcanic ash has a lower emissivity at 12.0 microns than at 10.8 microns. Thus, proportionally less radiation compared to a blackbody is being emitted at 12.0 microns than at 10.8 microns. When that emitted radiation is detected by the satellite, the proportionally smaller values at 12.0 microns yield cooler blackbody temperatures.

Indeed, a difference between the two channels can yield a rough approximation of the ash cloud outline, and that is shown above. Colored pixels here have 10.8-micron brightness temperatures at least 2 K warmer than the 12.0-micron brightness temperature. Maximum temperature differences exceed 10 K.

Meteosat-9 volcanic ash products (15 April)

15-16 April Update: The SEVIRI instrument on Meteosat-9, with more spectral resolution than AVHRR, can yield more information about the ash cloud, including total mass, maximum height, and effective radius. These derived products (courtesy of Mike Pavolonis, NOAA/NESDIS/STAR/CoRP/ASPB) are shown for 15 April (above; also available as a QuickTime movie), and for 16 April (below; also available as a QuickTime movie).

Meteosat-9 volcanic ash products (16 April)

18 April Update: below are individual quantitative volcanic ash product images that show characteristics of the volcanic ash features at various times and locations during the 16-18 April period.

Meteosat-9 volcanic ash products at 06:00 UTC on 16 April

=====

Meteosat-9 volcanic ash products at 18:30 UTC on 16 April

=====

MODIS volcanic ash products at 03:40 UTC on 17 April

=====

MODIS volcanic ash products at 04:20 UTC on 18 April

=====

MODIS volcanic ash products at 12:05 UTC on 18 April

=====

MODIS volcanic ash products at 14:00 UTC on 18 April

A McIDAS image of a 500-meter resolution Aqua MODIS Red/Green/Blue (RGB) composite using channels 01/04/03 (below) shows a beautiful view of the volcanic ash plume streaming southward on 17 April 2010. Annotated on the image are the tiny village of Skógar, as well as the Mýrdalsjökull Glacier. As an aside, it is interesting to note that a great deal of lightning has been observed associated with the volcanic ash cloud.

Aqua MODIS Red/Green/Blue (RGB) image showing the ash plume on 17 April 2010

NOAA-19 AVHRR 3.7 µm shortwave IR image

The Eyjafjallajökull volcano in southern Iceland (which had last erupted in the 1820s) experienced a minor eruption on 21 March 2010. An AVHRR 3.7 µm shortwave IR image from the polar-orbiting NOAA-19 satellite (above) showed evidence of a “hot spot” (black to yellow pixels) due to the resulting lava flows.

According to the London VAAC, the volcanic eruption did not produce significant volcanic ash above the 5000 foot level:

FVXX01 EGRR 211458
VA ADVISORY
DTG: 20100321/1200Z
VAAC: LONDON
VOLCANO: EYJAFJOLL
PSN: N6339 W01926
AREA: ICELAND
SUMMIT ELEV: 1000M
ADVISORY NR: 2010/006
INFO SOURCE: ICELAND MET OFFICE
AVIATION COLOUR CODE: UNKNOWN
ERUPTION DETAILS: ERUPTION CONTINUES
OBS VA DTG: 21/1200Z
OBS VA CLD: SFC/FL050 N6331 W01923-N6559 W02252-N6559 W03252-N6047 W03823-N6017 W0342 -N6331 W01923
FCST VA CLD +6HR: 21/1800Z SFC/FL050 N6331 W01919-N6705 W02525-N6704 W03621-N5801 W04323-N5633 W03545-N6143 W03035-N6331 W01919
FCST VA CLD +12HR: 22/0000Z SFC/FL050 N6331 W01903-N6750 W02833-N6750 W03955-N6131 W04520-N5435 W04459-N5501 W03207-N5954 W03105-N6331 W01903
FCST VA CLD +18HR: 22/0600Z SFC/FL050 N6342 W01929-N6838 W03232-N6808 W04515-N5426 W04601-N5202 W03737-N5644 W02954-N6143 W03247-N6342 W01929
RMK: THIS ADVISORY SUPERCEDES ADVISORY 2010/005. VOLCANIC ASH NOT ABOVE FL050, ERUPTION MAINLY LAVA
NXT ADVISORY: 20100321/1800Z=

Additional information is available from the Icelandic Met Office.

=========================

24 MARCH UPDATE

Aqua MODIS 3.7 µm shortwave IR image

The minor volcanic eruptions continued for several days; meteorological clouds often obscured Iceland during that time, but on 24 March an overpass of NASA’s Aqua satellite allowed another view of the lava flow “hot spot” (red pixels) on a 1-km resolution MODIS 3.7 µm shortwave IR image (above). The maximum IR brightness temperatures within the red pixel area were 330 K. Additional photos and video have been posted by the Icelandic Met Office.

]]> http://cimss.ssec.wisc.edu/goes/blog/archives/4872/feed 0 http://cimss.ssec.wisc.edu/goes/blog/archives/4513 http://cimss.ssec.wisc.edu/goes/blog/archives/4513#comments Thu, 11 Feb 2010 23:59:15 +0000 scott.bachmeier http://cimss.ssec.wisc.edu/goes/blog/?p=4513

GOES-12 visible images + METAR surface reports

A major eruption followed a partial dome collapse in the crater of the Soufriere Hills volcano on the West Indies island of Montserrat during the daytime hours on 11 February 2010. McIDAS images of the GOES-12 visible channel data (above) showed the rapid east-southeastward expansion of the volcanic cloud following the eruption around 17:00 UTC. Pilot reports placed the maximum height of the volcanic cloud around 50,000 feet above ground level (see the NOAA/NESDIS/SSD/OSDPD archive of Volcanic Ash Advisories and satellite images).

GOES-12 3.9 µm shortwave IR images (below) showed a thermal anomaly or “hot spot” during the hours leading up to the major eruption, with a maximum IR pixel value of 322 K or 49º C (yellow color enhancement) at 16:45 UTC. Also note the darker appearance of the western and southern portions of the volcanic cloud: these were areas of the cloud that were composed primarily of supercooled water droplet clouds, which strongly reflect solar radiation (which then leads to much warmer shortwave IR brightness temperature values).

GOES-12 3.9 µm shortwave IR images

GOES-12 10.7 µm longwave IR images (below) revealed an initial pulse of very cloud cloud top IR brightness temperatures within a couple of hours following the eruption — as cold as -75º C at 19:15 UTC — before the volcanic cloud appeared to thin out and exhibit warmer IR brightness temperatures as it spread eastward.

GOES-12 10.7 µm longwave IR images

AWIPS images of high-altitude GOES-12 derived atmospheric motion vectors in the vicinity of the volcanic plume (below) were generally in the 40-55 knot range — the 12 UTC rawinsonde data from station TFFR (Le Raiset, Guadaloupe) had maximum west-northwesterly winds of 68 knots at 280 hPa (around the 41,000 foot level).

GOES-12 IR images + GOES-12 atmospheric motion vectors

A comparison of 4-km resolution GOES-12 3.9 µm and 1-km resolution NOAA-15 AVHRR 3.7 µm shortwave IR images (below) showed the advantage of higher spatial resolution for detecting the magnitude of the volcano’s hot spot — the hottest pixel seen on the NOAA-15 image was 330 K or +57º C (red color enhancement), compared to only 293.5 K or +20º C (black color enhancement) on the GOES-12 image.

GOES-12 (top) and NOAA-15 (bottom) shortwave IR images

Similarly, the coldest longwave IR brightness temperature value seen on the 1-km resolution NOAA-15 AVHRR image was -72º C, compared to only -55º C on the 4-km resolution GOES-12 image (below).

GOES-12 (top) and NOAA-15 (bottom) longwave IR images

A natural color Red/Green/Blue (RGB) composite image using Aqua MODIS channels 01/04/03 (below) showed the volcanic cloud at 17:20 UTC, about 20 minutes after the explosive eruption. The tall volcanic cloud was casting a long shadow toward the north-northeast at that time. In addition, the hazy signal of previous volcanic emissions from earlier in the day could be seen covering a much larger portion of the region.

Aqua MODIS natural color Red/Green/Blue (RGB) image

A few hours later, a false-color Red/Green/Blue (RGB) composite image using NOAA-15 AVHRR channels 01/02/04 (below) shows a view of the volcanic cloud at 21:02 UTC. Again, the tall cloud feature was still seen to be casting a long shadow toward the north-northeast at that time. The thermal anomaly from the volcano hot spot appeared as the small yellow area on the RGB image.

NOAA-15 AVHRR false-color Red/Green/Blue (RGB) image at 21:02 UTC

A sequence of three sets of of images from the GOES-12 sounder (below) shows the sounder longwave IR window image (top panels) along with a sounder IR difference product (7.4 µm – 13.3 µm, bottom panels) before, during, and after the eruption. The darker gray to black image features intermingled with the brighter white water vapor and volcanic ash clouds are signals of a high concentration of SO2. The GOES Sounder is able to detect SO2 from a volcanic eruption, as long as it is not masked by both the water vapor and volcanic ash during and immediately following the eruption. This particular case was a situation where the extensive water vapor and volcanic ash clouds did in fact mask the SO2 signal resulting from the eruption of Soufriere Hills volcano. (GOES-12 sounder images provided by Tony Schreiner, CIMSS)

GOES-12 sounder IR images (top) and IR difference images (bottom)

===== 12 FEBRUARY UPDATE =====

The series of 4-panel displays below (provided by Mike Pavolonis, NOAA/NESDIS/ASPB) show AVHRR RGB images along with volcanic ash derived products (ash loading, ash height, and ash effective radius). Of particular interest was the fact that the maximum ash height decreased rather quickly, from 15.73 km (at 21:02 UTC on 11 February) to 5.58 km (at 06:24 UTC on 12 February) to 4.93 km (at 09:19 UTC on 12 February).

AVHRR RGB image and ash retrieval products

=====

AVHRR RGB image and volcanic ash retrieval products

=====

AVHRR RGB image and volcanic ash retrieval products

GOES-12 6.5 µm water vapor imagery with an overlay of Canadian Meteorological Center 400 hPa winds (below) revealed that an anticyclone was building aloft over the region following the eruption of the Soufriere Hills volcano — this would provide an environment of increasing mid-tropospheric subsidence that could explain the rapid decrease in retrieved volcanic ash heights. Subsequently, the water vapor image brightness temperature values were also increasing in the area of the building ridge, as seen by the warming trend of brightness temperatures averaging around -20º C (yellow color enhancement) to values averaging around -15º C (orange color enhancement).

GOES-12 water vapor images + CMC 400 hPa winds

]]> http://cimss.ssec.wisc.edu/goes/blog/archives/4513/feed 1