Eruption of the Mount Pavlof volcano in Alaska

March 28th, 2016

Himawari-8 AHI Shortwave Infrared (3.9 µm) images [click to play animation]

Himawari-8 AHI Shortwave Infrared (3.9 µm) images [click to play animation]

A major eruption of the Mount Pavlof volcano on the Alaska Peninsula began shortly before 0000 UTC on 28 March, or 4:00 pm on 27 March Alaska time (AVO report), as detected by a thermal anomaly (or “hot spot”, yellow to red color enhancement) on Himawari-8 AHI Shortwave Infrared (3.9 µm) images (above). The hot spot decreased in size and intensity toward the later hours of the day, signaling a lull in the volcanic eruption.

It is interesting to note on a comparison of the 0000 UTC Himawari-8 and GOES-15 Shortwave Infrared (3.9 um) images the large difference in the magnitude of the thermal anomaly — even though the viewing angle was larger for Himawari-8, the superior spatial resolution (2 km at nadir, compared to 4 km with GOES-15) detected a hot spot with an Infrared Brightness Temperature (IR BT) that was 36.6 K warmer (below). The Infrared channels on the GOES-R ABI instrument will also have a 2 km spatial resolution.

Himawari-8 AHI (left) and GOES-15 Imager (right) 3.9 µm Shortwave Infrared images [click to enlarge]

Himawari-8 AHI (left) and GOES-15 Imager (right) 3.9 µm Shortwave Infrared images [click to enlarge]

With the aid of reflected light from the Moon (in the Waxing Gibbous phase, at 75% of Full), a nighttime view using the Suomi NPP VIIRS Day/Night Band (0.7 µm) from the SSEC RealEarth site (below) revealed the bright glow of the eruption, along with the darker (compared to adjacent meteorological clouds) volcanic ash cloud streaming northeastward. The corresponding VIIRS Shortwave Infrared (3.74 µm) image showed the dark black hot spot of the volcano summit.

Suomi NPP VIIRS Shortwave Infrared (3.74 µm) and Day/Night Band (0.7 µm) image [click to enlarge]

Suomi NPP VIIRS Shortwave Infrared (3.74 µm) and Day/Night Band (0.7 µm) image [click to enlarge]

The volcanic ash cloud continued moving in a northeastward direction, as seen in a sequence of GOES-15 Infrared Window (10.7 µm) and either Terra/Aqua MODIS or Suomi NPP VIIRS retrieved Volcanic Ash Height products from the NOAA/CIMSS Volcanic Could Monitoring site (below).

GOES-15 Infrared (10.7 µm) images, with Terra/Aqua MODIS and Suomi NPP VIIRS Ash Height products [click to play animation]

GOES-15 Infrared (10.7 µm) images, with Terra/Aqua MODIS and Suomi NPP VIIRS Ash Height products [click to play animation]

Due to the oblique satellite view angle, the shadow cast by the tall volcanic ash cloud was easily seen on the following early morning (Alaska time) Himawari-8 AHI Visible (0.64 µm) images (below). A closer view (courtesy of Dan Lindsey, RAMMB/CIRA) revealed overshooting tops and gravity waves propagating downwind of the eruption site.

Himawari-8 AHI Visible (0.64 um) images (click to play animation]

Himawari-8 AHI Visible (0.64 um) images (click to play animation]

A few select Pilot reports (PIREPs) are shown below, plotted on GOES-15 Infrared Window (10.7 µm) and Aqua MODIS Ash Height derived products. Numerous flights were canceled as the ash cloud eventually began to drift over Western and Interior Alaska (media report).

GOES-15 Infrared Window (10.7 um) image, with METAR surface reports and Pilot reports [click to enlarge]

GOES-15 Infrared Window (10.7 µm) image, with METAR surface reports and Pilot reports [click to enlarge]

GOES-15 Infrared Window (10.7 um) image, with METAR surface reports and Pilot reports [click to enlarge]

GOES-15 Infrared Window (10.7 µm) image, with METAR surface reports and Pilot reports [click to enlarge]

GOES-15 Infrared Window (10.7 um) image, with METAR surface reports and Pilot reports [click to enlarge]

GOES-15 Infrared Window (10.7 µm) image, with METAR surface reports and Pilot reports [click to enlarge]

Aqua MODIS Ash Height product, with METAR surface reports and Pilot reports [click to enlarge]

Aqua MODIS Ash Height product, with METAR surface reports and Pilot reports [click to enlarge]

GOES-15 Infrared Window (10.7 um), with METAR surface reports and Pilot reports [click to enlarge]

GOES-15 Infrared Window (10.7 µm), with METAR surface reports and Pilot reports [click to enlarge]

A comparison of Suomi NPP VIIRS Shortwave Infrared (3.74 µm), Day/Night Band (0.7 µm), and true-color Red/Green/Blue (RGB) images (below) showed the volcanic hot spot and the brown to tan colored ash cloud at 2141 UTC on 28 March. Significant ash fall (as much as 2/3 of an inch) was experienced at the village of Nelson Lagoon, located 55 miles northeast of Pavlof (media report).

Suomi NPP VIIRS Shortwave Infrared (3.74 µm), Day/Night Band (0.7 µm), and true-color RGB images [click to enlarge]

Suomi NPP VIIRS Shortwave Infrared (3.74 µm), Day/Night Band (0.7 µm), and true-color RGB images [click to enlarge]

A comparison of the 3 Himawari-8 AHI Water Vapor bands (7.3 µm, 6.9 µm and 6.2 µm) covering the first 14 hours of the eruption from 0000 to 1400 UTC is shown below. Note that volcanic plume was best seen on the 7.3 µm images, which indicated that it began to move over the coast of Western Alaska after around 0600 UTC; this is due to the fact that the 7.3 µm band is not only a “water vapor absorption” band, but is also sensitive to high levels of SO2 loading in the atmosphere (as was pointed out in this blog post).

Himawari-8 AHI Water Vapor 7.3 µm (left), 6.9 µm (center) and 6.2 µm (right) images [click to play animation]

Himawari-8 AHI Water Vapor 7.3 µm (left), 6.9 µm (center) and 6.2 µm (right) images [click to play animation]

Large grass fire in Oklahoma and Kansas

March 23rd, 2016

GOES-13 Shortwave Infrared (3.9 µm) images, with surface reports [click to play animation]

GOES-13 Shortwave Infrared (3.9 µm) images, with surface reports [click to play animation]

A grass fire (now referred to as the “Anderson Creek fire”) was first reported in western Woods County, Oklahoma around 2245 UTC or 5:45 PM local time on 22 March 2016. “Hot spot” signatures (yellow to red to black pixels) on GOES-13 Shortwave Infrared (3.9 µm) images (above) showed that the fire proceeded to make a very fast run to the north during the overnight hours, crossing over the Kansas border into Comanche and Barber Counties. The fire eventually jumped Highway 160  — which runs west-to-east across the northern portion of those 2 counties (highways are plotted in violet) — forcing it to be closed for several hours. As of the afternoon of 23 March, the fire was reported to have burned at least 72,000 acres; on that evening, the mayor of Medicine Lodge, Kansas (station identifier KP28) called for a voluntary evacuation as the fire began to approach the edge of the town. Note that GOES-13 (GOES-East) had been placed into Rapid Scan Operations (RSO) mode specifically to monitor the extremely critical fire risk, and was providing images as frequently as every 5-7 minutes.

A nighttime comparison of Suomi NPP VIIRS Day/Night Band (0.7 µm) and Shortwave Infrared (3.74 µm) images at 0823 UTC or 3:23 AM local time (below) showed the hot spots and the bright glow of the large and very hot fire.

Suomi NPP VIIRS Day/Night Band (0.7 µm) and Shortwave Infrared (3.74 µm) images {click to enlarge]

Suomi NPP VIIRS Day/Night Band (0.7 µm) and Shortwave Infrared (3.74 µm) images {click to enlarge]

A sequence of Shortwave Infrared images from POES AVHRR, Terra/Aqua MODIS, and Suomi NPP VIIRS (below) provided higher-resolution snapshots of the rapid northward progression of the fire during the overnight hours (aided by strong southerly winds), followed by an east/northeastward expansion during the subsequent daylight hours (driven by a switch to strong southwesterly winds after the passage of a dryline).

POES AVHRR (3.7 µm), Terra/Aqua MODIS (3.7 µm), and Suomi NPP VIIRS (3.74 µm) Shortwave Infrared images [click to enlarge]

POES AVHRR (3.7 µm), Terra/Aqua MODIS (3.7 µm), and Suomi NPP VIIRS (3.74 µm) Shortwave Infrared images [click to enlarge]

GOES-13 Visible (0.63 µm) images (below) revealed a large increase in smoke produced by the fire during the day on 23 March. This smoke was drawn cyclonically northeastward then northward around the circulation of a storm system that was deepening over western Kansas. Afternoon wind gusts were as high as 61 mph in Newton, Kansas. Downstream of the fire source region, smoke reduced the surface visibility to 4 miles at Hutchinson, Kansas (station identifier KHUT) at 21 UTC or 4 PM local time, and Wichita (station identifier KICT) reported a visibility of 1.75 miles at 00 UTC or 7 PM local time; ash falling from the smoke aloft caused the surface air quality in Wichita to briefly deteriorate to unhealthy levels.

GOES-13 Visible (0.63 µm) images, with surface reports [click to play animation]

GOES-13 Visible (0.63 µm) images, with surface reports [click to play animation]

In the early afternoon at 1748 UTC or 12:48 PM local time, a pilot report near the northern flank of the fire (below) indicated that the tops of the smoke towers were already rising to altitudes of 8000 to 11000 feet above ground level.

GOES-13 Visible (0.63 µm) image, with surface reports and a pilot report of smoke altitude [click to enlarge]

GOES-13 Visible (0.63 µm) image, with surface reports and a pilot report of smoke altitude [click to enlarge]

It is of interest to note that a similar (albeit smaller) grass fire spread rapidly northward from Oklahoma into Kansas, one county to the west and about one month earlier: the Buffalo fire. That event had the benefit of Super Rapid Scan Operations of GOES-14, which provided imagery at 1-minute intervals. The ABI instrument on the GOES-R satellite will be capable of providing 1-minute images over 2 pre-defined mesoscale sectors.

===== 24 March Update =====

Anderson Creek Fire perimeter map [click to enlarge]

Anderson Creek Fire perimeter map [click to enlarge]

A map of the Anderson Creek Fire perimeter (above) was issued by the Oklahoma Forestry Services at 1642 UTC or 11:42 AM local time. At that time, an estimated 397,420 acres (621 square miles) had been burned — which makes it the largest wildfire on record for the state of Kansas.

A comparison of Suomi NPP VIIRS true-color and false-color Red/Green/Blue (RGB) images from the SSEC RealEarth site (below) showed the extent of the burn scar, with smoke plumes drifting south-southeastward from 2 small areas of fires that were still actively burning at 2106 UTC or 4:06 PM local time. As discussed above, it can be seen that the fire crossed (and forced the closure of) US Highway 160 between Coldwater and Medicine lodge, and came very close to the town of Medicine Lodge.

Suomi NPP VIIRS true-color and false-color images [click to enlarge]

Suomi NPP VIIRS true-color and false-color images [click to enlarge]

===== 25 March Update =====

Suomi NPP VIIRS Day/Night Band (0.7 µm) image [click to enlarge]

Suomi NPP VIIRS Day/Night Band (0.7 µm) image [click to enlarge]

With ample illumination from the Moon (in the Waning Gibbous phase, at 98% of Full), the contrast between the dark Anderson Creek fire burn scar and the lighter surrounding grassland was very apparent on a Suomi NPP VIIRS Day/Night Band (0.7 µm) image at 0742 UTC or 2:42 AM local time. This example demonstrates the “visible image at night” capability of the VIIRS Day/Night Band.

Aircraft “hole punch” and “dissipation trails” over the eastern Great Lakes

March 3rd, 2016

GOES-13 (GOES-East ) Visible (0.63 µm) images centered over Lake Erie, Lake Ontario, and central New York state (below) showed a variety of aircraft “hole punch” and “dissipation trails” over the eastern Great Lakes on 03 March 2016.

GOES-13 Visible (0.63 µm) images, centered over Lake Erie [click to enlarge]

GOES-13 Visible (0.63 µm) images, centered over Lake Erie [click to play animation]

GOES-13 Visible (0.63 µm) images, centered over Lake Ontario [click to play animation]

GOES-13 Visible (0.63 µm) images, centered over Lake Ontario [click to play animation]

GOES-13 Visible (0.63 µm) images, centered over New York state [click to play animation]

GOES-13 Visible (0.63 µm) images, centered over New York state [click to play animation]

These cloud features were caused by aircraft that were either ascending or descending through layers of cloud composed of supercooled water droplets, which covered much of the region as shown by the POES AVHRR Cloud Type product at 1545 UTC (below). Cooling from wake turbulence (reference) and/or the particles from the jet engine exhaust acting as ice condensation nuclei cause the small water droplets to turn into larger ice crystals (which then often fall from the cloud layer, creating “fall streak holes“). Similar features have been discussed in previous blog posts.

POES AVHRR Cloud Type product at 1545 UTC [click to enlarge]

POES AVHRR Cloud Type product at 1545 UTC [click to enlarge]

There were numerous pilot reports of light to moderate icing between FL120 and FL160 (flight level 12,000-16,000 feet) when passing through the supercooled water droplet cloud layers (below). The pilot report altitudes agree well with the POES AVHRR Cloud Top Height product values of 4-5 km over Lake Erie at 1545 UTC.

GOES-13 Visible (0.63 µm) images with pilot reports of icing [click to play animation]

GOES-13 Visible (0.63 µm) images with pilot reports of icing [click to play animation]

A comparison of 250-meter resolution Terra MODIS true-color and false-color Red/Green/Blue (RGB) images at 1649 UTC as visualized using RealEarth (below) indicated that the cloud material in the center of the aircraft dissipation trail over the north shore of Lake Erie had glaciated (snow, ice, and ice crystal clouds exhibit a darker cyan appearance on the false-color image).

Terra MODIS true-color and false-color images over Lake Erie [click to enlarge]

Terra MODIS true-color and false-color images over Lake Erie [click to enlarge]

A panorama photo from the ground was taken in Binghamton, New York (station identifier KBGM, located near the center of the New York GOES-13 images):


Why 1-minute satellite data matters: Monitoring Fires

February 18th, 2016

GOES-14 0.63 µm Visible (top) and 3.9 µm Shortwave Infrared (bottom) images [click to play MP4 animation]

GOES-14 0.63 µm Visible (top) and 3.9 µm Shortwave Infrared (bottom) images [click to play MP4 animation]

Extensive wildfires (well-forecast by the Storm Prediction Center) occurred over the southern Plains on Thursday 18 February 2016, while GOES-14 was operating in SRSO-R mode. A comparison of 1-minute GOES-14 Visible (0.63 µm) and Shortwave Infrared (3.9 µm) images (above; also available as a large 112 Mbyte animated GIF) showed the broad areal coverage of smoke plumes and fire hot spots (dark black to yellow to red pixels) during the day over eastern Oklahoma.

GOES-14 0.63 µm Visible (left) and 3.9 µm Shortwave Infrared (right) images [click to play MP4 animation]

GOES-14 0.63 µm Visible (left) and 3.9 µm Shortwave Infrared (right) images [click to play MP4 animation]

Of particular interest was a rapidly-intensifying and fast-moving grass fire over northwestern Oklahoma, in Harper County just west-northwest of the town of Buffalo, which burned 17,280 acres (media report). Note the warm air temperatures as seen in the surface plots — the high of 90º F at Gage OK (KGAG, south of the fire) tied for the warmest February temperature on record at that site. A closer view of the Buffalo fire is shown above — county outlines are shown as dashed white lines, while US and State highways are plotted in violet (also available as a large 63 Mbyte animated GIF). The shortwave infrared images revealed the initial appearance of a color-enhanced fire hot spot (exhibiting an IR brightness temperature of 327.5 K) at 2045 UTC; three minutes later (at 2048 UTC), the IR brightness temperature had already increased to 341.2 K (red enhancement) which is the saturation temperature of the GOES-14 shortwave IR detectors. The hot spots could also be seen racing northeastward toward the Oklahoma/Kansas border, with the fire eventually crossing US Highway 183 (which runs south-to-north through Buffalo and across the Kansas border). The early detection and subsequent accurate tracking of such rapid fire intensification and propagation could only have been possible using 1-minute imagery.

The two plots below show GOES-14 pixel values of 3.9 µm IR brightness temperature at the initial Buffalo fire site (top plot, at 36:51º N, 99:48º W) and at a site just to the northeast (bottom plot, at 36:54º N, 99:43º W) through which the moving fire propagated. The blue line shows every value, nominally at 1-minute intervals. The red dots show points sampled every five minutes. Very small temporal scale changes in the fire cannot be captured with a 5-minute sampling interval.

GOES-14 Shortwave Infrared (3.9 µm) Brightness Temperatures at 36:51:36º N, 99:48:27º W, 2040-2230 UTC on 18 February 2016 [click to enlarge]

GOES-14 Shortwave Infrared (3.9 µm) Brightness Temperatures at 36:51:36º N, 99:48:27º W, 2040-2230 UTC on 18 February 2016 [click to enlarge]

GOES-14 Shortwave Infrared (3.9 µm) Brightness Temperatures at 36:54:44º N, 99:43:22º W, 2115-2200 UTC on 18 February 2016 [click to enlarge]

GOES-14 Shortwave Infrared (3.9 µm) Brightness Temperatures at 36:54:44º N, 99:43:22º W, 2115-2200 UTC on 18 February 2016 [click to enlarge]

 

GOES-15 (left), GOES-14 (center), and GOES-13 (right) 3.9 µm Shortwave Infrared images covering the initial period 2030-2100 UTC [click to play animation]

GOES-15 (left), GOES-14 (center), and GOES-13 (right) 3.9 µm Shortwave Infrared images covering the initial period 2030-2100 UTC [click to play animation]

For the Buffalo fire, a three-satellite comparison of Shortwave Infrared (3.9 µm) images from GOES-15 (operational GOES-West), GOES-14, and GOES-13 (operational GOES-East) is shown for the initial 30-minute time period 2030-2100 UTC (above). The images are displayed in the native projection of each satellite. In terms of the first unambiguous fire hot spot detection (via a hot color-enhanced image pixel) during that initial period, it would appear from the image time stamps that both GOES-14 and GOES-13 detected the fire at 2045 UTC — however, because GOES-14 was scanning a much smaller sector, it did indeed scan the fire at 20:45 UTC (while GOES-13 scanned the fire at 2049 UTC, 4 minutes after its larger scan sector began in southern Canada). Also note that there were no GOES-15 images during that 30-minue period between 2030 and 2100 UTC, due to the satellite having to perform various “housekeeping” activities — so if a NWS forecast office AWIPS were localized to use GOES-15, initial fire detection would not have been posible until reception of the 2100 UTC image (which actually scanned the fire at 2104 UTC).

A faster animation covering a longer 2.5-hour period from 2030-2300 UTC is shown below. Again, a true sense of the fast northeastward speed of fire propagation could only be gained using 1-minute imagery.

GOES-15 (left), GOES-14 (center), and GOES-13 (right) 3.9 µm Shortwave Infrared images covering the 2.5-hour period 2030-2300 UTC [click to play animation]

GOES-15 (left), GOES-14 (center), and GOES-13 (right) 3.9 µm Shortwave Infrared images covering the 2.5 hour period 2030-2300 UTC [click to play animation]

GOES-14 Shortwave Infrared (3.9 µm) images [click to play animation]

GOES-14 Shortwave Infrared (3.9 µm) 9mages [click to play animation]

The animation above shows another view of 1-minute GOES-14 Shortwave Infrared (3.9 µm) imagery, centered over northeastern Oklahoma — in these images, the hottest fire pixels are darkest black. Time series of infrared brightness temperature values at two individual fire pixels (shown here) are plotted below. The Blue lines show the 1-minute data; Red dots show how 5-minute monitoring would have adequately captured the events. Pixel Brightness Temperature changes that occur on the order of 1 or 2 minutes are common, and peak values can be missed with 5-minute granularity.

GOES-14 Shortwave Infrared (3.9 µm) Brightness Temperatures at, 2138-2301 UTC on 18 February 2016 at 35:31:17 N, 96:05:55 W [click to enlarge]

GOES-14 Shortwave Infrared (3.9 µm) Brightness Temperatures from 2138-2301 UTC on 18 February 2016, at 35:31:17º N, 96:05:55º W [click to enlarge]

GOES-14 Shortwave Infrared (3.9 µm) Brightness Temperatures at, 2138-2301 UTC on 18 February 2016 at 35:23:51 N, 95:20:52 W [click to enlarge]

GOES-14 Shortwave Infrared (3.9 µm) Brightness Temperatures from 2138-2301 UTC on 18 February 2016, at 35:23:51º N, 95:20:52º W [click to enlarge]

In the GOES-R era, Fire Products will be produced every 5 minutes. Individual NWS Forecast Offices will be able to request Rapid-Scan Imagery (1-minute intervals) over a 1000 km x 1000 km mesoscale sector.

===== 19 February Update =====

Seen below are RealEarth comparisons of Aqua MODIS and Suomi NPP VIIRS true-color Red/Green/Blue (RGB) images from the early afternoon of 18 February (before the Buffalo OK fire) and 19 February (after the Buffalo OK fire), which revealed the long southwest-to-northeast oriented burn scar. As seen on the GOES-14 animation above, the fire crossed US Highway 183 just to the north of Buffalo (that portion of the highway was closed for several hours).

Aqua MODIS true-color images on 18 February and 19 February [click to enlarge]

Aqua MODIS true-color images on 18 February and 19 February [click to enlarge]

Suomi NPP VIIRS true-color images on 18 February and 19 February [click to enlarge]

Suomi NPP VIIRS true-color images on 18 February and 19 February [click to enlarge]

In addition, a comparison of Suomi NPP VIIRS true-color and false-color images (below) helps to discriminate between the darker burn scar and the cloud shadows seen on the true-color image — the Buffalo fire burn scar appears as varying shades of brown in both the true-color and the false-color images.

Suomi NPP VIIRS true-color and false-color images [click to enlarge]

Suomi NPP VIIRS true-color and false-color images [click to enlarge]

===== 27 February Update =====

Landsat-8 false-color RGB images on 18 February (a few hours prior to the start of the fire) and 27 February (several says after the fire) [click to enlarge]

Landsat-8 false-color RGB images on 18 February (a few hours prior to the start of the fire) and 27 February (several says after the fire) [click to enlarge]

A comparison of 30-meter resolution Landsat-8 false-color (created using OLI bands 6/5/4) RGB images from 18 February (about 3.5 hours prior to the start of the Buffalo OK fire) and 27 February (several days after the fire) provided a very detailed view of the burn scar. Note that a few green fields remained within the burn scar, and also appeared to prevent the spread of the fire along portions of its perimeter — this is a result of the vast difference between the very low moisture content of the dry grassland (which burned quickly and easily) and the high moisture content of the well-irrigated fields of winter wheat, alfalfa, and canola crops.