Eruption of the Cotopaxi volcano in Ecuador

August 14th, 2015

GOES-13 visible (0.63 µm) images [click to play animation]

GOES-13 visible (0.63 µm) images [click to play animation]

GOES-13 visible (0.63 µm) images (above; click to play animation) displayed distinct dark-gray ash plumes from 2 separate daytime eruptions of the Cotopaxi volcano in Ecuador on 14 August 2015 (there was also an initial eruption that occurred during the preceding nighttime hours). The asterisk near the center of the images marks the location of the volcano summit. Volcanic ash fall was observed in the capitol city of Quito (station identifier SEQU, located about 50 km or 30 miles north of the volcano), and some flights were diverted due to the volcanic ash cloud.

The corresponding GOES-13 infrared (10.7 µm) images (below; click image to play animation) showed that cloud-top IR brightness  temperatures were as cold a -53º C (orange color enhancement) at 1915 UTC.

GOES-13 infrared (10.7 µm) images [click to play animation]

GOES-13 infrared (10.7 µm) images [click to play animation]

The volcanic cloud features were also easily tracked on GOES-13 water vapor (6.5 µm) images (below; click image to play animation). In fact, note how the signature in the water vapor imagery is more distinctly seen for a longer period of time than on the 10.7 µm infrared imagery.

 GOES-13 water vapor (6.5 µm) images [click to play animation]

GOES-13 water vapor (6.5 µm) images [click to play animation]

The tan-colored volcanic ash cloud was also evident on Aqua MODIS and Suomi NPP VIIRS true-color Red/Green/Blue (RGB) imagery (below), as viewed using the SSEC RealEarth web map server.

Aqua MODIS true-color images [click to enlarge]

Aqua MODIS true-color images [click to enlarge]

Suomi NPP VIIRS true-color image [click to enlarge]

Suomi NPP VIIRS true-color image [click to enlarge]

A comparison of Suomi NPP VIIRS visible (0.64 µm) and infrared (11.45 µm) images is shown below (courtesy of William Straka, SSEC). The coldest cloud-top IR brightness temperature was -72.7º C.

Suomi NPP VIIRS visible (0.64 µm) and infrared (11.45 µm) images [click to enlarge]

Suomi NPP VIIRS visible (0.64 µm) and infrared (11.45 µm) images [click to enlarge]

Hail damage to Delta Flight 1889 over Nebraska

August 7th, 2015

GOES-13 Sounder Lifted Indices [click to play animation]

GOES-13 Sounder Lifted Indices [click to play animation]

Hail associated with a line of rapidly developing thunderstorms near the borders of Kansas, Nebraska and Colorado heavily damaged Delta Flight 1889 bound from Boston to Salt Lake City, forcing an emergency landing in Denver (media report). An excellent blog post on the radar presentation of the system is here. What did the satellite data show? GOES Sounder Derived Product Image (DPI) values of Lifted Index (LI), above, (realtime images available here) showed instability over the High Plains of Colorado throughout the day. At 2000 UTC, for example, values greater than -8º C prevailed (subsequent cloud development prevented the retrieval of LI values using the Sounder). GOES Sounder DPI of Convective Available Potential Energy (CAPE), below, (realtime images available here) also indicated strong destabilization during the late afternoon (1600, 1800 and 2000 UTC are shown in the animation). The 08 August/00 UTC rawinsonde report from North Platte, Nebraska had LI and CAPE values of -5ºC and 1592 J/kg, respectively.

GOES Sounder Convective Available Potential Energy (CAPE), 1600 - 2000 UTC 7 August 2015  [click to enlarge]

GOES Sounder Convective Available Potential Energy (CAPE), 1600 – 2000 UTC 7 August 2015 [click to enlarge]

LAP (Legacy Atmospheric Profiles) from GOES-13 (from here) also showed strong instability in between extensive cloud cover: the imagery at 1600 UTC on 7 August for CAPE and LI is shown below.

GOES-13 LAP estimates of Lifted Index (LI) and Convective Available Potential Energy (CAPE), 1600 UTC 7 August 2015  [click to enlarge]

GOES-13 LAP estimates of Lifted Index (LI) and Convective Available Potential Energy (CAPE), 1600 UTC 7 August 2015 [click to enlarge]

Given the instability present, rapid thunderstorm development should not surprise (the region was under a Severe Thunderstorm Watch, and a Mesoscale Convective Discussion had been issued specifically mentioning the possibility of severe hail). The visible animation from GOES-13, below, from 1900 UTC on 7 August through 0145 UTC on 8 August, showed rapid convective growth, and the damaging convective cell is quite apparent growing northward over northwestern Kansas at the end of the animation.

GOES-13 Visible imagery (0.63 µm) 1900 UTC 7 August - 0145 UTC 8 August [click to animate]

GOES-13 Visible imagery (0.63 µm) 1900 UTC 7 August – 0145 UTC 8 August [click to animate]

A slower animation of GOES-13 visible images from 0045-0130 UTC is shown below.

GOES-13 Visible imagery (0.63 µm) 0045 UTC 8 August - 0130 UTC 8 August [click to animate]

GOES-13 Visible imagery (0.63 µm) 0045 UTC 7 August – 0130 UTC 8 August [click to animate]

GOES-15 Visible imagery (0.63 µm) 1900 UTC 7 August - 0145 UTC 8 August [click to animate]

GOES-15 Visible imagery (0.63 µm) 1900 UTC 7 August – 0145 UTC 8 August [click to animate]

GOES-15 also viewed the rapid development of convection. The animation from 1900 UTC on 7 August 2015 through 0145 UTC on 8 August is shown above; the animation from 0000 UTC through 0145 UTC is shown below. Convective development over northwest Kansas was racing northward.

GOES-15 Visible imagery (0.62 µm) 1900 UTC 7 August - 0145 UTC 8 August [click to enlarge]

GOES-15 Visible imagery (0.62 µm) 0000 UTC 8 August – 0145 UTC 8 August [click to enlarge]

GOES-13 Infrared (10.7 µm) brightness temperatures confirmed the quick growth of the convection. The animation below showed strong cooling starting around 0115 UTC in extreme northwest Kansas. Coldest brightness temperatures at 0100 UTC (200.2 K or -73ºC) dropped to 196.2 K (-77ºC) at 0115 UTC, then to 194.0 K (-79ºC) at 0130 UTC, 192.8 (-80.4ºC) at 0145 and 192.2 K (about -81ºC!) at 0200 UTC. The rocking animation at bottom testifies to how quickly the developing convection was able to close the gap in convection through which the aircraft was attempting to fly.

GOES-13 Infrared imagery (10.7 µm) 0015 UTC 8 August - 0215 UTC 8 August [click to animate]

GOES-13 Infrared imagery (10.7 µm) 0015 UTC 8 August – 0215 UTC 8 August [click to animate]

Rocking animation of GOES-13 Infrared imagery (10.7 µm) 0015 UTC 8 August - 0215 UTC 8 August [click to enlarge]

Rocking animation of GOES-13 Infrared imagery (10.7 µm) 0015 UTC 8 August – 0215 UTC 8 August [click to enlarge]

The side-by-side comparisons shown below of GOES-15 (left) and GOES-13 (right) 10.7 µm Infrared and 0.63 µm Visible images also help to demonstrate the value of more frequent images for monitoring the rapid development of such features. GOES-15 was in Rapid Scan Operations (RSO) mode, providing up to 10 images every hour (at :00, :11, :15, :22, :30, :41, :45, :52, :55, and :57), while GOES-13 was in Routine Scan mode, providing up to 4 images every hour (at :00, :15, :30. and :45). Unfortunately, there were 30-minute gaps in both GOES-15 (between 0030 and 0100 UTC) and GOES-13 (between 0015 and 0045 UTC) during the time that the new line of thunderstorms began to rapidly build northward across far northwestern Kansas, between the 2 pre-existing areas of thunderstorm activity.

GOES-15 (left) and GOES-13 (right) 10.7 µm Infrared images [click to play animation]

GOES-15 (left) and GOES-13 (right) 10.7 µm Infrared images [click to play animation]

GOES-15 (left) and GOES-13 (right) 0.63 µm Visible images [click to play animation]

GOES-15 (left) and GOES-13 (right) 0.63 µm Visible images [click to play animation]

In addition to the animated GIFs, MP4 versions of the Infrared and Visible images are available here and here.

The flight positions of Delta 1889 are superimposed on a composite animation of GOES-13 Infrared (10.7 µm)and Goodland, Kansas radar reflectivity, below (courtesy of Rick Kohrs, SSEC).

Delta Flight 1889 position, GOES-13 Infrared images, and Goodland, Kansas radar reflectivity [click to play QuickTime movie]

Delta Flight 1889 position, GOES-13 Infrared images, and Goodland, Kansas radar reflectivity [click to play QuickTime movie]

Fires in Alaska, Canadian smoke over the Lower 48

June 29th, 2015
Suomi NPP VIIRS 3.74 µm infrared channel images, times as indicated (click to enlarge)

Suomi NPP VIIRS 3.74 µm infrared channel images, times as indicated (click to enlarge)

Suomi NPP 0.64 µm visible channel images, times as indicated (click to enlarge)

Suomi NPP 0.64 µm visible channel images, times as indicated (click to enlarge)

The 2015 Wildfire Season is off to a quick start in Alaska (continuing an observed trend). This map (from this site) shows more than 300 active fires over Alaska at 2000 UTC on 29 June 2015. This graph (from the Alaska Climate Info Facebook page) compares early burn acreage in 2015 to that in 2004 (the year with the most acreage burned — see this graph, courtesy of Uma Bhatt, University of Alaska-Fairbanks).

Soumi NPP VIIRS 3.74 µm infrared imagery from early morning on 29 June 2015 (top) shows numerous wildfire hot spots (dark black pixels) in the region surrounding the Yukon River (the middle portion of the imagery, south of Kotzebue Sound). VIIRS visible imagery from the same time, above, shows an extensive pall of smoke over much of central Alaska.

GOES-13 Visible (0.63 µm) imagery (click to play animation)

GOES-13 Visible (0.63 µm) imagery (click to play animation)

Meanwhile, thick smoke from fires burning over northern Canada (comparison of VIIRS visible and shortwave IR images from 28 June) was drifting southward over central portions of the Lower 48 states. The smoke plume on 28 June (above) was fairly narrow; however, a much broader and thicker plume was seen moving south on 29 June (GOES visible imagery below, then MODIS/VIIRS true-color RGB imagery as displayed using the SSEC RealEarth web map server). SSEC MODIS Today true-color imagery of this smoke plume is also available here. Pilot reports placed the lower and upper bounds of the thick smoke at 5000 and 17500 feet, with flight visibilities as low as 2 miles at 5000 feet. Some of the smoke subsided to the surface in southeastern South Dakota, restricting the surface visibility at Sioux Falls to 5 miles and raising the Air Quality Index there into the Unhealthy category. In fact, the smoke was so thick over far eastern South Dakota that it had the effect of reducing surface heating and slowing the rise of afternoon temperatures, such that convective temperatures were not being reached and probabilities of precipitation had to be scaled back:

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SIOUX FALLS SD
356 PM CDT MON JUN 29 2015

.SHORT TERM…(THIS EVENING THROUGH TUESDAY)
ISSUED AT 356 PM CDT MON JUN 29 2015

IN ADDITION…THICK PLUME OF SMOKE CONTINUES TO DRIFT SOUTHWARD IMPACTING NEARLY ALL OF THE FORECAST AREA…BUT MOST   NOTABLE ALONG AND EAST OF THE JAMES RIVER VALLEY. BECAUSE OF THIS…AFTERNOON TEMPERATURES ARE ABOUT 2 TO 4 DEGREES
COOLER THAN FORECAST AND WE ARE HAVING A HECK OF A TIME REACHING OUR CONVECTIVE TEMPERATURE. THEREFORE LOWERED THE LATE AFTERNOON AND EVENING POPS IN OUR EASTERN ZONES TO ONLY SLIGHT CHANCE POPS. BUT EVEN THOSE MAY BE TOO HIGH AND IF NOTHING DEVELOPS OVER THE NEXT COUPLE OF HOURS…THEY MAY NEED TO BE REMOVED ENTIRELY.

GOES-13 Visible (0.63 µm) imagery (click to play animation)

GOES-13 Visible (0.63 µm) imagery (click to play animation)

MODIS and VIIRS true-color imagery (click to enlarge)

MODIS and VIIRS true-color imagery (click to enlarge)

Daytime detection of smoke plumes is not difficult with visible (or true-color) imagery. At night, however, smoke detection is a challenge. The VIIRS Day/Night Band on Suomi NPP can detect smoke when Lunar Illumination is high (although detection is limited to one or sometimes two passes per night). Smoke is otherwise mostly transparent to infrared channels on the GOES Imager. Websites such as the NOAA/NESDIS IDEA and the GASP are helpful; however, the GASP product uses single-channel (visible) detection only.

Visible imagery from GOES-15, below, highlights the expansive region covered by smoke over northern Canada. Note that the smoke becomes less distinct with time as the sun rises higher in the sky, because forward scattering of visible light by smoke particles is more effective than backward scattering.

GOES-15 Visible (0.62 µm) imagery, times as indicated (click to animate)

GOES-15 Visible (0.62 µm) imagery, times as indicated (click to animate)

Singapore Airlines Flight SQ836: a loss of engine power due to “ice crystal icing”?

May 23rd, 2015
Singapore Airlines Flight SQ836 path, altitude, and airspeed (from flightradar24)

Singapore Airlines Flight SQ836 path, altitude, and airspeed (from flightradar24)

Singapore Airlines Flight SQ836 was en route to Shanghai from Singapore on 23 May 2015 when it lost power from both engines at an altitude of 39,000 feet over the South China Sea, not far south-southeast of Hong Kong (Aviation Herald). The aircraft lost about 13,000 feet in altitude (above) before the engines were successfully re-started. The violet portion of the flight path denotes the period when no ADS-B data were received, from 1246 to 1311 UTC.

Himawari-8 11.2 um IR channel images (click to play animation)

Himawari-8 11.2 um IR channel images (click to play animation)

Himawari-8 AHI 11.2 um IR channel images (above; click image to play animation; also available as an MP4 movie file) and 6.2 um water vapor channel images (below; click image to play animation; also available as an MP4 movie file) showed a broken line of vigorous deep convection to the north of where the engine power loss first occurred (approximately within the yellow circle; VHHH is the airport identifier for Hong Kong). On the IR imagery, the coldest cloud-top brightness temperatures were in the -80 to -90 C range (shades of violet), and anvil debris could be seen drifting south-southwestward.  This convective cloud debris may have contributed to a phenomenon known as ice crystal icing, which affected the engines of the aircraft.

Himawari-8 6.2 um water vapor channel images (click to play animation)

Himawari-8 6.2 um water vapor channel images (click to play animation)