Fatal wildfire in Valparaíso, Chile

April 13th, 2014
GOES-13 3.9 µm shortwave IR channel images

GOES-13 3.9 µm shortwave IR channel images

Strong winds helped a wildfire to spread very quickly through a portion of the city of Valparaíso, Chile — this fire forced large-scale evacuations, destroyed around 2000 homes, and was responsible for 12 fatalities. McIDAS images of 4-km resolution GOES-13 3.9 µm shortwave IR channel data (above) showed the fire “hot spot” (black to red color enhancement), which began late in the day on 12 April 2014, and burned through the night and into the day on 13 April. The hottest 3.9 µm IR brightness temperatures were 339.6 K (66.45º C) at 20:45 UTC and 340.8 K (67.65º C) at 23:45 UTC on 12 April.

Since the GOES-13 satellite only performs one full-disk scan (hence imaging the Southern Hemisphere) every 3 hours, the temporal behavior of this fire cannot be well ascertained. The ABI instrument on the future GOES-R satellite will perform a full-disk scan every 5 minutes.

Comparisons of 1-km resolution GOES-13 visible channel images and 4-km resolution GOES-13 3.9 µm shortwave IR images (below) showed that the narrow fire smoke plume spread rapidly to the northwest.

GOES-13 0.63 µm visible channel (left) and 3.9 µm shortwave channel images (right)

GOES-13 0.63 µm visible channel (left) and 3.9 µm shortwave channel images (right)

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Suomi NPP VIIRS 3.74 µm shortwave IR image

Suomi NPP VIIRS 3.74 µm shortwave IR image

A 375-meter resolution Suomi NPP VIIRS 3.74 µm (Band I4) shortwave IR image at 05:41 UTC (above) showed greater detail of the wildfire hot spot, which exhibited a maximum IR brightness temperature of 367.0 K (93.85º C). 367 K is actually the saturation temperature for the VIIRS Band I4 detectors, indicating that this was a very hot fire. Valparaiso is located about 112 km or 70 miles west-northwest of Santiago, Chile (station identifier SCEL).

By comparison, the 4-km resolution GOES-13 3.9 µm shortwave IR image close to that time (below) indicated that the maximum IR brightness temperature of the wildfire hot spot was only 316.5 K (43.35º C).

Suomi NPP VIIRS 3.74 µm shortwave IR channel image (left) and GOES-13 3.9 µm shortwave IR channel image (right)

Suomi NPP VIIRS 3.74 µm shortwave IR channel image (left) and GOES-13 3.9 µm shortwave IR channel image (right)

McIDAS-V images of VIIRS 3.9 µm (Band M15) shortwave IR and 0.7 µm Day/Night Band (DNB) data (below; courtesy of William Straka, CIMSS/SSEC) revealed that the large fire hot spot (yellow to red color enhancement on the shortwave IR image) was adjacent to and encroaching upon the bright night-time city lights of the Valparaiso area (as seen on the Day/Night Band image). In addition, ample illumination from a nearly-full Moon allowed the smoke plume to be seen on the DNB image, as it drifted northwestward over the adjacent waters of the Pacific Ocean.

Suomi NPP VIIRS 3.9 µm shortwave IR and 0.7 µm Day/Night Band images

Suomi NPP VIIRS 3.9 µm shortwave IR and 0.7 µm Day/Night Band images

Fires had been burning in parts of Chile since January 2014. Additional information on this Valparaíso fire can be found on the Wildfire Today site.

Fog and stratus along the California coast

March 14th, 2014

In their Area Forecast Discussion issued at 11:57 UTC or 4:57 AM local time on 14 March 2014, the NWS San Francisco/Monterey Bay Area forecast office mentioned the Suomi NPP VIIRS Day/Night Band imagery which showed the coverage of coastal fog in their area of responsibility:

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN FRANCISCO BAY AREA
457 AM PDT FRI MAR 14 2014

.DISCUSSION...AS OF 4:10 AM PDT FRIDAY...THE DRY TAIL END OF A
WEATHER SYSTEM MOVING IN TO THE PACIFIC NORTHWEST IS APPROACHING
OUR DISTRICT...AND RESULTING IN ENHANCEMENT OF THE MARINE LAYER
AND A RETURN OF THE MARINE STRATUS. LATEST GOES FOG PRODUCT
IMAGERY...AND IN RATHER SPECTACULAR DETAIL JUST REC`D SUOMI VIIRS
NIGHTTIME HIGH RES VISUAL IMAGE...SHOW COVERAGE ALONG MUCH OF THE
COAST FROM PT REYES SOUTH TO THE VICINITY OF THE MONTEREY
PENINSULA...AND A BROAD SWATH EXTENDING INLAND ACROSS SAN
FRANCISCO AND THROUGH THE GOLDEN GATE TO THE EAST BAY. LATEST
BODEGA BAY AND FT ORD PROFILER DATA INDICATE A MARINE LAYER DEPTH
OF ABOUT 1300 FT. SOME THIN HIGH CLOUDS ARE ALSO PASSING THROUGH ABOVE.

A comparison of AWIPS images of the Suomi NPP VIIRS 0.7 µm Day/Night Band (DNB) and the corresponding 11.45-3.74 µm IR brightness temperature difference (BTD) “fog/stratus product” (below) showed this band of fog and stratus at 09:39 UTC or 2:39 AM local time. With ample illumination by moonlight (the Moon was in the Waxing Gibbous phase, at 97% of full), the DNB image served as a “visible image at night” to help highlight the fog/stratus features along the coast. Farther inland over the eastern portion of the satellite scene, the bright signature of deep snow cover in the higher elevations of the Sierra Nevada was also very evident on the DNB image.

Suomi NPP VIIRS 0.7 µm Day/Night Band and IR BTD "Fog/stratus product" images

Suomi NPP VIIRS 0.7 µm Day/Night Band and IR BTD “Fog/stratus product” images

A sequence of three 1-km resolution IR BTD images (below) — Terra MODIS at 06:33 UTC, Suomi NPP VIIRS at 09:39 UTC, and Aqua MODIS at 10:44 UTC — offered detailed views of the inland progression of the fog/stratus features, especially in the San Francisco Bay area and also down the Salinas Valley. The appearance of degraded resolution of the features seen on the 10:44 UTC MODIS image is due to the so-called “bow-tie effect” near the edge of a MODIS scan swath — even with a bow-tie correction algorithm applied, the MODIS images tend to look less crisp and clear along the scan edges.

Terra MODIS, Suomi NPP VIIRS, and Aqua MODIS IR BTD "fog/stratus product" images

Terra MODIS, Suomi NPP VIIRS, and Aqua MODIS IR BTD “fog/stratus product” images

A GOES-R “Cloud Thickness – Highest Liquid Cloud Layer” product created using GOES-15 data (below; click image to play animation) showed the southward advancement of the band of fog/stratus during the overnight hours. The maximum thickness displayed was in excess of 1200 ft (lighter cyan color enhancement), which agreed well with the profiler depths mentioned in the NWS forecast discussion above.

GOES-15 Cloud Thickness product (click to play animation)

GOES-15 Cloud Thickness product (click to play animation)

Additional GOES-R products such as Marginal Visual Flight Rules (MVFR), Instrument Flight Rules (IFR), and Low Instrument Flight Rules (LIFR) Probability are shown below. These products help to better quantify the potential aviation impacts that features seen on the conventional BTD “fog/stratus product” might have.

GOES-15 MVFR Probability product (click to play animation)

GOES-15 MVFR Probability product (click to play animation)

GOES-15 IFR Probability product (click to play animation)

GOES-15 IFR Probability product (click to play animation)

GOES-15 LIFR Probability product (click to play animation)

GOES-15 LIFR Probability product (click to play animation)

For additional information on this event, see the GOES-R Fog Product Examples blog.

Eruption of the Kelut volcano in Java, Indonesia

February 13th, 2014
MTSAT-1R 10.8 µm IR channel images (click to play animation)

MTSAT-1R 10.8 µm IR channel images (click to play animation)

McIDAS-X images of MTSAT-1R 10.8 µm IR channel data (above; click image to play animation; also available as an MP4 animation) showed the rapid expansion of the volcanic umbrella cloud resulting from the eruption of Kelut (aka Kelud) on the Indonesian island of Java on 13 February 2014. The MTSAT-1R satellite was in rapid scan mode, providing images at 10-minute intervals (with some gaps). The initial signal of a volcanic cloud appeared as a small cluster of cold pixels on the 16:09 UTC (11:09 PM local time) IR image.

The dramatic signature of a distinct circular-shaped warm core (shades of red, around -60º C) surrounded by a ring of colder (shades of white, -75º to -80º C) cloud-top IR brightness temperatures possibly indicated that a portion of the cloud plume associated with the explosive eruption rose well into the lower stratosphere, and was therefore radiating at the warmer temperatures that existed far above the tropopause. The leading edge of the top of the cloud plume eventually exhibited IR brightness temperatures colder than -80º C (shades of violet) as it drifted toward the west-southwest, with a minimum of -84.5º C on the 19:29 UTC image. Along the upwind (eastern) portion of the volcanic cloud, a signature of “bow shock waves” was evident: an indication that the massive and dense volcanic cloud was acting as a barrier to the ambient easterly flow across the region. Volcanic lightning was also generated by the rising ash plume (see photos on the Wired Science “Eruptions” blog posts 1 and 2).

Suomi NPP VIIRS 11.45 µm IR channel and 0.7 µm Day/Night Band images

Suomi NPP VIIRS 11.45 µm IR channel and 0.7 µm Day/Night Band images

A more detailed view was provided by McIDAS-V images of Suomi NPP VIIRS 375-meter resolution 11.45 µm IR channel and 750-meter resolution 0.7 µm Day/Night Band data (above; images courtesy of William Straka, CIMSS). A ring of gravity waves could be seen around the periphery of the volcanic cloud shield; the coldest IR brightness temperature within the small cluster of “overshooting tops” was 175 K or -98º C (closer view). Since the Moon was in the Waxing Gibbous phase at 98% of full, it provided ample illumination for a “visible image at night” using the VIIRS Day/Night Band — note how the ash-laden volcanic cloud exhibited a darker gray appearance compared to the surrounding brighter white meteorological clouds.

Surabaya/Juanda rawinsonde data (12 UTC on 13 February)

Surabaya/Juanda rawinsonde data (12 UTC on 13 February)

A plot of the 13 February/12:00 UTC rawinsonde data from the nearby (map/IR image comparison) Surabaya/Juanda International Airport (above) showed that a very moist and marginally unstable (Lifted Index of only  -1.7) atmosphere existed over the region about 4 hours prior to the eruption — the tropopause was located at 105 millibars (mb), at an altitude of 16.29 km where the air temperature was -84.5º C. According to the volcanic ash advisory issued by the Darwin VAAC at 00:43 UTC on 14 February, the top of the volcanic ash extended to 55,000 feet or 16.76 km — somewhere between 100 mb and 87.1 mb on the Surabaya sounding. The warmest temperature recorded in the stratosphere by the sonde instrument was -71.3º C at 64.9 mb or 19.02 km.

A GOES-R Volcanic Ash Height product (VISITview lesson | PowerPoint) — derived using MTSAT-2 data — indicated that downwind portions of the ash cloud reached the 18-20 km ASL range (black color enhancement), with a maximum ash height value of 22 km (below; click image to play animation). CALIOP data from a CALIPSO overpass of the Kelut volcanic cloud just around 18:13 UTC on 13 February showed that the top of the volcanic cloud was generally at an altitude of 18-19 km, with some cloud/ash material reaching a maximum height of 26 km; taking that data source into consideration, a subsequent volcanic ash advisory issued by the Darwin VAAC at 17:09 UTC on 14 February revised the maximum ash height to 65,000 feet or 19.8 km.

MTSAT-2 Volcanic Ash Height product (click to play animation)

MTSAT-2 Volcanic Ash Height product (click to play animation)

With the arrival of early morning daylight, MTSAT-1R 0.68 µm visible channel images (below) showed the dense volcanic ash plume drifting west-southwestward; there was also a subtle signature of the “bow shock waves” seen along the eastern edge of the ash plume, similar to what was observed on the IR imagery.

MTSAT-1R 0.68 µm visible channel images

MTSAT-1R 0.68 µm visible channel images

Back to the topic of the 26 km height seen on the CALIPSO data: on the 10-minute interval MTSAT-1R 10.8 µm IR imagery, the warmest cloud-top IR brightness temperature within the “circular warm spot” of the volcanic cloud was -56ºC at 17:19 UTC. The 13 February/12 UTC Surabaya/Juanda rawinsonde only made it up to 64.9 mb or 19.02 km (where it was -71.3ºC) — however, the 14 February/00 UTC rawinsonde ascended all the way to 10 mb (below). So using this later sounding, the air temperature of -56ºC corresponded to an height somewhere between 24.9 mb (24.8 km) and 20 mb (26.2 km) — which roughly agrees with the 26 km height seen on the CALIOP data.

Surabaya/Juanda rawinsonde data (00 UTC on 14 February)

Surabaya/Juanda rawinsonde data (00 UTC on 14 February)

Additional satellite products showing details of the Kelut volcanic eruption can be found on Nicarnica Aviation blog posts (1 | 2).

 

Chaparrastique erupts in El Salvador

December 29th, 2013
GOES-13 0.63 µm visible imagery during Chaparrastique eruption (click to play animation)

GOES-13 0.63 µm visible imagery during Chaparrastique eruption (click to play animation)

The volcano Chapparastique in eastern El Salvador near the city of San Miguel experienced a brief eruption on Sunday the 29th of December (YouTube video). Half-hourly 0.63 µm visible channel imagery from GOES-13 or GOES-East (the most frequent imagery available at 13.5º N, the latitude of the volcano), above, plainly shows the appearance of the volcanic ash cloud between 16:15 and 16:45 UTC (media sources reported that the time of the eruption was 16:32 UTC). Most of the ash cloud then moved westward across the coast and over the adjacent waters of the Pacific Ocean, although parts of the ash cloud also moved eastward over Honduras. This is the first complete Chapparastique advisory from the VAAC in Washington DC on this eruption. The most recent volcanic ash advisories can be found here.

GOES-15 or GOES-West, positioned at 135º W, was also able to view the ash cloud, and that animation is below. El Salvador is near the eastern edge of the satellite view. Routine scanning that was taking place on Sunday 29 December only viewed El Salvador every three hours.

GOES-15 0.63 µm visible imagery during Chaparrastique eruption (click to play animation)

GOES-15 0.63 µm visible imagery during Chaparrastique eruption (click to play animation)

It happens occasionally that useful information about volcanic eruptions can be gleaned from extreme limb views from geostationary satellites (see here, for example, or this animation from this blog post). In the present case, the MTSAT-2 visible imagery, below, was a bit too far to the west to view the atmosphere over central America.

MTSAT-2 0.73 µm visible imagery during Chaparrastique eruption (click to play animation)

MTSAT-2 0.73 µm visible imagery during Chaparrastique eruption (click to play animation)

Meteosat-10 data possibly saw the eruption; however, the remapped imagery that is broadcast does not include pixels for which a latitude/longitude value can be computed, such as pixels that are at the extreme edge of the limb, in outer space. To ascertain the presence of a signal in the satellite data would require access to the raw data from the satellite, and that is not routinely available. Meteorsat-10 visible images surrounding the eruption time are shown below.

METEOSAT-10 0.6 µm visible imagery during Chaparrastique eruption (click to play animation)

METEOSAT-10 0.6 µm visible imagery during Chaparrastique eruption (click to play animation)

Note that when GOES-R ABI is broadcasting data, its limb edge will resemble the METEOSAT-10 data above rather than the more complete MTSAT-2 data. Level 0 data from ABI includes space looks at the limb; that level 0 data will be calibrated, navigated and remapped and distributed as level 1 GOES-R series ReBroadcast (GRB) data that will not include points at the limb that are un-navigable (but that nevertheless can include interesting data).

As part of CIMSS/ASPB participation in GOES-R Proving Ground activities, various volcanic ash detection and analysis products have been developed. Below is an animation of GOES-13 multi-spectral false-color Red/Green/Blue (RGB) images that also show the dispersion of the volcanic ash cloud.

GOES-13 multi-spectral RGB images (click to play animation)

GOES-13 multi-spectral RGB images (click to play animation)

Examples of some of the quantitative volcanic ash products are shown below, using MODIS data from an overpass of the Aqua satellite at 18:50 UTC. The maximum ash height appeared to be around 10 km along the eastern end of the cloud; the maximum ash loading approached 6 g/m2 on the western edge of the plume; the maximum ash particle effective radius was in the 14-16 µm range along the edges of the cloud.

Aqua MODIS Ash/Dust Cloud Height product

Aqua MODIS Ash/Dust Cloud Height product

Aqua MODIS Ash/Dust Loading product

Aqua MODIS Ash/Dust Loading product

Aqua MODIS Dust/Ash Particle Effective Radius product

Aqua MODIS Dust/Ash Particle Effective Radius product