Eruption of the Wolf Volcano in the Galapagos Islands

May 25th, 2015

GOES-13 0.63 µm visible channel (left) and 3.9 µm shortwave IR channel (right) images [click to play animation]

GOES-13 0.63 µm visible channel (left) and 3.9 µm shortwave IR channel (right) images [click to play animation]

After nearly 33 years of inactivity, a comparison of GOES-13 0.63 µm visible channel and 3.9 µm shortwave IR channel images (above; click to play animation; also available as an MP4 movie file) showed that the Wolf Volcano in the Galapagos Islands began to erupt sometime between 0645 and 0715 UTC on 25 May 2015. A large thermal anomaly or “hot spot” (red-enhanced pixels) was quite apparent, along with what appeared to be a brief post-eruption “shock wave” (warmer, darker gray enhancement) propagating radially outward from the eruption site on the 0715 and 0745 UTC shortwave IR images. Two plumes of volcanic cloud could be seen: a small one at a lower altitude propagating northeastward, and a second larger plume at a higher altitude moving south-southwestward.

With the arrival of daylight at 1215 UTC, a portion of the volcanic cloud could be seen at times (although identification was difficult with widespread meteorological clouds present in the area).

An Aqua MODIS false-color Red/Gren/Blue (RGB) image at 0800 UTC (below; courtesy of Michael Pavolonis, NOAA/NESDIS/CIMSS) displayed a signal of SO2 (green enhancement) along the edges of the larger volcanic cloud as it was moving southward.

Aqua MODIS false-color RGB image

Aqua MODIS false-color RGB image

GOES-13 10.7 µm IR channel images (below; click to play animation; also available as an MP4 movie file) indicated that the coldest cloud-top IR brightness temperature of -65º C appeared at 1015 UTC with the larger plume moving south-southwestward.

GOES-13 10.7 µm IR channel images [click to play animation]

GOES-13 10.7 µm IR channel images [click to play animation]

According to the nearby San Cristobal rawinsonde report at 12 UTC, the altitude of the -65º C temperature was around 14 km, at the 157 hPa pressure level. The tropopause for this sounding was coded to be at 16.1 km or 109.0 hPa, where the air temperature was -80.7º C.

San Cristobal, Galapagos Islands rawinsonde data profile

San Cristobal, Galapagos Islands rawinsonde data profile

The latest advisories issued by the Washington Volcanic Ash Advisory Center can be found here.

Severe thunderstorm over West Texas, as viewed from 3 GOES satellites

May 19th, 2015

GOES-15 (left), GOES-14 (center), and GOES-13 (right) 0.62 µm visible channel images [click to play animation]

GOES-15 (left), GOES-14 (center), and GOES-13 (right) 0.62 µm visible channel images [click to play animation]

Thunderstorms began to develop across West Texas during the afternoon hours on 19 May 2015, along and ahead of an eastward-moving dryline. One of the storms went on to produce a few brief tornadoes, and hail as large as 3.0 inches in diameter (SPC storm reports). Different views of this storm were provided by GOES-15 (GOES-West), GOES-14 (in SRSO-R mode), and GOES-13 (GOES-East) 0.62 µm visible channel images (above; click image to play 190 MB animated GIF; also available as an MP4 movie file, or on YouTube). This comparison highlights the advantages of 1-minute interval Super Rapid Scan images (which will be available from GOES-R) compared to the standard 15-minute interval Routine Scan images provided by the current generation of GOES.

One interesting feature seen on the visible channel images above was the apparent merger of the large dominant dryline storm and a smaller northward-moving storm that had formed in Mexico (radar animation). In GOES-13 10.7 µm IR imagery with an overlay of SPC storm reports (below; click image to play animation), one report of 2.0-inch diameter hail was seen around or shortly after the time of the storm merger.

GOES-13 10.7 µm IR channel images (click to play animation)

GOES-13 10.7 µm IR channel images (click to play animation)

With higher spatial resolution IR imagery from MODIS (1-km), VIIRS (375-meter), and AVHRR (1-km), much colder cloud-top IR brightness temperatures were seen (below) compared to the corresponding 4-km resolution GOES IR imagery at those times — especially during the early formative stages of the thunderstorms captured with MODIS and VIIRS. The coldest cloud-top IR brightness temperature on the 2128 UTC AVHHRR image was -80º C, compared to -67º C on the 2130 UTC GOES image.

Terra and Aqua MODIS 11.0 µm, Suomi NPP VIIRS 11.45 µm, and POES AVHRR 12.0 µm IR channel images

Terra and Aqua MODIS 11.0 µm, Suomi NPP VIIRS 11.45 µm, and POES AVHRR 12.0 µm IR channel images

A more detailed discussion of this event can be found on the RAMMB GOES-R Proving Ground Blog.

A mid-tropospheric atmospheric bore viewed by GOES-15, GOES-14, and GOES-13

May 16th, 2015

GOES-15 (left), GOES-14 (center), and GOES-13 (right) 6.5 µm water vapor channel images [click to play animation]

GOES-15 (left), GOES-14 (center), and GOES-13 (right) 6.5 µm water vapor channel images [click to play animation]

An elongated north-to-south oriented atmospheric bore was observed on GOES-15 (GOES-West), GOES-14, and GOES-13 (GOES-East) 6.5 µm water vapor channel images (above; click to play animation; also available as an MP4 movie file) on the morning of 16 May 2015. This bore feature was located in the area where strong westerly to southwesterly mid-tropospheric winds were impinging upon a consolidating dryline — this dryline later moved eastward and acted as the focus for severe thunderstorms across Texas (SPC storm reports). GOES-14 had been activated to perform Super Rapid Scan Operations for GOES-R (SRSOR) duties beginning on 18 May.

Note that there were no parallel cloud rolls present on the corresponding GOES-15/14/13 0.63 µm visible channel imagery (below) — so this gravity wave bore feature was forming in clear air.

GOES-15 (left), GOES-14 (center), and GOES-13 (right) 0.63 µm visible and 6.5 µm water vapor channel images

GOES-15 (left), GOES-14 (center), and GOES-13 (right) 0.63 µm visible and 6.5 µm water vapor channel images

A comparison of 12 UTC El Paso, Texas (yellow) and Midland, Texas (cyan) rawinsonde data (below) showed the differences in vertical moisture profile to the west and to the east of the bore feature — especially in the 500-600 hPa layer, where a good deal of the signal contributing to the overall water vapor brightness temperature was originating from.

El Paso and Midland, Texas rawinsonde data profiles

El Paso and Midland, Texas rawinsonde data profiles

Atmospheric Bore between the Grand Banks and New England

May 8th, 2015
GOES-13 0.63 µm Visible images (click to play animation)

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

Atmospheric Bores form in stable air and create horizontal cloud bands that propagate perpendicular to the along-band direction. The feature seen above in GOES-13 visible imagery formed in stable air south of a High Pressure system that pushed a backdoor cold front into New England (surface analyses). The southern edge of this bore was likely eroding as it became influenced by warmer less-stable air over with the Gulf Stream — the warm waters of the Gulf Stream were apparent in the toggle, below, of POES AVHRR 0.86 µm visible and 12.0 µm infrared imagery at 1055 UTC. The bore was apparently moving over the top of a shallow layer of sea fog that had formed in the colder waters north of the Gulf Stream.

POES AVHRR 0.86 µm Visible image and 12.0 µm Infrared image at 1055 UTC on 8 May 2015 (click to enlarge)

POES AVHRR 0.86 µm Visible image and 12.0 µm Infrared image at 1055 UTC on 8 May 2015 (click to enlarge)

Suomi NPP overflew the area at ~1800 UTC, affording a very high resolution view of the bore structures with the VIIRS 0.65 µm visible channel, below.

SNPP_DNB_1807UTC_08May2015

Suomi NPP VIIRS Visible (0.65 µm) imagery, 1807 UTC on 8 May 2015 (Click to enlarge)

The daytime propagation of the bore feature could also be followed on POES AVHRR 0.86 µm visible channel images, shown below.

POES AVHRR 0.86 µm visible images (click to enlarge)

POES AVHRR 0.86 µm visible images (click to enlarge)