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)

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GOES-13 0.63 µm visible channel images

McIDAS images of GOES-13 0.63 µm visible channel data (above) revealed a hazy plume moving southward along the Pacific Northwest coast of the US late in the day on 18 May 2011. The airborne smoke showed up very well due to the favorable “forward scattering angle” during the later hours of the early evening, as viewed from the GOES-13 (GOES East) satellite located at 75º West longitude.

It is very likely that this hazy plume was due to long range transport of smoke from recent fire activity in northern Alberta, Canada — large smoke plumes were seen over that region on GOES-11 and GOES-13 visible channel images as early as 15 May. NOAA ARL HYSPLIT model backward trajectories initialized at altitudes of 6 km, 7 km, and 8km (below) did indeed indicate transport from the region of the fires. Lidar data from the University of British Columbia showed that the portion of the aerosol layer over Vancouver was located at altitudes of 7-8 km.

NOAA ARL HYSPLIT model backward trajectories

AWIPS images of GOES-11 6.7 µm “water vapor channel” imagery with overlays of MADIS hourly atmospheric motion vectors or “satellite winds” (below) showed that there was a cyclonic circulation aloft around a small vortex located over British Columbia, Canada.

GOES-11 water vapor images + MADIS hourly atmospheric motion vectors

On the following morning of 19 May, a favorable forward scattering angle early in the day allowed the long smoke plume to be seen on AWIPS images of GOES-11 0.65 µm visible channel data (below; click image to play animation) — the leading edge of the smoke plume appeared to have reached southern California by that time. The AWIPS images are a composite of GOES-11 (GOES-West) and GOES-13 (GOES-East) visible channel data; the vertical “seam” between the 2 satellite sources should be fairly easy to see.

AWIPS GOES-11 / GOES-13 visible image composite (click image to play animation)

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MODIS 0.65 µm visible channel image + MODIS 2.1 µm near-IR "snow/ice channel" image

AWIPS images of MODIS 0.65 µm visible channel data and MODIS 2.1 µm near-IR “snow/ice channel” data (above) demonstrated the utility of the snow/ice channel imagery for highlighting the areal extent of flooding along parts of the lower Mississippi River on 17 May 2011. Water is a strong absorber at the 2.1 µm wavelength, so it appears very dark on the MODIS snow/ice channel image.

CIMSS participation in GOES-R Proving Ground activities includes making MODIS imagery available for National Weather Service forecasters to add to their AWIPS workstations. The VISIT training lesson “MODIS Products in AWIPS” is also available to help users understand the products and their applications to weather analysis and forecasting.

A closer view using 250-meter resolution MODIS true color (using channels 1/4/3) and false color (using channels 7/2/1) MODIS Red/Green/Blue (RGB) images from the SSEC MODIS Today site (below) revealed the darker brown “muddy” appearance of much of the flooded areas adjacent to the Mississippi River, due to high sediment loading of the water. Water exhibited a very dark blue appearance on the MODIS false color image.

250-m resolution MODIS true color and false color Red/Green/Blue (RGB) images

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GOES-13 0.63 µm visible channel images (click image to play animation)

AWIPS images of GOES-13 0.63 µm visible channel data (above; click image to play animation) showed that 17 May 2011 was a generally cloud-free day over the state of Wisconsin.

However, the GOES-13 6.5 µm “water vapor channel” images (below; click image to play animation) displayed a series of well-defined “dry cyclonic swirls” aloft that were propagating southwestward. Due to the dry air associated with these features, the weighting function of the GOES-13 imager water vapor channel was shifted downward, sampling a layer that peaked near 500 hPa. GOES imager and sounder weighting functions for a particular rawinsonde location are available here.

GOES-13 6.5 µm water vapor channel images (click image to play animation)

A comparison of the 1-km resolution MODIS 6.7 µm water vapor image with the corresponding 4-km resolution GOES-13 6.5 µm water vapor image (below) demonstrated the advantage of improved spatial resolution for displaying the edges and gradients associated with such features. The effect of parallax (due to the large viewing angle of the geostationary satellite positioned at the Equator) acted to shift the location of the GOES-13 features slightly to the northwest compared to the image from the polar-orbiting satellite that carries the MODIS instrument.

MODIS 6.7 µm water vapor image + GOES-13 6.5 µm water vapor image

Hourly images of the GOES-13 sounder Total Column Ozone product (below; click image to play animation) revealed that ozone levels were quite high (over 400 Dobson Units, darker red color enhancement) within the large “dry swirl” feature that was moving over Wisconsin — this suggests that the dry vortex features seen on the water vapor imagery were actually stratospheric intrusion vortices (since high ozone is a characteristic of stratospheric air).

GOES-13 sounder Total Column Ozone product (click image to play animation)

The Advanced Baseline Imager (ABI) instrument on the future GOES-R satellite will have an ozone channel, which will allow for this type of total column ozone product to be generated at higher spatial and temporal resolution that the current GOES Sounder instrument can provide.

A northwest-to-southeast oriented vertical cross section using RUC13 model fields (below) illustrated how low the tropopause (taken to be the height of the “PV1.5” Potential Vorticity surface) had descended within the PV anomaly associated with the stratospheric intrusion vortex over Wisconsin at 16:00 UTC.

RUC-13 model northwest-to-southeast oriented vertical cross section

As is sometimes the case with these features, there were a few pilot reports of light to moderate turbulence around the periphery of the well-defined stratospheric intrusion vortex as it moved across the region (below; click image to play animation).

GOES-13 6.5 µm water vapor images + pilot reports of turbulence (click image to play animation)

CIMSS participation in GOES-R Proving Ground activities includes making products such as the GOES Sounder Total Column Ozone and MODIS imagery available for National Weather Service forecasters to add to their AWIPS workstations. The VISIT training lessons “Water Vapor Imagery and Potential Vorticity Analysis” and “MODIS Products in AWIPS” are available to help users understand the products and their applications to weather analysis and forecasting.

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