GOES-13 0.63 µm visible and 3.9 µm shortwave IR images (click image to play animation)

A few large wildfires flared up during the afternoon hours on 20 May 2012 across parts of far eastern Ontario and far western Quebec. In a comparison of GOES-13 0.63 µm visible channel and 3.9 µm shortwave IR channel images (above; click image to play animation; also available as a QuickTime movie), large smoke plumes could be seen emanating from the larger fires, as the fire “hot spots” (black pixels on the shortwave IR imagery) grew in size. The GOES-13 satellite had been placed into Rapid Scan Operations (RSO) mode, providing images as frequently as every 5-10 minutes (compared to the routine operational 15-minute image interval).

View only this post Read Less

AVHRR 10.8 µm, MODIS 11.0 µm, and VIIRS 11.45 µm IR images

The 2012 Atlantic Basin tropical cyclone season began with the formation of Tropical Storm Alberto off the coast of South Carolina on 19 May 2012. A sequence of AWIPS images of 1-km resolution POES AVHRR 10.8 µm, Terra/Aqua MODIS 11.0 µm, and Suomi NPP VIIRS 11.45 µm IR images (above) showed the growth of deep convecion associated with Alberto as the system moved southwestward — cloud top IR brightness temperatures were as cold as -72º C on the MODIS image at 16:03 UTC.

A comparison of the 18:27 UTC 1-km resolution Suomi NPP VIIRS 11.45 µm IR image with the 18:15 UTC 4-km resolution GOES-13 10.7 µm IR image (below) demonstrated the improvement in cloud top feature identification with higher spatial resolution, as well as showed the effect of parallax due to the large satellite viewing angle from GOES-13.

GOES-13 10.7 µm IR + Suomi NPP VIIRS 11.45 µm IR image

An animation of GOES-13 0.63 µm visible channel images from the CIMSS Tropical Cyclones site (below) showed the development of a more organized cloud structure during the day. In addition, a 21 UTC ship report near the center of Alberto noted wind gusts to 65 knots, which promted NHC to issue an update to note an increase in intensity.

GOES-13 0.63 µm visible channel images + Ship reports

An AWIPS night-time image of the Suomi NPP VIIRS 0.7 µm “Day/Night Band” (below) revealed some of the cloud structure associated with Tropical Storm Alberto at 06:45 UTC (2:45 am local time). Given that there was a “New Moon” phase at this time, not a great deal of reflected light was avaiable to allow the Day/Night Band imagery to show more cloud detail.

Lights from cities and towns across the far southeastern US could also be seen in the Day/Night Band image (although some of the urban area light signatures were attenuated somewhat by overhead cloud cover).

Suomi NPP VIIRS 0.7 µm Day/Night Band image

View only this post Read Less

GOES-15 0.63 µm visible channel images (click image to play animation)

The GOES-15 satellite was placed into Super Rapid Scan Operations (SRSO) mode on 17 May 2012, in support of the Deep Convective Clouds and Chemistry (DC3) field experiment. SRSO provides bursts of imagery at 1-minute intervals (compared to the standard operational 15-minute interval). McIDAS images of 1-km resolution GOES-15 0.63 µm visible channel data (above; click image to play animation) showed the development of widespread deep convection over Colorado and the adjacent states during the afternoon hours.

The cloud motions revealed the presence of a strong cyclonic circulation aloft over the region, which was verified by satellite-derived atmospheric motion vectors and NAM model 500 hPa heights plotted on an AWIPS image of MODIS 6.7 µm water vapor channel data at 19:35 UTC (below).

MODIS 6.7 µm water vapor image + Satellite atmospheric motion vectors + NAM 500 hPa height

AWIPS images of 1-km resolution Suomi NPP VIIRS 11.45 µm, POES AVHRR 12.0 µm, and MODIS 11.0 µm IR channel data at 19:04, 19:14, and 19:35 UTC (below) revealed that cloud top IR brightness temperatures were as cold as -60 to -62 C (darker red color enhancement) with many of the stronger areas of convection.

VIIRS 11.45 µm, AVHRR 12.0 µm, and MODIS 11.0 µm IR channel images

View only this post Read Less

GOES-15 (left) and GOES-13 (right) 0.63 µm visible channel images (click image to play animation)

McIDAS images of GOES-15 (GOES-West) and GOES-13 (GOES-East) 0.63 µm visible channel data (above; click image to play animation) revealed the large smoke plume associated with the “Sunflower Fire” that was burning near Payson, Arizona on 15 May 2012. Note toward the end of the animation the appearance of pyrocumulous clouds with overshooting tops over the fire source region. Due to the different satellite viewing angles, the overshooting tops were brightly illuminated on the GOES-15 images, while casting a distinct shadow onto the top of the cloud/smoke plume on the GOES-13 images. Photos of the Sunflower fire from the ground can be seen on the Weather Underground site. Other fires were also burning at that time in Arizona, including the “Gladiator Fire“  located to the northwest of the Sunflower fire.

The GOES-13 satellite was placed into Rapid Scan Operations (RSO) mode later in the day, providing images as frequently as every 5-10 minutes (compared to the routine 15-minute image interval with GOES-15).

View only this post Read Less