Smoke and View Angle

May 23rd, 2012 |
GOES-13 0.63 µm Visible imagery

GOES-13 0.63 µm Visible imagery

GOES-East imagery of a fire that has been burning over western New Mexico for the past week shows a plume of smoke extending eastward from the fire, and spreading out over southeast New Mexico and parts of Texas and Mexico. It is difficult indeed to find the edges of the plume with the image.

GOES-15 0.62 µm Visible imagery

GOES-15 0.62 µm Visible imagery

Contrast that to the GOES-West image above, from the same time. The two images underscore the difference that view angle makes in viewing smoke from a fire: smoke is far more visible with a low sun angle.

View-angle differences for fire detection are less important. In this case, both the GOES-East and GOES-West similarly charaterize the fire temperature.

Suomi NPP 3.74 µm shortwave IR image + 0.7 µm Day/Night Band image

Suomi NPP 3.74 µm shortwave IR image + 0.7 µm Day/Night Band image

During the previous night-time hours before sunrise (at 09:09 UTC, or 3:09 am local time), an overpass of the Suomi NPP satellite offered a nice comparison between  a 1-km resolution VIIRS 3.74 µm shortwave IR image and the corresponding 1-km resolution VIIRS 0.7 µm “Day/Night Band” image of the Baldy Fire in far western New Mexico (above). On the shortwave IR image, a large cluster of hot pixels (red to yellow to black colors) indicated where the most active fires were burning; on the Day/Night Band image,  the widespread flames of the fire complex showed up as a large and very bright feature. As an aside, it is interesting to note that the dimly-illuminated path of Interstate 10 (I-10) also shows up on the Day/Night Band image.

Animations of GOES-West visible imagery from May 22nd and from May 23rd illustrate the pulsing nature of the fire. Distinct intensification as measured by the amount of emitted smoke is obvious after 2200 UTC on 22 May, and also after 1800 UTC on 23 May. Late afternoon dewpoint depressions at or above 70 degrees Fahrenheit are testament to the extreme fire danger in western New Mexico.

Large upper-level low approaches Hawaii

May 22nd, 2012 |
GOES-15 6.5 µm water vapor images + Water vapor winds (click image to play animation)

GOES-15 6.5 µm water vapor images + Water vapor winds (click image to play animation)

McIDAS images of GOES-15 6.5 µm water vapor channel data with overlays of hourly water vapor atmospheric motion vectors (above; click image to play animation) revealed the large cyclonic circulation of an upper-level low that was moving westward toward the Hawaiian Islands on 21 May – 22 May 2012. The warm water vapor brightness temperatures (yellow color enhancement) exhibited within the core of the low indicated that the air in the middle to upper troposphere was rather dry.

AWIPS images of the MIMIC Total Precipitable Water product (below; click image to play animation) showed that the upper-level low was not effectively tapping into the band of high moisture along the Inter-Tropical Convergence Zone (ITCZ). Since there was no surface feature associated with this upper-level low, the only significant impacts to Hawaii were strong winds at the higher elevations — a wind advisory was issued for the summits above 6000-8000 feet.

MIMIC Total Precipitable Water product (click image to play animation)

MIMIC Total Precipitable Water product (click image to play animation)

Annular Eclipse Shadow

May 21st, 2012 |
MTSAT 0.73 µm visible channel images (click image to play animation)

MTSAT 0.73 µm visible channel images (click image to play animation)

An annular eclipse of the sun took place on May 21, 2012, and its shadow was visible from satellite imagery (A previous example from this blog is here). The loop above shows MTSAT imagery; the shadow of the eclipse emerges shortly after sunrise and tracks northeastward into the Pacific Ocean. The loop below shows GOES-West imagery, tracking the shadow from the north Pacific Ocean to the coast of North America around sunset.

GOES-15 0.62 µm visible channel images (click image to play animation)

GOES-15 0.62 µm visible channel images (click image to play animation)

A portion of the eclipse shadow could also be seen on an AWIPS image of POES AVHRR 0.86 µm visible channel data (below), extending from the far northern Pacific Ocean across the Aleutian Islands and into the southern Bering Sea.

POES AVHRR 0.86 µm visible channel image

POES AVHRR 0.86 µm visible channel image

Wildfires in Ontario and Quebec, Canada

May 20th, 2012 |
GOES-13 0.63 µm visible and 3.9 µm shortwave IR images (click image to play animation)

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).