Chemical plant fire in Texas

March 18th, 2019 |

GOES-16 Shortwave Infrared (3.9 µm) images [click to play animation | MP4]

GOES-16 Shortwave Infrared (3.9 µm) images [click to play animation | MP4]

GOES-16 (GOES-East) Shortwave Infrared (3.9 µm) images (above) revealed the thermal anomaly or “hot spot” of a fire burning at the Intercontinental Terminals Company petrochemical plant in Deer Park, Texas on 18 March 2019. Although the thermal signature was often partially masked by the passage of high clouds overhead, it was still evident for much of the time period (0202-1457 UTC, or 9:02pm-9:57am CDT). The fire started around 1530 UTC (10:30am CDT) on 17 March.

Comparisons of 2-km resolution (at satellite subpoint) GOES-16 Shortwave Infrared and 375-meter resolution VIIRS Shortwave Infrared (3.74 µm) imagery from Suomi NPP (at 0741 UTC) and NOAA-20 (at 0835 UTC) are shown below. The thermal signature is better defined and more accurately located using the higher-resolution VIIRS imagery.

Shortwave Infrared images from Suomi NPP VIIRS (3.74 µm) and GOES-16 (3.9 µm) at 0741 UTC [click to enlarge]

Shortwave Infrared images from Suomi NPP VIIRS (3.74 µm) and GOES-16 (3.9 µm) at 0741 UTC [click to enlarge]

Shortwave Infrared images from NOAA-20 VIIRS (3.74 µm) and GOES-16 (3.9 µm) at 0835 UTC [click to enlarge]

Shortwave Infrared images from NOAA-20 VIIRS (3.74 µm) and GOES-16 (3.9 µm) at 0835 UTC [click to enlarge]

A comparison of 1-km resolution NOAA-19 AVHRR and 2-km resolution GOES-16 Shortwave Infrared images at 1132 UTC is shown below. This happened to be at a time when the GOES-16 thermal signature was being masked by high clouds overhead. The fire was located northeast of the Houston Hobby (station identifier KHOU) and Ellington (station identifier KEFD) airports.

Shortwave Infrared images from NOAA-19 (3.7 µm) and GOES-16 (3.9 µm) at 1132 UTC [click to enlarge]

Shortwave Infrared images from NOAA-19 (3.7 µm) and GOES-16 (3.9 µm) at 1132 UTC [click to enlarge]

In a sequence of GOES-16 “Red” Visible (0.64 µm), Near-Infrared “Vegetation” (0.86 µm) and Near-Infrared “Snow/Ice” (1.61 µm) images (below), the dark-colored smoke plume was most obvious in the Near-Infrared imagery — this is due to the fact that vegetation is more reflective at those wavelengths, helping to enhance the smoke/surface contrast. The smoke had drifted as far westward as Austin and Kerrville, a distance of over 100 miles.

GOES-16 "Red" Visible (0.64 µm), Near-Infrared "Vegetation" (0.86 µm) and Near-Infrared "Snow/Ice" (1.61 µm) images [click to play animation | MP4]

GOES-16 “Red” Visible (0.64 µm), Near-Infrared “Vegetation” (0.86 µm) and Near-Infrared “Snow/Ice” (1.61 µm) images [click to play animation | MP4]

Lake effect snow in Nevada

February 21st, 2019 |


GOES-17

GOES-17 “Clean” Infrared Window (10.3 µm) images [click to play animation | MP4]

GOES-17 (GOES-West) “Clean” Infrared Window (10.3 µm) images (above) showed an unusual lake effect snow feature downwind of Pyramid Lake in northwestern Nevada on 21 February 2019 — the surface visibility dropped to 0.5 mile with moderate snow as ihe lake effect cloud moved over Reno-Tahoe International Airport around 16 UTC. Prior to that, the lake effect snow also affected portions of Interstate 80 in the Patrick area.

A morning overpass of the NOAA-19 satellite provided a 1-km resolution Infrared Window (10.8 µm) image of the lake effect cloud at 1254 UTC (below). The coldest cloud-top infrared brightness temperature on that image was -46ºC.

NOAA-19 AVHRR Infrared Window (10.8 µm) image at 1254 UTC [click to enlarge]

NOAA-19 AVHRR Infrared Window (10.8 µm) image at 1254 UTC [click to enlarge]

GOES-17 cloud-top infrared brightness temperatures associated with this feature were as cold as -47ºC just after 15 UTC, which were very close to the tropopause temperature of -47.9ºC on 12 UTC rawinsonde data from Reno (below).

Plot of 12 UTC rawinsonde data from Reno, Nevada [click to enlarge]

Plot of 12 UTC rawinsonde data from Reno, Nevada [click to enlarge]

Although clouds often prevented a good view of Lake Pyramid, Terra MODIS Sea Surface Temperature values of 42º and 43ºF were sampled on 11 and 16 February (below). With a northerly flow of air having temperatures around 20ºF across such warm water, significant boundary layer instability was generated to aid the growth of the lake effect cloud feature.

Terra MODIS Sea Surface Temperature product on 11 and 16 February [click to enlarge]

Terra MODIS Sea Surface Temperature product on 11 and 16 February [click to enlarge]

Although the view angle from GOES-16 (GOES-East) was rather large, a Land Surface Temperature pixel mapped to the northern portion of the lake had a value of 39.3ºF at 1701 UTC (below).

GOES-16 Land Surface Temperature product at 1701 UTC [click to enlarge]

GOES-16 Land Surface Temperature product at 1701 UTC [click to enlarge]

Rope cloud in the East Pacific Ocean

January 16th, 2019 |
GOES-17

GOES-17 “Red” Visible (0.64 µm) image, with an overlay of the 12 UTC surface analysis [click to enlarge]

* GOES-17 images shown here are preliminary and non-operational *

An 1802 UTC GOES-17 “Red” Visible (0.64 µm) image with an overlay of the 12 UTC surface analysis (above) revealed a well-defined rope cloud which stretched for nearly 1000 miles, marking the cold front position at the time of the image. Rope clouds can therefore be used to diagnose the exact location of the leading edge of a cold frontal boundary between times when surface analyses are available. In this case, the cold front was associated with a Hurricane Force low over the East Pacific Ocean on 16 January 2019 (surface analyses).

GOES-17 "Red" Visible (0.64 µm) images [click to play animation]

GOES-17 “Red” Visible (0.64 µm) images [click to play animation]

An animation of GOES-17 Visible images is shown above, with a zoomed-in version closer to the rope cloud displayed below.

GOES-17 "Red" Visible (0.64 µm) images [click to play animation]

GOES-17 “Red” Visible (0.64 µm) images [click to play animation]

An even closer look (below) showed that the rope cloud was only about 2-3 miles wide.

GOES-17 "Red" Visible (0.64 µm) images [click to enlarge]

GOES-17 “Red” Visible (0.64 µm) images [click to enlarge]

When the 18 UTC surface analysis later became available, a close-up comparison with the 1802 UTC GOES-17 Visible image (below) indicated that the northern portion of the cold front (as indicated by the rope cloud) was slightly ahead of — and the southern portion slightly behind — the smoothed cold frontal position of the surface analysis product.

1802 UTC GOES-17 "Red" Visible (0.64 µm) image, with an overlay of the 18 UTC surface analysis [click to enlarge]

1802 UTC GOES-17 “Red” Visible (0.64 µm) image, with an overlay of the 18 UTC surface analysis [click to enlarge]

NOAA-15 AVHRR Visible (0.63 µm) and Infrared Window (10.8 µm) images at 1617 UTC [click to enlarge]

NOAA-15 AVHRR Visible (0.63 µm) and Infrared Window (10.8 µm) images at 1617 UTC [click to enlarge]

1-km resolution AVHRR Visible (0.63 µm) and Infrared Window (10.8 µm) images of the rope cloud were captured by NOAA-15 at 1617 UTC (above) and by NOAA-18 at 1710 UTC (below). Along the northeastern portion of the rope cloud, there were a few convective clouds which exhibited cloud-top infrared brightness temperatures as cold as -55 to -60ºC (darker shades of red) and were tall enough to be casting shadows due to the low morning sun angle.

NOAA-18 AVHRR Visible (0.63 µm) and Infrared Window (10.8 µm) images [click to enlarge]

NOAA-18 AVHRR Visible (0.63 µm) and Infrared Window (10.8 µm) images at 1710 UTC [click to enlarge]


===== 17 January Update =====

GOES-17 True Color RGB images [click to play animation | MP4]

GOES-17 True Color RGB images [click to play animation | MP4]

On the following day, another rope cloud (one that was more fractured) was seen moving across Hawai’i as a cold front passed the island of Kaua’i — the southeastward progression of the rope cloud was evident on GOES-17 True Color Red-Green-Blue (RGB) images (above)  from the UW AOS site.

Surface observations plotted on GOES-17 Visible images (below) showed the wind shift from southwest to north as the cold front moved through Lihue on Kauwa’i around 00 UTC.

GOES-17

GOES-17 “Red” Visible (0.64 µm) images, with plots of surface reports [click to play animation | MP4]

===== 18 January Update =====

Suomi NPP VIIRS Day/Night Band (0.7 µm) image, with and without buoy observations [click to enlarge]

Suomi NPP VIIRS Day/Night Band (0.7 µm) image, with and without buoy observations [click to enlarge]

Not all rope clouds are associated with cold fronts; with ample illumination from the Moon — in the Waxing Gibbous phase, at 90% of Full — a Suomi NPP VIIRS Day/Night Band (0.7 µm) image (above) provided a “visible image at night” of a rope cloud in the northern Gulf of Mexico which highlighted a surface wind shift axis.

A sequence of VIIRS Day/Night Band images from NOAA-20 and Suomi NPP (below) showed the movement of the rope cloud during a time span of about 1.5 hours.

NOAA-20 and Suomi NPP VIIRS Day/Night Band (0.7 µm) images [click to enlarge]

NOAA-20 and Suomi NPP VIIRS Day/Night Band (0.7 µm) images [click to enlarge]

Train of standing waves south of Hawai’i

November 25th, 2018 |
GOES-17 Low-level (7.3 µm), Mid-level (6.9 µm) and Upper-level (6.2 µm) Water Vapor images [click to play animation | MP4]

GOES-17 Low-level (7.3 µm), Mid-level (6.9 µm) and Upper-level (6.2 µm) Water Vapor images [click to play animation | MP4]

* GOES-17 images shown here are preliminary and non-operational *

GOES-17 Low-level (7.3 µm), Mid-level (6.9 µm) and Upper-level (6.2 µm) Water Vapor images (above) revealed an interesting train of standing waves about 100-150 miles south of the Big Island of Hawai’i on 25 November 2018. With the presence of moisture aloft, the 3 water vapor weighting functions — calculated using the 00 UTC Hilo sounding — were shifted to high enough altitudes to eliminate the sensing of radiation from features in the lower troposphere. There were no pilot reports of turbulence in the vicinity of these standing waves — but they were located outside of the primary commercial air traffic corridors to/from the islands.

GOES-17 “Clean” Infrared Window (10.3 µm) and Near-Infrared “Cirrus” (1.37 µm) images (below) showed that these wave clouds were radiometrically transparent to longwave thermal energy being emitted from/near the surface — note that marine boundary layer stratocumulus clouds could be seen drifting westward within the easterly trade wind flow. As a result, the satellite-sensed 10.3 µm infrared brightness temperatures of the standing wave clouds were significantly warmer than that of the air at higher altitudes where they existed. These standing wave cloud features were, however, very apparent in 1.37 µm Cirrus imagery, along with what appeared to be other thin filaments of cirrus cascading southward overhead. The southward motion of the features seen on Cirrus imagery suggests that they existed at pressure levels of 370 hPa (26,900 feet / 8.2 km) or higher — altitudes where northerly winds were found on the Hilo sounding.

GOES-17 "Clean" Infrared Window (10.3 µm) and Near-Infrared "Cirrus" (1.37 µm) images [click to play animation | MP4]

GOES-17 “Clean” Infrared Window (10.3 µm) and Near-Infrared “Cirrus” (1.37 µm) images [click to play animation | MP4]

A comparison of all 16 ABI spectral bands is shown below. Note that in the longwave infrared bands along the bottom 4 panels, the brightness temperatures are progressively colder (darker shades of green) on the 11.2 µm, 12.3 µm and 13.3 µm images — each of these bands are increasingly affected by water vapor absorption aloft, therefore more effectively sensing the thin layer of higher-altitude standing wave clouds. AWIPS cursor sampling showed the differences in detected brightness temperature at 3 different points along the feature: here, here and here. The increasing sensitivity to radiation emitted from higher altitudes can also be seen in a comparison of weighting functions for ABI bands 13, 14, 15 and 16.

GOES-17 images of all 16 ABI bands [click to play animation | MP4]

GOES-17 images of all 16 ABI spectral bands [click to play animation | MP4]

GOES-15 (GOES-West) Water Vapor (6.5 µm), Infrared Window (10.7 µm) and Infrared CO2 (13.3 µm) images (below) showed that the lower spatial resolution of the legacy GOES Imager infrared bands (4 km at satellite sub-point) was not able to resolve the individual waves as well as the 2-km GOES-17 ABI images . Also, as was seen with the GOES-17 imagery, the 13.3 µm CO2 brightness temperatures of the standing wave clouds were significantly colder (shades of blue) compared to those of the conventional 10.7 µm Infrared Window. The corresponding GOES-15 Visible imagery (0.63 µm) is also available: animated GIF | MP4.

GOES-15 Water Vapor (6.5 µm, keft), Infrared Window (10.7 µm, center) and Infraered CO2 (13.3 µm, right) images [click to play animation | MP4]

GOES-15 Water Vapor (6.5 µm, keft), Infrared Window (10.7 µm, center) and Infraered CO2 (13.3 µm, right) images [click to play animation | MP4]

In comparisons of VIIRS True Color Red-Green-Blue (RGB) and Infrared Window (11.45 µm) images from Suomi NPP and NOAA-20 visualized using RealEarth (below), note the highly-transparent nature of the standing wave clouds on the RGB images; only the earliest 2256 UTC VIIRS 11.45 µm image displayed brightness temperatures of -20ºC and colder (cyan to blue enhancement).

Suomi NPP VIIRS True Color RGB and Infrared Window (11.45 µm) images at 2256 UTC [click to enlarge]

Suomi NPP VIIRS True Color RGB and Infrared Window (11.45 µm) images at 2256 UTC [click to enlarge]

NOAA-20 VIIRS True Color RGB and Infrared Window (11.45 µm) images at 2336 UTC [click to enlarge]

NOAA-20 VIIRS True Color RGB and Infrared Window (11.45 µm) images at 2336 UTC [click to enlarge]

Suomi NPP VIIRS True Color RGB and Infrared Window (11.45 µm) images at 0028 UTC [click to enlarge]

Suomi NPP VIIRS True Color RGB and Infrared Window (11.45 µm) images at 0028 UTC [click to enlarge]

Terra (at 2043 UTC) and Aqua (at 2347 UTC) MODIS True Color RGB images along with retrievals of Cloud Phase, Cloud Top Temperature, Cloud Top Height and Cloud Top Pressure from the WorldView site (below) indicated that the standing wave feature was composed of ice crystal clouds exhibiting temperature values of -53ºC and colder (dark purple enhancement) located at heights of 12 km or higher (and at pressure levels at or above 250 hPa). These temperature/height/pressure values roughly corresponded to the upper portion of a layer of increasing relative humidity between 200-274 hPa on the Hilo sounding.

Terra MODIS True Color RGB image and retrievals of Cloud Phase, Cloud Top Temperature, Cloud Top Height and Cloud Top Pressure at 2043 UTC [click to enlarge]

Terra MODIS True Color RGB image and retrievals of Cloud Phase, Cloud Top Temperature, Cloud Top Height and Cloud Top Pressure at 2043 UTC [click to enlarge]

Aqua MODIS True Color RGB image and retrievals of Cloud Phase, Cloud Top Temperature, Cloud Top Height and Cloud Top Pressure at 2347 UTC [click to enlarge]

Aqua MODIS True Color RGB image and retrievals of Cloud Phase, Cloud Top Temperature, Cloud Top Height and Cloud Top Pressure at 2347 UTC [click to enlarge]

However, an experimental CLAVR-x version of GOES-17 Cloud Type, Cloud Top Temperature and Cloud Top Height products (below; courtesy of Steve Wanzong, CIMSS) indicated Cirrus clouds having temperature values in the 210-200 K (-63 to -73ºC) range at heights within the 13-16 km range. These colder/higher values raise the question of whether the wave clouds might have formed and been ducted within the shallow temperature inversion near 15 km on the Hilo sounding.

GOES-17 Cloud Type product [click to play animation | MP4]

GOES-17 Cloud Type product [click to play animation | MP4]

GOES-17 Cloud Top Temperature product [click to play animation | MP4]

GOES-17 Cloud Top Temperature product [click to play animation | MP4]

GOES-17 Cloud Top Height product [click to play animation | MP4]

GOES-17 Cloud Top Height product [click to play animation | MP4]

GOES-17 False Color RGB images (below) vividly portrayed the transparent nature of the high-altitude standing wave cloud feature, which allowed westward-moving stratocumulus clouds within the marine boundary layer to plainly be seen. The RGB components are 1.38 µm / 0.64 µm /  1.61 µm.

GOES-17 False Color RGB images [click to play animation | MP4]

GOES-17 False Color RGB images [click to play animation | MP4]

A coherent explanation of this feature and what caused it to form remains elusive, earning it a distinguished place in the what the heck is this? blog category. Perhaps one clue existed in the winds aloft, as depicted by the NAM at 200 hPa, 250 hPa and 300 hPa (below), which showed northerly/northeasterly flow that was decelerating as it entered a trough axis (the region within the red box). Could this flow deceleration have induced a “reverse flow” which then caused enough weak lift to form the thin standing wave clouds within the aforementioned semi-moist 200-274 hPa layer seen on the Hilo sounding? No other obvious forcing mechanisms were in the immediate area — a slowly-approaching surface cold front was too far north of Hawai’i to have played a role.

NAM Winds at 200 hPa, 250 hPa and 300 hPa [click to enlarge]

NAM Winds at 200 hPa, 250 hPa and 300 hPa [click to enlarge]