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]

Camp Fire in northern California

November 8th, 2018 |

GOES-16

GOES-16 “Red” Visible (0.64 µm, top left), Shortwave Infrared (3.9 µm, top right), “Clean” Infrared Window (10.3 µm, bottom left) and Fire Temperature (bottom right) [click to play animation | MP4]

The Camp Fire started at 1433 UTC or 6:33 AM local time on 08 November 2018 in Northern California; the rapid spread of the fire prompted evacuations and forced road closures. GOES-16 (GOES-East) GOES-16 “Red” Visible (0.64 µm), Shortwave Infrared (3.9 µm), “Clean” Infrared Window (10.3 µm) and Fire Temperature (above) showed the evolution of the fire at 5-minute intervals — especially noteworthy were the rapid vertical jump of the smoke column seen at 1547 UTC (which cast a long shadow), and Fire Temperature values that exceeded 2000 K (bright red pixels) at numerous times with a maximum value just over 2300 K.

A GOES-16 Mesoscale Domain Sector was positioned over California beginning at 2115 UTC, providing imagery at 1-minute intervals — a comparison of Visible and Shortwave Infrared images (below) showed how quickly the hot thermal signature of the fire (yellow to red enhancement) advanced southwestward during the remaining 3 hours of daylight. Just northwest of the fire, Chico (station identifier KCIC) reported very low relative humidity values (6% at 21 UTC), as seen by the large spread between temperature and dewpoint late in the day.

GOES-16

GOES-16 “Red” Visible (0.64 µm, left) and Shortwave Infrared (3.9 µm, right) images [click to play MP4 animation]

1-km resolution NOAA-18 AVHRR Visible (0.64 µm), Near-Infrared “Vegetation” (0.86 µm), Shortwave Infrared (3.7 µm) and Infrared Window (10.8 µm) images (below) showed the bifurcation of the smoke plume as well as the large, very hot thermal signature of the fire at 1712 UTC or 9:12 AM local time.

NOAA-18 AVHRR Visible (0.64 µm), Near-Infrared "Vegetation" (0.86 µm), Shortwave Infrared (3.7 µm) and Infrared Window (10.8 µµ) images [click to enlarge]

NOAA-18 AVHRR Visible (0.64 µm), Near-Infrared “Vegetation” (0.86 µm), Shortwave Infrared (3.7 µm) and Infrared Window (10.8 µm) images [click to enlarge]

NOAA-20 Visible (0.64 µm), Near-Infrared

NOAA-20 VIIRS Visible (0.64 µm), Near-Infrared “Snow/Ice” (1.61 µm) and Infrared Window (11.45 µm) images [click to enlarge]

Higher spatial resolution views were provided by NOAA-20 VIIRS Visible (0.64 µm), Near-Infrared “Snow/Ice” (1.61 µm) and Infrared Window (11.45 µm) images (above) and by Aqua MODIS Visible (0.65 µm), Near-Infrared “Snow/Ice” (1.61 µm) and Infrared Window (11.0 µm) images (below). [Note: the NOAA-20 VIIRS images are incorrectly labeled as Suomi NPP]

Aqua MODIS Visible (0.65 µm), Near-Infrared

Aqua MODIS Visible (0.65 µm), Near-Infrared “Snow/Ice” (1.61 µm) and Infrared Window (11.0 µm) images [click to enlarge]

Alternative views of the NOAA-20 VIIRS and Aqua MODIS images are shown below (using legacy AWIPS-1).They include Shortwave Infrared images from the 2 satellites, which reveal the very large (approximately 10 miles in length) thermal anomaly or fire “hot spot”. Due to the very dry atmosphere over the region (MODIS 6.7 µm Water Vapor image), the smoke could be clearly seen on the MODIS 1.37 µm Cirrus image (since there was very little attenuation of upwelling 1.37 µm radiation by middle/upper-tropospheric water vapor).

NOAA-20 Visible (0.64 µm), Day/Night Band (0.7 µm), Near-Infrared "Snow/Ice" (1.61 µm), Shortwave Infrared (3.74 µm) and Infrared Window (11.45 µm) images [click to enlarge]

NOAA-20 Visible (0.64 µm), Day/Night Band (0.7 µm), Near-Infrared “Snow/Ice” (1.61 µm), Shortwave Infrared (3.74 µm) and Infrared Window (11.45 µm) images [click to enlarge]

Aqua MODIS Visible (0.65 µm), Near-Infrared "Cirrus" (1.37 µm), Near-Infrared "Snow/Ice" (1.61 µm), Shortwave Infrared (3.7 µm) and Infrared Window (11.0 µm) images [click to enlarge]

Aqua MODIS Visible (0.65 µm), Near-Infrared “Cirrus” (1.37 µm), Near-Infrared “Snow/Ice” (1.61 µm), Shortwave Infrared (3.7 µm) and Infrared Window (11.0 µm) images [click to enlarge]

As a result of the unusual dryness air mass across the region, the 00 UTC Oakland sounding set a record low Total Precipitable Water value for the date (3 mm or 0.12 inch):

 

The Aqua MODIS Total Precipitable Water product at 2123 UTC (below) showed widespread values in the 3-5 mm range (darker shades of brown) over much or northern California. 12 hours later, the TPW value from the 12 UTC Oakland sounding was slightly lower (2.9 mm or 0.11 inch) — and the MODIS TPW product at 0921 UTC continued to show widespread dry air over California.

Aqua MODIS Total Precipitable Water product and Visible (0.65 µm) image at 2123 UTC [click to enlarge]

Aqua MODIS Total Precipitable Water product and Visible (0.65 µm) image at 2123 UTC [click to enlarge]

True Color Red-Green-Blue (RGB) imagery from NOAA-20 VIIRS (below) provided a good view of the smoke.

NOAA-20 VIIRS True Color RGB image [click to enlarge]

NOAA-20 VIIRS True Color RGB image [click to enlarge]

A NOAA-15 AVHRR Shortwave Infrared image at 0225 UTC or 6:25 PM local time (below) depicted the very large thermal anomaly of the fire.

NOAA-15 AVHRR Shortwave Infrared (3.7 µm) image; major highways are plotted in cyan, with Interstate highways plotted in red [click to enlarge]

NOAA-15 AVHRR Shortwave Infrared (3.7 µm) image; major highways are plotted in cyan, with Interstate highways plotted in red [click to enlarge]

The smoke had an adverse  impact on air quality over 100 miles from the fire source: the surface visibility dropped to 1 mile at Santa Rosa KSTS and 2 miles at San Francisco International Airport KSFO (below).

Time series of surface observations for Santa Rosa [click to enlarge]

Time series of surface observations from Santa Rosa [click to enlarge]

Time series of surface observations from San Francisco International Airport [click to enlarge]

Time series of surface observations from San Francisco International Airport [click to enlarge]

===== 09 November Update =====

NOAA-20 VIIRS Day/Night Band (0.7 µm) and Shortwave Infrared (3.74 µm) images [click to enlarge]

NOAA-20 VIIRS Day/Night Band (0.7 µm) and Shortwave Infrared (3.74 µm) images [click to enlarge]

Nighttime VIIRS Day/Night Band (0.7 µm) and Shortwave Infrared (3.74 µm) images from NOAA-20 at 0849 UTC (above) and Suomi NPP at 0942 UTC (below) revealed the bright glow and the large, hot thermal anomaly of the Camp Fire.

Suomi NPP VIIRS Day/Night Band (0.7 µm) and Shortwave Infrared (3.74 µm) images [click to enlarge]

Suomi NPP VIIRS Day/Night Band (0.7 µm) and Shortwave Infrared (3.74 µm) images [click to enlarge]

VIIRS True Color RGB images from Suomi NPP at 2104 UTC and NOAA-20 at 2154 UTC (below) showed the broad extent of the smoke from the Camp Fire in northern California as well as the Woolsey Fire in southern California. These images were captured and processed by the CIMSS/SSEC Direct Broadcast ground station.

Suomi NPP VIIRS True Color RGB image at 2104 UTC [click to enlarge]

Suomi NPP VIIRS True Color RGB image at 2104 UTC [click to enlarge]

NOAA-20 VIIRS True Color RGB image at 2154 UTC [click to enlarge]

NOAA-20 VIIRS True Color RGB image at 2154 UTC [click to enlarge]

An animation of 1-minute GOES-16 Visible and Shortwave Infrared images (below) revealed several plume jumps over the fire source from 15-19 UTC — and toward the end of the day, a decrease in the areal coverage and intensity of hot pixels indicated that extreme fire conditions were easing and containment efforts were slowing the spread of the fire.

GOES-16 "Red" Visible (0.64 µm, left) and Shortwave Infrared (3.9 µm, right) images [click to play MP4 animation]

GOES-16 “Red” Visible (0.64 µm, left) and Shortwave Infrared (3.9 µm, right) images [click to play MP4 animation]

Abnormally dry to extreme drought conditions across California were a contributing factor to this and other wildfires across the state.

US Drought Monitor conditions as of 06 November [click to enlarge]

US Drought Monitor conditions as of 06 November [click to enlarge]

====== 11 November Update =====

Suomi NPP VIIRS Shortwave Infrared (3.74 µm) images [click to play animation]

Suomi NPP VIIRS Shortwave Infrared (3.74 µm) images [click to play animation]

A sequence of Suomi NPP VIIRS Shortwave Infrared (3.74 µm) images centered at Paradise, California viewed using RealEarth (above) showed the spread of the Camp Fire thermal anomaly (dark black pixels) during the period 1943 UTC on 08 November to 1046 UTC on 11 November.

1-minute GOES-16 Visible and Shortwave Infrared images (below) showed the development of new smoke plume and hot thermal signatures around the periphery of the ongoing Camp Fire during the day on 11 November. As of 1849 UTC (10:49 AM local time), the fire had burned 109,000 acres and was listed as 25% contained.

GOES-16 “Red” Visible (0.64 µm, left) and Shortwave Infrared (3.9 µm, right) images [click to play MP4 animation]

GOES-16 “Red” Visible (0.64 µm, left) and Shortwave Infrared (3.9 µm, right) images [click to play MP4 animation]

The new smoke plume — as well as residual smoke from previous days of burning — could be seen on VIIRS True Color RGB imagery from Suomi NPP at 2029 UTC and NOAA-20 at 2114 UTC (below). The entire image swaths as captured and processed by the Direct Broadcast ground station at CIMSS/SSEC can be seen here and here.

Suomi NPP VIIRS True Color RGB image at 2029 UTC [click to enlarge]

Suomi NPP VIIRS True Color RGB image at 2029 UTC [click to enlarge]

NOAA-20 VIIRS True Color RGB image at 2114 UTC [click to enlarge]

NOAA-20 VIIRS True Color RGB image at 2114 UTC [click to enlarge]

The Camp Fire has claimed 42 lives and destroyed 6,522 homes and 260 businesses, making it both the deadliest and the most destructive wildfire on record for the state of California.

Ferguson Fire in California forms a pyrocumulonimbus cloud

July 15th, 2018 |
GOES-16

GOES-16 “Red” Visible (0.64 µm, left), Shortwave Infrared (3.9 µm, center) and “Clean” Infrared Window (10.3 µm, right) images [click to play MP4 animation]

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

The Ferguson Fire in central California produced a pyrocumulonimbus (pyroCb) cloud during the afternoon hours on 15 July 2018. GOES-16 (GOES-East) “Red” Visible (0.64 µm), Shortwave Infrared (3.9 µm) and “Clean” Infrared Window (10.3 µm) images (above) showed that the high-altitude portion of the pyroCb cloud then drifted northeastward toward the California/Nevada border, where cloud-top infrared brightness temperatures cooled to near -55ºC (orange enhancement) as it crossed the border around 0005 UTC on 16 July.

A comparison of Visible images from GOES-15 (0.63 µm), GOES-17 (0.64 µm) and GOES-16 (0.64 µm) is shown below — with the imagery displayed in the native projection of each satellite. Images from GOES-16/17 are at 5-minute intervals, while images from GOES-15 are every 5-15 minutes depending on the operational scan schedule of that GOES-West satellite. GOES-17 was at its post-launch checkout position of 89.5ºW longitude, so it offered a more direct view of the pyroCb cloud.

Visible images from GOES-15 (0.63 µm, left), GOES-17 (0.64 µm, center) and GOES-16 (0.64 µm, right) [click to play animation]

Visible images from GOES-15 (0.63 µm, left), GOES-17 (0.64 µm, center) and GOES-16 (0.64 µm, right) [click to play animation]

A toggle between NOAA-19 Visible (0.63 µm), Shortwave Infrared (3.7 µm) and Infrared Window (10.8 µm) images (below) showed the pyroCb cloud southwest of the California/Nevada border (between Bridgeport KBAN and Mammoth KMMH) at 2327 UTC. In spite of a minimum cloud-top 10.8 µm infrared brightness temperature of -59ºC (red enhancement), note the darker (warmer) appearance of the cloud on the 3.7 µm image — this is due to reflection of solar radiation off the smaller ice particles of the pyroCb anvil. The -59ºC temperature roughly corresponded to an altitude of 13 km or 42.6 kft on the 00 UTC Reno, Nevada rawinsonde report (plot | data)

NOAA-19 Visible (0.63 µm), Shortwave Infrared (3.7 µm) and Infrared Window (10.8 µm) images [click to enlarge]

NOAA-19 Visible (0.63 µm), Shortwave Infrared (3.7 µm) and Infrared Window (10.8 µm) images [click to enlarge]

A time lapse of the pyroCb was created by Sierra Fire Watch (below).

Time lapse [click to play YouTube video]

Time lapse [click to play YouTube video]

Mesoscale Convective Vortex generated by monsoon thunderstorms in Arizona

July 9th, 2018 |

As mentioned by NWS San Diego, monsoon thunderstorms that developed over Arizona spawned a small Mesoscale Convective Vortex (MCV). The animation below shows nighttime GOES-16 (GOES-East) “Clean” Infrared Window (10.3 µm) images, followed by daytime GOES-16 “Red” Visible (0.64 µm) images — the center of the MCV circulation briefly exhibited an “eye-like” appearance just after 16 UTC (south of the California/Mexico border).

GOES-16

GOES-16 “Clean” Infrared Window (10.3 µm) and “Red” Visible (0.64 µm) images, with hourly plots of surface reports [click to play MP4 animation]

A 1-km resolution NOAA-19 Infrared Window (10.8 µm) image at 1132 UTC (below) showed a more detailed view of the small cluster of thunderstorms responsible for the MCV — the convection produced 0.68″ of rainfall near Yuma KNYZ in far southwestern Arizona, and generated an outflow boundary which produced wind gusts to 46 mph at Thermal, California KTRM (NWS statements).

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

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

A toggle between 1-km resolution NOAA-15 and NOAA-18 Visible (0.63 µm) images (below) revealed the emergence of the eye-like MCV center in far northern Baja California (just southeast of Campo, California KCZZ) at 1547 UTC.

NOAA-15 and NOAA-18 Visible (0.63 µm) images [click to enlarge]

NOAA-15 and NOAA-18 Visible (0.63 µm) images [click to enlarge]