Turbulence over the central Pacific Ocean

December 27th, 2016
Himawari-8 Water Vapor Imagery (6.2 µm, top; 6.9 µm, middle; 7.3 µm, bottom), 1700-1900 UTC on 27 December 2016 [click to enlarge]

Himawari-8 Water Vapor Imagery (6.2 µm, top; 6.9 µm, middle; 7.3 µm, bottom), 1700-1900 UTC on 27 December 2016 [click to enlarge]

Turbulence over the Pacific Ocean affected at least one flight on Tuesday 27 December 2016 near 24º N, 162º E, as indicated by a pilot report issued at 1745 UTC:

PGUA UUA /OV 24N 162E/TM 1745/FL340/TP B777/TB MOD-SEV/RM ZOA

In the animation above of the three Himawari-8 Water Vapor bands (sensing radiation emitted at 6.2 µm, 6.9 µm and 7.3 µm), a characteristic banded gravity wave structure is evident which is associated with the pilot report of moderate to severe turbulence (Note: the ABI instrument on the GOES-R series of satellites will feature these same 3 upper level, mid-level and lower level water vapor bands). In contrast to a turbulence event earlier this month, documented here on this blog, the wave features responsible for this turbulence were more distinct in 8-bit McIDAS-X imagery, and were also apparent in all three water vapor bands.

The Himawari-8 satellite data were used in the subsequent issuance of a SIGMET (Significant Meteorological Information) advisory:

WSPA06 PHFO 271824
SIGPAS

KZAK SIGMET SIERRA 1 VALID 271825/272225 PHFO-
OAKLAND OCEANIC FIR MOD OCNL SEV TURB FCST BTN FL280 AND FL360.
WI N2640 E16810 – N2120 E16810 – N2120 E16240 – N2640 E16250
– N2640 E16810. MOV E 25KT. BASED ON ACFT AND SAT.

The full 11-bit McIDAS-V imagery from the 6.2 µm Water Vapor band on Himawari-8, below, shows multiple ephemeral signatures of potential turbulence. In contrast to the event on 14 December, the gravity waves in this event perturbed clouds enough that they were also apparent in the Infrared Window band, as shown in this toggle between the 10.4 µm and 6.2 µm images. Himawari-8 Infrared Window brightness temperatures exhibited by the gravity wave were in the -30º to -40ºC range at 1740 UTC, which roughly corresponded to altitudes of 30,000-34,000 feet according to data from the 12 UTC rawinsonde report from Minamitorishima RJAM (IR image | text) located about 890 km or 550 miles to the west of the wave feature. Additional Himawari-8 Water Vapor images created using AWIPS II are here for the 6.2 µm imagery (from 1720-1740 UTC); this is a toggle between 6.2 µm and 7.3 µm imagery at 1720 UTC.

Himawari-8 Infrared Imagery (6.2 µm), 1600-1900 UTC on 27 December 2016 [click to animate]

Himawari-8 Water Vapor (6.2 µm) Imagery, 1600-1900 UTC on 27 December 2016 [click to animate]

The superior spatial resolution of Himawari-8 (2-km at the sub-satellite point) was vital in detecting the gravity wave features causing the turbulence. Water Vapor imagery from COMS-1, with a nominal resolution of 4 km, does not show the features associated with the turbulence report.

COMS-1 Infrared Imagery (6.75 µm), 1630-1800 UTC on 27 December 2016 [click to animate]

COMS-1 Water Vapor (6.75 µm) Imagery, 1630-1800 UTC on 27 December 2016 [click to animate]

Similarly, HimawariCast data that is broadcast at reduced resolution was insufficient to monitor this event. See the toggle below from 1740 UTC.

Himawari-8 Infrared Imagery (6.2 µm) at 1740 UTC on 27 December 2016, native resolution and as distributed via Himawaricast [click to enlarge]

Himawari-8 Water Vapor (6.2 µm) Imagery at 1740 UTC on 27 December 2016, at native resolution and as distributed via Himawaricast [click to enlarge]

Moderate to severe turbulence aloft near the International Date Line

December 14th, 2016

Himawari-8 Water Vapor (6.2 µm) images, with pilot reports of turbulence [click to play animation]

Himawari-8 Water Vapor (6.2 µm) images, with pilot reports of turbulence [click to play animation]

Himawari-8 Water Vapor (6.2 µm) images (above; also available as MP4 and McIDAS-V animations) revealed the presence of a subtle packet of upper-tropospheric gravity waves propagating southeastward near the International Date Line (180º longitude over the central Pacific Ocean), just to the west/southwest of Midway Atoll on 14 December 2016 — and there were a few pilot reports of moderate to severe turbulence (which were responsible for at least one injury) in the general vicinity of this gravity wave feature from 1530 to 1740 UTC, at altitudes of 35,000 to 38,000 feet:

PHNL UUA /OV 2800N 18000W/TM 1530/FL380/TP B767/TB MOD-SEV/RM ZOA CWSU
PHNL UUA /OV 2643N 17757W/TM 1732/FL350/TP A330/TB SEV/RM ZOA CWSU
PHNL UUA /OV 2626N 17917W/TM 1740/FL360/TP B747/TB SEV/RM ZOA CWSU

A larger-scale view using all 3 water vapor bands of the AHI instrument on the Himawari-8/9 satellites (below; also available as an MP4 animation) showed that a broad trough was moving eastward away from the International Date Line, with the signature of a jet streak diving southward toward the region of the turbulence reports (Note: the ABI instrument on the GOES-R series of satellites will feature these same 3 upper level, mid-level and lower level water vapor bands).

Himawari-8 Water Vapor (6.2 µm, top; 6.9 µm, middle; 7.4 µm, bottom) images [click to play animation]

Himawari-8 Water Vapor (6.2 µm, top; 6.9 µm, middle; 7.4 µm, bottom) images [click to play animation]

GFS model 250 hPa analyses (12 UTC | 18 UTC | source) confirmed that the region of turbulence reports was located within the exit region an approaching 50-70 m/s or 97-136 knot upper tropospheric jet, where convergence (red contours) was maximized.


——————————————————————————–
Similarly, Himawari-8 water vapor image Derived Motion Winds, below, also indicated increasing upper-tropospheric convergence along the International Date Line (180º longitude) between 25º and 30º N latitude from 12 UTC to 18 UTC (below; source).

Himawari-8 water vapor image Derived Motion Winds at 12 UTC, with corresponding contours of Upper-tropospheric divvergence [click to enlarge]

Himawari-8 water vapor image Derived Motion Winds at 12 UTC, with corresponding contours of Upper-tropospheric divvergence [click to enlarge]

Himawari-8 water vapor image Derived Motion Winds at 15 UTC, with corresponding contours of Upper-tropospheric divergence [click to enlarge]

Himawari-8 water vapor image Derived Motion Winds at 15 UTC, with corresponding contours of Upper-tropospheric divergence [click to enlarge]

Himawari-8 water vapor image Derived Motion Winds at 18 UTC, with corresponding contours of Upper-tropospheric divergence [click to enlarge]

Himawari-8 water vapor image Derived Motion Winds at 18 UTC, with corresponding contours of Upper-tropospheric divergence [click to enlarge]

A comparison of 2-km resolution Himawari-8 and 4-km resolution GOES-15 Water Vapor images (below; also available as an MP4 animation) showed that the gravity wave feature was not readily apparent on the lower spatial resolution GOES-15 images (which were only available every 30 minutes, in contrast to every 10 minutes from Himawari-8). The same color enhancement is applied to both sets of images — but because of differences between the Himawari-8 vs GOES-15 water vapor band characteristics (namely the central wavelength and the spectral response function, but also the water vapor weighting function profiles as influenced by the dissimilar satellite viewing angles) the resulting water vapor images differ in their general appearance.

Himawari-8 Water Vapor (6.2 µm, left) and GOES-15 Water Vapor (6.5 µm, right) images, with pilot reports of turbulence [click to play animation]

Himawari-8 Water Vapor (6.2 µm, left) and GOES-15 Water Vapor (6.5 µm, right) images, with pilot reports of turbulence [click to play animation]

This case demonstrated well the importance of viewing all 11 bits of information contained in the Himawari-8 Imagery. The animation at the top of the Blog Post shows an 8-bit display; a similar 8-bit display that uses a different color enhancement is here, courtesy of Dan Lindsey at CIRA. All 8-bit displays are limited to 256 different colors. The image below compares 8-bit (McIDAS-X on the left) and 11-bit (McIDAS-V on the right) displays at 1530 UTC.

Himawari-8 Water Vapor (6.2 µm) image at 1530 UTC, as viewed using 8-bit McIDAS-X (left) and 11-bit McIDAS-V (right) displays [click to enlarge]

Himawari-8 Water Vapor (6.2 µm) image at 1530 UTC, as viewed using 8-bit McIDAS-X (left) and 11-bit McIDAS-V (right) displays [click to enlarge]

Here is a toggle from AWIPS that compares 11-bit and 8-bit displays. The feature causing the turbulence is quite subtle, and 11-bit displays (which allow 2048 different colors) are necessary to accurately show it.

 

Fires continue in the southeast United States

November 14th, 2016

Terra MODIS (1650 UTC), Aqua MODIS (1829 UTC) and Suomi NPP VIIRS (1913 UTC) true-color images [click to enlarge]

Terra MODIS (1650 UTC), Aqua MODIS (1829 UTC) and Suomi NPP VIIRS (1913 UTC) true-color images [click to enlarge]

Fires (as seen on 07 and 10 November) continued to burn in parts of the southeast US on 14 November 2016. A sequence of 3 consecutive true-color Red/Green/Blue (RGB) images from Terra MODIS (1650 UTC), Aqua MODIS (1829 UTC) and Suomi NPP VIIRS (1913 UTC) viewed using RealEarth, above, showed the aerial extent of the dense smoke that was most concentrated over Tennessee, Georgia, North Carolina and South Carolina. With the aid of some of the 16 spectral bands on the ABI instrument aboard GOES-R, true-color images like these will be available at least once every 5 minutes over the Lower 48 states and adjacent areas.

GOES-13 (GOES-East) Visible (0.63 µm) images with plots of surface weather and visibility (below; also available as an MP4 animation) revealed that visibility was restricted to 3 miles or less at one or more sites in all of the aforementioned states. A pair of pilot reports in eastern Tennessee indicated that he top of the smoke layer was at 6000 feet above ground level.

GOES-13 Visible (0.63 µm) images, with hourly plots of surface weather (yellow) and visibility (statute miles, in cyan) [click to animate]

GOES-13 Visible (0.63 µm) images, with hourly plots of surface weather (yellow) and visibility (statute miles, in cyan) [click to animate]

High loading of particulate matter (PM) due to smoke led to AIRNow Air Quality Index ratings of Unhealthy (red)  to Very Unhealthy (purple) over much of that 4-state region (below).

Hourly AIRNow Particulate Matter (PM) Air Quality Index (AQI)

Hourly AIRNow Particulate Matter (PM) Air Quality Index (AQI)

===== 15 November Update =====

Suomi NPP VIIRS Shortwave Infrared (3.74 um) and Day/Night Band (0.7 um) images, plus METAR surface reports [click to enlarge]

Suomi NPP VIIRS Shortwave Infrared (3.74 um) and Day/Night Band (0.7 um) images, plus METAR surface reports [click to enlarge]

A toggle between Suomi NPP VIIRS Shortwave Infrared (3.74 um) and Day/Night Band (0.7 um) images (with and without METAR surface reports) at 0735 UTC or 3:35 am local time on 15 November (above) showed the “hot spot” signatures and bright glow from the larger fires that were burning in northern Georgia and western North Carolina. With ample illumination from the Moon — which was in the Waning Gibbous phase, at 99% of Full — smoke plumes from some of these fires could be seen drifting southward or southeastward,  thanks to the “visible image at night” capability of the Day/Night Band.

During the subsequent daytime hours, Terra MODIS and Suomi NPP VIIRS true-color RGB images (below) again revealed the vast coverage of the thick smoke — and VIIRS Aerosol Optical Depth values were quite high over South Carolina. Unhealthy AQI values persisted during much of the day across parts of Tennessee, Georgia and South Carolina.

Terra MODIS and Suomi NPP VIIRS true-color images, with VIIRS Aerosol Optical Depth (click to enlarge]

Terra MODIS and Suomi NPP VIIRS true-color images, with VIIRS Aerosol Optical Depth (click to enlarge]

A sampling of pilot reports (PIREPS) showed some of the impacts that the smoke was having on aviation (below).

Suomi NPP VIIRS Visible (0.64 µm) image with a PIREP over South Carolina [click to enlarge]

Suomi NPP VIIRS Visible (0.64 µm) image with a PIREP over South Carolina [click to enlarge]

Aqua MODIS Visible (0.65 µm) image with a PIREP over Georgia [click to enlarge]

Aqua MODIS Visible (0.65 µm) image with a PIREP over Georgia [click to enlarge]

GOES-13 Visible (0.63 µm) image with a PIREP over North Carolina [click to enlarge]

GOES-13 Visible (0.63 µm) image with a PIREP over North Carolina [click to enlarge]

===== 16 November Update =====

Terra/Aqua MODIS and Suomi NPP VIIRS true- color images [click to enlarge]

Terra/Aqua MODIS and Suomi NPP VIIRS true- color images [click to enlarge]

Terra/Aqua MODIS and Suomi NPP VIIRS true-color images (above) showed that much of the smoke had moved over the adjacent offshore waters of the Atlantic Ocean on 16 November.

 

Fires in the southeast United States

November 7th, 2016
terramodis_truecolor_7nov2016

Terra MODIS True-Color Imagery over the Smoky Mountains, 7 November 2016 (Click to enlarge)

Persistent moderate to severe drought (shown here, from this site) over the southeastern United States has supported the development of fires in and around the Great Smoky Mountains on 7 November 2016. True-color imagery from Terra MODIS, above, (source: MODIS Today) showed the active fires and plumes of smoke spreading northward into the Ohio River Valley.

Suomi NPP VIIRS true-color imagery also captured the smoke emanating from the active fires, and the Aerosol Optical Depth product, toggled below (data sources: RealEarth) showed the extent of the thickest smoke layer (click here for an animation that does not include the RealEarth framing).

Suomi NPP VIIRS true-color image with fire detection locations (red dots), and VIIRS Aerosol Optical Depth product [click to enlarge]

Suomi NPP VIIRS true-color image with fire detection locations (red dots), and VIIRS Aerosol Optical Depth product [click to enlarge]

A sequence of true-color Red/Green/Blue (RGB) images from Terra MODIS (1643 UTC), Suomi NPP VIIRS (1809 UTC) and Aqua MODIS (1824 UTC) is shown below.

Terra MODIS, Suomi NPP VIIRS and Aqua MODIS true-color images [click to enlarge]

Terra MODIS, Suomi NPP VIIRS and Aqua MODIS true-color images [click to enlarge]

The temporal evolution of the smoke was captured on GOES-13 Visible (0.63 µm) images (below; also available as an MP4 animation). Smoke reduced the surface visibility to 2.5 – 3.0 miles at some locations in Kentucky (KJKL | KLOZ) and Tennessee (KOQT), leading to EPA Air Quality Index values in the “Unhealthy” category.

GOES-13 Visible (0.63 µm) images; hourly surface weather symbols are plotted in yellow, with surface visibility (statute miles) plotted in cyan [click to play animation]

GOES-13 Visible (0.63 µm) images; hourly surface weather symbols are plotted in yellow, with surface visibility (statute miles) plotted in cyan [click to play animation]

===== 10 November Update =====

GOES-13 Visible (0.63 µm) images; hourly surface weather symbols are plotted in yellow, with surface visibility (statute miles) plotted in cyan [click to play animation]

GOES-13 Visible (0.63 µm) images; hourly surface weather symbols are plotted in yellow, with surface visibility (statute miles) plotted in cyan [click to play animation]

In the wake of a cold frontal passage on 09 November, northerly to northeasterly winds were transporting the smoke south-southwestward as the fires continued to burn on 10 November. GOES-13 Visible (0.63 µm) images, above, showed the dense smoke plumes — some of which were briefly reducing the surface visibility to less than 1 statute mile in far western North Carolina (Andrews | Franklin). In Georgia, smoke restricted the visibility to 2.5 miles as far south as Columbus.

A Pilot Report (PIREP) in northern Georgia at 1530 UTC, below, indicated that the top of the smoke layer was around 3500 feet (where the Flight Visibility was 4 miles).  Surface reports in the vicinity of that PIREP indicated a ceiling of 1500 to 1700 feet, suggesting that the dense smoke layer aloft was about 1800-2000 feet thick over northern Georgia.

GOES-13 Visible (0.63 µm) image, with cloud ceiling (hundreds of feet above ground level) and visibility (statute miles) plotted in cyan and a Pilot Report in yellow [click to enlarge]

GOES-13 Visible (0.63 µm) image, with cloud ceiling (hundreds of feet above ground level) and visibility (statute miles) plotted in cyan and a Pilot Report in yellow [click to enlarge]

The smoke plumes showed up very well on an Aqua MODIS true-color RGB image from the MODIS Today site, below.

Aqua MODIS true-color image [click to enlarge]

Aqua MODIS true-color image [click to enlarge]

The 1858 UTC Suomi NPP VIIRS true-color image (with fire detections) and the Aerosol Optical Depth product, below, depicted the aerial coverage of the smoke.

Suomi NPP VIIRS true-color image (with fire detection locations in red) and Aerosol Optical Depth product [click to enlarge]

Suomi NPP VIIRS true-color image (with fire detection locations in red) and Aerosol Optical Depth product [click to enlarge]