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]

Super Typhoon Nock-Ten strikes the Philippines

December 25th, 2016

Himawari-8 Infrared Window (10.4 µm) images [click to play MP4 animation]

Himawari-8 Infrared Window (10.4 µm) images [click to play MP4 animation]

Rapid-scan (2.5-minute interval) 2-km resolution Himawari-8 Infrared Window (11.45 µm) images (above; also available as a 173 Mbyte animated GIF) showed Category 4 Super Typhoon Nock-Ten making landfall in the Philippines on 25 December 2016. Nock-Ten became the strongest typhoon on record (SATCON | ADT | source) in the Philippines so late in the year:

A 375-meter resolution Suomi NPP VIIRS Infrared Window (11.45 µm) image at 1724 UTC on 24 December (below; courtesy of William Straka, SSEC) was acquired just before the beginning of the Himawari-8 animations above; note the presence of cloud-top gravity waves propagating southeastward away from the eye of Nock-Ten, in addition to prominent larger-scale transverse banding farther out within the eastern semicircle of the storm.

Suomi NPP VIIRS Infrared Window (11.45 µm) image [click to enlarge]

Suomi NPP VIIRS Infrared Window (11.45 µm) image [click to enlarge]

Eruption of Alaska’s Bogoslof volcano

December 22nd, 2016

Himawari-8 0.64 µm (left) and GOES-15 0.63 µm (right) Visible images [click to play animation]

Himawari-8 0.64 µm (left) and GOES-15 0.63 µm (right) Visible images [click to play animation]

Following a short-lived eruption on 21 December, the Bogoslof volcano in the eastern Aleutian Island chain of Alaska erupted again at about 0110 UTC on 22 December 2016. The volcanic cloud could be seen moving north/northeastward away from Bogoslof (denoted by the yellow * symbol) on Himawari-8 and GOES-15 Visible images (above). The higher spatial and temporal resolution from Himawari-8 (0.5 km at nadir, with images every 10 minutes) provided a more detailed view of the cloud feature compared to GOES-15 (with 1.0 km resolution at nadir, and images every 15 minutes); however, the ABI instrument on the GOES-R series will have an identical 0.5 km resolution Visible band. Another Himawari-8 Visible image animation is available from RAMMB.

Multispectral Red/Green/Blue (RGB) images from the NOAA/CIMSS Volcanic Cloud Monitoring site (below) displayed a signal of the volcanic cloud during the ~2.5 hours following the onset of the eruption — since this particular RGB combination uses the 3.9 µm Shortwave Infrared band, the volcanic cloud feature appeared as darker shades of magenta during the first few images while reflected solar illumination was present before sunset.

Himawari-8 false-color RGB images [click to play animation]

Himawari-8 false-color RGB images [click to play animation]

Another variant of RGB images (below) uses the 8.5 µm “cloud top phase” band, which is also sensitive to SO2 absorption; in this case, the appearance of the volcanic cloud feature was dominated by shades of yellow, indicating high levels of SO2.

Himawari-8 false-color RGB images [click to play animation]

Himawari-8 false-color RGB images [click to play animation]

A comparison of the 3 Himawari-8 water vapor bands (below) showed that a strong signature of the volcanic cloud was seen on the lower-tropospheric 7.3 µm band; this was due to the fact that the 7.3 µm band is also sensitive to elevated levels of SO2 loading in the atmosphere (which was also noted at the bottom of this Mount Pavlof eruption blog post). These same 3 water vapor bands (Upper-level, Mid-level and Lower-level) will be available from the GOES-R series ABI instrument.

Himawari-8 6.2 µm (top), 6.9 µm (middle) and 7.3 µm (bottom) Water Vapor images [click to play animation]

Himawari-8 6.2 µm (top), 6.9 µm (middle) and 7.3 µm (bottom) Water Vapor images [click to play animation]

A closer view using Himawari-8 false-color images (below) includes a magenta polygon surrounding the volcanic cloud soon after the onset of the eruption — this is an example of an experimental automated volcanic eruption alerting system. According to Michael Pavolonis (NOAA/NESDIS), “Using our automated cloud object tracking algorithm, the eruption produced a cloud at 01:30 UTC that was about 19 deg C colder than the background imaged by Himawari-8 at 01:20 UTC.  Taking into account the pixel size, background cloud cover, and time interval between successive images, the 19 deg C change is about an 11 standard deviation outlier relative to a very large database of meteorological clouds.  The vertical growth anomaly calculation is the basis of one the components of our experimental automated volcanic eruption alerting system”.

Himawari-8 false-color images, with a polygon surrounding the volcanic cloud [click to enlarge]

Himawari-8 false-color images, with a polygon surrounding the volcanic cloud [click to enlarge]

The creation of RGB images such as those shown above will be possible from the GOES-R series of satellites (beginning with GOES-16), since the ABI instrument has the 8.4 µm and 12.3 µm bands that are not available from the current generation of GOES imager instruments.

Additional satellite images of this event are available from NWS Anchorage.

2016 Northern Hemisphere winter / Southern Hemisphere summer solstice

December 21st, 2016

Meteosat-10 Visible (0.635 µm) images [click to enlarge]

Meteosat-10 Visible (0.635 µm) images [click to enlarge]

The 2016 Northern Hemisphere winter / Southern Hemisphere summer solstice occurred at 1044 UTC on 21 December. EUMETSAT Meteosat-10 Visible (0.635 µm) images (above; source) showed the westward progression of the solar terminator (which separates daylight from darkness) at 3-hour intervals.

Nearly the entire continent of Antarctica was illuminated by 24 hours of daylight, as seen on JMA Himawari-8 Visible (0.64 µm) images (below; also available as a 60 Mbyte animated GIF). Full-disk images are routinely available at 10-minute intervals from Himawari-8 (and can be available as frequently as every 5 minutes from the GOES-R series).

Himawari-8 Visible (0.64 µm) images [click to play MP4 animation]

Himawari-8 Visible (0.64 µm) images [click to play MP4 animation]

With the continuous daylight, Antarctic surface air temperatures from AMRC Automated Weather Stations (below; source) were seen to warm above 40ºF along the coast, and above -30ºF in the interior.

AMRC AWS station surface temperatures at 20 December (22 UTC) and 21 December (05 and 11 UTC) [click to enlarge]

AMRC AWS station surface temperatures at 20 December (22 UTC) and 21 December (05 and 11 UTC) [click to enlarge]