Even though cloud cover was increasing, a detailed view of the fire hot spot was provided by an AWIPS II image of 375-meter resolution Suomi NPP VIIRS Shortwave Infrared (3.74 µm) data at 1815 UTC on 28 November (below). An AWIPS I version of this image is available here. Due to the cloudiness, no discernible hot spot appeared on the lower-resolution 1815 UTC GOES-13 Shortwave Infrared image.Props to NWS meteorologist Carl Jones for spotting this somewhat unexpected result: the glow of the fire was evident on the following nighttime Suomi NPP VIIRS Day/Night Band (0.7 µm) image, even though there was a thick layer of clouds over the fire itself:
#Gatlinburg fire shines brightly despite clouds on VIIRS DNB overnight pass. @TravelGburg @NASANPP @CIMSS_Satellite @UWSSEC @UWCIMSS #tnwx pic.twitter.com/8CiIdL8Rrg
— Carl Jones (@northflwx) November 29, 2016
An AWIPS II image comparison of VIIRS Infrared Window (11.45 µm), Shortwave Infrared (3.74 µm) and Day/Night Band (0.7 µm) data at 0816 UTC on 29 November is shown below. Cloud-top Infrared Window brightness temperatures were in the -40 to -55º C range over the fire region (such air temperatures were foundd within the 9.5-10.5 km altitude range on the Nashville sounding when the cloud band was over central Tennessee at 00 UTC). While no fire hot spot signature was evident on the Shortwave Infrared image (due to masking by the clouds), the very distinct bright glow of the fire (which appeared rather large in size, due to scattering of light by the water and ice particles present in the various cloud layers) was seen on the Day/Night Band image. AWIPS I versions of these images are available here.Additional information is available on the Wildfire Today site (post 1 | post 2 | post 3 | post 4 | post 5). ]]>
A comparison of GOES-13 Visible (0.63 um) and Infrared Window (10.7 um) images (below) revealed multiple convective bursts during the day, some of which exhibited IR brightness temperatures of -80º C and colder (violet enhancement). Because of Otto’s central dense overcast, no eye was apparent in the GOES-13 imagery; even on a DMSP-16 SSMIS Microwave (85 GHz) image at 2049 UTC the eyewall was not fully closed.
===== 24 November Update =====As Otto slowly approached the coast of southern Nicaragua on 24 November, it rapidly intensified (SATCON plot) to a Category 2 hurricane. GOES-13 Infrared Window (10.7 µm) images (above; also available as a 36 Mbyte animated GIF) and Visible (0.63 µm) images (below; also available as a 18 Mbyte animated GIF) showed the development of an eye just offshore, which rapidly filled as the storm moved inland after 17 UTC on 24 November and began to interact with the terrain. After crossing Nicaragua and Costa Rica, an eye was once again discernible around 02 UTC on 15 November (as Otto emerged over the Pacific Ocean).
Before the formation of an eye, a Suomi NPP VIIRS Infrared Window (11.45 µm) image at 0639 UTC (below; courtesy of William Straka, SSEC) showed the presence of cloud-top gravity waves propagating westward along the Nicaragua/Costa Rica border; these waves were likely a response to deep convective bursts offshore near the center of Otto. A comparison of DMSP-17 SSMIS Microwave (85 GHz) and GOES-13 Infrared Window (10.7 µm) images around 1115 UTC on 24 November (below) revealed a much larger (albeit not completely closed) eye signature using the microwave data. Otto became the southernmost landfalling hurricane on record for Central America. It was also the strongest hurricane on record for so late in the season within the Atlantic basin. A DMSP-18 SSMIS Microwave (85 GHz) image at 0043 UTC on 25 November (above) showed that the eye of Otto was still well-defined as it began to move into northern Costa Rica (making this the first hurricane or tropical storm on record for that country). The eye structure could be tracked on MIMIC-TC imagery (below) as it moved inland from the Atlantic Ocean, across far southern Nicaragua and far northern Costa Rica, and eventually emerged over the Pacific Ocean after about 03 UTC on 25 November.
===== 26 November Update =====As Tropical Storm Otto was weakening during its west-southwestward motion over Pacific Ocean waters with low Ocean Heat Content, nighttime images of Suomi NPP VIIRS Infrared Window (11.45 µm) and Day/Night Band (0.7 µm) data at 0744 UTC on 26 November (above; courtesy of William Straka, SSEC) displayed shorter-wavelength cloud-top gravity waves on the Infrared image and longer-wavelength mesospheric airglow waves (reference) on the Day/Night Band image (all of which were propagating west-southwestward away from the deep convective cluster near the center of Otto). Bright lightning streaks were also seen on the Day/Night Band image.
More facts on the historic aspects of Otto are available from The Weather Channel and Weather Underground; see the National Hurricane Center and the CIMSS Tropical Cyclones websites for the latest information on this storm.]]>
Also of note was an apparent land breeze boundary that moved west-northwestward away from the Yucatan Peninsula of Mexico during the day.Gravity waves like those observed here are usually ducted within a strong air temperature inversion — so Suomi NPP NUCAPS (NOAA-Unique CrIS/ATMS Processing System) soundings around 1828 UTC (above) were examined for evidence of such an inversion. Training material for NUCAPS Soundings in AWIPS is available here.
One of the NUCAPS vertical profiles of temperature and moisture is shown below, for a point over the southern Gulf of Mexico (designated by the cyan rectangle, approximately 50 miles northwest of the coast of the Yucatan Peninsula) — several of the waves had passed through this location prior to the image time. A well-defined temperature inversion did indeed exist aloft, within the 1-2 km layer above the surface (and just above the top of the moist marine boundary layer, where the stratocumulus cloud field existed). It therefore appears likely that this series of southeastward-moving gravity waves was mildly perturbing the tops of the stratocumulus clouds.Since there were no nearby surface frontal boundaries or areas of organized deep convection inland over the southern US during the preceding 24 hours, it is unclear as to what may have been the catalyst for these gravity waves. ]]>
A late-season tropical depression has formed in the southwestern Caribbean Sea. The morning Metop-A pass on 21 November 2016 allowed ASCAT scatterometer winds to be sampled over the system: rain-flagged values near tropical storm force were present as shown above. A similar image (from this site) is available here, and also here (from this site).
Infrared (10.7 µm) imagery from GOES-13, above, from 1315 through 1715 UTC on 21 November, shows periodic deep convection over the Depression; the grey regions in the deepest convection over the system correspond to brightness temperatures colder than -75 C. The environment surrounding this system, shown below, is marginally favorable for strengthening; sea-surface temperatures are warm, although the oceanic heat content suggests the warmth does not extend through a deep column of water. Wind shear over the storm is modest (but far stronger north of the storm). (Imagery below is from this site). The system is forecast to become a tropical storm within the next 24 hours.
Update: Otto was named a tropical storm at 2100 UTC 21 November; GOES-13 Visible (0.63 µm) Imagery is shown below. Numerous tropical overshooting tops can be seen during the course of the day.
MIMIC Total Precipitable Water fields, below, show that Otto emerged from a region of persistent deep moisture over the southwestern Caribbean Sea that has been contracting as the storm formed. This region of moisture was focused along the intersection of a stalled and decaying Atlantic frontal zone and the Pacific monsoon trough (hourly animation).
DMSP-16 Microwave (85 GHz) imagery, below, showed evidence of a closed eye associated with Otto at 2132 UTC.]]>
Although it was more of an oblique viewing angle, JMA Himawari-8 AHI Water Vapor (6.2 µm, 6,9 µm and 7.3 µm) images (below; also available as a 27 Mbyte animated GIF) provided a nice view of the storm on 15 November as it was intensifying to produce Hurricane Force winds.Since the ABI instrument on GOES-R is nearly identical to the AHI, there will also be imagery from 3 water vapor bands (6.2 µm, 6.9 µm and 7.3 µm) available once GOES-R becomes operational (as GOES-16) in 2017.
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.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).
===== 15 November Update =====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.
A sampling of pilot reports (PIREPS) showed some of the impacts that the smoke was having on aviation (below).
===== 16 November Update =====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.
Photos taken by SSEC scientist Claire Pettersen at 1615 UTC (above) and 1623 UTC (below) revealed several examples of ice crystal cloud optics over Madison, Wisconsin on 14 November 2016. More information on the various types of ice cloud halos can be found here and here.
1650 UTC Terra MODIS Visible (0.65 µm), near-infrared Cirrus (1.375 µm) and Infrared Window (11.0 µm) images (below) showed the patches of cirrus clouds that were over southern Wisconsin not long after the photos above were taken. Many of the cirrus cloud features over the Madison (KMSN) area appeared very thin and nearly transparent on the Visible image; they also exhibited very warm Infrared Window brightness temperature values (warmer than -20ºC), since a great deal of radiation from the warmer surface of the Earth was reaching the MODIS detectors through the thin clouds. The 1.375 µm Cirrus band is able to detect the presence of airborne particles that are efficient scatterers of light — such as cirrus cloud ice crystals, dust, volcanic ash, smoke, haze — so the thin cirrus clouds exhibited a good signature on that image.A similar 1.37 µm Cirrus Band will be on the ABI instrument aboard GOES-R. ]]>
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).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. 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.
===== 10 November Update =====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.The smoke plumes showed up very well on an Aqua MODIS true-color RGB image from the MODIS Today site, below. 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. ]]>
Japan successfully launched the Himawari-9 satellite from the Tanegashima Space Center (near the southern tip of Tanegashima in the Osumi Islands south of Kyushu), a back-up to Himawari-8, shortly after 3:20 PM local time (0620 UTC) on 2 November 2016 (News Link 1, 2, 3, 4). Images showing all 16 Himawari-8 AHI spectral bands bracketing the 0620 UTC launch time are shown above; signatures of the warm thermal anomaly (from the burning of the solid rocket boosters) as well as the moisture of the rocket condensation cloud plume were evident in the Shortwave Infrared (3.9 µm) and Water Vapor (6.2 µm, 6.9 µm and 7.3 µm) bands, but a signal was also detectable in the Infrared 8.6 µm, 12.2 µm and 13.3 µm bands. The Himawari-8/9 AHI instrument is nearly identical to the ABI instrument on GOES-R — so similar imagery will be routinely available once GOES-R becomes operational in 2017.
The animation above shows the rocket plume in the Band 4 (0.86 µm) imagery (Band 4, the so-called “Veggie Band”, better discriminates between land and water so that the island of Tanegashima is more distinct) from Himawari-8, in the image at 0622 UTC. (Annotated 0622 UTC Image is here). The plume appears north of the launch site (which is located at the southern tip of the island).
A true-color image, below, that includes the three visible channels from Himawari-8 (Band 1 at 0.47 µm, Band 2 at 0.51 µm and Band 3 at 0.64 µm, with the Band 2 “Green Band” boosted by information in the Veggie Band at 0.86 µm) shows a plume, perhaps, emerging from the cloud field at the southern tip of the island.
Another view of the 3.9 µm Shortwave Infrared imagery, below, shows a short-lived hot-spot near where the Band 4 imagery shows the plume. Note: due to parallax, the location of the high-altitude hot spot appears farther north than its actual location.
Visible Imagery for the same three times, below, suggests a plume may be present (toggle between Visible and Shortwave Infrared images).
As mentioned above, signatures of the warm thermal anomaly and the moisture of the rocket condensation cloud plume were also evident on the three Himawari-8 Water Vapor bands, shown below — strong westerly winds aloft (satellite | model) quickly transported the high-altitude portion of the rocket plume eastward.
A video of the launch is here, with the launch itself at 44 minutes.]]>
The corresponding EUMETSAT Meteosat-10 Visible (0.64 um) images (below; also available as a 17 Mbyte animated GIF) provided a more detailed look at the structure of the storm during the daylight hours of those 4 days.Daily snapshots of Suomi NPP VIIRS true-color Red/Green/Blue (RGB) images viewed using RealEarth are shown below. The hazy signature of blowing dust/sand from northern Africa could be seen within the broad southeast quadrant of the storm circulation. There was ample moisture available to fuel convection around the storm, as seen in the MIMIC Total Precipitable Water product (below). The surface wind circulation of the medicane was well-sampled on a variety of Metop-A and Metop-B overpasses, using ASCAT plots (below) from this site. Suomi NPP ATMS images (below; courtesy of Derrick Herndon, CIMSS) revealed the areal coverage of the small “warm core” on Channel 8 (54.94 GHz) and Channel 7 (53.596 GHz); a north-to-south oriented vertical cross section showed the depth of the thermal anomaly associated with the medicane. For additional information, see this blog post from the Capital Weather Gang.