GOES-16 Visible and Cirrus Channels

March 21st, 2017 |

GOES-16 Visible (0.64 µm) images, 1202-1732 UTC on 21 March [click to play animated gif]

GOES-16 Visible (0.64 µm) images, 1202-1732 UTC on 21 March [click to play animated gif]

GOES-16 data posted on this page are preliminary, non-operational data that are undergoing testing.

GOES-16 Visible imagery captured the erosion of near-surface clouds over Ohio on 21 March 2017. A benefit of the routine 5-minute imagery is that it allows better estimates of exactly when the low clouds will clear out. There is ample suggestion in the animation above of the presence of cirrus clouds. The GOES-16 ABI has a channel at 1.38 µm that is specifically designed to detect cirrus clouds because that is a region in the electromagnetic spectrum where strong water vapor absorption occurs. The animation of ‘cirrus channel’ imagery, below, confirms the presence of widespread cirrus clouds.

GOES-16 Cirrus Channel (1.38 µm) images, 1202-1732 UTC on 21 March [click to play animated gif]

GOES-16 Cirrus Channel (1.38 µm) images, 1202-1732 UTC on 21 March [click to play animated gif]

The MODIS instrument also has a similar near-infrared Cirrus spectral band — and a comparison of Terra MODIS Visible (0.65 µm) and Cirrus (1.375 µm) images at 1601 UTC is shown below.

Terra MODIS Visible (0.65 µm) and Cirrus (1.375 µm) images [click to enlarge]

Terra MODIS Visible (0.65 µm) and Cirrus (1.375 µm) images [click to enlarge]

GOES-16 Mesoscale Sectors: improved monitoring of fire activity

March 19th, 2017 |

GOES-16 Shortwave Infrared (3.9 µm, left) and GOES-13 Shortwave Infrared (3.9 µm, right) images [click to play MP4 animation]

GOES-16 Shortwave Infrared (3.9 µm, left) and GOES-13 Shortwave Infrared (3.9 µm, right) images [click to play MP4 animation]

** The GOES-16 data posted on this page are preliminary, non-operational data and are undergoing testing. **

The ABI instrument on GOES-16 is able to scan 2 Mesoscale Sectors, each of which provides images at 1-minute intervals. For what was likely a prescribed burn in the Francis Marion National Forest (near the coast of South Carolina) on 19 March 2017, a comparison of 1 minute Mesoscale Sector GOES-16 and 15-30 minute Routine Scan GOES-13 Shortwave Infrared (3.9 µm) images (above; also available as a 50 Mbyte animated GIF) demonstrated the clear advantage of 1-minute imagery in terms of monitoring the short-term intensity fluctuations that are often exhibited by fire activity. In this case,  the intensity of the fire began to increase during 15:15-15:45 UTC — a time period when there was a 30-minute gap in routine scan imagery from GOES-13. The GOES-16 shortwave infrared brightness temperature then became very hot (red enhancement) beginning at 15:46:58 UTC, which again was not captured by GOES-13 — even on the 16:00 UTC and later images (however, this might be due to the more coarse 4-km spatial resolution of GOES-13, compared to the 2-km resolution of the shortwave infrared band on GOES-16). Similar short-term intensity fluctuations of a smaller fire (burning just to the southwest) were not adequately captured by GOES-13.

The corresponding GOES-16 vs GOES-13 Visible image comparison (below; also available as a 72 Mbyte animated GIF) also showed the advantage of 1-minute scans, along with the improved 0.5-km spatial resolution of the 0.64 µm spectral band on GOES-16 (which allowed brief pulses of pyrocumulus clouds to be seen developing over the fire source region).

GOES-16 Visible (0.64 µm, left) and GOES-13 Visible (0.63 µm, right) images [click to play MP4 animation]

GOES-16 Visible (0.64 µm, left) and GOES-13 Visible (0.63 µm, right) images [click to play MP4 animation]

 The rapid south-southeastward spread of the smoke plume could also be seen on true-color Red/Green/Blue (RGB) images from Terra/Aqua MODIS and Suomi NPP VIIRS, as viewed using RealEarth (below).

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

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

GOES-16 water vapor imagery: wave structures within a dry slot

March 8th, 2017 |

GOES-16 Water Vapor images: 6.2 µm (top), 6.9 µm (middle) and 7.4 µm (bottom) [click to play animation]

GOES-16 Water Vapor images: 6.2 µm (top), 6.9 µm (middle) and 7.4 µm (bottom) [click to play animation]

** The GOES-16 data posted on this page are preliminary, non-operational data and are undergoing testing. **

(Hat tip to T.J. Turnage, NWS Grand Rapids, for alerting us to this case): A variety of mesoscale wave structures were seen in NOAA GOES-16 Lower-Tropospheric Water Vapor (7.3 µm) and Middle-Tropospheric Water Vapor 6.9 µm images (above; also available as an MP4 animation) within a dry slot along the southern periphery of a trough associated with a large and intense mid-latitude cyclone centered over Hudson Bay, Canada on 08 March 2017. Beneath this dry slot, wind gusts exceeded 60 mph across southern portions of Minnesota, Wisconsin and Lower Michigan as momentum aloft was mixed downward to the surface.

Using the GOES-13 (GOES-East) Sounder water vapor bands as a proxy for the three ABI water vapor bands, weighting functions calculated using 12 UTC rawinsonde data from Chanhassen, Minnesota (below) showed a dramatic downward shift in the weighting function curves (compared to a US Standard Atmosphere) — this meant that the 3 water vapor bands were sensing radiation from layers much closer to the surface on 08 March (where the strong winds could interact with terrain and cause standing waves to form). It is interesting to note that the outline of the southern part of Lake Michigan could be seen on GOES-16 Lower-Tropospheric Water Vapor (7.3 µm) imagery (animated GIF | MP4 animation) — the signal of the thermal contrast between the lake water (MODIS SST values in the upper 30s to low 40s F) and the adjacent land surfaces (MODIS LST values in the middle 50s to low 60s F) was “bleeding up” through what little water vapor was present aloft.

GOES-13 Sounder water vapor weighting functions: 12 UTC Chanhassen, Minnesota sounding vs US Standard Atmosphere [click to enlarge]

GOES-13 Sounder water vapor weighting functions: 12 UTC Chanhassen, Minnesota sounding vs US Standard Atmosphere [click to enlarge]

A comparison of GOES-16 Visible (0.64 µm) and Middle/Lower-Level Water Vapor images (below; also available as an MP4 animation) showed that these water vapor wave structures were forming in cloud-free air — this is a signature of the potential for low-altitude turbulence.

GOES-16 images: 0.64 µm Visible (top), 6.9 µm Water Vapor (middle) and 7.4 µm Water Vapor (bottom) [click to play animation]

GOES-16 images: 0.64 µm Visible (top), 6.9 µm Water Vapor (middle) and 7.4 µm Water Vapor (bottom) [click to play animation]

In fact, there were widespread pilot reports of moderate turbulence within the dry slot (below), with a few isolated reports of severe to even extreme turbulence in eastern Wisconsin and southern Lower Michigan.

GOES-13 Water Vapor (6.5 µm) images, with pilot reports of turbulence [click to play animation]

GOES-13 Water Vapor (6.5 µm) images, with pilot reports of turbulence [click to play animation]

Storm “Doris” affects the British Isles

February 23rd, 2017 |

Meteosat-10 Water Vapor (6.25 µm) images, with hourly surface wind gusts in knots [click to play animation]

Meteosat-10 Water Vapor (6.25 µm) images, with hourly surface wind gusts in knots [click to play animation]

Storm “Doris” affected the British Isles on 23 February 2017, producing strong winds and heavy rainfall. The mid-latitude cyclone rapidly intensified from a central pressure of 1004 hPa at 12 UTC on 22 February to 972 hPa at 12 UTC on 23 February (surface analyses) . EUMETSAT Meteosat-10 Water Vapor (6.25 µm) images (above) exhibited the “scorpion tail” signature of a sting jet (Monthly Weather Review | Wikipedia), and surface wind gusts included 58 knots at Dublin, 64 knots at Wittering and 69 knots at Valley.

The corresponding daylight Meteosat-10 High Resolution Visible (0.8 µm) images (below) revealed better detail of the various cloud structures associated with the storm.

Meteosat-10 High Resolution Visible (0.8 µm) images, with hourly surface wind gusts in knots [click to play animation]

Meteosat-10 High Resolution Visible (0.8 µm) images, with hourly surface wind gusts in knots [click to play animation]

True-color Red/Green/Blue (RGB) images from Terra/Aqua MODIS and Suomi NPP VIIRS visualized using RealEarth are shown below. EUMETSAT posted a natural-color RGB animation here.

Terra MODIS (1039 UTC), Aqua MODIS (1226 UTC) and Suomi NPP VIIRS (1248 UTC) true-color RGB images [click to enlarge]

Terra MODIS (1039 UTC), Aqua MODIS (1226 UTC) and Suomi NPP VIIRS (1248 UTC) true-color RGB images [click to enlarge]