Fog at Sunrise with RGBs using Visible Imagery

Fog at Sunrise with RGBs using Visible Imagery


Nighttime Microphysics RGB via GOES-16 at 1122 UTC, 13 August 2018 over the Southeast U.S.

During the early morning of 13 August 2018, clear skies resulted in wide spread low clouds and fog over the East/Southeast.  The image above is the Nighttime Microphysics (NtMicro) RGB via GOES-16 at 1122 UTC or 7:22 and 6:22 AM for Eastern and Central times respectively.  At this time the low clouds and fog in shades of cyan are still apparent, but soon this coloring will fade as solar reflectance at sunrise will influence the shortwave IR used in the RGB and therefore, the NtMicro will be rendered ineffective (see mp4 animation).  Typically, visible imagery is used at sunrise to continue to monitor fog in small-scale valleys, often with a lack of in situ observations.  The new capabilities of GOES-16 provide new RGBs for daytime use that include the 0.64 micron visible channel.  The Natural Color RGB, originally developed by EUMETSAT is available within AWIPS (as ‘Day Land Cloud’), and it uses the visible channel in it’s blue component.  Below is a slide show of the NtMicro, Natural Color and Visible RGBs just after sunrise (1222 UTC).  Note that the Natural Color RGB (also see mp4 animation) shows the fog and water clouds in gray while ice clouds are in cyan.  The Natural Color RGB can be used through the day to monitor the microphysics of cloud tops due to the use of the 1.61 micron channel, and it also provides qualitative land surface information via the 0.87 micron channel.   A legacy ‘Visible’ RGB (also see mp4 animation) that uses the visible in the red and green components (‘Day Land Convection’ within AWIPS), also provides value to monitor fog after sunrise as it depicts warm clouds in yellows and cold clouds in grays to white in daytime.

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Geostationary Lightning Mapper (GLM) observes three tropical cyclones in the eastern Pacific

The large field of view of the Geostationary Lightning Mapper (GLM) offers forecasters a new way to monitor tropical cyclones.  In particular, the GLM will offer the opportunity to monitor total lightning (i.e., cloud-to-ground and intra-cloud) trends over the entire life cycle of the system.

The past few days have offered a very interesting opportunity with three tropical cyclones in the eastern Pacific basin; Tropical Storm Greg, Hurricane Hilary, and Tropical Storm Irwin.  The movie covers from 1310 UTC on July 23 through 1610 UTC on July 24.  A few features are interesting to point out.  First, notice the amount of lightning activity and diurnal change associated with the storms across Mexico (upper right of movie) versus the activity with the three tropical systems.  Also, check out the location of the lightning in tropical systems and whether it is in the central core or the outer bands.

Figure 1 is a still from the linked mp4 movie that is approximately 37 megabytes in size.


Figure 1:  A still image from 0600 UTC on 24 July 2017 showing Tropical Storms Greg and Irwin as well as Hurricane Hilary in the eastern Pacific basin.  The cyclones are viewed with ABI at the full disk, 15 minute temporal resolution (and intentionally darkened to make the lightning observations stand out) and the GLM 8 km, 5 minute group densities. (Please click on image to enlarge.)

[37 MB] GLM group density over three tropical cyclones

NOTE:  NOAA’s GOES-16 satellite has not been declared operational and its data are preliminary and undergoing testing. Users receiving these data through any dissemination means  (including, but not limited to, PDA and GRB) assume all risk related to their use of GOES-16 data and NOAA disclaims any and all warranties, whether express or implied, including (without limitation) any implied warranties of merchantability or fitness for a particular purpose.