A daytime comparison of GOES-16 “Blue” Visible (0.47 µm), “Red” Visible (0.64 µm) and Shortwave Infrared (3.9 µm) images (above; also available as an MP4 animation) displayed the smoke plume and “hot spots” (black to yellow to red pixels) associated with the West Mims Fire that was burning in far southeastern Georgia on 25 April 2017. Downwind of the fire in far northeastern Florida, smoke reduced the surface visibility to 2 miles at Jacksonville and 5 miles at Fernandina Beach.
During the subsequent nighttime hours — as the fires were beginning to decrease in both intensity and areal coverage — a comparison of “Snow/Ice” Near-Infrared (1.61 µm), “Cloud-Top Phase” Near-Infrared (2.24 µm) and Shortwave Infrared (3.9 µm) images (below; also available as an MP4 animation) showed that a bright glow from the most intense fires was evident in both of the Near-Infrared spectral bands.Although the spatial resolution of the 1.61 µm Band 5 is 1 km (at satellite sub-point) versus 2 km for the 2.24 µm Band 6, the bright nighttime fire signature was more defined on the 2.24 µm imagery; this is explained by examining a plot of the Spectral Response Function (SRF) for each band (below; courtesy of Mat Gunshor, CIMSS). For a very hot fire target — represented by the red 1200 K line — the 2.24 µm Band 6 SRF is located near the peak of the 1200 K plot, so more of the fire-emitted radiance can be sensed by Band 6 (in spite of its lower spatial resolution). ]]>
** The GOES-16 data posted on this page are preliminary, non-operational data and are undergoing testing. **
To commemorate Earth Day 2017, Full Disk images using all 16 spectral bands on the GOES-16 ABI instrument at 17:25:22 UTC on 22 April are displayed above. One feature that was prominent in most of the shorter-wavelength bands — which are able to sense a good deal of radiation/reflectance from the Earth’s surface — was the large area of sun glint near the center of the images (over the Pacific Ocean, just west of Panama/Costa Rica). The westward migration of this sun glint signature could be followed on an animation of Visible (0.64 µm) images (below). GOES-16 remained in a Mode 4 scan strategy during much of the day (until 1930 UTC), providing Full Disk images every 5 minutes.Taking a closer look at a portion of the Amazon River in Brazil, a comparison of Blue Visible (0.47 µm), Red Visible (0.64 µm) and Near-Infrared Vegetation (0.86 µm) band imagery (below) highlighted the ability of the 0.86 µm images to discriminate between land and water (water appears very dark). This makes 0.86 µm imagery useful for identifying and monitoring areas of inland flooding. ]]>
GOES-16 was operated in “Mode 4” on 21 April 2017 — this scanning strategy provides Full Disk images every 5 minutes (the current routine scan schedule for GOES-15 and GOES-13 only provides one Full Disk image every 3 hours). Shown below are animations of Upper-Level Water Vapor (6.2 µm), Mid-Level Water Vapor (6.9 µm) and Lower-Level Water Vapor (7.3 µm) Full Disk images covering the 12:00 to 23:55 UTC period. You can explore the differences between Water Vapor weighting functions for these 3 ABI bands (and how they change depending on airmass type, satellite viewing angle, etc) at this site.]]>
A comparison of GOES-16 Visible (0.64 um) and Infrared Window (10.3 um) images (above) showed the development of Tropical Storm Arlene in the Atlantic Ocean on 20 April 2017. Arlene has been one of only two tropical storms to be observed in the Atlantic Basin during the month of April in the satellite era.
A DMSP-15 SSMI Microwave (85 GHz) image from the CIMSS Tropical Cyclones site (below) revealed the formative stage of a convective ring around the core of Arlene at 1654 UTC.The MIMIC Total Precipitable Water product (below) showed that Tropical Depression 1 / Arlene was embedded within a plume of modest TPW (30-40 mm) which was wrapping into a large mid-latitude cyclone to the west. ]]>
A comparison of GOES-16 Lower-level (7.3 µm), Mid-level (6.9 µm) and Upper-level (6.2 µm) Water Vapor images (above) revealed the presence of numerous mountain waves over parts of California and Nevada on 13 April 2017. The more pronounced of these waves were caused by strong southwesterly winds interacting with higher terrain of the Sierra Nevada.
A 3-satellite comparison of GOES-15 (GOES-West), GOES-16 and GOES-13 (GOES-East) Water Vapor images (below) highlighted 2 factors that allowed better detection of these mountain waves by GOES-16 — improved spatial resolution (2 km for GOES-16 at satellite sub-point, vs 4 km for GOES-15/13), and a more direct satellite viewing angle (GOES-16 is positioned at 105ºW longitude, while GOES-15 is at 135ºW and GOES-13 is at 75ºW).Note that there were no Visible cloud features associated with many of the waves seen on Water Vapor imagery (below); encounters of Clear Air Turbulence (CAT) often occur with these types of mountain waves, as seen by scattered pilot reports of moderate turbulence (plotted as Category 4). ]]>
A comparison of GOES-16 and GOES-13 Shortwave Infrared (3.9 µm) images (above) showed numerous fire “hot spot” signatures (black to yellow to red pixels, with red being the hottest) from prescribed burning across the Flint Hills region of eastern Kansas and northeastern Oklahoma on 11 April 2017. Such fires are an annual tradition in this area, required to preserve the tallgrass prairies — for example, over 2.7 million acres were burned during Spring 2016. The 2-km spatial resolution (at satellite sub-point) and 5-minute scan interval of GOES-16 allowed for more accurate detection and monitoring of the fires (compared to the 4-km spatial resolution and 15-30 minute scan interval of GOES-13).
The corresponding Visible GOES-16 (0.64 µm) vs GOES-13 (0.63 µm) images (below) tracked the development and transport of smoke from the fires. Hourly reports of surface visibility (in statute miles) are plotted in red; at Fort Riley, Kansas, smoke reduced the visibility from 10.0 miles at 21 UTC to 1.0 mile at 23 UTC, adversely affecting air quality there.]]>
GOES-16 Visible (0.64 µm) images (above) revealed the presence of an eddy in the high-turbidity nearshore waters of southern Lake Michigan on 08 April 2017. The animation was created using 5-minute “CONUS” Sector images; an animation using 1-minute Mesoscale Sector images is available here.
A sequence of Terra and Aqua MODIS true-color Red/Green/Blue (RGB) images viewed using RealEarth (below) showed that the eddy began to develop on 07 April.]]>
GOES-16 data posted on this page are preliminary, non-operational data and are undergoing testing.
GOES-16 includes both a clean infrared window (10.33 µm) and a so-called ‘dirty’ infrared window channel (12.30 µm). The clean infrared window is in a part of the electromagnetic spectrum where there is very little absorption of energy by water vapor; in the dirty infrared window, modest amounts of water vapor absorption occur. The brightness temperature difference, nicknamed the Split Window Difference (SWD for short), can highlight differences in moisture in clear skies.
The toggle above shows the SWD (10.33 µm – 12.30 µm) at 1430 UTC on 7 April 2017. A pronounced gradient stretches southeast to northwest from Louisiana to northeast Kansas and extreme southeastern Nebraska. Values over Missouri, for example, are around 0.9-1.0 K vs. 1.7-2.2 K over Oklahoma. The gradient in the brightness temperature difference aligns very neatly with the 850-mb dewpoint temperature from the Rapid Refresh. You can use this product to monitor moisture return from the Gulf of Mexico.
AWIPS Note: The Default enhancement in AWIPS for the Split Window Difference, shown above, does not include large enough negative values. The Split Window Difference value can exceed -5 K in regions of dust. See this link for a different enhancement for this case with a wider range of temperature differences. A similar image uses the mean 1000-700 mb dewpoint temperature rather than values from the single 850-mb level.
An animation of this imagery (not shown) shows general increases in the SWD values with time. A consistent signal of moisture will be present only if the temperature decreases with height in the moist layer (that is — if there is no inversion). An increase in the SWD does not necessarily show an increase in moisture — it can, rather, signify an increase in near-surface temperature (for more information, consult this article by Lindsey et al.). The gradient in the field can remain, however, as in this example.
The Split Window Difference field does an exemplary job of detecting contrails over the southern Plains. The toggle below shows that the SWD signal of cirrus is more distinct than in the 1.378 µm Cirrus Channel! (Thanks to Matt Bunkers of WFO Rapid City for noting this!)
(Note that the SWD was something that was available from GOES-8 through GOES-11. Link)]]>
A toggle between the 0015 and 0030 UTC images displayed using McIDAS-V (below; courtesy of William Straka, SSEC) highlights the appearance of the thermal signature at Shayrat Air Base. Two persistent hot spots located northeast of Palmyra could have been due to refinery or mining activities.]]>
Following several days of heavy rainfall across northwestern Missouri, Flood Warnings remained in effect for many areas on 06 April 2017 (above).
A comparison of GOES-16 Visible (0.47 µm and 0.64 µm) and Near-Infrared (0.86 µm and 1.61 µm) images at 1507 UTC (below) shows that the Vegetation and Snow/Ice spectral bands are useful for identifying areas of swollen rivers and adjacent flooded lands (since water appears darker on those 2 images).