Note: GOES-16 data shown on this page are preliminary, non-operational data and are undergoing on-orbit testing.

The ABI Band at 0.86 µm (Fact Sheet) allows superior land/sea discrimination. This occurs because land is more reflective to radiation at 0.86 µm than to radiation at 0.64 µm. The toggle above shows Florida in the standard visible (0.64 µm) and at 0.86 µm. Coastal boundaries and islands (such as the Keys and the Bahamas) are far more distinct in the near-infrared so-called ‘veggie’ channel at 0.86 µm. Inland lakes are also better defined with the 0.86 µm channel. Because the land is so bright, land/cloud contrast is reduced in the 0.86 µm imagery, so clouds over land appear more distinct in the 0.64 µm imagery.

The toggle below shows a similar scene over the Tidewater region of southeast Virginia and points to the south.  Again, inland lakes and rivers and the coastal boundary is more apparent in the 0.86 µm imagery than in the 0.64 µm imagery.

Use the 0.86 µm band when land/water distinction is important!

Because ABI does not have a spectral band in the ‘green’ part of the electromagnetic spectrum (Band 1 at 0.47 µm is in the blue, Band 2 at 0.64 µm is in the red), information from the 0.86 µm band is used in construction of simulated ‘true color’ imagery (as discussed here).

In addition, the 0.86 µm channel provides useful burn scar information in ‘False Color’ imagery (that combines 2.2 µm, 0.86 µm and 0.64 µm imagery) because burn scars appear dark in 0.86 µm imagery.

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Note: GOES-16 data shown on this page are preliminary, non-operational data and are undergoing on-orbit testing.

The Advanced Baseline Imager (ABI) on the GOES-R Series of satellites (including GOES-16) includes a band that detects radiation at 1.37 µm (Fact Sheet Link). This 2-km resolution band is unique to GOES-16 among geostationary satellites. The animation above shows a subset of Full-Disk imagery at 15-minute intervals (GOES-16 produces a full disk every 15 minutes, in contrast to GOES-13/GOES-15’s 3-hour Full Disk cadence). The Cirrus channel highlights only the highest clouds associated with the wave cyclone over the central part of the United States. Clouds are not initially obvious early in the animation over the northern Plains: this band detects reflected solar radiation and therefore gives little information at night.

The Band 4 Cirrus Channel to the Band 2 visible (0.64 µm) toggle, below, enables an observer to distinguish between low/middle cloud levels and high clouds quite easily. Water vapor in the atmosphere above the low clouds in Illinois and Missouri (and elsewhere) is absorbing any reflected radiation at 1.37 µm there. If precipitation is being produced by a seeder/feeder mechanism, the presence of high clouds as detected in the Cirrus channel could help refine analyses of falling precipitation.

A similar band (with 1-km resolution) is present on Terra and Aqua as part of MODIS and there are numerous CIMSS Satellite Blog Posts that incorporate snapshots from this MODIS cirrus-detection channel:  Detecting thin cirrus and contrails over Arkansas and Tennessee; Thin Cirrus over the Midwest; Cirrus associated with Haloes; The Cirrus Canopy of Hurricane Matthew; Transverse Banding, for example.

Although this band on ABI is called the Cirrus Channel, it has other uses.  It can be used to detect any highly reflective aerosol, such as volcanic ash or blowing dust, as long as the features are not obscured by water vapor.  It can also view the surface if the atmosphere is sufficiently dry:  Research suggests that a total precipitable water of about 12 mm is sufficient to attenuate the radiation.

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The GOES-15 Water Vapor animation, above, shows a potent cold front moving through southern California late on 27 February. This front that passed through San Diego at 0500 UTC on 28 February (9 PM PST) was accompanied by abundant precipitation, the heaviest rainfall in 13 years at the San Diego airport (link), with widespread 2+-inch rains that caused power outages and flooding. The image below (from this site), shows the 24-hours precipitation ending at 1200 UTC on 28 February 2017. Values in excess of 6″ occurred in the mountains east of San Diego.

Satellite estimates of Total Precipitable Water (TPW) suggested that heavy rains were likely. MIMIC total precipitable water plots, above (source), show a moisture source that tapped the rich moisture of the Intertropical Convergence Zone. NOAA/NESDIS Blended Precipitable Water Percent-of-Normal plots (source, at this site), shown below, show values exceeding 200% of normal over southern California. Both MIMIC and Blended TPW products offer excellent situational awareness.

An interesting aspect of the GOES-15 Water Vapor animation, at the top of this post, is the appearance of land features. The spine of the mountains over Baja California appears throughout the animation, for example, as does the Front Range of the Rockies from Colorado southward to New Mexico. Should land features be visible in water vapor imagery? An answer to that lies in computed weighting functions, shown below (from this site), that describe from where in the atmosphere energy at a particular wavelength is being detected by the satellite.

At the start of the water vapor animation, near 0000 UTC, thick clouds cover southern California (and the sounding from San Diego shows saturated conditions); dry layers in the sounding appear by 1200 UTC. The 7.4 µm weighting function shows that information is detected by the satellite from lower down in the atmosphere; energy detected at 6.5 µm comes from higher in the atmosphere. This difference arises because of the better absorptive qualities of water vapor gas for 6.5 µm radiation vs. 7.4 µm radiation. By 1200 UTC, sufficient drying has occurred that the 7.4 µm Sounder Channel is detecting radiation that emanates from sea level. Note also at 1200 UTC that each individual moist layer influences the weighting function — but there is insufficient moisture at 1200 UTC in those moist layers that they are opaque to energy at either 6.5 µm or 7.4 µm.

Note: GOES-R Series satellites, including GOES-16, have ‘water vapor’ channels at 6.2 µm, 6.9 µm and 7.3 µm.

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GOES-16 — the first of the GOES-R series — ABI visible (0.64 µm) images captured the Lunar Umbra (or solar eclipse shadow) of the “ring of fire” annular eclipse that occurred in the Southern Hemisphere on 26 February 2017. The dark eclipse shadow could be seen moving from west to east, beginning over the southern Pacific Ocean, passing over far southern Chile and Argentina, and finally moving over the southern Atlantic Ocean. GOES-16 will routinely scan the Full Disk every 15 minutes (the current GOES Full Disk scan interval is once every 3 hours), but in a special mode can scan the Full Disk every 5 minutes.

The path of the eclipse shadow (courtesy of EarthSky.org) is shown below.

True-color GOES-16 Red/Green/Blue (RGB) images are shown below (courtesy of Kaba Bah, CIMSS).

Note: the GOES-16 data posted on this page are preliminary, non-operational data and are undergoing on-orbit testing.

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