General interpretation « CIMSS Satellite Blog

Stereoscopic views in the Visible and Near-Infrared

February 20th, 2019 | Scott Lindstrom

GOES-16 (left) and GOES-17 (right) Visible Imagery (0.64 µm) from 1422 UTC to 2257 UTC on 20 February 2019 (Click to play mp4 animation)

Stereoscopic views of Visible Imagery (from GOES-16 and GOES-17, above) allow for visualization of three dimensions, as shown in the mp4 animation above (click here for an animated gif of the same scene). The imagery captures multiple cloud layers over the western United States (a map will show up in the animation) as a potent system moved eastward.

GOES-R includes four channels in the near-visible including the Cirrus Channel at 1.37 µm. The Cirrus Channel is useful here because the water vapor absorption of 1.37 µm energy means that any near-surface signal is absorbed, so mostly high-level clouds are present (low clouds become visible in the cirrus channel in very dry atmospheres). The animation below (the animated gif is here) is a stereoscopic view created with 1.37 µm imagery and the structure of the high clouds is more apparent.

GOES-16 (left) and GOES-17 (right) Band 4 Near-Infrared Imagery (1.37 µm) from 1422 UTC to 2257 UTC on 20 February 2019 (Click to play mp4 animation)

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Stereoscopic views of a small storm over the North Pacific Ocean

January 16th, 2019 | Scott Lindstrom

Himawari-8 AHI and GOES-17 ABI Band 13 (10.41 µm and 10.35 µm, respectively) at 0400 UTC on 16 January 2019 (Click to enlarge)

GOES-17 Data in this post are preliminary and non-operational.

The toggle above shows clean window imagery from the Advanced Himawari Imager (Band 13, 10.41 µm) on Himawari-8 (data courtesy JMA) and clean window imagery from the Advanced Baseline Imager (ABI, Band 13, 10.3 µm) on GOES-17 (GOES-17 data are non-operational). There is a small developing storm between the Hawai’ian Islands and Alaska that is resolved by both satellites. The storm is in between the two satellites and therefore ideal for stereoscopic views created from Visible 0.64 µm imagery (Band 3 for AHI, Band 2 for GOES-17). That is shown below. Thirty-minute timesteps are used because GOES-17 scans a full disk every 15 minutes (in Mode 3 that is currently operational; Mode 6, if used, scans a Full Disk every 10 minutes; and Mode 4, continuous Full Disk, the highest data rate for the GOES-R series, scans a Full Disk every 5 minutes). Himawari scans a Full Disk every 10 minutes. The three-dimensional representation facilitates the identification of warm conveyor belts associated with this developing storm. (This link shows the same animation but with the imagery flipped so it can be viewed in Google Daydream).

GOES-17 non-operational Visible (0.64 µm) imagery (left) and Himawari-8 Visible (0.64 µm) imagery (right), every half-hour from 2000 UTC on 15 January to 0400 UTC on 16 January (Click to animate)

Thanks to Mary Ellen Craddock, Northrop-Grumman, for the reminder that stereo imagery is possible with GOES-17 and Himawari. (It should be even better with Himawari-8 and South Korea’s GEOKOMPSAT-2A!)

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Stereoscopic Views of a storm on the West Coast of the United States

January 14th, 2019 | Scott Lindstrom

GOES-16 (left) and GOES-17 (non-operational, right) Visible Imagery (0.64 µm) at 15-minute timesteps from 1500 to 2245 UTC on 14 January 2019 (Click to animate)

GOES-17 images shown here are preliminary and non-operational

When GOES-17 was in the test position at 89.5 degrees W Longitude, GOES-16 and GOES-17 in satellite projections could be used to create stereoscopic imagery (example 1; example 2; example 3); the human brain could correct for any projection differences to create 3-dimensional imagery (as explained here, for example). Because GOES-17 is now in its operational position at 137.2 degrees W Longitude, the perspective differences are too great. However, a simple remap of the imagery to the same native projection (Mercator in this case) allows for the construction of animations that show three dimensions, as shown above for the storm making landfall over southern California on 14 January 2019. The coastlines of Washington and Oregon are apparent in the imagery, as is Baja California. Multiple cloud layers become apparent in the imagery.

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Mode 4 Testing for both GOES-16 and GOES-17

October 1st, 2018 | Scott Lindstrom

GOES-17 upper-level water vapor infrared imagery (6.19 µm) from 1425-1550 UTC on 1 October (Click to animate)

GOES-17 Data shown in this post are preliminary and non-operational.

Continuous Full Disk (Mode 4) Testing is occurring on October 1 2018. Mode 4 is the highest data flow rate for the ABI and results in a Full Disk image every 5 minutes. No mesoscale sectors are produced during Mode 4 operations. Five-minute CONUS imagery can be produced by subsecting the 5-minute Full-Disk Imagery. This testing started at 0000 UTC on 1 October and will end at 0000 UTC on 2 October.

The animation above shows GOES-17 Full-Disk imagery for the upper-level water vapor imagery (6.19 µm) with a 5-minute cadence. The GOES-16 animation for the same time and location is below.

GOES-16 upper-level water vapor infrared imagery (6.19 µm) from 1425-1550 UTC on 1 October (Click to animate)

Careful inspection of the imagery from the two satellites might reveal differences in brightness temperatures between the two instruments. This difference is due to view-angle differences. When the satellite is scanning near the limb, computed brightness temperatures will be cooler because more information detected by the satellite comes from the upper part of the atmosphere. Compare, for example, brightness temperatures just west of former Pacific Hurricane Rosa just west of Baja California. GOES-17, at 89.5 W Longitude, sees warmer temperatures than GOES-16 at 75.2 W Longitude. GOES-16’s view is more oblique, and is through more of the colder upper atmosphere.

GOES-16 and GOES-17 upper-level water vapor infrared (6.19 µm) imagery at 1500 UTC on 1 October 2018 (Click to enlarge)

(Update: GOES-16 returned to Mode-3 scanning at 1549 UTC on 1 October. Continuous Full Disk scanning on GOES-16 lead to degradation of derived products).

Update #2: Animations of 5-minute Full Disk GOES-17 Mid-level Water Vapor (6.9 µm) and “Red” Visible (0.64 µm) images from 0000-2355 UTC on 01 October are shown below.

GOES-17 Mid-level Water Vapor (6.9 µm) images [click to play MP4 animation]

GOES-17 “Red” Visible (0.64 µm) images [click to play MP4 animation]

One interesting feature on GOES-17 Visible imagery was the east-to-west progression of sun glint off the water of the Amazon River and its tributaries, beginning near the mouth of the river in northeastern Brazil and ending in Ecuador (below).