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

October 1st, 2018 |

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

GOES-17

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).

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

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

Posted in Calibration/Anomalies, General interpretation, GOES-16, GOES-17 | No Comments »

GOES-17 Data are flowing in GRB

August 28th, 2018 |

GOES-17 0.86 µm Near-Infrared and 3.9 µm Infrared imagery, 1607 UTC on 28 August 2018 (Click to enlarge)

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

The GOES Rebroadcast (GRB) is now transmitting GOES-17 data that remain Preliminary and non-operational.  The first data sent were at 1530 UTC on 28 August. The toggle above shows Bands 3 (“Veggie Band”, 0.86 µm) and Band 7 (“Shortwave Infrared”, 3.9 µm) from the Meso-1 sector that was positioned over the West Coast at 1607 UTC on 28 August 2018.  Band 13 (“Clean Window”, 10.3 µm), below, from the Meso-2 sector is over the High Plains.

GOES-17 10.3 µm Infrared imagery, 1613 UTC on 28 August 2018 (Click to enlarge)

Visible (Band 2, 0.64 µm) Imagery from 1531 UTC, below, was produced using CSPP Geo, a software package that reads the GRB signal and produces imagery. (Image courtesy Graeme Martin, CIMSS)

GOES-17 Visible (0.64) Imagery at 1531 UTC on 28 August 2018 (Click to enlarge)

The Geo2Grid Software Package can be used with GRB output to produce True-Color imagery, as shown below. The full-disk image was created in about 8 minutes using a centOS server, and it is corrected for atmospheric and solar zenith angle effects. Green Band information is simulated from other ABI channels.

Geo2Grid True Color Imagery, 1700 UTC on 28 August 2018 (Click to enlarge)

Full Disk examples of imagery from all 16 ABI bands (in addition to a Natural Color RGB image) are shown below (courtesy Mat Gunshor, CIMSS).

GOES-17 Natural Color RGB and individual ABI band images (Click to animate)

GOES-17 Natural Color RGB and individual ABI band images (Click to animate)

Posted in General interpretation, GOES-17, Red-Green-Blue (RGB) images | No Comments »

Blooming canola fields in North Dakota and Manitoba

July 9th, 2018 |

Terra MODIS True Color RGB images on 06 June, 05 July and 09 July 2018 [click to enlarge]

Terra MODIS True Color RGB images on 06 June, 05 July and 09 July 2018 [click to enlarge]

A toggle between Terra MODIS True Color Red-Green-Blue (RGB) images (from the MODIS Today site) on 06 June, 05 July and 09 July 2018 (above) revealed the brightening yellow-green hues of blooming canola fields across parts of northeastern North Dakota and southern Manitoba. Note that changes can even be seen between the 2 days in early July!

Credit to NWS Grand Forks for alerting us to this interesting phenomenon.


Posted in General interpretation, MODIS, Red-Green-Blue (RGB) images, Terra | No Comments »

The Split Window Difference over Iowa

June 5th, 2018 |

GOES-16 ABI Split Window Difference (10.3 µm – 12.3 µm) at 1402 UTC on 5 June 2018 (Click to enlarge)

The Split Window Difference field (SWD, the 10.3 µm brightness temperature minus the 12.3 µm brightness temperature) can be used to identify regions of moisture and dust in the atmosphere.  (Click here for a previous blog post).  On 5 June 2018, the SWD showed a strong gradient over the upper Midwest, with large values over Iowa and relatively smaller values to the northeast over Wisconsin (and to the south over Missouri). Is this showing a moisture gradient between Iowa and Wisconsin? Do you trust its placement? Given that convection will frequently fire along the gradient of a field (HWT Link; Old HWT link), it’s important to trust the placement of the gradient.

The toggle below shows both the SWD and the (clear sky only) Baseline Derived Stability Lifted Index.  The Lifted Index shows negative values over the southern Plains, and also a lobe of instability stretching WNW-ESE from southwestern Minnesota to Chicago.  If you look carefully, you will note that the axis of instability in the Lifted Index is offset from the Split Window Difference field.  Why?

GOES-16 ABI Baseline Derived Stability Index Lifted Index and GOES-16 Split Window Difference (10.3 µm – 12.3 µm) at 1402 UTC on 5 June 2018 (Click to enlarge)

The toggles below show the Split Window Difference field and the Rapid Refresh Model estimates of moisture in the lowest 3 km of the atmosphere, followed by the Split Window Difference toggled with the Baseline Land Surface Temperature field. The maximum in moisture is along the northern edge of the Split Window Difference field, and aligns well with the Lifted Index (Toggle between those two is here).

The Split Window Difference better matches the Land Surface Temperature Baseline product, and that reinforces an important caveat in the use of the SWD to detect moisture: SWD is greatly influenced by the skin temperature. Gradients in surface temperature and gradients in moisture both will affect the Split Window Difference. Make sure you understand the underlying cause of the gradient in the Split Window Difference field.

Toggle between the GOES-16 ABI Split Window Difference (10.3 µm – 12.3 µm) and Mean 0-3km AGL Dewpoint from the Rapid Refresh Model, 1402 UTC on 5 June (Click to enlarge)

GOES-16 ABI Split Window Difference (10.3 µm – 12.3 µm) and Land Surface Temperature Baseline Product, 1402 UTC on 5 June 2018 (Click to enlarge)

By 2002 UTC on 5 June, the GOES-16 Lifted Index fields and the SWD more closely align, in part because the axis of moisture has shifted southward. See the toggle below.

GOES-16 ABI Baseline Lifted Index, Split Window Difference (10.3 µm – 12.3 µm) and 0-3 km AGL Rapid Refresh Dewpoint, 2002 UTC on 5 June 2018 (Click to enlarge)

Posted in General interpretation, GOES-16 | No Comments »

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