Eclipse season for GOES-16 occurs around the Equinoxes when the satellite can enters the Earth’s shadow. Long ago (before GOES-12), Eclipse Season meant the satellite lost power because the solar array that powers the satellite was in a shadow. GOES-16 has batteries that allow it to function when solar power is missing. However, as the satellite emerges from the Earth’s shadow, the Advanced Baseline Imager can point too close to the Sun, so portions of the image are not scanned and sent to the receiving station. The two animations above step through four different channels on ABI (Band 8 (6.19 µm), Band 10 (7.34 µm), Band 12 (9.6 µm) and Band 13 (10.3 µm), at 0430 UTC, when the Keep-Out Zone (KOZ, sometimes called the Cookie Monster effect) is northwest of the subsatellite point, and at 0530 UTC, (also Band 8 (6.19 µm), Band 10 (7.34 µm), Band 12 (9.6 µm) and Band 13 (10.3 µm)) when the KOZ is northeast of the subsatellite point.  Note in particular that the size of the KOZ is different with different channels.

If Channel Differences are used in a product, this intra-band size difference of the KOZ has an affect.  The toggle below shows the Airmass RGB (Red Component:  Split Water Vapor (6.19 µm – 7.34 µm) ; Green Component: Split Ozone, (9.6 µm – 10.3 µm); Blue Component: 6.19 µm) at 0430 UTC and 0530 UTC on 6 April 2018.  At 0430 UTC, there is a region where only the blue part of the Airmass RGB (from the 6.19 µm band) is present;  at 0530 UTC, the Keep-Out Zone border shows only magenta (i.e., a lack of Green) because the Split Ozone Channel (9.6 µm – 10.3 µm) is missing there.

NOAA’s Office of Satellite and Product Operations (OSPO) maintains a website that describes Eclipses and Keep Out Zones.

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An outbreak of severe weather occurred across parts of the Mid-South, Ohio Valley and mid Mississippi Valley on 03 April 2018. A GOES-16 Mesoscale Sector provided images at 1-minute intervals — “Red” Visible (0.64 µm) images (above) and “Clean” Infrared Window (10.3 µm) images (below) include plots of SPC storm reports.

Looking farther to the southwest over parts of Texas, Louisiana and Arkansas, similar animations of 1-minute GOES-16 “Red” Visible (0.64 µm) and “Clean” Infrared Window (10.3 µm) images are shown below.

NOAA/CIMSS ProbSevere All Hazards (Prob Hail, Prob Wind, Prob Tor) use during this event is discussed here.

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A cold front moving southward along the western Great Plains showed a distinct signature in GOES-16 Water Vapor Imagery.  The hourly animation above, with surface observations, shows the front in the Low-Level Water Vapor passing over stations where winds shift from westerly and southwesterly to strong northerly.  The feature is far more trackable in GOES-16 ABI Imagery with a 5-minute cadence as is typical over CONUS, as shown below for both low-level water vapor infrared imagery (Band 10, 7.34 µm) and upper-level water vapor infrared imagery (Band 8, 6.19 µm). The infrared imagery allowed a precise determination of when the cold front would reach a location. (In fact, because a GOES-16 Mesoscale Sector was placed over west Texas, the time of arrival could be observed down to the minute, as shown in this animation of the clean window (10.3 µm) infrared imagery from GOES-16).

Visible Imagery after sunrise (below) shows that some surface cloudiness was associated with this feature — but other parts were clear.

It is not common for surface features to appear in the Upper-Level Water Vapor Imagery, even when the surface is near 900 mb, as over the High Plains of west Texas. Weighting Functions show from which layers in the atmosphere energy detected by the satellite originates. The Weighting function from Amarillo TX at 1200 UTC on 3 April is shown below.  The low-level water vapor weighting function — shown in magenta — shows contributions from the surface, but the upper-level water vapor weighting function — shown in green, shows contributions ending about 200 mb above the surface, at around 700 mb.  A conclusion might be that the depth of the cold air quickly increases to around 200 mb behind the front.  Thus is can appear in the Upper-Level water vapor imagery.   The cold front passes Amarillo (here is a meteorogram) shortly before 1200 UTC (and before the Radiosonde was launched).  The radiosonde from Dodge City Kansas, however, at 1200 UTC, shows a cold layer about 200 mb thick.  (Here is the Amarillo Sounding for the same time;  it’s shown in the Weighting Function plot below as well).

Interpretation of water vapor imagery is simplified if you use information from weighting functions to understand the three-dimensional aspect of the water vapor imagery.

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Some remnant signatures of Winter could be seen on 01 April 2018 — the first were seen  on GOES-16 (GOES-East) GOES-16 “Red” Visible (0.64 µm) and Near-Infrared “Snow/Ice (1.61 µm) over North Dakota and South Dakota, in the form of snow cover and snow/ice on parts of the Missouri River (above). With the high April sun angle, the lesser snow cover over northern South Dakota melted rather quickly, and the southern edge of the deeper snow cover in southern North Dakota also receded during the day.

Farther to the east, the motion and breakup of ice in Green Bay was evident on GOES-16 “Red” Visible (0.64 µm)  images (below).

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