GOES-16 ABI RGB product artifacts related to Keep Out Zones
GOES-16 ABI Full Disk Imagery at 0430 UTC on 6 April. Bands 8 (6.19 µm), 10 (7.34 µm), 12 (9.6 µm) and 13 (10.3 µm) are shown (Click to enlarge)
GOES-16 ABI Full Disk Imagery at 0530 UTC on 6 April. Bands 8 (6.19 µm), 10 (7.34 µm), 12 (9.6 µm) and 13 (10.3 µm) are shown (Click to enlarge)
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.
AIrMass RGB (defined in Text) at 0430 and 0530 UTC on 6 April 2018 (Click to enlarge)
NOAA’s Office of Satellite and Product Operations (OSPO) maintains a website that describes Eclipses and Keep Out Zones.