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MODIS/VIIRS Land Product Quality Assessment

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Opening Date: 2020-10-06 Last update: 2021-07-06 Status: Note

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PWA-41: UPDATE 10.06.20
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On DOY 2020.279 (10.05.20) MODIS Terra experienced a PWA failure that affected two more PWA-41 (supersets 80 and 81), bringing down the total number of MODIS SS to 28. The current PWA failure event happened around 15:21:12z. FOT was able to move the two corrupt supersets to the bad superset list at the contact on 2020.280/03:28:00 - 03:46:00z. Science recording was disabled at 03:32:56 to handle the moving of the supersets and re-enabled at 03:41:56z.

Terra MODIS shows partial to full science data loss on 2020.279 for NRT and C6/C61 forward production over the following time ranges (15:05, 16:45, 18:30), where the data could not be played back because of recording on the faulty PWA-41. The image below for DOY 2020.279, shows these gaps across the globe. On day 2020.280 science data acquisition was disabled temporarily between 03:32:56-03:41:56 to move the bad supersets to the bad superset list. The global browse image for DOY 2020.280 is provided below. The 2020.280 global browse image shows the L1B B29 night time orbits and additional missing data for periods for 00:00-00:30, 01:20-01:55, 03:25-03:45, and 21:30-21:45.

**** NOTE: 10.27.20 **** MODAPS has filled in the data to the best possible extent, based on additional L0 from the MODIS Direct Broadcast (DB) stations. The Terra Data Loss has been finalized from the PWA anomaly. MODIS:2020.279 (15:04:02 - 15:08:36, 16:47:03 - 16:51:37, 18:30:02 - 18:34:36, 20:13:01 - 20:17:34, 21:56:00 - 22:00:33, 23:38:59 - 280/00:31:41) have been lost due to this event, and are not recoverable. Additionally, DOY 2020.280 granules 01:30, 01:35, 01:50, 01:55, 02:00, 03:00, 21:35 and 21:40 were found to contain impacts to geolocation information.

MOD02SSH, TOP-OF-THE-ATMOSPHERE REFLECTANCE BANDS 1,4,3
day A2020279 (2020-10-05), 006
Global Browse image.

MOD02SSH, BAND 29, night time orbits
day A2020280 (2020-10-06), 006
Global Browse image.

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PWA-47: UPDATE 07.06.21
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On June 29, 2021 (DOY 180), Terra experienced another PWA failure (PWA-47), affecting the supersets of 92/93, bringing down the total number of MODIS SS to 26. The failed MODIS supersets from PWA 47 were successfully removed and operations were completed during the contact (181/01:55:09 - 02:05:44z) at 01:58z. Post anomaly collection (13 PWAs: 26 SS) will be reduced to 37.6% day (loss of 11:56 minutes daytime data per orbit). All data lost will be at the poles. No impact on thermal emissive bands data collection. Terra MODIS shows partial to full science data loss on 2021.180 and 2021.181 for NRT and C6/C61 forward production, the complete impacted range for MODIS: 180/13:06:23 - 181/00:07:41. MODAPS is currently working to fill in the data to the best possible extent, and more information will be posted when recovery efforts have been completed. Currently, the following time ranges are directly impacted or missing for DOY 2021.180: (13:05, 14:50, 18:20-1835, 20:10-20:25, 21:55-22:15), and DOY 2021,181: (00:00-00:05, 01:00-01:55). Images below for DOY 2021.180 and 2021.181 show these gaps across the globe.