SSEC forums

Topic: Suomi-NPP VIIRS Emissive Band Calibration scheduled for September 19-21, 2016

Date/Time Issued: Sept 16, 2016 2115Z

Product(s) or Data Impacted: Suomi-NPP VIIRS Sensor Data

Date/Time of Initial Impact: Sept 19, 2016 0600Z

Date/Time of Expected End: Sept 21, 2016 0300Z

Length of Outage: N/A

Details/Specifics of Change: The VIIRS sensor on Suomi-NPP will be conducting its quarterly emissive band calibration on September 19-21. Due to the VIIRS Blackbody temperature changes during the calibration, the VIIRS science data quality may be affected for certain applications, but the data is expected to remain within specification.

See below for scheduled Blackbody temperature changes.

VIIRS Blackbody Set Point(K) Time (UTC)
297.5 9/19 06:00:00
302.5 9/19 09:00:00
307.5 9/19 12:00:00
312.5 9/19 15:00:00
315.0 9/19 18:00:00
OFF 9/19 21:00:00
272.5 9/20 21:00:00
282.5 9/21 00:00:00
292.5 9/21 03:00:00

Regarding the above announcement;

We run a processing chain that uses CSPP (V2.2 patched) to process VIIRS from L0 to L1B prior to ingestion into seadas to create L2 products. Our L0 data is sourced from a local receiving station in the UK. From 0600Z on September 19th, the QF2_SCAN_SDR for band 12 has a bit value that is out of the expected range (uses more than the expected first two bits). This causes the L1B to L2 section of the processing chain to fail with the following error:

-E- /data3/swdev/V2016.2/build/src/l2gen/l1_viirs_h5.c Line 884: QF2_SCAN_SDR mismatch, val# 18, bnd 11

Prior to 19/09/2016 0600 all scans were processing correctly. All LUTs and ancillary data have been checked and match JPSS data. Only band 12 is affected (reported as band 11 in the debugging output due to 0/1 indexing). Is it at all possible that the band calibration is causing these strange QF2_SCAN_SDR values?

I think you have identified the problem correctly. The VIIRS thermal infrared bands (M-Bands 12-16) all showed QF2_SCAN_SDR values of 32 or 33 during this period of the Emissive Band Calibration procedure. The values came back to normal after the procedure was completed. Our SeaDAS Level 2 product processing also failed during this time period, but is now completing normally. Can you check to see if your installation is executing correctly now? If not, please let me know, and we will investigate further.

Kathy

Hi Kathy,

Confirmed that everything is working properly for me now. We also had a reported value of 32/33 for QF2_SCAN_SDR. Despite the actual data degradation apparently being small, it seems that this issue is likely to cost ~3-days of data loss every 3 months, though (based on the calibration schedule). If you have a work-around, I would love to hear it!

Regards

Ben

Hi Ben,

Is the software that you are concerned with the SeaDAS Level 2 software? Are there other packages too? Let me know, and we can give better advice.

I think you are right about the small changes. The data is expected to remain within spec.

Kathy