MODAPS PCR VNP 24-015
| PCR Number | VNP 24-015 |
|---|---|
| Date | 2024-11-18 |
| Initiator | Carol Davidson |
| Abstract | PGE595 2.0.11 Revision to PGE595.pl script for JPSS2 to correct mapping of APID034 inputs to GPS outputs (VJ2[ST]034) and APID037 inputs to BUS (VJ2[ST]037) outputs. We also revised PGE595.pl for the JPSS2 inputs filesizes and output split L0 sizes to improve the check that the products are of appropriate size. For JPSS2, we also implemented logic for NRT processing similar to that used for JPSS1 NRT where it confirms the split L0 size of all but the SCI APIDs and if smaller than expected it will error to allow for more L0 data to come in. It will retry up to 4 times automatically and continue on if the output size is correct. After that, operator intervention is needed. |
| Problem Statement | 11/7/24, we came to the realization that the JPSS2 L1A data is not being created correctly in that at Land SIPS we were mistakenly using APID 037 data for GPS data and APID 034 data for BUS data. It should be the other way around. It's true for all JPSS2 processing that the APIDs were staged in the reverse order, so impacts data in nrt3, nrt4, and standard processing AS5200 and the AS5201. We came to this realization because we had put an update in for the LSIPS L0 splitter/merger PGE595 in nrt4 (where the problem actually starts) and saw the difference between nrt3 and nrt4. When the mismatch was discovered, we reached out to the L1WG to inquire what impact the reversed data would potentially have, and they indicated it should have no impact on the actual geolocation. The S/C bus-critical (APID 37) and GPS (APID 34) telemetry are included in the files for information only. APID 37 is used by geolocation only to set a few status bits, and APID 34 isn't used at all. |
| Description of Change | Revision to PGE595.pl script for JPSS2 to correct mapping of APID034 inputs to GPS outputs (VJ2[ST]034) and APID037 inputs to BUS (VJ2[ST]037) outputs. We also revised PGE595.pl for the JPSS2 inputs filesizes and output split L0 sizes to improve the check that the products are of appropriate size. For JPSS2, we also implemented logic for NRT processing similar to that used for JPSS1 NRT where it confirms the split L0 size of all but the SCI APIDs and if smaller than expected it will error to allow for more L0 data to come in. It will retry up to 4 times automatically and continue on if the output size is correct. After that, operator intervention is needed. |
| Products Affected | VJ2T034, VJ2S034, VJ2T037, VJ2S037 |
| Software Affected | PGE595 2.0.11 |
| Processing String to Receive the Change | J2 Foward Processing. J2 Reprocessing. NRT |
| Downstream Product Effects | All VIIRS land products. |
| Data Granules to be Used for Science Testing | PGE595 2.0.11-0 in VJ2_00nrtglu 2.0.5 was put onto nrt4 and has been running there since 11/6/24 . This allowed us to see how the outputs differed initially and how it helped capture filesize mismatches. A science test was also conducted using revised PGE595 and processing through L1B and Control Point over 2 8-day periods using JPSS2 data. Test results from the science test were reviewed by Geolocation, VCST and LDOPE teams and all teams indicated that no differences were detected between test results and data in AS5201. |
| Justification | To use the L0 input datasets consistent with how ATMOS SIPS and Oceans SIPS do for JPSS2 processing, and to reduce gaps in JPSS2 NRT processing. |
| Effective Date for Implementation of Change | VJ2_00nrtglu 2.0.5 PGE595 2.0.11-0 went into nrt4 on 11/6/24; VJ2_00nrtglu 2.0.6 PGE595 2.0.11 is going into nrt3 and nrt4 on 11/19/24; VJ2_00glu 2.0.6 PGE595 2.0.11 is going into use at the leading edge for C2 starting 11/19/24, and into C2.1 starting with day 2024-057. |
| Status | Major algorithm development completed. V. Chiang approved 11/14/2024. G. Lin approved 11/14/2024. Sadashiva Devadiga approved 11/22/2024. Sudipta Sakar implemented 11/19/2024. |
