MODAPS PCR VNP 24-009
| PCR Number | VNP 24-009 |
|---|---|
| Date | 2024-07-10 |
| Initiator | Carol Davidson |
| Abstract | NPP VIIRS Orbit Files Installed the orbit text files for NPP, viirs_orbit_times.txt, and JPSS1, viirs_j1_orbit_times.txt, to the set provided by OCEANS SIPS which they created in 2019 with test version of PGE500/L1A v3.0.16-0, so they could be tested with. Performed SSTG tests for both NPP and J1, no differences identified for NPP, but found improvements for JPSS1 orbit numbers. Used PGE500 3.0.16-0 in science test to confirm changes for JPSS1 orbit numbers were as expected/desired. Once test results were approved, asked CM to install updated orbit text files to production coefficients area. Install was done on 7/1/2024. |
| Problem Statement | A user flagged that the orbit numbers for JPSS1 data were not changing in line with NOAA orbit numbers. Investigation revealed that the text file used by the L1A code for setting orbit numbers in data. Investigation found that the orbit text files used for NPP and JPSS1 were not the most recent set. |
| Description of Change | Installed the orbit text files for NPP, viirs_orbit_times.txt, and JPSS1, viirs_j1_orbit_times.txt, to the set provided by OCEANS SIPS which they created in 2019 with test version of PGE500/L1A v3.0.16-0, so they could be tested with. Performed SSTG tests for both NPP and J1, no differences identified for NPP, but found improvements for JPSS1 orbit numbers. Used PGE500 3.0.16-0 in science test to confirm changes for JPSS1 orbit numbers were as expected/desired. Once test results were approved, asked CM to install updated orbit text files to production coefficients area. Install was done on 7/1/2024. |
| Products Affected | VNP01, VJ101 |
| Software Affected | NPP VIIRS Orbit Files |
| Processing String to Receive the Change | S-NPP Forward Processing. J1 Foward Processing. |
| Downstream Product Effects | All VIIRS land products. |
| Data Granules to be Used for Science Testing | A one day science test was conducted using J1 data and PGE500/L1A 3.0.16-0, which pointed to revised orbit number text file. Test was run in AS4053 and processed from L1A through LSR CMG and L2G Light LSR. Test executed without issue and was reviewed by LDOPE. Separate tests were also run for 8-day LSR and 16-day VI using output from single day test combined with standard production tests to confirm codes could successfully process mixed orbit numbers, and they ran without issue. |
| Justification | To have JPSS1 orbit numbers more in line with NOAA orbit numbers; to have the orbit text files for NPP and JPSS1 in line with the L1WG set. |
| Effective Date for Implementation of Change | Revised orbit files installed by CM on 7/1/24 and picked up for use right away. |
| Status | Major algorithm development completed. Sadashiva Devadiga approved 07/12/2024. Sudipta Sakar implemented 07/10/2024. |
