MODAPS PCR VNP 19-002
| PCR Number | VNP 19-002 |
|---|---|
| Date | 2019-12-14 |
| Initiator | Sudipta Sarkar |
| Abstract | PGE500 3.0.7 PGE501 3.0. 23 PGE502 3.0.21 PGE502B 3.0.21 PGE560 2.0.1 PGE591 2.0.0 PGE592 2.0.0 PGE595 2.0.4 PGE599 1.0.1 1. Use of NASA Land SIPS variation of L1B/Geo code delivered by L1WG (V3.1.0.rc). 2. Changes to the GEO LUT approach to include: a. VIGMU (VIIRS instrument geometric model update), LUT and code changes b. Corrections for temporal pointing variations, unified LUT and code changes c. Kalman filter “module” in L1A to improve attitude accuracy, thus geolocation accuracy. d. Update EFL (effective focal length) in LUTs. 3. Changes to the L1B LUT, including: a. Accounting for the whole mission period for S-NPP VIIRS b. Improvements to RSB calibration factor estimations: 4. The major improvements on RSB are: 5. Apply 7 years of lunar F to calculate H_rta, from comparing with SD F(H_sdsm). 6. Use DCC and Libya4 data to determine H_rta SD positional dependence to remove the striping seen in the current version. 7. Solar azimuth dependence of H_rta for all bands. 8. Apply new DeltaC table for entire mission. a. Improvements to DNB: 9. Update DN0 table to remove striping seen in the current version. 10. Update LGS gain and gain ratios with updated H-factor. 11. Fixed some contaminated straylight correction tables which were affected by aurora light. |
| Problem Statement | Generate S-NPP Collection 2 (C2) L1B/Geo products using NASA Land SIPS variation of L1 codes and updated L1B/GEO LUTs developed using the entire S-NPP mission period, with additional improvements. |
| Description of Change | Major changes for S-NPP C2 L1B/Geo product includes 1. Use of NASA Land SIPS variation of L1 code delivered by L1WG (V3.1.0.rc). 2. Changes to the GEO LUT approach to include: a. VIGMU (VIIRS instrument geometric model update), LUT and code changes b. Corrections for temporal pointing variations, unified LUT and code changes c. Kalman filter “module” in L1A to improve attitude accuracy, thus geolocation accuracy. d. Update EFL (effective focal length) in LUTs. 3. Changes to the L1B LUT, including: a. Accounting for the whole mission period for S-NPP VIIRS b. Improvements to RSB calibration factor estimations: - Apply 7 years of lunar F to calculate H_rta, from comparing with SD F(H_sdsm). - Use DCC and Libya4 data to determine H_rta SD positional dependence to remove the striping seen in the current version. - Solar azimuth dependence of H_rta for all bands. - Apply new DeltaC table for entire mission. c. Improvements to DNB: - Update DN0 table to remove striping seen in the current version. - Update LGS gain and gain ratios with updated H-factor. - Fixed some contaminated straylight correction tables which were affected by aurora light. |
| Products Affected | All S-NPP L1A/L1B/Geo products including VNP02MOD/IMG/DNB, VNP03MOD/IMG/DNB. |
| Software Affected | PGE500 3.0.7 PGE501 3.0. 23 PGE502 3.0.21 PGE502B 3.0.21 PGE560 2.0.1 PGE591 2.0.0 PGE592 2.0.0 PGE595 2.0.4 PGE599 1.0.1 |
| Processing String to Receive the Change | S-NPP Forward Processing. S-NPP Reprocessing. NRT |
| Downstream Product Effects | None |
| Data Granules to be Used for Science Testing | Several science tests have been run to test and confirm the changes to the L1B/Geo code and LUTs and their impact on all downstream L2 products. |
| Justification | This S-NPP C2 re-processing will take advantage of the new NASA Land SIPS variation of the L1 code as well as the more refined and updated set of LUTs, created using the whole S-NPP mission period. In addition, the transition to the NASA L1 code will introduce some other improvements and additions like: 1. Eliminate instances of false fires that are seen in AS 5000 on certain data days due to anomalously high band I4 value. 2. Introduce a 375m land water mask (LWM) dataset known as “water_present” as part of the VNP03MOD files. 3. Reduce impact of South Atlantic Anomaly over active fires The S-NPP C2 reprocessing when completed is expected to provide user with temporally consistent set of land product suite from the full mission period of Terra and Aqua |
| Effective Date for Implementation of Change | The S-NPP C2 reprocessing as well as forward processing of all L1A/L1B and Geo products can commence from the week of November 25, 2019. |
| Status | Chris Justice approved 01/07/2020. Gang Ye approved on 01/09/2020. |
