MODAPS PCR 20-027
| PCR Number | 20-027 |
|---|---|
| Date | 2020-12-15 |
| Initiator | Jim Ray |
| Abstract | PGE199 1.0.9 -- 1. Updated a solar zenith threshold from 105 to 110 degrees in no_EPH_prescan() (in file PGE199/GAPS/src/navigate.c). Several other non-science changes (metadata changes) for outputs were also made (in postprocessing programs), to reflect the contents of the SDSs more accurately. 2. Updated PGEVER to '1.0.9' in PGE199/GAPS/src/gaps_HDF.c and postprocessing programs. |
| Problem Statement | A routine (no_EPH_prescan()) was used to recognize which scans in an input file were to be processed, based upon several criteria, including whether the scan is in day or night. Day or night was determined by thresholding the solar zenith values for each scan in the input file -- but the threshold was set too low, so this routine was interpreting scans still in the daytime as nighttime. (Affecting MetOP-B processing only.) |
| Description of Change | A new version of PGE199 (V1.0.9) was delivered, with an increase of the solar zenith threshold in the prescan routine (no_EPH_prescan()). |
| Products Affected | AVHRR Version 5 LTDR products. |
| Software Affected | PGE199 1.0.9 |
| Processing String to Receive the Change | NOAA-N* Reprocessing. MetOp-B Reprocessing. MetOp-B Forward Processing. |
| Downstream Product Effects | None |
| Data Granules to be Used for Science Testing | A science test was run in AS 1813 and verified by both the science team and LDOPE. |
| Justification | This change will enable PGE199 to process all the orbits for a given day and no longer incorrectly skip orbits, for MetOp processing. |
| Effective Date for Implementation of Change | This PGE199 V1.0.9 will be used to resume LTDR V5 forward processing from day 2020-338 (December 3) and also to re-process the days 2020/326 - 337 (November 21 - December 2). |
| Status | Major algorithm development completed. Sadashiva Devadiga approved on 12/16/2020. Gang Ye approved on 12/16/2020. |
