MODAPS PCR 21-001
| PCR Number | 21-001 |
|---|---|
| Date | 2021-01-12 |
| Initiator | Jim Ray |
| Abstract | PGE199 1.0.10 -- - Added lat/lon prescreening to the "Projection into grid" portion of main() (gaps.c) -- if geolocation has problems (zeros in it (lt/gt +/-0.005)), replace such values with -999.0. - Updated PGEVER to '1.0.10' in PGE199/GAPS/src/gaps_HDF.c and postprocessing programs |
| Problem Statement | A few AVHRR GAC files contain zeros as geolocation fill values, leading to artifact in the outputs. |
| Description of Change | A new version of PGE199 (V1.0.10) was delivered, which replaces zeros in geolocation fill values with fill values the algorithm was designed to handle (-999.0). |
| Products Affected | AVHRR Version 5 LTDR products. |
| Software Affected | PGE199 1.0.10 |
| Processing String to Receive the Change | NOAA-N* Reprocessing. MetOp-B Reprocessing. MetOp-B Forward Processing. |
| Downstream Product Effects | Given the rarity of bad geolocation fill values in the GAC record, there is improvement (elimination of artifact) to only a small number of outputs. |
| Data Granules to be Used for Science Testing | Science test run in AS 1821 and products verified by both the science team and LDOPE. |
| Justification | This change will eliminate geolocation-based artifact in PGE199's products. |
| Effective Date for Implementation of Change | This PGE199 V1.0.10 will be used in LTDR V5 forward processing from day 2021-011 (January 11) and to resume the V5 MetOp-B reprocessing (2018 and 2019). Some of the days affected by this issue, both in reprocessing and forward processing, like days 2014-188, 2017-031 and 2020-351 will also be reprocessed using this version. |
| Status | Major algorithm development completed. Sadashiva Devadiga approved on 01/12/2021. Gang Ye approved on 01/21/2021. |
