MODAPS PCR 16-011
| PCR Number | 16-011 |
|---|---|
| Date | 2016-06-17 |
| Initiator | Zhuosen Wang |
| Abstract | PGE24 v6.0.8 and 6.0.8_1. Fix the floating point comparison while deciding the overall quality of the CMG pixels in PGE24. Update the snow flag when at least one band is non-fill. Version 6.0.8 to be used in forward processing - export all CMG products to LP-DAAC, 6.0.8_1 to be implemented in re-reprocessing to replace only selected CMG products (MCD43C1/2/3/4 and MCD43D40) at LP-DAAC. |
| Problem Statement | Daily BRDF-Albedo CMG product MCD43C2 generated by the on-going C6 reprocessing wasn't flagging any retrieval as good quality in the quality dataset. Snow flag does not match the spectral QA. |
| Description of Change | Update the PGE24 to account for the precision error while comparing the floating point value against an integer, and set the snow flag when at least one band is not fill value. |
| Products Affected | MCD43C1, MCD43C2, MCD43C3, MCD43C4 |
| Software Affected | MOD_PR24 |
| Processing String to Receive the Change | Terra and Aqua Reprocessing |
| Downstream Product Effects | None. |
| Data Granules to be Used for Science Testing | Process 8-day period starting data day 2010009 generating the BRDF-Albedo product for all land tiles for each of the data days using the 16-day input from the C6 archive. 2010-059 |
| Justification | Due to the error in the floating point comparison no retrievals in the CMG product were flagged as good, misleading the data users of the overall quality of the product. Without this fix user applications would consider the retrievals to be of non-nominal quality. Reprocessing of CMG from the beginning of the mission is required for users to be able to correctly interpret the product quality. Updating the snow flag in CMG will benefit the gap-filling process to avoid removing valid values for some bands due to the lack of snow information. |
| Effective Date for Implementation of Change | Completed. |
| Status | Major algorithm development completed. Sadashiva Devadiga approved on 07/05/2016. Michael King approved on 07/06/2016. Gang Ye approved on 07/07/2016. |
