MODAPS PCR 15-039
| PCR Number | 15-039 |
|---|---|
| Date | 2015-11-30 |
| Initiator | Zhuosen Wang |
| Abstract | PGE23 v6.0.29. Modified the PGE to delete update files of the previous day from the database: 1. Pass QA to function calc_albedo() (line 2344 in funcs.c), in which the band QA and mandatory QA can be altered to fill value if the calculated albedo is invalid. 2. Add function init_qa() to util.c (line 153). 3. Pass starting row and ending row number to the function main() to be able to split a tile into multiple simultaneous processes. 4. Add copy_hdf.c to merge files that processed by multiple processes. |
| Problem Statement | Some of the quality datasets in the suite of daily BRDF-Albedo tiled product are incorrect. Additionally high latitude tiles are taking nearly 2 hours to complete processing resulting in potential delay in the completion of the C6 reprocessing of the Albedo product suite and other downstream products such as LST. |
| Description of Change | Changes to PGE23 to: a. Inaccuracies in the quality datasets were caused by uninitialized QA datasets. Processing code was updated to properly initialize the quality datasets. b. To speed up the processing of tiles, split tile processing scheme was implemented with pre-processing and post-processing units to process a quarter of a full resolution tile on multiple processors and then merge the quarter tiles into one full tile. |
| Products Affected | MCD43A1, MCD43A2, MCD43A3, MCD43A4 |
| Software Affected | PGE23 v6.0.29 |
| Processing String to Receive the Change | Terra Reprocessing, Aqua Reprocessing |
| Downstream Product Effects | None. |
| Data Granules to be Used for Science Testing | Process two 16-day period starting with the data day 2001345 and 2006345 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 | For data users to be able to correctly use the science data in an applications, science quality datasets accurately reflecting the quality of the retrieved science parameters are required. BRDF-Albedo science data products are mostly correct, though some of the quality flags were incorrect inhibiting correct scientific interpretation of these data. Inaccuracies in the quality flag of the daily tiled product have negative impact on the quality of the downstream BRDF-Albedo products. In addition to fixing this issue at the leading edge of the C6 reprocessing, a re-reprocessing of the entire suite of BRDF-Albedo products is required to remove any temporal inconsistency in the product series from the collection version. An additional update to the PGE to process a tile using split-tile processing will let MODAPS continue processing of this product at nearly 2x the current rate, and also possibly even faster using additional dedicated resources available to the processing system after the recent completion of the tier1 reprocessing of other land products. |
| Effective Date for Implementation of Change | Completed. |
| Status | Major algorithm development completed. Sadashiva Devadiga approved on 11/30/2015. Michael King approved on 12/07/2015. |
