MODAPS PCR 07-020
| PCR Number | 07-020 |
|---|---|
| Date | 2007-10-18 |
| Initiator | James Kuyper |
| Abstract | Several minor updates to PGE02. |
| Problem Statement | This PCR addresses several unrelated minor problems at one time: 1. The PGEVersion ECS Inventory metadata is filled in with a value obtained from one of the input LUT files. 2. The 5km subset Latitude and Longitude SDSs in the 1KM product files are chunked with a chunk size of 10x1354. 3. All header files currently have header guard macros with names that start with two underscores. 4. The code currently checks for a Scan Type of "Mixed" in the L1A file. |
| Description of Change | 1. Change to obtain the PGEVersion from the PCF. This will be the MODAPS PGE Version number, rather than the GDAAC PGE Version number, which means that there will be a jump from 5.0.6 to 5.0.40 when this change finally goes into production, since the MODAPS PGE number has changed more frequently than the GDAAC number. 2. Change the chunk sizes for the 5km Latitude and Longitude SDSs to 16x271. 3. Remove the initial underscores from all header guard macro names. 4. Remove all code and comments referring to the "Mixed" scan type. |
| Products Affected | M[O|Y]D021KM, M[O|Y]D02HKM, M[O|Y]D02QKM, M[O|Y]D02OBC, M[O|Y]D021QA |
| Software Affected | PGE02 |
| Processing String to Receive the Change | Terra Forward, Aqua Forward |
| Downstream Product Effects | Downstream PGEs will have ProductionHistory values which reflect the change in the PGE02 Version number. |
| Data Granules to be Used for Science Testing | 2007-238, 11:00-13:00, Terra and Aqua |
| Justification | 1. The MODIS Science Software Delivery Guide requires that MODIS software should obtain the PGEVersion from the PCF. This is MCST's Razor Issue #210. 2. The current chunk size is wasteful. The typical 1KM file has 406x271 = 110,026 Latitude values. It takes 41 chunks of size 10x1354 to cover the Latitude array, with a total size of 555,140 values. It only takes 26 chunks of size 16x271 to cover the array, with a total size of 112,736. Most importantly, a chunk size of 16x271 is what was originally announced when it was decided that PGE02 product files must be chunked. 3. According to the ISO C standard, identifiers starting with two underscores are reserved to the implementation for all uses. Any program which defines such an identifier therefore has undefined behavior. EOSDIS coding standards require our delivered code to conform to the C standard. Razor issue #205. 4. L1A files have never had a value of "Mixed" for the scan type. Razor issue #209 |
| Effective Date for Implementation of Change | |
| Status |
