MODAPS PCR 2004-12-09
| PCR Number | |
|---|---|
| Date | 2004-12-09 |
| Initiator | Lorraine Remer |
| Abstract | Multiple changes to L2 aerosol retrieval algorithm. |
| Problem Statement | Land: Subpixel snow causes aerosol retrievals 2 to 10 times greater than reality. Current cloud mask logic permits cloud contamination. Geographic distribution of aerosol models leads to underprediction in highly absorbing regions of Asia. Current cloud fraction not a true cloud fraction. Unnecessary SDS's still in product. Bugs in the code permit occasional land retrieval over ocean. Ocean: Units incorrect for CCN. Cloud fraction not a true cloud fraction. Unnecessary SDS's still in product. |
| Description of Change | 1. Subpixel snow test and mask implemented. 2. Land cloud mask logic adjusted and QA flag set to 0 in some circumstances. 3. Geographic distribution of land aerosol models adjusted to agree with observed ranges of heavily absorbing aerosol. 4. Cloud fraction redefined to be a true cloud fraction, no longer containing pixels discarded for non-cloud reasons, and a new SDS introduced to hold cloud mask by products for better understanding of the cloud mask subtleties. 5. Bugs corrected and unnecessary SDS's removed. 6. CCN units corrected. |
| Products Affected | M[O|Y]D04_L2 |
| Software Affected | PGE04 |
| Processing String to Receive the Change | Terra Reprocessing, Aqua Reprocessing |
| Downstream Product Effects | Atmosphere Level 3 (all products) |
| Data Granules to be Used for Science Testing | Use Atmosphere 18-day science test data set. |
| Justification | Users must have confidence in product on a regional as well as global basis. Regions at snow boundaries, for example, must improve. Unnecessary SDS's take up resources and should be eliminated. Aerosol-cloud studies are very important and a true cloud product to be used in these studies is necessary. Cloud contamination is a difficult issue requiring adjustment and refinement. More cloud mask diagnostics are needed to be able to evaluate the final aerosol product. |
| Effective Date for Implementation of Change | Start of C5 Terra and Aqua Reprocessing. |
| Status |
