MODAPS PCR 06-014
| PCR Number | 06-014 |
|---|---|
| Date | 2006-08-11 |
| Initiator | Kamel Didan |
| Abstract | Fix to bypass LSR with a solar zenith angle greater than 85 degrees. |
| Problem Statement | A problem at the land surface reflectance product (daily MOD09, input to the VI algorithm) caused the algorithm to ingest bad data and subsequently produce unrealistic NDVI and EVI values over high latitude ice covered areas (70 to 80 deg. latitude). Some of the output pixels in the VI product are flagged as both snow/ice and cloud. |
| Description of Change | Although fixing the surface reflectance algorithm would have been sufficient, we decided to develop a work around at the VI level. This work around consisted of bypassing all observations with sun angle greater than 85 degrees. Patch also includes fix to flag output pixel either as cloud or snow/ice, not both. |
| Products Affected | L3 16-day VI (MOD13) |
| Software Affected | PGE25, PGE26, PGE27, PGE28, PGE35 |
| Processing String to Receive the Change | Terra Reprocessing |
| Downstream Product Effects | None. |
| Data Granules to be Used for Science Testing | h15v01, h16v01, h15v02, h16v02 for day 2000-065. |
| Justification | Since the SZ angle issue is a problem caused at the upstream level affecting the reprocessed MODIS VI products the fix is needed to correct the reprocessed data for the early period of 2000, no enhancements are expected. |
| Effective Date for Implementation of Change | Data day 2000-065 for C5 Terra Reprocessing. |
| Status | PI approved. Sadashiva Devadiga approved for Land, Vincent Salomonsom approved on 08/18/06. |
