MODAPS PCR 2004-11-03
| PCR Number | |
|---|---|
| Date | 2004-11-03 |
| Initiator | Lorraine Remer |
| Abstract | Corrected logic to allow aerosol retrievals under very clear conditions. |
| Problem Statement | Negative values in the L1B radiances of the 1.38 µm channel are currently being categorized as "bad input data:" by the MOD04 algorithm. No aerosol retrieval is attempted on such pixels. However, the negative values indicate very small reflectance at this channel, which implies a very clear scene with no high clouds. These are good pixels. Currently we are throwing out a great many good pixels. |
| Description of Change | We now permit small negative values of 1.38 µm, equating these values to "0", in the internal MOD04 cloud mask for aerosols. |
| Products Affected | M[OY]D04_L2 and M[OY]05_L2 |
| Software Affected | PGE04 |
| Processing String to Receive the Change | Terra Forward, Aqua Forward |
| Downstream Product Effects | Atmosphere Level 3 (all products) |
| Data Granules to be Used for Science Testing | Test on one day of data, Terra or Aqua |
| Justification | A great many good scenes go without aerosol retrieval because we currently throw out a pixel when the 1.38 µm value is negative. Our users in the Air Quality community complain that there is no aerosol data when conditions are best suited for a good retrieval (i.e. when skies are clear of clouds). |
| Effective Date for Implementation of Change | |
| Status |
