Description

Terra mirror side differences and striping is seen in L1B EV image data.

Impact to L1B Data Set

It is significant in Band 8, noticeable in Band 9, and minimal in other bands.

Estimated Impact to L2 Science Products

L2 science products have a polarization correction, so the impact will be less in L2.

Cause of Effect

The consensus is that this is primarily a polarization effect which is coupled with the viewing geometry.

Mitigation Approach/Added Testing to Characterize Effect

MCST has been working with the Ocean Color Group to address the improvement of the absolute accuracy of Band 8. An analysis package describing the problem was presented on 10/17/07. In summary, the mirror side difference is a function of geolocation, season, and AOI. This mirror side dependency has increased over time from approximately 3% in 2003 to about 11% in 2007. The dependency is indirectly included in the current RVS correction and there is no easy way to decouple these effects. The geolocation variation occurs too rapidy to be handled by our Look-up Tables. Currently no polarization correction is applied in L1B processing and it would require major code changes to the L1B algorithm to incorporate some form of a decoupled RVS and polarization correction. One option for dealing with this issue is to provide users with a modeled polarization correction which they could apply to the L1B data. The current RVS derivation for Terra uses mirror side ratio data over one specific Ocean site. MCST is in the process of investigating the use of alternate sites in the Terra RVS derivation.

Estimated Schedule to Complete

N/A

History of Characteristic