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Optical cross-talk (Band 31 into Bands 32 - 36)

Description

The light through the Terra band 31 (11 µm) filter leaks into bands 32-36 (12-14 µm).

Impact to L1B Data Set

The light leak from Band 31 (sensitive to signals from the surface) produces surface feature "ghosts" in the images for Bands 32-36. A correction is applied to each detector response in bands 32-36. The correction, which is frame shift dependent, subtracts a small portion of the detector response of Band 31's nearest detector from the band 32-36 response. The coefficients for receiving Bands 32 - 36 are approximately 1%, 1.5%, 2.5%, 5% and 2.5%, respectively.

Estimated Impact to L2 Science Products

Following implementation of the mitigation approach in L1B, the impact of this optical crosstalk on L2 products is less than 0.1% of the EV radiance.

Cause of Effect

This optical cross-talk is caused by scattering off the bottom edge of the Band 31 spectral filter. The scattered energy is reflected between the filters and the detectors for Bands 32-36.

Mitigation Approach/Added Testing to Characterize Effect

Corrections have been applied based on pre-launch testing and on-orbit studies (moon observation and SRCA data), including studies of these ghosts. The correction coefficients in the LUT for receiving Bands 32 - 36 are approximately 1%, 1.5%, 2.5%, 5% and 2.5%, respectively.

Estimated Schedule to Complete

The correction is used in the collection 5 product after August 10, 2000. For collection 6, the correction will be used for all time periods in the mission.

History of Characteristic

Epoch
Number
Time SpanVersion Number at
start of epoch
General CharacteristicsImprovementsDocumentation
1Entire mission6Light leakCorrection coefficients appliedMemos M215, 222, 842, 919, 960, 976, 1049, 1052