Beginning April 1, 2011, an updated absolute radiometric calibration will be applied to all Multi-Spectral Scanner (MSS) products generated by the USGS. The newly processed image data will appear darker by 17.6% in band 1, 8.6% in band 2, 5.2% in band 3 and 4.5% in band 4. Consequently, the sensor dynamic ranges (LMIN/LMAX values) will be proportionally reduced.
Previously, the MSS products were processed using radiometric calibration that was consistent among the five sensors, but not linked to an absolute scale. The absolute calibration was estimated by comparing scene data acquired simultaneously by both MSS and Thematic Mapper (TM) sensors onboard Landsat 5 while accounting for differences in spectral bandpasses of the two sensors. This update puts the MSS products on the same absolute radiometric scale with the TM and Enhanced Thematic Mapper Plus (ETM+) products.
Users need to be aware that although the MSS data now mirror the TM radiometric scale, the image-derived spectral radiances (W/m2 sr um) are not equivalent due to significant differences in the spectral bandpasses between TM and MSS instruments.