Starting today, Feb 3, 2014, the USGS will remove all Landsat 8 scenes from the online cache and reprocess the entire archive using updated calibration parameters.
The reprocessing will begin with the most recent acquisitions and then progress backwards to the beginning of the Landsat 8 mission. The entire reprocessing exercise is expected to take 50 days; however, scenes will also be available for reprocessing through on-demand product orders.
Rest assured, both the Operational Land Imager (OLI) and Thermal Infrared Sensor (TIRS) on Landsat 8 are operating correctly and producing quality measurements. The reprocessing is being undertaken to implement improvements in the calibration parameters, taking advantage of “radiometric and geometric refinements” that have been identified since launch, to “ensure good calibration and data continuity.”
The USGS states that “Most users will not need to reorder data currently in their local archive; however, users are encouraged to review all Landsat 8 calibration notices and evaluate the improvements as they relate to specific applications.”
“These corrections include all calibration parameter file updates since launch; improved OLI reflectance conversion coefficients for the cirrus band; improved OLI radiance conversion coefficients for all bands; refined OLI detector linearization to decrease striping; a radiometric offset correction for both TIRS bands; and a slight improvement to the geolocation of the TIRS data.”
More specifically, as outlined in the calibration notices:
- OLI bands 1-8 will have reflectance changes of up to 0.8 percent.
- OLI cirrus band 9 will have a more substantial reflectance change of about 7 percent.
- Vertical striping in OLI bands for dark uniform areas, such as water, will be reduced.
- TIRS offsets will remove about 2.1 K from band 10 and about 4.4 K from band 11.
So if you’re using Landsat 8, be sure to check the reprocessing details to evaluate whether the changes will impact your analysis.
For more info on Landsat: http://landsat.usgs.gov/