Semi-Annual Landsat Calibration Meeting Held

Jun. 20–21 • On June 20-21, 2007 the joint NASA-USGS Landsat calibration working group met at South Dakota State University in Brookings, SD. Some key results/recommendations presented at the current meeting included:

• The Landsat-7 ETM+ geodetic error (RMSE) has degraded slightly to about 30 meters in the cross track and along track directions. It is still about a factor of 2 better than before the shut down of the noisy gyro in March 2005. 
• A smooth transition from Scan Angle Monitor (SAM) to bumper mode for L7 ETM+ occurred on April 1, 2007.  The performance with the updated CPF bumper mode parameters is at about 5m (RMSE), versus 4 m (RMSE) for Scan Angle Monitor mode.
• The Band-to-band registration for all the L7 ETM+ bands remains within the specifications and shows no need for calibration update.
• The MTF of the Landsat-7 ETM+ bands have stabilized, consistent with pre-launch outgassing predictions. Hurricane Katrina damaged cross-scan MTF target – Interstate Highway 10 bridge - on 8/29/2005. The construction of the new bridge next to the original bridge makes it too variable to use as an MTF target.
• Banding has been observed in Landsat-7 ETM+ thermal band data since the switch to bumper mode.  The banding has been traced to a shift in the location of the internal calibrator data for the reverse scans as result of the bumper mode transition.  Updates to the calibration parameter file (CPF) were implemented with the July 1, 2007 CPF releases.
• The Landsat 7 ETM+ reflective band radiometric calibration gains continue to be stable to an uncertainty of several tenths of a percent per year. No changes were recommended.
• An update to the Landsat-5 TM reflective bands calibration was implemented on April 2, 2007. Although this calibration update applies to all archived and future L5 TM data, the principal improvements in the calibration are for data acquired during the first eight years of the mission (1984-1991), where the changes in the instrument gain values are as much as 15 percent. This update is a result of analyses conducted using North African test sites with the data made available from the European Space Agency (ESA).

  This update is described in: Chander, G., Markham, B., and Barsi, J. 2007. Revised Landsat-5 Thematic Mapper radiometric calibration. IEEE Geoscience and Remote Sensing Letters 4(3) (in press). See also: http://landsat.usgs.gov/resources/project_documentation.php

• An update to the Landsat-5 TM band 6 calibration was also implemented on April 2, 2007. An instrument offset correction of 0.092 W/ (m2 sr mm) or about 0.68 °K (at 300 °K) will be added to all L5 TM thermal band (Band 6) data acquired since April 1999. For users who already own processed thermal band data with acquisition date on or after April 1, 1999, and processing data between April 1, 1999 and March 4, 2007, adding 0.092 W/m2 sr µm to a radiance level product will be the equivalent of getting the data reprocessed after the correction is made to the processing system. A procedure has been developed to calibrate Landsat-5 thermal band data using long standing buoys in the Great Lakes; this analysis to proceed over the next six months should allow evaluation of the calibration back to launch in 1984.

  This update is described in: Barsi, J., Hook, S., Schott, J., Raqueno, N., and Markham, B. 2007. Landsat-5 Thematic Mapper thermal band calibration update. IEEE Geoscience and Remote Sensing Letters 4(4) (in press).

Contributor: Brian Markham

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