MODIS reprocessing 1.1

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genecarlfeldman
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Joined: Fri Jan 30, 2004 9:11 am America/New_York
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MODIS reprocessing 1.1

by genecarlfeldman » Wed Jul 27, 2005 3:26 pm America/New_York

Ocean Color User Community,In February, we completed reprocessings of both the SeaWiFS and MODIS data sets which incorporated a number of improvements.  Shortly after the MODIS reprocessing, it became evident that the MODIS calibration sensitivity was changing in a completely different manner than was anticipated.  This was discussed at the NASA Ocean Biology Program meeting in Portland as were recommendations on algorithm revisions (K_490) and new products (calcite and fluorescence line height) stemming from the ocean color algorithm workshop and MODIS science team meeting held earlier.  As a result, another reprocessing seemed warranted and we alerted the user community about this in an earlier message a month or so ago.MODIS/Aqua ocean color reprocessing 1.1 is now underway. The main purpose for this reprocessing is to update the radiometric calibration coefficients for the ocean color bands based on the most recent solar diffuser trends, and to incorporate the modified K_490 algorithm. At the same time, we have introduced a small, one time adjustment in the relative gain between detectors to reduce striping in the derived products.  In addition, and to be consistent with SeaWiFS reprocessing 5.1 (completed last month), this MODIS/Aqua reprocessing will also take advantage of the updated (Version 8) TOMS ozone products, and the 9-km-resolution SMI maps will be changed from 4096x2048 to 4320x2160.  More detailed information regarding these changes is available at http://oceancolor.gsfc.nasa.gov/REPROCE ... 1/.Level-2 products from the previous MODIS/Aqua reprocessing have already been deleted from the Ocean Color Web archives.  These files will be replaced within the next 1-2 weeks as Reprocessing 1.1 proceeds. The current Level-3 products will remain accessible until the Level-2 reprocessing is completed and Level-3 products can be regenerated.  The new calcite and fluorescence line height products will be generated separately once all this is completed.We are quite sensitive to the impact of this recent flurry of reprocessings on you as users trying to get research results finalized and published.  However, it has been necessary in order to address issues of consistency between the two data sets and to get the procedures for handling the MODIS calibrations worked out.  Given the level of consistency between SeaWiFS and MODIS resulting from this reprocessing (5.1 for SeaWiFS and 1.1 for MODIS/Aqua), we believe we will not need to reprocess either dataset anytime soon and will start focusing our work on utilization of the 250 and 500 m bands for nearshore applications.  Thanks for your patience.The NASA Ocean Color Processing Group

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