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Sinusoidal versus geographic products

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The sinusoidal products are produced according to the NASA SeaWiFS binning algorithm (“Level-3 SeaWiFS Data Products: Spatial and Temporal Binning Algorithms" J.W. Campbell, J.M. Blasidell, and M. Darzi, NASA Technical Memorandum 104566, Vol.32.); unlike the original NASA format, all grid cells are retained and those with no valid data contain NetCDF fill values. These products are transformed into regular grid geographic products (8640 by 4320 pixels in size as a Plate Carrée projection), but this can result in Moiré effects i.e. pixels with missing data where the input and output spatial resolutions are similar.

The sinusoidal products should be used in preference, but it’s acknowledged that many software packages cannot deal with this format and need to resample the data to a geographic projection in order to display it.

The PUG provides detailed information on how to read the products and there is also the freely available ESA BEAM VISAT package http://www.brockmann-consult.de/cms/web/beam/