Noticeable shift in select 4km global datasets

Content Type
Ocean Color data shown shifted approximately 9km westward from the correct position.

Please be aware NOAA CoastWatch has noted a positional shift in S-NPP/NOAA-20 VIIRS ocean color global mapped datasets.  We are investigating the cause within the processing chain and correction/re-processing that will be taken to resolve the issue.  The shift in data appears to be a systematic 2 pixel (9.3 km) westward shift in data pixels.  Although the shifted data predominantly occurs beginning June 29, 2022 (Day of Year 180) there are some interspersed reprocessed datasets pre-dating that date.

NOAA CoastWatch will reprocess the affected datasets and update this notice as more information is known (note,  during a Government shutdown,  updates will not be published but may occur. Please contact for information).

Datasets affected by this include:

  • Global 4km Anomaly Ratio and Difference Products (NRT + Science Quality):

    • Path: /pub0011/mecb/coastwatch/viirs/nrt/L3/global/chlora/anom[_n20]/WW00

    • Example Filenames:,

  • Global 4km Chlorophyll OCI S-NPP+NOAA-20 (NRT)

    • Path: /pub0016/coastwatch/mixed_viirs/L3/global/chlora/daily/WW00

    • Example Filename:

  • Global 4km Ocean Color IOP (NRT)

    • Path: /pub0011/mecb/coastwatch/viirs/nrt/L3/global/iop/daily/WW00

    • Example Filename:

  • Global 4km Ocean Color S-NPP VIIRS (Science Quality)

    • Daily, Weekly, and Monthly (Chlorophyll-a, kd490, kdPAR, nLw[410,443,486,551,671,638ag], PAR, SPM)

    • Path: /pub0011/mecb/coastwatch/viirs/science/L3/global/

    • Example Filenames:,