ELECTRONIC OVERSHOOT AND OTHER BIAS IN THE CZCS-GLOBAL-DATA-SET - COMPARISON WITH GROUND TRUTH FROM THE SUB-ARCTIC PACIFIC

For an area near Ocean Weather Station P in the eastern subarctic Paci fic, in situ observations of surface phytoplankton pigment are compare d to pigment concentration estimates from the Coastal Zone Color Scann er (CZCS). CZCS data favourably supplement the in situ data, but a few extreme CZCS estimates have erroneously elevated the temporal composi tes of the region in the NASA Global Data Set. Effects of CZCS subsamp ling, atmospheric correction, cloud and systematic error detection on accuracy and variability are examined. For the open ocean, accurate at mospheric correction and detection of cloud contamination are the most important requirements for quantitative application of CZCS data.