Global Distribution of the Random Uncertainty Associated With Satellite-Derived Chl a

The comparison of coincident daily records of the concentration of chlorophylla(Chla) derived from the Sea-viewing Wide Field-of-view Sensor and the Moderate Resolution Imaging Spectroradiometer can provide the distribution of the standard deviation ¿ associated with the zero-mean random component of the uncertainty budget. The proposed approach does not quantify the bias characterizing the Chlasatellite product, but it is spatially and temporally resolved and thus appears as a useful complement to validation exercises within situdata. The global median of ¿ is equal to 0.074 for log-transformed Chla. The values of ¿ that are around or larger than 0.1 are found in a significant part of the ocean, including the centers of the subtropical gyres, some Arctic and Antarctic areas, or eastern boundary upwelling regions. In general, ¿ increases at the low and high ends of the Chlarange, whereas it is lowest in the interval 0.1-0.3 mg ·m-3.