We systematically explore the cumulative effect of MISR research aerosol retrieval algorithm assumptions, quantifying and correcting the main sources of uncertainty over ocean. High median spectral aerosol optical depth biases of ~0.024 at low AOD are reduced to ~0.01 with an improved, physically based ocean surface model, particle properties and mixtures, adaptive reflectance uncertainty estimates and pixel selection, minor radiometric calibration adjustments and more stringent cloud screening.