A SIMPLE, MODERATELY ACCURATE, ATMOSPHERIC CORRECTION ALGORITHM FOR SEAWIFS

We present a simple modification to the standard coastal zone color sc anner (CZCS) atmospheric correction algorithm for application to Sea-v iewing-wide-field-of-view-sensor (Sea WiFS). The modification reduces the error in the water-leaving reflectance using the standard algorith m by a factor of 2-6 when the aerosol behaves as predicted by the LOWT RAN-6 models. For many aerosol models likely to approximate aerosol pr operties over the oceans the error in the retrieved water-leaving refl ectance is predicted to be less than or similar to +/- 0.002 at 443 nm for an aerosol load approximately 2 to 3 times that normally occurrin g in a maritime atmosphere. These errors in atmospheric correction lea d to an error in the pigment concentration (C), retrieved using the bl ue-green ratio algorithm, of less than or similar to 50% for more than 75% of the aerosol models tested, whenever the algorithm retrieves a ''reasonable'' pigment concentration, and when 0.1 less than or equal to C less than or equal to 1 mg/m(3). This accuracy may be sufficient for some applications, for example, at-sea processing to guide ships t o desirable sampling locations. An important feature of this algorithm is that, unlike more sophisticated and computational intensive algori thms, aerosol models are not required to effect the actual atmospheric correction. Investigators already having the CZCS algorithm implement ed on an image processing system should be able to process Sea-WiFS im agery by making very simple modifications to the code.