Figure 8 - SeaWiFS Navigation

SeaWiFS channels (bands) are different from AVHRR. As you can see at the top of this figure, SeaWiFS looks at 8 channels of data, six of which are in the visible spectrum. AVHRR has 5 channels, only 1 of which is visble, but it also looks at temperature wavelenghts, which SeaWiFS does not. With SeaWiFS looking at ocean color and AVHRR looking at temperature, these two satellites compliment eachother nicely.

Now, they also differ in one other way. You remember how we navigated the AVHRR imagery. With SeaWiFS it is necessary to navigate before the image is processed. In the above figure, the image on the left is raw, while the processed image is on the right. The processed image has lost all details of the bays and coastline, giving you little detailed land mass to navigate off of. So we navigate the raw imagery, and then process, while in AVHRR imagery, it is not necessary to reprocess each raw image. One can navigate the final AVHRR SST product, unless you are using the data for assimilation, where you remove as much land as is removed with the SeaWiFS process.

Next step? Let's compare some AVHRR and SeaWifs images.