A new active-passive airborne data correlation technique has been developed which allows the validation of existing in-water ocean color algorithms and the rapid search, identification, and evaluation of new sensor band locations and algorithm wavelength intervals. Thus far, applied only in conjunction with the spectral curvature algorithm (SCA), the active-passive correlation spectroscopy (APCS) technique shows that (a) the usual 490-nm (center-band) chlorophyll SCA could satisfactorily be placed anywhere within the nominal 460–510-nm interval, and (b) two other spectral regions, 645–660 and 680–695 nm, show considerable promise for chlorophyll pigment measurement. Additionally, the APCS method reveals potentially useful wavelength regions (at 600 and ~670 nm) of very low chlorophyll-in-water spectral curvature into which accessory pigment algorithms for phycoerythrin might be carefully positioned. In combination, the APCS and SCA methods strongly suggest that significant information content resides within the seemingly featureless ocean color spectrum.
Frank E. Hoge and Robert N. Swift, "Active-passive correlation spectroscopy: a new technique for identifying ocean color algorithm spectral regions," Appl. Opt. 25, 2571-2583 (1986)