Ocean province classification using ocean colour data: observing biological signatures of variations in physical dynamics

We have used satellite colour data to classify ocean environments for monit oring interannual changes in the ocean. The unsupervised classification met hod is based on our observation that the frequency distributions of Coastal Zone Color Scanner (CZCS) annual pigment means and standard deviations are nonuniform and contain distinct clusters. The frequency distributions are used to objectively determine ocean areas with similar pigment statistical characteristics. A major separation between high variance, high pigment and lower variance, lower pigment waters is observed in terms of global ocean area. The ocean areas determined with our method reflect different bio-logi cal responses to variations in ocean physical dynamics. Pigment means and v ariances around the Joint Global Ocean Flux Study (JGOFS) Time Series stati ons are used as fiducial characteristics. Hawaii Ocean Time-series (HOT) st ation is associated with the low-variance portion of the global annual pigm ent distribution characteristic of the central gyres, but shows slightly hi gher mean and variance than the minima in the central Pacific gyre. The Ber muda Atlantic Time Series (BATS) pigment associations comprise a transition al region between the gyres and high-variance pigment areas, and circumscri be the HOT pigment associations. Together, these associations encompass 23% (HOT-like) and 48% (BATS-like) of the Northern Hemisphere open ocean. The Pacific regions delineated by the JGOFS station pigment-based patterns are similar to distributions described historically for Pacific zooplankton com munities. Interannual variation for the northern hemisphere gyre area is on the order of by 10% for the 11/78-10/81 period.