| One of the primary goals of biological oceanographers has been to accurately estimate and predict both global carbon and heat budgets, including interactions between the oceans, land, and atmosphere. A feasible means of achieving this goal is through the use of remotely-sensed data assessing sea-surface color, which serves as an indication of the light absorption within the sea. Despite the fact that total particulate absorption (a$sb{rm p}(lambda))$ determinations are routinely performed as part of oceanographic cruise surveys, it appears that we are not obtaining all the information available from these spectra. This study demonstrates a statistical partitioning of the total particulate absorption into contributions made by the most commonly observed particle-types (coccolithophorids, cyanobacteria, detritus, diatoms, dinoflagellates and "green" algae) within most marine euphotic zones. Such a partitioning is possible with the availability of absorption spectra obtained from individual particles using microphometry, and the use of a least-squares multicomponent analysis. Results presented in these studies confirm heterogeneous particle distributions, which change composition with season, distance from shore, and depth. Patterns emerge indicating relationships between surface detritus distributions and dynamic height anomalies, as well as evidence of layering by taxonomic groups with depth. This layering by depth in the Sargasso Sea and the California Current System demonstrated a restriction of diatom abundance to the upper water column, while "green" algae were observed toward the bottom of the euphotic zone. The coccolithophorids and dinoflagellates typically reached maximum absorption contributions at intermediate depths, while the cyanobacterial absorption contributions only appeared to reach percentage values above ten when other particle-types were scarce. As appropriate, the observed patterns in particulate distribution were coupled to environmental conditions (temperature, nutrients, PAR). The application presented should provide improvements in our understanding of the sources and extent of variability in light absorption by suspended particles in the water column which is necessary for our continued efforts to estimate global carbon budgets, as well as predict and estimate primary production. This effort is timely due to increased reliance upon data obtained from ocean color-sensors which are likely to detect signals from above the chlorophyll maximum, but not below. |
