Satellite-derived estimates of marine primary productivity in the North Atlantic

At the heart of biological pump, which plays an important role in the removal of carbon into the ocean interior, is primary productivity. There are still many unknowns about the relationships between marine primary producers and their surrounding physical environment. This project is planned to improve the understanding of these relationships. The main goal of the project is to accurately quantify marine primary productivity and its seasonal to interannual variability, related to changes in sea surface t emperature, wind stress, fresh water fluxes and ocean circulation dynamics in the North Atlantic subpolar gyre. Primary productivity estimates will be calculated by a state-of-the-art algorithm, utilizing satellite observations of ocean colour in the pe riod from September 1997 onwards. The algorithm (Behrenfeld, et al., 2005) is based on a novel approach, and is developed using the knowledge obtained from laboratory studies. The main project goal will be achieved by fulfilling two specific objectives: The first specific objective is to assess the accuracy of the algorithm by means of the field estimates of primary productivity from the C-14 uptake method. If the algorithm shows a significant departure from the C-14 productivity estimates, its formulat ions will be investigated and improved accordingly. The second specific objective is to examine the relationship between primary productivity in the North Atlantic carbon sink region and the reported weakening of the sink (Lefèvre, et al., 2004), taking into account the changing physical conditions in the region. The knowledge achieved within this project is expected to contribute to a better understanding of the physical-biogeochemical feedbacks, which is highly important for carbon cycle studies and c limate-related research.