Influence of Phytoplankton on Ocean Albedo

Abstract

Using numerical methods for solving the radiation transfer equation, ocean albedo values were calculated for a set of bio-op tical characteristics corresponding to situations with different chlorophyll concentrations (1 μg/L and 10 μg/L) and the case of intense coccolithophore bloom (8–12 million cells/L). Calculations were carried out in the spectral range of 280–2800 nm for cases of cloudless sky at various wind speeds and atmospheric transmission. It has been shown that for Case 1 waters, a change in chlorophyll concentration from 1 to 10 μg/L does not lead to changes in albedo. In the case of intense coccolithophore blooms, the ocean albedo can increase more than threefold. Calculation of average monthly albedo values for selected points in the Barents and Black seas showed that the presence of intense coccolithophore blooms significantly increases average monthly albedo values. The calculation of the values of radiation absorbed in the seawater column depending on the time of day, carried out for these points, demonstrated that the presence of blooms significantly reduces the values of absorbed radiation. It is shown that the contribution to the albedo of radiation emerging from water used in the state-of-the-art NEMO numerical ocean model, amounting to 0.005 ± ± 0.0005, corresponds only to Case 1 waters. Intense coccolithophore blooms can increase this contribution by more than 14 times. A simple formula is proposed for correcting albedo values taking into account the influence of bio-optical characteristics.