Ocean colour orbital sensors can collect information of the first quarter of the photic zone depth. This study proposed to calculate the chlorophyll-a concentration for this penetration depth and to compare it with the satellite product. The photic and penetration depths at the Bermuda Atlantic Time Series (BATS) station were obtained from the diffuse light attenuation profiles. These, in turn, were based on the inherent optical properties, absorption and scattering, estimated from in situ chlorophyll-a measurements. The chlorophyll-a concentrations were calculated for the penetration depths of 440 nm, 550 nm and of the entire photosynthetic active region (PAR 400-700 nm). The results show good linear correlations between the satellite product and penetration depth chlorophyll-a concentrations (R 2 > 0.6). Both monthly and weekly SeaWiFS products underestimate in situ chlorophyll-a when its concentration is higher than 0.15 mg m -3 , probably due to the algorithm scheme of chlorophyll-a retrieval. Ten-year time series were constructed to analyze the seasonal patterns. The photic and penetration depths, as the subsurface chlorophyll-a maximum, tend to become shallower at the beginning of spring season (February to April) and deepen in summer season (June to July). This pattern might be associated with phytoplankton blooms and the mixed layer depth (MLD) seasonality.Pages: 7106-711
