Prediction Of The Annual Cycle Of Phytoplankton Production In The North East Atlantic

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SeaWiFS satellite measurements of ocean colour, available for the whole globe on a weekly basis, are routinely converted into estimates of chlorophyll a concentration using calibration algorithms. These calibration algorithms are validated using bottle measurements collected in clear, open ocean waters, where chlorophyll a concentrations are low. The North East Atlantic has large areas of coastal and polar waters, where these calibration algorithms do not work well. Thus, although the satellite measurements describe the broad-scale patterns in chlorophyll a concentration, quantitative agreement between satellite estimates and bottle measurements is poor. The actual relationship between bottle measurements and satellite estimates is complex and varies with water characteristics, which in turn vary with depth and time of year. We therefore model bottle measurements as a function of SeaWiFS estimates, depth and time of year, using three- dimensional thin plate regression splines. The resulting model provides plausible predictions in time and space, which capture the main features of both the satellite and bottle data.