Assimilating GlobColour ocean colour data into a pre-operational physical-biogeochemical model

[摘要] As part of the GlobColour project, daily chlorophyll a observations,derived using remotely sensed ocean colour data from the MERIS, MODIS andSeaWiFS sensors, are produced. The ability of these products to beassimilated into a pre-operational global coupled physical-biogeochemicalmodel has been tested, on both a hindcast and near-real-time basis, and theimpact on the system assessed. The assimilation was found to immediately andconsiderably improve the bias, root mean square error and correlation ofmodelled surface chlorophyll concentration compared to the GlobColourobservations, an improvement which was sustained throughout the year and inevery ocean basin. Errors against independent in situ chlorophyllobservations were also reduced, both at and beneath the ocean surface.However, the model fit to in situ observations was not consistently betterthan that of climatology, due to errors in the underlying model. Theassimilation scheme used is multivariate, updating all biogeochemical modelstate variables at all depths. The other variables were not degraded by theassimilation, with annual mean surface fields of nutrients, alkalinity andcarbon variables remaining of similar quality compared to climatology. Therewas evidence of improved representation of zooplankton concentration, andreduced errors were seen against in situ observations of nitrate andpCO₂, but too few observations were available to conclude about globalmodel skill. The near-real-time GlobColour products were found to besufficiently reliable for operational purposes, and of benefit to bothoperational-style systems and reanalyses.

[学科分类] 海洋学与技术