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Argo in the Nordic Seas

The original international Argo array lacked the high latitude and the regional seas. The Institute of Marine Research (IMR), Norway together with other European institutes, mainly from Germany, recognized this deficit and started to deploy Argo floats in the Nordic Seas already in 2001. Since 2006 the total number of float profiles has reached a stable amount above 800 profiles per year.

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Number of Argo profiles per year in the Nordic Seas.

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Dots for every Argo float profiles in the Nordic Seas since 2001. Bottom depth contours: 500, 1000, 1500, 2000, 2500, 3000 and 3500 m.

The ecosystem has traditionally been observed by ship surveys that can provide reasonable spatial resolution but lack information on the temporal variability. This is particular important with respect to the onset of the spring bloom and the evolution of chlorophyll concentrations throughout the season. We also expect that the timing of the bloom, the amount of new production, and the link between primary and secondary producers are prone to climatic influence through variable conditions of stratification and wind mixing. To increase our knowledge about climate’s influence on the primary production IMR will therefore in the coming years deploy several bio-Argo floats with additional biogeochemical sensors like oxygen, chlorophyll-a (fluorescence), etc. in the Nordic Seas.

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Fluoressence (chlorophyll-a) and mixed layer depth (MLD) from an Argo float in the Norwegian Sea plotted together with Sverdrup’s Critical Depth (Dcr). The spring bloom in May occurs just after the Dcr line cross the MLD line.