Berlin 2014 – scientific programme

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UP: Fachverband Umweltphysik

UP 6: Kryosphäre und Ozeanographie

UP 6.2: Talk

Wednesday, March 19, 2014, 11:15–11:30, MAG 100

Sensitivity of phytoplankton growth to vertical mixing along a North Atlantic transect — •Lisa Hahn-Woernle¹, Henk Dijkstr¹, and Hans van der Woerd² — ¹Institute for Marine and Atmospheric research Utrecht, Utrecht University, The Netherlands — ²Institute for Environmental Studies, VU University, Amsterdam, The Netherlands

During the "Stratiphyt" cruises in Summer 2009 and Spring 2011 in-situ plankton and nutrient concentrations as well as upper-ocean turbulence characteristics were measured from Las Palmas to Reykjavik [1]. The measurements agree with previous findings that the incoming light intensity and the stratification of the upper ocean set important conditions for the initiation of the phytoplankton bloom close to the surface and also for a possible shift to a deep chlorophyll maximum below the mixed layer. To understand the influence of the upper-ocean turbulence on the meridional depth (upper 200 m) variation of the phytoplankton distributions, a advection-reaction-diffusion phytoplankton model was calibrated to fit the measured optical and biological measurements and then forced by the in-situ vertical mixing profiles. The results show, that the vertical phytoplankton distribution depends strongly on the characteristics of the applied vertical turbulence profile. [1] E. Jurado, H. van der Woerd and H. A. Dijkstra, Microstructure measurements along a quasi-meridional transect in the North Atlantic, J. Geophysical Res. Oceans, 117,(2012).