(Sub-)mesoscale Processes Lessen Climate Change Induced Primary Production Decline in an Idealized Simulation of the North Atlantic/Pacific.

Decline in primary production is observed in several areas of the world ocean since the late 20th century [Behrenfeld et al., 2006; Henson et al., 2010; Gregg and Rousseaux, 2014]. Earth System Models (ESM) predict a further decline by the end of the 21st century [Bopp et al., 2013]. However ESM do not resolve (sub-)mesoscale processes which have been shown to significantly modifiy productivity [Mahadevan, 2016; McGillicuddy Jr., 2016]. In order to examine how our current predictions of these changes are biased due to the absence of (sub-)mesoscale processes, we carry a model study in which an idealized configuration of the North Atlantic/Pacific is run for several decades with 3 horizontal resolutions : 100km, 12km and 4km. Two scenarios are examined : a preindustrial scenario, with a seasonally repeating atmospheric forcing, and a climate change scenario where a constant temperature trend is added to the previous forcing. In the climate change scenario, relatively to the preindustrial scenarion, we show primary production decline by 18%, 13% and 12% in the 100km, 12km and 4km resolution respectively.

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