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Abstract. Phytoplankton form the base of marine food webs and playan important role in carbon cycling, making it important to quantify ratesof biomass accumulation and loss. As phytoplankton drift with oceancurrents, rates should be evaluated in a Lagrangian as opposed to an Eulerianframework. In this study, we quantify the Lagrangian (from Bio-Argo floatsand surface drifters with satellite ocean colour) and Eulerian (fromsatellite ocean colour and altimetry) statistics of mesoscale chlorophylland velocity by computing decorrelation time and length scales and relatethe frames by scaling the material derivative of chlorophyll. Because floatsprofile vertically and are not perfect Lagrangian observers, we quantify themean distance between float and surface geostrophic trajectories over thetime spanned by three consecutive profiles (quasi-planktonic index, QPI) toassess how their sampling is a function of their deviations from surfacemotion. Lagrangian and Eulerian statistics of chlorophyll are sensitive to thefiltering used to compute anomalies. Chlorophyll anomalies about a 31 dtime filter reveal an approximate equivalence of Lagrangian and Euleriantendencies, suggesting they are driven by ocean colour pixel-scale processesand sources or sinks. On the other hand, chlorophyll anomalies about aseasonal cycle have Eulerian scales similar to those of velocity, suggestingmesoscale stirring helps set distributions of biological properties, andratios of Lagrangian to Eulerian timescales depend on the magnitude ofvelocity fluctuations relative to an evolution speed of the chlorophyllfields in a manner similar to earlier theoretical results for velocityscales. The results suggest that stirring by eddies largely sets Lagrangiantime and length scales of chlorophyll anomalies at the mesoscale.