Abstract

In the Southern Ocean, increasing evidence from recent studies is highlighting the need for high-resolution sampling at fine spatial (meso- to sub-mesoscale) and temporal scales (intra-seasonal) in order to understand longer-term variability of phytoplankton and the controlling physical and biogeochemical processes. Here, high-resolution glider data (3 hourly, 2 km horizontal resolution) and satellite ocean colour data (2-4 km) from the Sub-Antarctic zone (SAZ) were used to 1) quantify the dominant scales of variability of the glider time series, 2) determine the minimum sampling frequency required to adequately characterise the glider time series and 3) discriminate how much of the variability measured with a glider is the result of temporal variations versus spatial patchiness. Results highlight the important role of signals shorter than 10 days in characterising surface chlorophyll (chl-a) variability , particularly in spring (97%) and to a lesser degree in summer (27%). These small scales of variability were also evident in the physical indices of SST, wind stress and mixed layer depth. Further analysis revealed that sampling at high frequencies (

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Box-and-whisker plots for the mean and standard deviation for subsampling at periodic frequencies (blue boxes) and the corresponding random extraction (red boxes) for the summer surface chl-a time series.

Box-and-whisker plots for the mean and standard deviation for subsampling at periodic frequencies (blue boxes) and the corresponding random extraction (red boxes) for the summer surface chl-a time series.

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