Interactive comment on “Description of the biogeochemical features of the subtropical southeastern Atlantic and the Southern Ocean south off South Africa during the austral summer of the International Polar Year” by F. A. C. Le Moigne et al

ical data (water column profiles) for this undersampled HNLC region of the Southern Ocean. The data obtained is divided into four biogeochemical domains namely, Subtropical domain, the confluence of Subtropical and Sub-antarctic domains, the Polar Frontal zone (PFZ) and the northeastern branch of the Weddell Gyre. Each domain is discussed relative to its corresponding hydrography and biogeochemical characteristics, relating the observed chemical distributions to underlying physics. Overall the manuscript should be improved according to the “Specific and Technical comments”, and there is some discussion points that should be better contextualised, in the discussion section, particularly relating the observed distribution to temporal timescales. Oligotrophic conditions in the surface waters in the northern (subtropical) region are supported by relatively low export production estimates from cited literature. The authors suggest no significant variation in nutrient concentrations throughout the growing season, however this highly turbulent region (Agulhas retroflection), observed Eddy activity and the elevated and variable chl concentrations in the surface throughout the year possibly could indicate highly variable conditions through the growing season. In the Subantarctic where the eddy activity was observed, tongue-shaped density contours are called on in support of the observed nutrient distributions. It is not clear how these silicate from Fig6 (taking the individual profiles adjacent to and within the eddies) support this trapping of ‘distant waters’ (in the cyclonic eddy) and winter convection (in the anticyclone). I think this section could benefit from seeing (a figure) the actual density contours from the cited literature. A diatom bloom in the Polar Front zone is inferred from the silicate gradient across the Polar Front, the depletion of silicate, low concentrations of chl-a, and relative accumulation of ammonium, based on previous published data in other regions. It is however difficult to infer temporal variability in nutrient concentrations from the current dataset, particularly referring to the bloom as a single event. Seasonal drawdown of silicate and nitrate well as daily production rates are estimated from seasonal drawdown of silicate and nitrate assuming a 90 day productive period, is useful, however the dataset gives stronger supports for spatial distribution patterns than for temporal variability. For instance Si* data support the spatial