| Summary: | Maintenance and Update Frequency: notPlanned Statement: The data presented here were obtained during the 42 day SOLACE (Southern Ocean Large Areal Carbon Export) voyage on the RV Investigator (IN2020_V08) to the Southern Ocean from 6 December 2020 to 15 January 2021, and include several months of observations from a robotic profiling BGC-ARGO float deployed at a polar site (55.48°S 138.5°E) during this voyage. SOLACE occupied three sites, one in the sub-Antarctic (47.1°S, 141.4°E) near the Southern Ocean Time Series (SOTS) station, and two south of the Polar Front (55.8°S 138.5°E (24 to 31 December 2020), 57.8°S 141.5°E (1 to 11 January), S-Figure 1). The results presented here focus only on the two polar sites, both sampled in a quasi-Lagrangian mode following the deployment of a holey-sock drogue at the mid-depth of the seasonal mixed layer. The drogue drift trajectory over 10 days at the 55.8°S site is presented in S-Figure 2. The trajectory was typical of the low advective regimes we sought on SOLACE, and was similar to that observed at the southern site. At each polar site, vertical oceanographic profiles were obtained using a Sea-Bird SBE911-plus CTD unit (conductivity, temperature, and depth) that was linked to calibrated fluorometer (Chelsea Aqua-Tracker Mk3), oxygen (SBE 43 electrode), photosynthetically active radiation (i.e., PAR, Biospherical Laboratories) and transmissometer (Wetlabs C-Star 700 nm) sensors. Mixed layer depths were computed for each CTD profile using the mean of a density threshold and density gradient algorithm. For the threshold, we followed Boyer Montegut's ???????? ????????. (2004) criteria (via Holte and Talley, 2009): a density difference of 0.03 kg m⁻³ referenced to the closest measurement to 10 dbar. For the mixed layer gradient, we followed Dong ???????? ????????. (2007) (via Holte and Talley, 2009) where the gradient criterion was 0.0005 kg m⁻³ dbar⁻¹. For CTD profiles of chlorophyll fluorescence, generally daytime values exhibiting NPQ (non-photochemical quenching) were interpolated between ...
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