Concentration of biogeochemical components of Marine Snow Catcher particulate samples from the mesopelagic zone of the Southeast Pacific sector of the Southern Ocean (CUSTARD-DY111).

This dataset provides concentrations of chlorophyll a (Chla; analysed with a Turner Designs Trilogy fluorometer), biogenic silica (BSi; analysed with a QuAAtro 39 segmented flow autoanalyser), particulate inorganic carbon (PIC; analysed with a Thermo iCap Duo ICP-OES) and particulate organic carbon (POC; analysed with a Thermo Scientific Flash Smart Organic Elemental Analyser) and particulate organic nitrogen (PON; analysed with a Thermo Scientific Flash Smart Organic Elemental Analyser) in four fractions from the marine snow catcher: tzero, top, bottom and tray. The POC and PON samples underwent replicate analysis and so the propagated analytical error is included for each sample. No replicate analysis was possible for the Chla, BSi or PIC samples. The CUSTARD DY111 cruise sampled three regions of contrasting productivity in the Pacific sector of the Southern Ocean in a North- South transect near 89W going from 55S to 60S. There were three sites, OOI which was the site of the US ocean Observatories Initiative Global Southern Ocean mooring, TN which was just north of the subantarctic front and TS which was just north of the polar front. Each of the sites were visited 4 times from December 2018 to January 2019. Four marine snow catchers (MSCs) were used to collect particulates of different particle pools (sinking vs suspended) at a given depth in the mesopelagic zone. At the fourth visit to TS and TN an inter- and intra-MSC variability study was undertaken to by deploying four MSCs to the same depth in quick succession. These data were collected to understand the role of the Southern Ocean in regulating global climate as part of the Carbon Uptake and Seasonal Traits in Antarctic Remineralisation Depth (CUSTARD) project (NERC grant NE/P021247/1).