Carbonate system parameters calculated from measured TA/DIC and measured TA/pH pairs, respectively, during POLARSTERN cruise PS111 (ANT-XXXIII/2)

Aragonite undersaturation (Ωar < 1) events are projected to rapidly increase in frequency and duration in the Antarctic Weddell Sea by 2050 due to uptake of increasing amounts of anthropogenic CO2. Thecosome pteropods are bioindicators of ocean acidification (OA) because their aragonite shell dissolves easily at low Ωar. This study aimed to establish a baseline of the current shell dissolution state of the pteropod Limacina helicina antarctica in relation to the water column Ωar in the southern Weddell Sea during austral summer 2018 that can be used for monitoring of progressing OA in the Weddell Sea. The present dataset provides depth profiles of the carbonate system parameters determined on water bottle samples collected alongside the CTD casts during PS111 covering pteropod collection depth and beyond. The carbonate system was calculated with the R package 'seacarb' from measured TA/DIC and TA/pH pairs, respectively. Included in this dataset are also concentrations of silicate, phosphate and chlorophyll a.