Radiocarbon distributions in the past deep Atlantic ocean at 21,000 cal BP (around the Last Glacial Maximum, file = MRA_21000_calBP_30W.nc) and 42,000 cal BP (the onset of the Laschamps Geomagnetic Excursion, file = MRA_42000_calBP_30W.nc) according to simulations running from 55,000 cal BP to 0 cal BP carried out with the LSG ocean general circulation model (Butzin et al., 2020) forced with IntCal20 atmospheric Δ14C and ice core CO2. Each data set displays the median of nine simulation results. Shown is the depletion of dissolved 14C with respect to the contemporaneous atmosphere expressed in terms of 14C age. Low 14C concentrations translate to high 14C ages and vice versa. In both data sets the average ocean circulation is the same. The differences between 21,000 cal BP and 42,000 cal BP are rather due to changes in atmospheric Δ14C levels, and different leads and lags between this atmospheric 14C and its oceanic uptake and dispersal. Data contain marine reservoir age (MRA) which is calculated out of oceanic and atmospheric D14C according to Eq 1 in Butzin et al (2017).

Atlantic meridional sections along 30°W as plotted in Figure 6.