Fig 1.
Schematic view of our DA system for the first two cycles.
Fig 2.
Effect of DA using different radius.
Effect of DA increment at first analysis step on ST field using 2500, 5000, 7500, and 10000 km radius.
Fig 3.
Ensemble members (coloured lines) and ensemble mean before DA in (a) Exp_GLAC1D and (b) Exp_PaleoMist.
Fig 4.
GMST from free runs of the last deglaciation and comparison with the proxy-based reconstruction.
a) GMST from free runs of the last deglaciation using the different ice sheet reconstructions, GLAC-1D and PaleoMist. b) Comparison of GMST anomaly from the early Holocene of our free runs compared to [9].
Fig 5.
ΔGMST calculated by raw averaging over the observation locations.
Mean surface temperature change (ΔMST) calculated by averaging over the proxy locations for (a) Exp_GLAC1D and (b) Exp_PaleoMist. The orange, green, and black lines illustrate trajectories for observation, DA ensemble, and prior ensemble means, respectively.
Fig 6.
Climate variables trajectories in Exp_GLAC1D.
North Atlantic FW (a), SSS (b), AMOC at 26° north (c), and ΔGMSTs based on the model field (d) for Exp_GLAC1D. Different colours in (a), (b), and (c) correspond to ensemble members. The red line in (d) represents ΔGMST for the free run. The orange line in (d) is the proxy reconstruction of ΔGMST by [9] projected to 5° × 5° resolution. The blue line in (d) is the DA-based reconstruction of ΔGMST by [25].
Fig 7.
Climate variables trajectories in Exp_PaleoMist.
North Atlantic FW (a), SSS (b), AMOC at 26° north (c), and ΔGMSTs based on the model field (d) for Exp_PaleoMist. Different colours in (a), (b), and (c) correspond to ensemble members. The red line in (d) represents ΔGMST for the free run. The orange line in (d) is the proxy reconstruction of ΔGMST by [9] projected to 5° × 5° resolution. The blue line in (d) is the DA-based reconstruction of ΔGMST by [25].
Fig 8.
Effect of DA on ST fields in Exp_GLAC1D and Exp_PaleoMist.
ΔST anomaly (DA minus Prior) in LGM, BA, and YD. (a), (b), and (c) show anomaly for Exp_GLAC1D and (d), (e), and (f) for Exp_PaleoMist. The green dots indicate the observation locations.
Fig 9.
Comparison of ST anomalies in Exp_GLAC1D before and after DA.
ΔST anomalies field for different time intervals in Exp_GLAC1D for before DA’s implementation (a), (b), and (c) and after DA (d), (e), and (f).
Fig 10.
Comparison of ST anomalies in Exp_PaleoMist before and after DA.
ΔST anomalies field for different time intervals in Exp_Paleomist for before DA’s implementation (a), (b), and (c) and after DA (d), (e), and (f).