Simulated Two-Stage Recovery of Atlantic Meridional Overturning Circulation During the Last Deglaciation - Abrupt Climate Change: Mechanisms, Patterns, and Impacts - page 78

layer depths [Renold et al., 2009] or area mean vertical
velocity [Vellinga and Wood, 2002], this method is one alter-
native way to precisely quantify the NADW formation vol-
ume and to detect variation of the regional volume of NADW
formation in its multiple origins.
A two-stage feature of AMOC recovery is revealed in this
regional analysis of NADW formation during the AMOC
recovery period (BA onset), based on the asynchronous
reinitiation of NADW in the Labrador Sea and GIN seas
(Figure 1). After meltwater discharge in the North Atlantic,

NADW formation in the Labrador Sea and GIN seas is
suppressed to nearly a “ turned off ” state after the H1 event,
the state in which nearly no NADW was formed. After that,
during the recovery period of the AMOC (starting from
14.67 ka), NADW formation first reinitiates in the Labrador
Sea, de ned here as stage 1 of AMOC recovery (from pre-

BA to REC), and subsequently reinitiates in the GIN seas,
which constitutes stage 2 (from REC to BA).
During stage 1, once the meltwater forcing in the North
Atlantic is suddenly halted, NADW formation in the Labrador

Figure 3. Change in (a and b) annual mean sea ice concentration (AICE), (c and d) surface heat flux (SHF), and (e and f )

maximum mixed layer depth (XMXL) during (left) stage 1 and (right) stage 2. SHF is downward; negative value means
oceanic heat loss.