AMOC flow and period vs. mixed layer temperature.
The curves show calculated AMOC volumetric flow (Ψ) and oscillation period (T-) for mixed layer temperatures at the south end of the flow path (TML) ranging from 26 to 32°C with mixed layer depths (ZML) of 60, 80, and 100 m (blue, red and black lines). The curves relating flow to mixed layer temperature show the values for density gradients (∇ρ) calculated from the equations. The depth to the bottom of the thermocline (ZH) is set at 350 m. The length of the flow path (LF) is set at 4000 km, roughly the annual average distance between the 28°C SST isotherm and the 10°C SST isotherm. The width of the flow path (WF) is set to the same value, consistent with Fig. 3. The shaded areas on the figures indicate the approximate range of observed values for AMOC flow (12–22 Sv) and oscillation period (60–80 years). Values for flow and oscillation period cannot be calculated independently; fixing one necessarily fixes the other.