Fig. 4: The response of the simulated North Pacific westerlies to orbital forcing, Greenhouse gases (GHG) concentrations, and Northern Hemisphere (NH) ice sheets.
a Precession (red curve) and obliquity (black curve)60. b Northern Hemisphere (NH) ice volume anomaly as compared to pre-industrial (PI)64. c Annual mean westerlies at 500 hPa over the North Pacific (35°N-55°N, 120°E-240°E); A 1000-year running mean was applied. d Annual mean zonal wind stress over the North Pacific (35°N-55°N, 120°E-240°E); A 1000-year running mean was applied. e Difference of the 500-hPa annual mean zonal wind between Pmin (127 ka) and Pmax (97 ka) from the Orb experiment over the North Pacific. f Difference of the 500 hPa annual mean zonal wind at 91 ka between the OrbGHGICE and OrbGHG experiments. g 500 hPa annual mean zonal wind over the North Pacific for the selected cases in (e, f). The vertical dashed lines in (g) represent the position of the maximum zonal wind. Orb: experiment considering orbital parameters; OrbGHG: experiment considering orbital parameters and greenhouse gases; OrbGHGICE: experiment considering orbital parameters, greenhouse gases and Northern Hemisphere ice sheets. Source data are provided as a Source Data file.
