Extended Data Fig. 4: Schematic of the key physical processes driving the North Pacific mid-latitude MCB teleconnection under 2010 conditions.

The schematic diagram begins with (0) the marine cloud brightening perturbation in the mid-latitude region causing a negative temperature anomaly within the seeding region. Then (1) mean wind in the North Pacific High advects the cool temperatures southward along the coast of North America, which develops (2) a high sea-level pressure anomaly. Increased SLP in this region (3) strengthens the trade winds which amplifies cooling throughout the subtropical Pacific basin through evaporative cooling. Perturbed trade winds alter equatorial convective processes, strengthening the Northern Hemisphere Hadley cell and shifting the Intertropical Convergence Zone southward (not shown). (4) Increased subtropical subsidence, further strengthens the high SLP anomaly and increases lower troposphere stability which is conducive toward surface cooling and low cloud formation. The shading shows the 95% confidence mean air temperature anomalies at 2 m averaged over the 30-year analysis period for the 2010 mid-latitude MCB case. Arrows not drawn to scale.