Table 3. Summary of the Peak-To-Peak Amplitude in ppb, Month of Maximum, and Month of Minimum in the Seasonal Cycles Shown in Figure 1d and Figures 2a-2f

Station	Amplitude	Maximum Month	Minimum Month
Alert	1.15	March	Sep
Barrow	1.06	Jan	Sep
Mace Head	0.57	March	Aug
Cape Kumukahi	0.50	Feb	June
Cape Matatula	0.55	Jan	June
Cape Grim	0.42	Dec	May
South Pole	0.29	Nov	April