Airborne observation of CO₂ mixing ratio in the Arctic troposphere and lower stratosphere

Tropospheric and lower stratospheric CO₂ mixing ratios were measured onboard an aircraft in the Arctic Airborne Measurement Program 1998. Steep vertical gradients in CO₂ mixing ratio were observed in the lower stratosphere. Small gradients were seen in the troposphere, reflecting weak sources and sinks for CO₂ in winter. A significant increase in CO₂ mixing ratio was found during level flight in the lower stratosphere. Back trajectory analysis indicated that rapid upward transport brought high CO₂ to the observation area. Spatial variations of CO₂ mixing ratio were highly correlated with O₃ mixing ratio. It is suggested that CO₂ distribution was produced mainly by air transport and mixing.