Surface Ozone-Meteorology Relationships: Spatial Variations and the Role of the Jet Stream

We investigate the relationships among summertime ozone (O-3), temperature, and humidity on daily timescales across the Northern Hemisphere using observations and model simulations. Temperature and humidity are significantly positively correlated with O-3 across continental regions in the midlatitudes (similar to 35-60 degrees N). Over the oceans, the relationships are consistently negative. For continental regions outside the midlatitudes, the O-3-meteorology correlations are mixed in strength and sign but generally weak. Over some high latitude, low latitude, and marine regions, temperature and humidity are significantly anticorrelated with O-3. Daily variations in transport patterns linked to the position and meridional movement of the jet stream drive the relationships among O-3, temperature, and humidity. Within the latitudinal range of the jet, there is an increase (decrease) in O-3, temperature, and humidity over land with poleward (equatorward) movement of the jet, while over the oceans poleward movement of the jet results in decreases of these fields. Beyond the latitudes where the jet traverses, the meridional movement of the jet stream has variable or negligible effects on surface-level O-3, temperature, and humidity. The O-3-meteorology relationships are largely the product of the jet-induced changes in the surface-level meridional flow acting on the background meridional O-3 gradient. Our results underscore the importance of considering the role of the jet stream and surface-level flow for the O-3-meteorology relationships, especially in light of expected changes to these features under climate change.