Chemistry-turbulence interactions impact ozone in urban areas

The fraction of ozone near the surface in urban areas tends to be overestimated in atmospheric models. New observations at the IAO reveal a possible explanation, which is presented in the following paper

Short summary: Long-term eddy covariance measurements of O3, NO and NO2, combined with models and remote sensing observations over an urban area,  allowed disentangling important physical and chemical processes. When generalized our findings suggest that the depositional ozone flux near the surface in urban environments is negligible compared to the flux caused by chemical conversion of ozone. This leads to an underestimation of the Leighton ratio, and is a key process for modulating urban NO2 mixing ratios. 

 Chemical ozone fluxes measured at the IAO
 Chemical ozone fluxes measured at the IAO during different seasons (Karl et al., Sci. Adv. 2023)
IAO at night
IAO at night
IAO Measurement Tower
IAO Measurement Tower

Half a decade of Trace Gas Flux Observations

Entering our 6th year of #urban #CO2 flux observations.

We will start posting flux data on

So far we have collected 5 years of CO2 (H2O), heat, momentum and NOx fluxes, 3+ years of O3 fluxes, 2+ years of CH4 fluxes and 6+ years of intermittent VOC fluxes.

some recent papers:

FWF Project on Urban Methane Sources

Methane (CH4)  is an important greenhouse gas in the atmosphere. The methane emission budget has a sizeable anthropogenic contribution, which makes methane the most important non-CO2 greenhouse gas released from anthropogenic activities. Methane emissions play a key role in hydroxyl consumption, thus contributing to complex interactions central to atmospheric chemistry and climate. Reduction of CH4 emissions can provide quick and cost effective cuts in global warming, but requires a sound understanding of the different anthropogenic sources. Although the total global CH4 budget is relatively well understood, the contributions of individual sources to CH4 emissions are poorly constrained. Anthropogenic methane emissions in Austria are largely based on Tier 1 bottom-up scaling and urban emission sources are subject to significant  uncertainty.  In collaboration with the JRC Ispra, we propose a holistic top-down approach to constrain methane emissions on the local to urban scale based on eddy flux observations of methane along with a suite of additional chemical markers.

IAO Flux Tower in Innsbruck