Evaluating 14CO as a tracer for the long-term trend in tropospheric OH

The hydroxyl radical (OH) is one of the most important molecules in the atmosphere due to its reaction with atmospheric pollutants and its potential to affect future climate. However, OH concentrations are challenging to measure, so that other atmospheric gases must be used to infer OH trends over time. Here, we show the results of atmospheric model simulations using one of these gases, $^{14}$CO. Our results show that $^{14}$CO and OH are strongly correlated, implying that $^{14}$CO can provide the needed information on OH trends. Our model could be used with measurements to determine long-term trends in OH, vital to understanding the future climate and air quality.