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Estimating US background ozone levels using data fusion
Citation:
Skipper, T., Y. Hu, M. Odman, B. Henderson, C. Hogrefe, R. Mathur, AND A. Russell. Estimating US background ozone levels using data fusion. CMAS Conference, NA (Virtual Conference), NC, October 26 - 30, 2020.
Impact/Purpose:
Accurately quantifying background ozone is important for many air quality management applications. Often, background ozone estimates are based solely on chemical transport models and are thus uncertain due to potential errors in model process descriptions and inputs. The research presented here develops and applies a method to combine model-based estimates of background ozone with observations to account for model biases and increase confidence is estimated background concentrations.
Description:
US background (US-B) ozone is the ozone that would be observed in the absence of US anthropogenic emissions. US-B ozone originates from noncontrollable sources (e.g., wildfires, stratosphere-troposphere exchange, non-domestic pollution) and can vary significantly by region, elevation, and season. Typically, US-B ozone is quantified using a chemical transport model (CTM), though results are uncertain due to potential errors in model process descriptions and inputs. There are also significant differences in various model estimates of US-B ozone. A method to fuse observed ozone with US-B ozone simulated by a regional CTM (CMAQ) has been developed. We apportion the model bias as a function of space and time to US-B and US anthropogenic (US-A) ozone. Trends in ozone bias are explored across different simulation years and varying model scales. The estimated bias differs by season and location, by model resolution, and by ozone origin (US-B vs. US-A). Exploration of these findings can help illuminate the timing and location of biases within the model and inform the planning of more targeted research to investigate specific causes of bias. With the application of our data fusion bias adjustment method, we estimate a significant improvement in the agreement of adjusted US-B ozone.
