Gridded global surface ozone metrics for atmospheric chemistry model evaluation

Abstract

Abstract. The concentration of ozone at the Earth's surface is measured at many locations across the globe for the purposes of air quality monitoring and atmospheric chemistry research. We have brought together all publicly available surface ozone observations from online databases from the modern era to build a consistent data set for the evaluation of chemical transport and chemistry-climate (Earth System) models for projects such as the Chemistry-Climate Model Initiative and Aer-Chem-MIP. From a total data set of approximately 6600 sites and 500 million hourly observations from 1971-2015, approximately 2200 sites and 200 million hourly observations pass screening as high-quality sites in regionally representative locations that are appropriate for use in global model evaluation. There is generally good data volume since the start of air quality monitoring networks in 1990 through 2013. Ozone observations are biased heavily toward North America and Europe with sparse coverage over the rest of the globe. This data set is made available for the purposes of model evaluation as a set of gridded metrics intended to describe the distribution of ozone concentrations on monthly and annual timescales. Metrics include the moments of the distribution, percentiles, maximum daily 8-hour average (MDA8), sum of means over 35 ppb (daily maximum 8-h; SOMO35), accumulated ozone exposure above a threshold of 40 ppbv (AOT40), and metrics related to air quality regulatory thresholds. Gridded data sets are stored as netCDF-4 files and are available to download from the British Atmospheric Data Centre (doi:10.5285/08fbe63d-fa6d-4a7a-b952-5932e3ab0452). We provide recommendations to the ozone measurement community regarding improving metadata reporting to simplify ongoing and future efforts in working with ozone data from disparate networks in a consistent manner.

Spectral analysis of atmospheric composition: application to surface ozone model–measurement comparisons

“…4 (Sofen et al, 2016), we find almost all sites show significant peaks at the fundamentals (and most harmonics) of the annual and daily timescales. It is notable that we do not find any sites that show significance of a 7-day cycle (Altshuler et al, 1995;Marr and Harley, 2002;Beirle et al, 2003).…”

Tropospheric Ozone Assessment Report: Assessment of global-scale model performance for global and regional ozone distributions, variability, and trends

“…Model evaluation relies on the availability of high quality observations with high spatial and temporal coverage. Reasonably comprehensive "baseline" (TOARObservations) surface ozone observations over the U.S., Canada, Europe, and Japan augmented with data over numerous polluted sites in these regions have facilitated a thorough evaluation of global chemistry models over those regions (e.g., Fiore et al, 2009;Reidmiller et al, 2009;Schnell et al, 2015;Sofen et al, 2016b). Evaluation elsewhere is limited by poor data availability.…”

“…One issue of representativeness relates to the fact that the atmosphere is not completely sampled (Sofen et al, 2016a(Sofen et al, , 2016bTOAR-Observations), meaning that there are important locations and times where there are no constraints for the model (e.g., a globally sparse distribution of monitoring stations, coarse vertical data from satellites, poor constraints on pre-industrial ozone). Given the incomplete sampling, the primary issue for representativeness where we have observations relates to the fact that the spatial and temporal resolutions of global models are necessarily coarse.…”

Future changes in surface ozone over the Mediterranean basin in the framework of the Chemistry-Aerosol Mediterranean Experiment (ChArMEx)

“…The first part consists of a model assessment based on the REF period, in which we compare the outputs of different models to a set of available surface O 3 observations based on the gridded observations 10 given by Sofen et al (2015). We use several statistical diagnostics to assess the performances of different model outputs.…”

“…Natural emissions, such as CO and VOCs from vegetation and oceans, and NO x from soil and lightning, were determined by each model group. In this study, we use available surface O 3 observations based on the gridded observations given by Sofen et al (2015) in order to evaluate uncertainty related to model simulations. Sofen et al (2015) built a consistent gridded dataset for the evaluation of chemical transport and chemistry-climate models from all publicly available surface O 3 observations from online databases of the modern era: the World Meteorological Organization (WMO) Global Atmospheric …”