A synoptic climatology of tropospheric ozone episodes in Sydney, Australia

Abstract

Concentrations of tropospheric ozone often exceed Australian air quality goals in Sydney during summer. However, features in the occurrence of ozone in Sydney are yet to be fully explained. Meteorological conditions associated with ozone episodes in Sydney are caused by complex interactions between synoptic and meso-scale processes. This paper discusses the meteorological influences behind ozone pollution episodes in Sydney.A synoptic climatology of ozone episodes in Sydney was generated using multivariate statistical techniques, including principal component analysis (PCA) and a two-stage cluster analysis, to classify days into meteorologically homogeneous synoptic categories. Surface and upper air meteorological data for warm months (Oct-Mar) over a 10-year period were used as input into the statistical analyses. Eleven synoptic categories were identified in Sydney during the warm season and ozone concentrations associated with each of the synoptic categories were investigated. One synoptic category was found to be associated almost exclusively with high pollution concentrations. High ozone concentrations were found to be associated with a high-pressure system located in the middle to eastern Tasman Sea producing light northwesterly gradient winds, an afternoon sea breeze, high afternoon temperatures, a shallow mixing height at the coast and warming aloft during the day.Over 90% of all days exceeding current air quality goals for ozone in Sydney fell within the synoptic category associated with the highest ozone concentrations. It is envisaged that results from this research will be useful to Australian regulatory bodies from both a forecast point of view and for the siting of future ozone precursor sources in Sydney and surrounding regions.

Assessment of an extended version of the Jenkinson–Collison classification on CMIP5 models over Europe

“…Such classifications have covered almost all of Europe , and there have also been many studies describing synoptic situations over the world: North America (Sheridan 2002;Lee 2015), Australia (Hart et al 2006), New Zealand (Jiang 2010), or Asia (Chen et al 2008). …”

On the use of radon for quantifying the effects of atmospheric stability on urban emissions

“…Hinkley et al, 2008;Gupta et al, 2007;Corbyn, 2005;Duc et al, 2000;Leighton and Spark, 1997;Liu et al, 1996). In summer, however, photochemical pollution events are more common; their severity linked to prevailing winds and cloudiness (Hart et al, 2006;Leslie and Speer, 2004;Azzi and Johnson, 1994;Hawke and Iverach, 1974). Clearer understanding of the processes that lead to haze or smog exceedance events, as well as an ability to quantify their magnitude, is important for assessing po-tential health impacts on residents, as well as identifying the need for, and evaluating the efficacy of, emissions mitigation strategies.…”

Particulate Pollution in the Sydney Region: Source Diagnostics and Synoptic Controls

“…In the Sydney region, links have been established between meteorology and overall air quality (e.g., Leighton and Spark, 1997;Hart et al, 2006;Jiang et al, 2013a). High ozone days are associated with high-pressure systems centred over the Tasman Sea, a ridge extending northwest across New South Wales and north-easterly sea-breezes.…”