Synoptic and climatological controls of particulate matter pollution in a Southern Hemisphere coastal city

Abstract

A complex interaction of local meteorology and source characteristics regularly leads to nocturnal smog events during winter in Christchurch, New Zealand. The main focus of this article is on improving understanding of the relationship between atmospheric processes operating at a range of scales that leads to poor air quality in such urban environments. This research therefore aims to provide a quantitative analysis of atmospheric influences on particulate matter pollution in Christchurch across a wide range of spatial and temporal scales, from local to hemispheric and daily to interannual. The probability of exceeding the National Environmental Standard for PM 10 for a range of local atmospheric conditions is calculated using the classification and regression trees technique, and links between these probabilities, local meteorology and synoptic weather situations are established. The effect of the transition between synoptic types on local air quality is also examined, and the progression of anticyclones across the country is identified to be the dominant synoptic control mechanism. It is shown that variation in latitudinal location of the path of anticyclones over New Zealand influences the predicted exceedance probability. On interdecadal and hemispheric scales, it is found that the particular combination of local and synoptic atmospheric conditions that favours air quality degradation shows a reoccurring pattern of frequency maxima (and minima) with a periodicity of approximately 14-16 years. In relation to the identified interdecadal variability of synoptic circulation, a close relationship to Southern Hemisphere pressure anomalies at high latitudes is revealed. The results of this research show that, in addition to daily weather variation, air quality in Christchurch is influenced by longerterm climatic processes that operate on interannual hemispheric scales with the implication that, in general, air pollution potential can also be expected to vary on a periodic interdecadal time scale.

Air Quality and Climate Connections

“…Mid-latitude cyclones migrate under the jet stream, suggesting that jet location may affect air quality, as has been found for decadal time scales (Barnes and Fiore, 2013). A few studies emphasize the role of synoptic meteorology in driving observed daily variations in PM 2.5, developing predictors that encapsulate changes in numerous meteorological variables (Appelhans et al, 2012;Tai et al, 2012aTai et al, , 2012b. These statistical predictors are based upon the most frequent meteorological patterns, which resemble the stagnation-cold front progression just described (Tai et al, 2012a).…”

The Influence of Weather Systems in Controlling Mass Balance in the Southern Alps of New Zealand

“…One approach that can be used to bridge the gap between atmospheric scales is to use synoptic weather types (e.g., Isaksen et al, 2016;Käsmacher & Schneider, 2011;Matthews et al, 2015;Romolo et al, 2006;Yarnal, 1984), with the Kidson (2000) weather types (Renwick, 2011) providing a time series of 12-hourly synoptic conditions that is suitable for a range of applications in the New Zealand region. Kidson weather types have been used to account for variations in the accumulation and redistribution of snow in mountainous terrain (Purdie et al, 2011;Webster et al, 2015), hydrological flows (McKerchar et al, 2010), and in paleoclimate research (Lorrey et al, 2007(Lorrey et al, , 2014, as well as in a range of other applications outside the snow and glacier hydrology space (e.g., Appelhans et al, 2013;Beentjes & Renwick, 2001;Gibson & Cullen, 2015;Sturman & Quénol, 2013).…”

Projected changes in synoptic weather patterns over New Zealand examined through self‐organizing maps

“…Across New Zealand, weather typing procedures have been extensively used to understand the sensitivity of local climate variability (and associated impacts) to the larger-scale circulation better. The 'Kidson weather types' (KTs) (Kidson, 2000;Renwick, 2011) have been most commonly applied, with applications including particulate matter air pollution (Appelhans et al, 2013), quantitative fisheries (Beentjes and Renwick, 2001), viticulture (Sturman and Quénol, 2013), renewable energy assessments (Gibson and Cullen, 2015), snow accumulation and distribution in mountainous terrain (Purdie et al, 2011;Webster et al, 2015), hydrological flows (McKerchar et al, 2010) and paleoclimate research (Lorrey et al, 2007(Lorrey et al, , 2014. Many of these studies have been motivated by the need to understand the sensitivity of the particular application to weather/climate variability as an introductory step to understanding climate change impacts (e.g.…”

“…Many of these studies have been motivated by the need to understand the sensitivity of the particular application to weather/climate variability as an introductory step to understanding climate change impacts (e.g. McKerchar et al, 2010;Appelhans et al, 2013;Sturman and Quénol, 2013).…”