In situ measurement of CO, CH4, and CO2 combined with selected meteorological measueremts at the University of Wollongong, Australia

Wollongong, Australia is an urban site at the intersection of anthropogenic, biomass burning, biogenic and marine sources of atmospheric trace gases. The location offers a valuable opportunity to study drivers of atmospheric composition in the Southern Hemisphere. Here, a record of surface carbon monoxide (CO), methane (CH4) and carbon dioxide (CO2) was measured with an in situ Fourier transform infrared trace gas analyser between April 2011 and August 2014. Clean air was found to arrive at Wollongong in approximately 10% of air masses. Biomass burning influence was evident in the average annual cycle of clean air CO during austral spring. A significant negative short-term trend was found in clean air CO (-1.5 nmol/mol/a), driven by a reduction in northern Australian biomass burning. Significant short-term positive trends in clean air CH4 (5.4 nmol/mol/a) and CO2 (1.9 µmol/mol/a) were consistent with the long-term global average trends. Polluted Wollongong air was investigated using wind-direction/wind-speed clustering, which revealed major influence from local urban and industrial sources from the south. High values of CH4, with anthropogenic DCH4/DCO2 enhancement ratio signatures, originated from the northwest, in the direction of local coal mining. A pollution climatology was developed for the region using back trajectory analysis and DO3/DCO enhancement ratios. Ozone production environments in austral spring and summer were associated with anticyclonic meteorology on the east coast of Australia, while ozone depletion environments in autumn and winter were associated with continental transport, or fast moving trajectories from southern latitudes. This implies the need to consider meteorological conditions when developing policies for controlling air quality.澳大利亚伍伦贡（Wollongong）是一处受人为活动、生物质燃烧、生物源与海洋源大气痕量气体共同影响的城市观测站点，该站点为研究南半球大气组成的驱动机制提供了宝贵的研究契机。本数据集收录了2011年4月至2014年8月期间，采用原位傅里叶变换红外痕量气体分析仪（in situ Fourier transform infrared trace gas analyser）测得的地表一氧化碳（carbon monoxide, CO）、甲烷（methane, CH4）与二氧化碳（carbon dioxide, CO2）浓度序列。 观测结果显示，约10%的大气气团属于清洁气团。在南半球春季，清洁大气中一氧化碳浓度的年平均周期特征体现出显著的生物质燃烧影响信号。研究发现清洁大气中的一氧化碳存在显著短期负向趋势（-1.5纳摩尔每摩尔每年），该趋势由澳大利亚北部生物质燃烧活动的减少所驱动。清洁大气中的甲烷（5.4纳摩尔每摩尔每年）与二氧化碳（1.9微摩尔每摩尔每年）则呈现出显著短期正向趋势，这与全球长期平均变化趋势保持一致。 研究团队通过风向/风速聚类分析对伍伦贡的污染大气开展溯源，结果表明其主要受南部本地城市与工业排放源的影响。甲烷浓度偏高且具备人为源DCH4/DCO2增强比特征的气团，主要源自西北方向的本地煤矿开采区域。研究结合后向轨迹分析（back trajectory analysis）与DO3/DCO增强比，构建了该区域的污染气候学特征。 南半球春季与夏季的臭氧生成环境，与澳大利亚东海岸的反气旋气象（anticyclonic meteorology）条件相关联；而秋季与冬季的臭氧消耗环境，则与大陆气团输送或来自南纬区域的快速移动气团轨迹相关。该研究结果表明，在制定空气质量管控政策时，需充分考虑气象条件的影响。