Assessment of fossil fuel carbon dioxide and other anthropogenic trace gas emissions from airborne measurements over Sacramento, California in spring 2009
Assessment of fossil fuel carbon dioxide and other anthropogenic trace gas emissions from airborne measurements over Sacramento, California in spring 2009
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DOI：
10.5194/acp-11-705-2011
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发表时间：
2011-01
影响因子：
6.3
通讯作者：
J. Turnbull;A. Karion;M. Fischer;I. Faloona;T. Guilderson;S. Lehman;B. Miller;John B. Miller;S. Montzka;T. Sherwood;S. Saripalli;C. Sweeney;P. Tans
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文献类型：
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作者：
J. Turnbull;A. Karion;M. Fischer;I. Faloona;T. Guilderson;S. Lehman;B. Miller;John B. Miller;S. Montzka;T. Sherwood;S. Saripalli;C. Sweeney;P. Tans
抽象的。大气样品中化石燃料二氧化碳(CO2 Ff)的直接定量可以用来研究几个碳循环和空气质量问题。2009年春季，我们在美国加利福尼亚州萨克拉门托的边界层和自由对流层进行了两次飞机飞越和顺风飞行，现场采集了CO2、CO和CH4的测量数据和烧瓶样本。对烧瓶样品进行了Δ-14CO2和CO2的分析，以确定最近添加的CO2 ff摩尔分数。在相同的样本中测量了一套温室气体和其他痕量气体，包括碳氢化合物和卤代烃。观察到与城市排放有关的大量痕量气体与CO2 ff之间存在很强的相关性。根据这些相关性，我们估计了CO2 ff和这些物种之间的排放比率，并与自下而上的清单估计值进行了比较。加州空气资源委员会CEPAM数据库最近对一氧化碳(CO)和苯的县级库存估计与我们测量的排放比率非常一致，而较早的排放清单似乎将这些气体的排放量高估了两倍。对于大多数其他痕量物种，我们测量的排放比率与现有排放清单得出的排放比率之间有很大差异(200-500%)。对于第一次飞行，我们将现场测量的CO与测量的CO：CO2 ff排放比14±2 ppbCO/ppmCO2相结合，得到整个飞行过程中CO2 ff摩尔分数的估计值，并根据总CO2和化石CO2的差值估计生物圈CO2混合比(CO2 Bio)。由此产生的二氧化碳生物量变化很大，从城市羽流中的高达8±2ppm到周围边界层空气中的−6±1ppm。最后，我们使用现场估计的CO2 ff摩尔分数来推断萨克拉门托地区化石燃料CO2的总排放量，使用质量平衡方法。由于风速和边界层高度的不确定性，由此产生的排放量不确定到两倍以内。然而，首次尝试从大气放射性碳测量中估计城市尺度的CO2 ff表明，CO2 ff可用于验证和改善许多鲜为人知的人为物种的排放清单，分离生物圈CO2，并表明如果运输的不确定性减少，则有可能限制CO2 ff的排放。
Abstract. Direct quantification of fossil fuel CO 2 (CO 2 ff) in atmospheric samples can be used to examine several carbon cycle and air quality questions. We collected in situ CO 2 , CO, and CH 4 measurements and flask samples in the boundary layer and free troposphere over Sacramento, California, USA, during two aircraft flights over and downwind of this urban area during spring of 2009. The flask samples were analyzed for Δ 14 CO 2 and CO 2 to determine the recently added CO 2 ff mole fraction. A suite of greenhouse and other trace gases, including hydrocarbons and halocarbons, were measured in the same samples. Strong correlations were observed between CO 2 ff and numerous trace gases associated with urban emissions. From these correlations we estimate emission ratios between CO 2 ff and these species, and compare these with bottom-up inventory-derived estimates. Recent county level inventory estimates for carbon monoxide (CO) and benzene from the California Air Resources Board CEPAM database are in good agreement with our measured emission ratios, whereas older emissions inventories appear to overestimate emissions of these gases by a factor of two. For most other trace species, there are substantial differences (200–500%) between our measured emission ratios and those derived from available emission inventories. For the first flight, we combine in situ CO measurements with the measured CO:CO 2 ff emission ratio of 14 ± 2 ppbCO/ppmCO 2 to derive an estimate of CO 2 ff mole fraction throughout this flight, and also estimate the biospheric CO 2 mixing ratio (CO 2 bio) from the difference of total and fossil CO 2 . The resulting CO 2 bio varies dramatically from up to 8 ± 2 ppm in the urban plume to −6 ± 1 ppm in the surrounding boundary layer air. Finally, we use the in situ estimates of CO 2 ff mole fraction to infer total fossil fuel CO 2 emissions from the Sacramento region, using a mass balance approach. The resulting emissions are uncertain to within a factor of two due to uncertainties in wind speed and boundary layer height. Nevertheless, this first attempt to estimate urban-scale CO 2 ff from atmospheric radiocarbon measurements shows that CO 2 ff can be used to verify and improve emission inventories for many poorly known anthropogenic species, separate biospheric CO 2 , and indicates the potential to constrain CO 2 ff emissions if transport uncertainties are reduced.