An inter-comparison of two black carbon aerosol instruments and a semi-continuous elemental carbon instrument in the urban environment
An inter-comparison of two black carbon aerosol instruments and a semi-continuous elemental carbon instrument in the urban environment
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DOI：
10.1080/02786820701222819
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发表时间：
2007-05-01
影响因子：
5.2
通讯作者：
Schauer, James J.
中科院分区：
文献类型：
--
作者：
Snyder, David C.;Schauer, James J.
2005年7月和8月在加利福尼亚州河滨使用两种版本的MAGEE科学气像仪和粒子烟尘吸收光度计(PSAP)获得了气溶胶吸收系数。随后将这些测量结果相互比较，并与日落实验室半连续OCEC分析仪测定的每小时元素碳(EC)质量浓度进行比较。所有四种仪器的测量结果显示高度相关(R2=0.83至0.92)。PSAP和Atheraleter测量的吸光度之间的差异被发现是由各自仪器使用的过滤介质的不同决定的。光学和热学测量的比较表明，吸光碳(LAC)的比衰减截面(sigma(ATN))随一天中的时间变化，最明显的是在工作日。最小Sigma(ATN)值出现在早上高峰时段，此时EC浓度最大，最大值出现在下午晚些时候。这些变化与OC/EC比值和吸收的Angstrom指数的变化相关，这与初级EC颗粒上与二次气溶胶凝结相关的元素碳的混合状态的变化相一致。
Aerosol absorption coefficients were obtained using two versions of the Magee Scientific Aethalometer and a Particle Soot Absorption Photometer (PSAP) in Riverside, California during July and August of 2005. These measurements were subsequently compared to each other and to hourly elemental carbon (EC) mass concentrations as determined by a Sunset Labs semi-continuous OCEC analyzer. Measurements from all four instruments were shown to be highly correlated (R-2 = 0.83 to 0.92). Differences between absorption values measured by the PSAP and the Aethalometer were found to be dominated by differences in the filter media used by the respective instruments. Comparison of optical and thermal measurements revealed that the specific attenuation cross section (sigma(ATN)) of light absorbing carbon (LAC) varied as a function of the time of the day, most notably during weekdays. Minimum sigma(ATN) values were observed during morning rush hour when EC concentrations were at their greatest and maxima were seen in the late afternoon. These variations correlated with changes in the OC/EC ratio and the Angstrom exponent for absorption, which is consistent with changes in the mixing state of elemental carbon associated with secondary aerosol condensation on primary EC particles.