Retrieval of black carbon and specific absorption over Kanpur city, northern India during 2001-2003 using AERONET data
Retrieval of black carbon and specific absorption over Kanpur city, northern India during 2001-2003 using AERONET data
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DOI：
10.1016/j.atmosenv.2005.09.053
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发表时间：
2006
影响因子：
5
通讯作者：
S. Dey;S. Tripathi;Ramesh P. Singh;B. Holben
中科院分区：
文献类型：
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作者：
S. Dey;S. Tripathi;Ramesh P. Singh;B. Holben
2001-2003年首次在坎普尔(印度北部恒河盆地的一个工业城市)上空提取了柱状综合气溶胶黑碳浓度[BC]。在水、BC和(NH4)2SO4的混合物中，根据Maxwell-Garnett和Bruggeman混合规则，从BC体积分数和AERONET检索的粒度分布推导出[BC]。此外，根据季节的不同，将有机碳(OC)和粉尘等部分吸收成分添加到Maxwell-Garnett混合物中，以研究它们在提取[BC]中的作用。通过将混合折射率(实数n(λ)和虚数k(λ))与AERONET检索的折射率进行匹配来检索各组分的体积分数。[BC]表现出季节变化，季风后和冬季观测到高值(>；10mgm-2)，季风季观测到低值(<；6mgm-2)。比吸收截面(αa)随[Bc]的增加呈非线性减小，但当有其他吸收组分存在时，减小的幅度变为线性。2001年、2002年和2003年的年平均[BC]和α分别为9.99±1.95、5.52±1.07、7.9±1.53mgm−~2和7.9±1.83和9.67±3.45、12.74±2.92m~2g−~1，与布鲁格曼混合的∼相差15%。[BC]表现出日变化，有上午和下午的峰值和中午的最低值。振幅被抑制，因为它代表总柱，这更多地受到人为活动的影响，而不是边界层动力学。为了准确估计[BC]，当k(0.44μm)与k(1.02μm)的绝对差值大于0.0015时，必须考虑OC。在强沙尘负荷期间，由于粉尘n(λ)引起的[BC]的灵敏度变得很重要。发现[BC]对粉尘k(λ)比粉尘n(λ)更敏感，因为k(∼)每增加10%，[BC]就会使λ增加10-13%。反演的[BC]与现场测量结果吻合较好。因此，我们的检索可以作为一种替代方法来推断BC和OC的全球特异性吸收。
Column-integrated aerosol black carbon (BC) concentration, [BC] has been retrieved over Kanpur (an industrial city in the Gangetic basin, northern India) during 2001–2003 for the first time. [BC] is derived from BC volume fraction and AERONET-retrieved size distribution using Maxwell–Garnett and Bruggeman mixing rules in a mixture of water, BC and (NH4)2SO4. In addition partly absorbing components like organic carbon (OC) and dust are added to the Maxwell–Garnett mixture depending on the season to investigate their role in the retrieval of [BC]. The volume fraction of each component is retrieved by matching the mixture refractive index (real, n(λ) and imaginary, k(λ)) with AERONET-retrieved refractive index. [BC] shows seasonal variations with high values (>10mgm-2) observed during the post-monsoon and winter seasons and low values (<6mgm-2) during the monsoon season. Specific absorption cross-section (αa) decreases non-linearly with the increase in [BC], however, the decrease becomes linear when other absorbing components are present. Yearly averaged [BC] and αaare 9.99±1.95, 5.52±1.07, 7.9±1.53mgm−2and 7.9±1.83 and 9.67±3.45, 12.74±2.92m2g−1for 2001, 2002 and 2003, respectively, using Maxwell–Garnett mixing, which differ by ∼15% from those using Bruggeman mixing. [BC] shows diurnal variation with morning and afternoon peaks and mid-day minimum. The amplitude is subdued as it represents the total column, which is more influenced by anthropogenic activities than by boundary layer dynamics. In order to estimate [BC] accurately, OC has to be considered when the absolute difference between k(0.44μm) and k(1.02μm) becomes higher than 0.0015. The sensitivity of [BC] due to dust n(λ) becomes important during the intense dust loading period. It was found that [BC] is more sensitive to dust k(λ) than dust n(λ), as [BC] increases ∼10–13% for 10% rise in k(λ). Retrieved [BC] shows good agreement with the in situ measurements. Therefore our retrieval can be used as an alternate method to infer BC and OC specific absorption globally.