科研之友
微信
新浪微博
Facebook
分享链接
摘要
Aircraft emissions of black carbon (BC) contribute to anthropogenic climate forcing and degrade air quality. The smoke number (SN) is the current regulatory measure of aircraft particulate matter emissions and quantifies exhaust plume visibility. Several correlations between SN and the exhaust mass concentration of BC (C-BC) have been developed, based on measurements relevant to older aircraft engines. These form the basis of the current standard method used to estimate aircraft BC emissions (First Order Approximation version 3 [FOA3]) for the purposes of environmental impact analyses. In this study, BC with a geometric mean diameter (GMD) of 20, 30, and 60nm and filter diameters of 19 and 35mm are used to investigate the effect of particle size and sampling variability on SN measurements. For BC with 20 and 30nm GMD, corresponding to BC emitted by modern aircraft engines, a smaller SN results from a given C-BC than is the case for BC with 60nm GMD, which is more typical of older engines. An updated correlation between C-BC and SN that accounts for typical size of BC emitted by modern aircraft is proposed. An uncertainty of 25% accounts for variation in GMD in the range 20-30nm and for the range of filter diameters. The SN-C-BC correlation currently used in FOA3 underestimates by a factor of 2.5-3 for SN 15, implying that current estimates of aircraft BC emissions derived from SN are underestimated by the same factor.
- 出版日期2013-11-1
