In this study, a size-resolved BC particle number emission inventory (details included as Supplementary Data 1) was developed for the global civil aviation based on the recent measurements. The development of the BC number emission inventory with size distribution information for global aviation is still in its infancy. Several recent attempts to estimate BC number emissions from the mass inventories indicated that the geometric mean diameter (GMD) and the geometric standard deviation (GSD) of the emitted particles were the key parameters 36, 37, 38. As more and more information becomes available for the aviation emitted BC (e.g., mass, number, and size distribution), opportunities arise for the development of a size-resolved aircraft exhaust BC number emission inventory. Many new standard (ARP6320) 32 compliant measurement campaigns have been conducted 33, e.g., Aviation-Particle Regulatory Instrumentation Demonstration Experiment (A-PRIDE) 34, 35. In order to standardize the aircraft exhaust BC measurements, Aerospace Information Reports 31 and Aerospace Recommended Practice (ARP) 32 have been issued by the Society of Automotive Engineers E-31 Particulate Matter Committee. Recently, ICAO has dedicated strong efforts to restricting particle mass and number emissions from aircraft engines and developing related regulations. As the only currently available BC number inventory, AERO2k estimated the number-based emission using simplified general characteristic of particle number emission from different engines. The emergence of these methods led to the developments of BC mass emission inventories, e.g., AERO2k 29, AEIC 26, and AEDT 30. Many studies tried to correlate the BC mass emission with the current regulatory metric Smoke Number (SN), including the SN dependent First Order Approximation (FOA1.0 to FOA3.0) methods 24, 25, the semi-empirical SN independent Formation OXidation methods FOX 26 and imFOX 27, and the scaling methods for the cruise emissions 28. Due to the paucity of BC particle emission data in the ICAO (International Civil Aviation Organization) Emission Databank (EDB) 19, majority of the currently commonly utilized global aviation emission inventories 20, 21, 22, 23 only contain gaseous emissions including unburnt hydrocarbons (HC), carbon monoxide (CO) and oxides of nitrogen (NO x). However, the BC particle number emission is not available in most of the existing inventories. The radiative forcing from indirect effects of the aviation-induced cloudiness still remains highly uncertain 15, 16, 17.Īviation emission inventory is the crucial data for an appropriate assessment of these impacts 18. It is shown that the formation of the contrail and the contrail cirrus is dependent on the BC number emission 12, 13, hence the number and the size distribution of aviation emitted particles are required to investigate such climate effects 14. The aviation emissions mainly occur in the upper troposphere and lowermost stratosphere where the high-altitude clouds influence the global climate by trapping outgoing long-wave radiation and reflecting solar short-wave radiation 11. The emitted black carbon (BC) particles, which are agglomerates of nearly spherical primary particles mainly composed of graphene lamellae 7, absorb sunlight and may also increase the cirrus cloudiness 8, 9 and modify the optical thickness of already-existing cirrus 10. Toxicological studies showed that there is strong evidence that the particle size, shape, surface and surface properties affect the particles’ toxicity 5, 6. On the ground, the ultrafine particles (<100 nm) from aircrafts significantly increase the particle number concentrations near airports 3, 4. The potential impacts of aviation emissions on public health, environment and climate have attracted more and more attentions 2. The inventory provides new data for assessing the aviation impacts.Īir traffic is estimated to increase more than twofold (in revenue passenger kilometers) in the next 20 years 1. The variabilities of GMDs and GSDs for all flights are about 4.8 and 0.08 nm, respectively. The global aviation emitted BC particles follow a lognormal distribution with a geometric mean diameter (GMD) of 31.99 ± 0.8 nm and a geometric standard deviation (GSD) of 1.85 ± 0.016. The BC particle number emission is approximately (10.9 ± 2.1) × 10 25 per year with an average emission index of (6.06 ± 1.18) × 10 14 per kg of burned fuel, which is about 1.3% of the total ground anthropogenic emissions, and 3.6% of the road transport emission. Here, a size-resolved BC particle number emission inventory was developed for the global civil aviation. The particle number and size distribution are crucial metrics for toxicological analysis and aerosol-cloud interactions. With the rapidly growing global air traffic, the impacts of the black carbon (BC) in the aviation exhaust on climate, environment and public health are likely rising.
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