Fig. 3.

Particle number emission index of detectable volatile particles in non-contrail plumes versus Fuel Sulphur Content (FSC) from various measurements, normalized to plume age 3 s, CNC cut-off 5 nm, and various sulphur conversion fractions ɛ and emission indices of condensable organic matter, EIOM (μg g⁻¹ fuel). The curves emphasizing the trend of observed particle number emission index with increasing FSC are results computed with a model (Kärcher et al., 2000) at the same values of plume age, cut-off, and EI of CIs of 2 × 10¹⁷ kg⁻¹, and different EIOM and ɛ values: 20 μg g⁻¹ fuel and 0.5% for dashed curve, and 30 μg g⁻¹ fuel and 8% for full curve (Schumann et al., 2002; Copyright, 2002; American Geophysical Union. Reproduced by permission of American Geophysical Union).