Contrail Modeling of ECLIF2/ND‑MAX flights: Effects of nvPM Particle Numbers and Fuel Sulfur Content

Abstract

The formation of contrail ice particles under the conditions observed during the ECLIF2/ND‑MAX flight campaign was simulated to understand two specific aspects of the contrail measurements. In both the experimental results and the simulations, fewer ice particles formed than were present in the soot (non-volatile Particulate Matter: nvPM) emissions' full distribution. This is due to the larger particles being more effective in capturing water vapor and growing, even though all the particles are active ice nuclei. These results suggest that, under the contrail forming conditions of ECLIF2/ND‑MAX, 85 % or less of the activated nvPM particles can grow to contrail ice particles.The lowest nvPM concentration point (SAF2) was also the lowest Fuel Sulfur Content (FSC) point. This point seems to deviate from the line defined by the other points and the deviation can be simulated by assuming that only 60 % of the nvPM particles are activated. Due to uncertainties in the data and simulation, this observation is far from conclusive, but strongly suggests that the low FSC of the SAF2 case may be starting to indicate a lowering of the activation of the emitted nvPM for contrail formation.These results suggest that further field campaigns would be valuable to measure the effect of FSC on contrail formation when the FSC is significantly below 10 ppmm and that careful experiments with FSC of below 0.1 ppmm, and preferably below 0.05 ppmm, would be needed to fully explore the role FSC has in activating the nvPM particles for contrail formation.

Keywords

• contrail
• fuel sulfur content
• nvpm
• particle emissions