The aerosol dynamics of H2O–H2SO4–HNO3 mixtures in aircraft wakes. A modeling study

Abstract

The aerosol dynamics of H₂O–H₂SO₄–HNO₃ mixtures formed (i) by homogeneous nucleation and (ii) by adsorption on emitted soot particles in the jet regime of a B 747 airliner have been investigated by modeling studies. Emission indices of 0.05 g kg(fuel)^-1 and 1.0 g kg(fuel)^-1 for soot and SO₂, respectively, were chosen. In addition, the influence of both chemiions (EI(HSO₄^-)=2.9×10^-5 g kg(fuel)^-1) and different initial S(VI)/(S(VI)+S(IV)) ratios (0.8–10%) have been taken into consideration. As opposed to previous studies which were restricted to the binary H₂O–H₂SO₄ system, the presence of HNO₃ in the plume has been included. Both, composition and size spectra of the H₂O–H₂SO₄–HNO₃ clusters have been investigated. It is found that, caused by the presence of HNO₃ in liquid aerosols, the reduced vapour pressure of H₂O leads to enhanced water uptake. In analogy to H₂O–H₂SO₄–HNO₃-coated soot particles and especially for high fuel sulfur contents, a fraction of these aerosols can then also freeze and hence contribute to visible contrails.