CCN from boundary layer nucleation
Following on from our global simulation of boundary layer nucleation we have now estimated the impact on global cloud condensation nuclei.
We estimate that particle formation increases springtime boundary layer global mean CCN (0.2% supersaturation) concentrations by 3–20% and CCN (1%) by 5–50%. The model predicts localized short-term enhancements in CCN of a factor of 3–4, which agree well with observed enhancements (e.g., Lihavainen et al., 2003).
Model sensitivity tests show where further work is needed to constrain the magnitude of this source of CCN. A four-order-of-magnitude change in nucleation rate coefficient (within the range of analysed observations) results in a factor of 5–10 change in the predicted enhancement in CCN. We also explored the uncertainty due to poorly constrained SOA. Varying the SOA yield from monoterpenes by a factor of 5 leads to up to a factor of 3 change in the predicted
enhancement to CCN from particle formation.
Dominick V. Spracklen, Kenneth S. Carslaw, Markku Kulmala, Veli-Matti Kerminen, Sanna-Liisa Sihto, Ilona Riipinen, Joonas Merikanto, Graham W. Mann, Martyn P. Chipperfield, Alfred Wiedensohler, Wolfram Birmili, and Heikki Lihavainen, Contribution of particle formation to global cloud condensation nuclei concentrations, GEOPHYSICAL RESEARCH LETTERS, 35, L06808, doi:10.1029/2007GL033038, 2008. Read it here