Impact of temperature dependence on the possible contribution of organics to new particle formation in the atmosphere

Yu, Fangqun; Luo, Gan; Nadykto, Alexey B.; Herb, Jason

Secondary particles formed via new particle formation (NPF) dominate cloud condensation nuclei (CCN) abundance in most parts of the troposphere and are important for aerosol indirect radiative forcing (IRF). Laboratory measurements have shown that certain organic compounds can significantly enhance the binary nucleation of sulfuric acid and H 2O. According to our recent study comparing particle size distributions measured in nine forest areas in North America with those predicted by a global size-resolved aerosol model, current H 2SO 4–organics nucleation parameterizations appear to significantly overpredict NPF and particle number concentrations in summer. The lack of temperature dependence in the current H 2SO 4–organics nucleation parameterization has been suggested to be a possible reason for the observed overprediction. In this work, H 2SO 4–organics clustering thermodynamics from quantum chemical studies has been employed to develop a scheme to incorporate temperature dependence into H 2SO 4–organics nucleation parameterization. We show that temperature has a strong impact on H 2SO 4–organics nucleation rates and may reduce the nucleation rate by  ∼  1 order of magnitude per 10 K of temperature increase. The particle number concentrations in summer over North America based on the revised scheme is a factor of more than 2 lower, which is in much better agreement with the observations. With the temperature-dependent H 2SO 4–organics nucleation parameterization, the summer CCN concentrations in the lower troposphere in the Northern Hemisphere are about 10–30 % lower compared to the temperature-independent parameterization. This study highlights the importance of the temperature effect and its impacts on NPF in the global modeling of aerosol number abundance.

Zitieren

Zitierform:

Yu, Fangqun / Luo, Gan / Nadykto, Alexey B. / et al: Impact of temperature dependence on the possible contribution of organics to new particle formation in the atmosphere. 2017. Copernicus Publications.

Zugriffsstatistik

Gesamt:
Volltextzugriffe:
Metadatenansicht:
12 Monate:
Volltextzugriffe:
Metadatenansicht:

Grafik öffnen

Rechte

Rechteinhaber: Fangqun Yu et al.

Nutzung und Vervielfältigung:

Export